Modulated ignition system

An AC powered ignition system employs a rectangular wave power source and a logic circuit for controlling igniter firing. Such logic circuit intermittently interrupts the flow of DC bias current in active stages of the AC power source and activates an electronic switch to charge the output winding of the AC power source and the primary winding of an ignition transformer by means of a DC source, and then discharge such windings into a capacitor at the same time as the AC power source provides its alternating current output by deactivating such electronic switch. Large transient intermodulated currents and voltages result thereby to provide high energy firing levels to igniters in a fuel burning engine. Provisions are made to include a second capacitor in series with the output and primary windings and/or a second electronic switch that prevent residual charge in the AC power source from appearing as a voltage or current during periods between igniter firing.

INCORPORATION BY REFERENCE 
U.S. Pat. No. 4,122,815, owned by same applicant, is incorporated by 
reference for details of the ignition timing method discussed therein. 
BACKGROUND OF THE INVENTION 
This invention is in the field of ignition systems for fuel burning engines 
and more particularly in such systems wherein the igniters thereof are AC 
powered with superimposed transient modulation. Still more specifically, 
it is in an area of such ignition systems wherein the AC powering means 
have active signal generating stages which are controlled by logic 
circuits to switch the bias current in such stages on and off for each 
firing cycle, as well as to precharge inductive components and then 
discharge such components during each igniter firing cycle. 
The prior art does not appear to deal with bias modulation control of 
ignition systems for fuel burning engines nor in suppressing residual 
stored energy in such systems between firing cycles. 
SUMMARY OF THE INVENTION 
To avoid the inefficiencies, slow time response control of transient 
modulated AC voltages and currents and to inhibit stored energy in an 
output transformer of the system from flowing in between firing cycles, a 
system was devised that keys or modulates DC bias currents in power 
generation stages, so that high level power transients will be efficiently 
created upon such keying or modulation without objectionable energy 
flowing between igniter firing cycles due to storage of residual energy in 
inductive means of the system. 
Hence, an objective of this invention is to provide the ability to control 
high power output from an AC power source by keying on and off the DC bias 
to transistors of such power source, or to equivalents of such 
transistors. 
Another objective of this invention is to produce high transient current 
and high transient induced voltage modulation patterns which are only 
possible when the system is switched on and off by current flow 
interruption of the input or bias circuits and not possible by magnetic 
saturation of an output transformer core which is inherently slow-acting. 
A further objective of this invention is to obtain operation of the system 
at high efficiency, and where semiconductor components are used to 
maintain them cool throughout the operation period of the system, which 
objective is also not possible when a circuit is magnetically saturated to 
quench oscillation for predetermined or random periods of time. 
Yet a further objective of this invention is the ability to utilize a 
simple output transformer with a minimum of three windings, which 
objective is not possible by other systems and still obtain on and off 
control of AC power, and additionally to utilize such magnetic cores 
having very high flux density characteristics so as to enable 
exceptionally large charges to be stored in such core and released during 
igniter firing cycles. 
Still a further objective of this invention is to provide an ignition 
system which draws very low DC power from an automotive battery and yet 
provides high instantaneous power and energy to fire the igniters. 
Yet another objective of this invention is to provide means for precharging 
the output winding of the transformer in the AC generator and discharging 
such winding during the firing cycle of each igniter. 
Accordingly, the inventive ignition system comprises an AC power generation 
source, logic means for intermittently interrupting flow of DC biasing 
current in such stages, and an output transformer coupled to such stages. 
The output transformer is coupled to an ignition transformer primary 
winding, to a capacitor and to a conventional high voltage distributor, 
which capacitor is used to compensate for at least a portion of the 
inductances of the output transformer and ignition transformer. 
The capacitor is intermittently short-circuited when the AC generator is 
biased to its non-oscillatory state by the logic of the system, so as to 
store energy in the output winding of the transformer of the AC generator 
and also to store energy in the ignition transformer primary winding. Such 
stored energy is released in the capacitor when an electronic switch is 
biased to remove the short-circuit from across the capacitor at which time 
the logic means initiates oscillation of the AC power source, so that the 
transient created by the released stored energy intermodulates with the AC 
generated power during each firing cycle of the igniters. 
Another capacitor of larger capacitive value than the first mentioned 
capacitor is in series with such first mentioned capacitor, or 
alternatively another electronic switch connected to the primary circuit 
of the AC generator is used for preventing residual energy stored in the 
transformer of the AC generator from flowing in the system during periods 
intermediate igniter firing periods. 
The first mentioned capacitor is a reactance compensator and therefore 
performs a multiple function, including its normal capacitive function in 
an oscillator as well as its reactance compensation function for 
maximizing AC current flow in the ignition transformer primary winding. 
The output transformer of the AC generator, has a three winding structure, 
one of which is used for feedback of induced AC from the primary winding 
of such output transformer to the inputs of the power generation stages, 
and the keyed DC bias is applied through this feedback winding by means of 
one of several different types of logic circuits. 
Such output transformer employs a laminated core such as may be used in AC 
power or audio power transformers, in relays or the like, generally made 
of materials such as cold rolled steel, relay steel, soft iron, silicon 
steel or alloys thereof, which core can help produce the largest magnetic 
flux density possible without having too much of remnant flux in the core 
that inhibits the generation of high voltages in windings thereon. The 
higher voltages thus produced due to the high flux storage and rapid 
release from such core materials will result in more intense and greater 
number of arcs during igniter firing as compared with the more expensive 
cores which do not provide such advantages. 
It should be noted that although discussion of the AC power generation 
means is in terms of a rectangular wave output pattern, it should be 
understood that AC units providing triangular, saw-tooth, sinusoidal or 
other waveforms may likewise be used in this system.

DETAILED DESCRIPTION 
Referring to FIG. 1, the inventive system shown therein is used to provide 
a transient to intermodulate with another transient generated by AC power 
to fire igniters of a fuel burning engine. Logic control circuits which 
include timers are provided for intermittently keying or modulating DC 
bias so as to switch the AC power unit on and off, and to precharge the 
ignition transformer primary winding and the output winding of an output 
transformer of the AC power unit, thereby providing high transient current 
and voltage waves to fire igniters. 
A transistor power generator 40 includes an output transformer having a 
center-tapped primary winding 41, a secondary or output winding 42, and a 
center-tapped tertiary or feedback winding 43, all wound on a laminated 
core 45 made of cold rolled steel, relay steel, soft iron, silicon steel 
or mixtures or alloys thereof. The basic repetition rate of the generally 
rectangular waves provided by generator 40 are in the order of about 2 
kilohertz, although higher or lower frequency rates can be used. It should 
be understood that a generator such as 40 may also be used wherein the 
waveform output is triangular, saw-tooth, sinusoidal or even random wave 
shapes. 
The use of the types of magnetic materials for core 45, as above stated, 
makes all the difference between a system that produces the type of arcs 
as seen in FIG. 10, or merely a few sparks of relatively low intensity. An 
alternative to the use of a transformer wound on the indicated core 
material 45, when a conventional transformer made from more expensive but 
less effective cores are used, is to use a simple solenoid winding of 
about 75 turns of number 18 to 22 gage wire, to correspond with the wire 
size of such conventional transformer, wound on a one inch square core of 
the material indicated for core 45 and such device should have a closed 
magnetic path. Such device is inserted in series with primary 61 and will 
accumulate charge rapidly and deliver such charge to the system to provide 
the desired arcs. 
Winding 41 is connected at its outer ends respectively to the collectors of 
a pair of transistors Q, in this illustration of the NPN type, the 
emitters of which are connected to the collector of transistor Q2, which 
is also an NPN type, and the emitter of Q2 is at ground potential. It will 
be shown below that in another mode of operation the need for Q2 is 
eliminated and consequently when not used the base thereof is disconnected 
from junction terminal 47 and the emitters of transistors Q are grounded. 
It will be understood throughout this specification that the conventional 
ground symbol indicates the negative terminal of battery 11 as well as 
being a common return path for either AC or DC currents flowing in the 
system. 
The center tap of winding 41 is connected at positive DC battery potential 
at 15 and to junction 13. Junctions 13 and 15 are therefore both at 
positive DC potential since junction 13 is connected to the positive 
terminal of battery 11. 
Winding 43 of the output transformer has its outer ends connected each to 
one base respectively of transistors Q for feeding induced voltage from 
primary 41 to such bases so as to maintain transistors Q in oscillation 
mode when positive DC bias is applied to the center tap of winding 43 
through resistor 44 by logic means 20, hereinbelow discussed. 
Type 2N3055H type transistor Q1 and type 2N6284 Darlington circuit power 
transistors Q have been found to give excellent and reliable results. 
Likewise types 2N6284, 2N6547 or Motorola's types MJ 10009 or MJ 10014 
have provided good results as the Q2 transistor. In this configuration 
transistor Q3 is required of the PNP type and Motorola's type 2N6287 
supplied good results with high reliability. 
It should be noted that capacitor 50 connected in series with winding 42 
and in parallel with Q3 provides a dual function in this system. It 
firstly acts as a capacitor in a typical transient reliant system, which 
capacitor is by-passed during charging mode of the ignition transformer 
primary winding and herein also winding 42, and secondly when the proper 
capacitive value is selected, it acts as a means for maximizing AC current 
flow from source 40 circulating in the primary circuit which consists of 
winding 41 and the Q transistors, wherein maximum current is transferred 
to the circuit which includes output winding 42. Maximum AC current will 
flow when the capacitive value of capacitor 50 is such so as to compensate 
for the inductive reactances of windings 42 and 61, including the 
reactance reflected into winding 61 from winding 62 when an igniter is 
firing, to the principal generated frequency component of the AC unit. 
Logic means 20, has a timing component consisting of reluctance wheel 21 
having regularly spaced ribs 22 at the wheel periphery, wherein wheel 21 
and its ribs 22 are made of a suitable magnetic material and wherein such 
wheel is driven by distributor shaft 10 which is common to any automotive 
engine. Such timing component employs permanent magnet 23 having a sensor 
winding 24 thereon. Magnet 23 has pole piece 25 at one end, so that when 
shaft 10 is driven by the engine, ribs 22 will interrupt magnetic flux 
lines between such ribs 22 and pole piece 25, and induce a voltage in 
winding 24 to create the timing gate. 
The magnetic timing component may be designed with respect to the 
orientation of the north and south magnetic poles of magnet 23 as well as 
with respect to the direction of the turns of wire comprising winding 24, 
so as to provide either a leading negative or leading positive going pulse 
as an output of winding 24 when one of ribs 22 is driven past pole piece 
25. The leading negative pulse design was adopted herein since this is 
conventional in the automotive industry, and accordingly the components of 
logic means 20 are tailored to recognize such timer pulse. The voltage 
output in the form of such pulse is fed to transistor switch Q1, to the 
base thereof at 35 to enable Q1 to provide the igniter firing timing gate 
at its collector. 
Logic means 20 also comprises a voltage divider consisting of resistors 31 
and 32 having a capacitor 34 shunting resistor 32. Such voltage divider is 
connected to positive DC power at 13 and 15. Resistors 31 and 32 are 
chosen so that a positive DC potential of about 1.2 volts appears at 
junction 33 to which one end of winding 24 is connected. Such logic 
circuit herein utilizes an NPN type transistor switch Q1, the collector of 
which is connected through resistor 38 to junction 15 so as to provide DC 
power to switch Q1. The other side of winding 24 is connected to the base 
of Q1, and such base has capacitor 36 connected between it and the emitter 
of Q1, which emitter is at ground potential. The function of capacitors 34 
and 36 are to filter out and reject AC components riding on the gate pulse 
and initiated by winding 24 due to switching action of timer reluctor 
wheel 21 when shaft 10 drives the reluctor wheel past pole piece 25. If 
desired, an additional capacitor 37 may be connected between junction 35 
and the collector of Q1 for effecting additional rejection of such timer 
generated AC components. However, in this system, it may be an advantage 
to pass such timer generated AC components as they serve to modulate the 
gate or firing pulse, provided at junction terminals 47, thereby adding 
more firing energy by increasing the alternating current output from 
source 40. Junction terminals 47 is the point in the system which will 
change in its potential to enable switching control of the alternating 
current source 40, residual energy inhibit switch Q2 and charging of 
inductors 42 and 61 by control of switch Q3. It is of course to be noted 
that it would be a simple matter to utilize PNP types as the Q transistors 
with appropriate changes in the rest of the circuit comprising logic 
circuit 20, Q2 and Q3. 
Operatively, when shaft 10 is not being rotated or driven by the engine, no 
voltage is provided by winding 24 across junctions 33 and 35. Under such 
condition, the base of Q1 will be at a positive potential, sufficient to 
maintain Q1 in its ON mode, so that junction terminals 47 will be at 
ground potential. In this case, DC current will flow through winding 24 to 
maintain the base of Q1 at a positive potential, thereby maintaining Q1 in 
its ON state, in which case junction terminals 47 will be at ground 
potential thus causing the base of Q2 to be at ground potential as well as 
the bases of both Q transistors, thereby preventing source 40 from 
oscillating and Q2 from conducting. 
When shaft 10 is driven, a pulse having a negative going excursion is 
induced in winding 24 at the time when one of ribs 22 is driven past pole 
piece 25, providing such negative going pulse to the base of Q1 at 35 and 
turning off Q1, thereby causing junction terminals 47 to be at positive 
potential, and under these conditions, turning on oscillator 40 by virtue 
of positive DC being applied to the bases of transistors Q through the 
center-tap of winding 43, as well as by turning on switch Q2 by virtue of 
such same DC positive bias being applied to its base through resistor 46. 
The following table shows the switching logic of the circuits of FIG. 1: 
______________________________________ 
Q2 
Potential 
Q1 Potential 
Q3 and Q Windings 
Rib 22 at 35 State at 47 State 
States 
42 and 61 
______________________________________ 
not positive ON ground ON OFF charge 
driven 
opposite 
pole 
piece 25 
driven past 
negative OFF positive 
OFF ON discharge 
pole piece 
25 
______________________________________ 
Since Q1 is generally a silicon device, it requires a base potential 
between 0.6 and 0.8 volts to mantain it in conductive state, and hence the 
positive 1.2 volts provided between junction 33 and ground, even 
considering the voltage drop in winding 24, will still maintain adequate 
voltage level at 35 within the stated limits for minimum sustaining 
voltage, so that Q1 will be in the ON state when shaft 10 is at standstill 
as well as when shaft 10 is driven but when ribs 22 are not opposite pole 
piece 25. In the ON state of Q1, junction terminals 47 will be at ground 
potential thereby biasing the base of Q2 and the bases of the Q 
transistors to cause them to be non-conductive, or in the OFF states. 
The divider network consisting of resistors 31 and 32 is chosen so that the 
voltage at junction 33 with be 1/10 th the voltage of battery 11. Hence if 
the battery or power source charging such battery is defective so that 
only 8 volts is provided by the battery, there will still be 0.8 volts at 
junction 33 which will be sufficient to maintain switching action of Q1 
and operate logic means 20. Additionally, the manner in which winding 24 
is connected in the logic means and the large capacitance of capacitor 34, 
permitted at its shown location, act to provide a stable source of input 
voltage to winding 24, thereby providing a very reliable switching 
circuit. 
When saft 10 is driven and one of ribs 22 is driven past pole piece 25, a 
negative going pulse will be induced in winding 24 which is between 1.5 
and 2 volts in amplitude, thereby overcoming the positive bias of the base 
of Q1 and driving such base negative thereby cutting off current 
conduction between the collector and emitter of Q1, so that Q1 in 
switching to its OFF state, will cause junction terminals 47 to be raised 
to a positive potential so as to turn on the Q transistors of power source 
40 and also turn on Q2. The manner in which the Q transistors of source 40 
provide switching action at particular repetition rates is well known in 
the art. For instance, the theory of such type of oscillator is discussed 
at pages 45 and 46 including schematic 22 therein of Bulletin TC-101B 
printed by Arnold Engineering Company of Marengo, Ill., and is on record 
in the search room of the United States Patent and Trademark Office since 
same was provided from such purpose by applicant in connection with other 
matters. It should be noted however, that applicant has succeeded in 
simplifying and making such oscillator in the form of generator 40 in FIG. 
1 or generator 40a in FIG. 2 hereof, more reliable. 
When power source 40 is turned on during each firing cycle, that is, each 
time one of ribs 22 is driven past pole piece 25, such source stays on for 
the duration when any portion of rib 22 is opposite any portion of pole 
piece 25, providing the firing gate or firing period at 47 to enable 
firing of an igniter in an engine. Power source 40 will keep on generating 
rectangular waves during such firing gate by virtue of Q1 being in its OFF 
state and consequently Q2 and the Q transistors being biased so as to 
cause Q2 to conduct during such firing gate period and the Q transistors 
to oscillate. By virtue of rotation of wheel 21, when pole piece 25 is 
between ribs 22, no firing gate is provided because there is absent the 
required negative going pulse as input at 35, so that Q1 is again biased 
sufficiently positive to switch it to its ON state thereby turning off Q2 
and the Q transistors and turning on Q3. 
The transformer of source 40 has a secondary winding 42 which provides 
energy to an external load such as capacitor 50 and primary winding 61 of 
ignition transformer 60, as well as being an enabling means to initiate 
conduction in Q3 when jumper wire 56 is removed and capacitor 55 is in 
series with winding 42, by virtue of the negative going peaks of the 
waveform generated by generator 40 during each firing cycle. 
A capacitor at 50 is connected between junction 13 and winding 42. 
Capacitor 50 is the means for enabling current, and hence power, to be 
transferred in sufficient magnitude from primary circuit winding 41 
through secondary winding 42 to the load, in this case to transformer 
primary 61. Without such capacitor current i.sub.1 would not be present in 
sufficient quantity in winding 61 and consequently voltage e.sub.1 across 
primary 61 would be inadequate. Considering that the circuit comprising 
winding 42, primary 61 including inductive reactance reflected by 
secondary 62 when under igniter firing, the capacitive reactance presented 
by capacitor 59 enables compensation of these inductive reactances 
resulting in an increased current i.sub.1. The resonance principle cannot 
be used in its entirety to explain the phenomena involving the capacitor's 
compensation function, since resonance generally involves a single 
frequency and consequently unique reactance value, and in this system 
multiple frequencies are generated by power source 40 which involve a like 
number of different reactances. In any event, such capacitor 50 is 
selected by trying various values of capacitors until current i.sub.1 is 
at a maximum. Current i.sub.1 may be conveniently measured and observed by 
using a one-ohm high power resistor in series with primary 61 and 
measuring the voltage across such resistor by means of an accurately 
calibrated high frequency oscilloscope. Typical values for capacitor 50, 
depending on repetition rate of source 40, will be in the order of 0.2 to 
1.0 microfarads. 
Ignition transformer 60 was selected to have a turns ratio of 100, somewhat 
higher than stock automobile transformer turns ratios, since this will 
provide a greater voltage induced in primary 61 and transferred to 
secondary 62 to either an igniter or to a switching distributor or the 
like connected to high voltage cable at 65. It should be noted that this 
system lends itself to making a common ground connection at 63 of the 
primary 61 and the secondary 62 of transformer 60, so that the voltages 
and currents in transformers 60 will have a common reference point rather 
than a swinging impedance, absent such common junction ground connection. 
Such ground common connection can only be made since switch Q3 was located 
at a low impedance location in the system rather than close to primary 
winding 61. In the latter instance, the voltages developed between 
collector and emitter of such switch would be in the order of 500 to 600 
volts during the non-conductive state thereof and although there are 
semiconductor switches with such ratings, it has been found that such 
switches will last only a brief period of time before failing, whereas 
connecting Q3 as shown only a peak-to-peak value of 50 volts was measured 
during the OFF state of Q3 between its collector and emitter. 
Bias resistor 52 of switch Q3 is selected of sufficient ohmic value to 
limit the base current to a safe level within the rating limits of that 
transistor, and a resistor value is used that permits just enough base 
current to flow so as to enable Q3 to perform its switching function 
rapidly. Providing too much base current in Q3 by having too low an ohmic 
value for resistor 52 will slow down switching time of Q3 from its ON to 
its OFF state, and will tend to defeat the major purpose and use of this 
switch. 
When jumper wire 56 is removed so that capacitor 55 is in series with 
windings 42 and 61, no DC current can flow through windings 42 and 61 
during the ON mode of Q3 to charge windings 42 and 61 therewith. However 
the switching action of Q3 produces a transient current both when Q3 is 
switched ON or when Q3 is switched OFF. The transient current produced 
when Q3 is switched ON provides some initial charge to windings 42 and 61 
as well as to capacitor 55 to precharge same therewith. When Q3 is 
switched OFF, the precharged windings 42 and 61 and capacitor 55 will 
cause their charges to combine with the AC provided by generator 40. Since 
at this time Q2 need not be in circuit as discussed above, but can be if 
desired, the positive DC bias provided to transistors Q through resistor 
44 will turn on generator 40, so that generator 40 waveform output will 
intermodulate with the charges released by windings 42 and 61 and by 
capacitor 55 through capacitor 50. The fact that such system is 
operational is evidenced by the oscilloscopic current pattern in FIG. 9, 
showing a peak-to-peak current of 5 amperes through primary winding 61. 
In a high power system such as illustrated, separation of firing waveforms 
will not be possible by virtue of the fact that energy generated by source 
40 and residual in its transformer winding, will tend to cause the current 
i.sub.1 to continue to flow after the Q transistors are biased to their 
OFF states. Consequently, in the system when jumper wire 56 is connected 
to short-circuit capacitor 55, switch Q2 is used to simultaneously cut off 
emitter current, and in FIG. 2 to cut off collector current, when 
transistors Q are biased to their OFF states, thereby preventing 
accumulation of added charge in winding 41 at that time and hence such 
added charge is not available to be transferred to winding 42, so that 
current i.sub.1 will not exhibit energy transfer between igniter firing 
cycles. An example of such effectiveness of Q2, and Q4 in FIG. 2 circuit, 
may be seen from examination of FIG. 6 which shows energy present due to 
attempted precharge of windings 42 and 61 with DC power between igniter 
firing periods, whereas with Q2 in circuit, or Q4 in the circuit of FIG. 
2, the elimination of such energy between igniter firings is seen in the 
FIG. 7 waveform, as well as in its corresponding voltage waveform of FIG. 
8. If such in-between igniter firing energy levels become too high then 
pre-ignition firing can result in the next-in-sequence to fire igniter, 
and the use of Q2 in FIG. 1 or Q4 in FIG. 2 circuits prevents such 
occurrance. 
Another feature of the inventive system, including of course the variations 
of such system as discussed below in conjunction with the other system 
figures herein, is the quiescent state of power source 40 for about 25% of 
the system on-time. Inasmuch as Darlington circuits are used for the Q s, 
high AC currents circulate in their collector circuits in the ON modes of 
such Q s. Such high currents will contribute to high induced voltages in 
winding 42, and would normally require large heat sinks to dissipate the 
heat generated thereby. Since in this power generator, each of the Q's is 
in its ON state only half the time of each cyclic excursion of the AC 
current produced therein, and since each igniter firing period is less 
than one-half its non-firing period in time duration, triggering bias 
winding 43 in order to turn the Q s on and off, will permit the 
transistors to be maintained at relatively low operating temperatures 
because each of the Q s will in effect have a duty cycle of less than 25%. 
Further, switching such power source 40 to its ON mode will create a 
transient voltage at the beginning of each firing cycle which will be 
greater in amplitude than the voltage normally deliverable by such source 
40, absent this type of switching. 
Accordingly, in its charging mode, when junction terminals 47 are at ground 
potential and jumper wire 56 is connected across capacitor 55, Q3 will 
by-pass capacitor 50, will permit DC from battery 11 to flow through and 
charge output winding 42 and primary winding 61. During such charging 
mode, the base of Q2 and the bases of transistors Q being at ground 
potential, these transistors will not conduct and power source 40 will not 
oscillate. Conversely, during firing mode, junction terminals 47 will be 
at positive DC potential and Q3 will not conduct but Q2 and transistors Q 
will have base current flowing therein and hence will conduct providing an 
AC voltage across winding 42 and current i.sub.1 flowing through windings 
42 and 61 and through capacitor 50 to provide voltage e.sub.1 induced in 
primary winding 61. Current i.sub.1 can be considered as having two 
components, one due to the AC from source 40 and the other due to the 
pre-charged windings 42 and 61, now discharged through the entire circuit 
consisting of winding 61, winding 42, capacitor 50 and through battery 11 
to ground. Such two components intermodulate to produce the current 
waveform shown in FIGS. 6 or 7, and the voltage waveform shown in FIG. 8. 
Another convenient method of elimination of residual energy seen between 
firing cycles, is the use of capacitor 55, enabled by removal of jumper 
wire 56. In such case, it is optional whether switch Q2 is retained in 
circuit. However, assuming Q2 is electrically removed from the circuit by 
removing transistor Q2 from its socket and connecting the collector to the 
emitter thereof at the socket terminals, it may be seen from FIG. 9 that 
current i.sub.1 will flow with absence of energy between firing cycles. 
Although the current amplitude is somewhat higher with the use of 
capacitor 55, which capacitor has a value of about 10 times the 
capacitance value of capacitor 50, higher cross-modulation frequency 
components are lost and as a result the effective duty cycle of the system 
is reduced in time per igniter firing. Accordingly, an actual firing of an 
igniter will produce a lesser quantity of arcs as compared with the 
configuration where capacitor 55 is not in circuit and Q2 is in circuit. 
Referring to FIG. 2, the system herein performs in identical manner as in 
the case of FIG. 1, except that AC source 40a having PNP transistors Qa 
are used, Q4 replaces Q2 of FIG. 1, and Q5 replaces Q3 of FIG. 1. 
Except for the use of Q4, which is located in the collector circuit of 
source 40a which illustrates the equivalence with the analogous control 
transistor switch used in circuit 40 of FIG. 1 in the emitter circuit, the 
same functions are performed by FIG. 2 system as discussed in connection 
with the FIG. 1 system, the only difference being that logic means 20a 
replaces the magnetic pulse actuated logic of circuit 20 of FIG. 1. 
Logic means 20a employs cam actuated contactors, cam 71 being driven by 
distributor shaft 10 to causes contactors 72 and 73 to be opened and 
closed in accordance with the cam action. Contactor 72 is at ground 
potential and contactor 73 is connected through resistor 74 to junction 15 
so as to obtain positive DC potential thereat. Contactor 73 is connected 
to junction terminals 47 to provide the modes of operation at this control 
point as already discussed in connection with FIG. 1, except that the FIG. 
1 discussion was couched in terms of a power source to provide the 
alternating current which has NPN transistors and consequently required 
its complementary PNP type of transistor to perform the function which Q5 
herein performs, and also except that control function of Q4 was performed 
in the emitter circuit of the FIG. 1 configuration instead of the 
collector circuit as herein. 
Consequently, when contactors 72 and 73 are opened by the high portion of 
cam 71 being in cooperation with contactor 72, the potential at 47 will be 
positive and Q4 and the Qa transistors will be in the non-conductive 
states, whereas Q5 will be in its conductive state, and windings 42 and 61 
will be charged by passing DC from battery 11 therethrough, at which time 
capacitor 50 will be by-passed by virtue of conductive state of Q5. When 
contactors 72 and 73 are closed, junction terminals 47 will be at ground 
potential and Q4 and the Qa transistors will be in their ON states to 
cause circuit 40a to oscillate and at that time Q5 will be in its OFF 
state to remove the effective short circuit from across capacitor 50 and 
thereby permit discharge current from windings 42 and 61 to flow through 
capacitor 50 and battery 11 to ground so as to provide the same modulation 
of the alternating current produced by circuit 40a, as obtained with the 
FIG. 1 configuration. Here too, the use of capacitor 55 instead of Q4 
provides the identical results as discussed in connection with such 
capacitor usage in the FIG. 1 configuration, all other functions being 
identical to those discussed in conjunction with FIG. 1 configuration. The 
logic of the system of FIG. 2 may be summarized by the following table 
showing the switching logic: 
______________________________________ 
Contactors 
Potential Windings 
Q4 and Qa 
72-73 at 47 Q5 State 42 and 61 
States 
______________________________________ 
open positive ON charge OFF 
closed ground OFF discharge 
ON 
______________________________________ 
Referring to FIG. 2a, the system of either FIGS. 1 or 2 can be connected to 
logic means 20b to perform the functions as described in connection with 
FIG. 1. Logic means 20b is different from logic means 20a only with 
respect to addition of NPN switching transistor Q1 the base of which is 
connected to contactor 73, its collector being connected through resistor 
75 to junction terminal 15 and the emitter thereof being at ground 
potential. The collector of Q1 is therefore the point connected to 
junctions terminals 47 and is the point in the system where switching 
functions of the system are controlled. The only advantage of logic 
circuit 20b over circuit 20a is that of the amplifying characteristics of 
such circuit. By connecting terminals 47 to the collector of Q1 a larger 
gate pulse will be provided which will result in current tails 
superimposed on the i.sub.1 current waveform to result in increased 
current flow in primary winding 61. Hence the logic table shown in 
connection with FIG. 2, is equally applicable to the system when used with 
the logic means 20b. 
Referring to FIG. 3, logic means 20c used therein provides the same 
functions as provided by logic means 20a of FIG. 2 and hence the logic 
table for FIG. 2 is equally applicable to summarize the logic of FIG. 3 
with components 81-83 substituting for components 71-73. Logic means 20c 
employs an electrically conductive disk 81 attached to and driven by shaft 
10 of the engine. The shaft being at ground potential will electrically 
ground disk 81. Disk 81 has a plural number of electrically insulative 
members 82 regularly spaced at the periphery of the disk within the disk 
confines. The number of members 82 will be equal to the number of igniter 
circuits as provided by a conventional high voltage distributor. Here, 
four igniter circuits and corresponding four igniters, one for each of the 
four engine cylinders, is assumed. Contactor 83 is connected to junction 
86 and such contactor is in cooperation with the periphery of the disk. 
Resistor 84 is connected between junction 86 and junction 15 to provide 
positive DC potential at junction 86. Consequently, when the electrically 
conductive portion of disk 81 is in cooperation with contactor 83, 
junction terminals 47 will be at ground potential causing Q3 of FIG. 1 to 
conduct and charging windings 42 and 61. When member 82 is in cooperation 
with contactor 83, junctions 86 and 47 will be at positive potential 
thereby biasing Q3 to its non-conductive state and removing a virtual 
short-circuit from across capacitor 50 and causing discharge of the 
charged windings 42 and 61 through capacitor 50. In the case of the use of 
FIG. 2 configuration with logic circuit 20c, the results are opposite, 
that is when contactor 83 is in cooperation with the electrically 
conductive portion of disk 81 and junctions 86 and 47 are at ground 
potential, Q5 being an NPN type transistor, discharge of previously 
charged windings 42 and 61 through capacitor 50 will take place, and of 
course the charging of windings 42 and 61 will occur herein when contactor 
83 is in cooperation with insulative member 82 causing junctions 86 and 47 
to be at positive potential. 
The logic discussed in connection with FIG. 3 is equally applicable to FIG. 
3a as well as the logic circuit 20a of FIG. 2 or logic circuit 20b of FIG. 
2a, except that in circuits 20a and 20b contactors 72-73 are used in lieu 
of disk 81 with its insulative members 82 and in lieu of contactor 83. 
Referring to FIG. 3a, logic circuit 20d is substantially similar in 
providing the functions as performed by circuit 20c of FIG. 3, except that 
in circuit 20d, Q1 switch is added by connecting the base thereof to 
junction 86 and by connecting the collector through resistor 85 to 
junction 15 so as to obtain DC positive potential thereat. The emitter of 
Q1 is at ground potential. The collector of Q1 will therefore be at the 
same potential as discussed in connection with logic circuit 20b of FIG. 
2a, such collector being connected to junction terminal 47. Since the 
logic performed by circuit 20d is the same as in the case of circuits 20b 
or 20c, the foregoing discussion is applicable to FIG. 3a logic circuit 
when used to replace the logic circuit 20 of FIG. 1 or the logic circuit 
20a of FIG. 2. 
Referring to FIG. 4, logic means 20e has the optical type timing mechanism, 
which connects to terminal junctions 47 to either of the structures of 
FIG. 1 or FIG. 2 by a connection made from the collector of optically 
sensitive semiconductor switch Q6 to junction terminals 47. 
Circuit 20e comprises a disk 91 driven by distributor shaft 10. Disk 91 has 
apertures 92 regularly spaced in the disk at the periphery thereof. 
Powered illumination means 93 is provided at one face of disk 91 for 
optically intermittently illuminating base 95 of Q6 by means of light beam 
94 passing through such apertures 92 to turn Q6 on each time light beam 94 
impinges on base 95 and thereby causes the collector of Q6 to take on 
ground potential by virtue of collector current flowing in Q6. When light 
beam 94 is blocked by the opaque portion of disk 91, Q6 is in its 
nonconducting state and no collector current flows, and consequently the 
potential at either end of release 96 is the same, namely positive DC 
potential. Hence, when Q6 is in its ON state, junction terminals 47 will 
be at ground potential maintaining Q3 of FIG. 1 in its ON state and the Q 
transistors of FIG. 1 in their OFF states thereby charging windings 42 and 
61. On the other hand, when Q6 is in its OFF state, junction terminals 47 
will be at positive DC potential switching Q3 to its OFF state and the Q 
transistors to their oscillatory states, thereby discharging windings 42 
and 61 through capacitor 50 at the same time as AC power is delivered by 
circuit 40 to intermodulate with the discharge current. The following 
logic table is applicable to show the logic of FIG. 4 switching function 
when FIG. 4 circuit is used with the circuit of FIG. 1: 
______________________________________ 
Light Q6 Potential Windings 
Q2 and Q 
Beam 94 State at 47 Q3 State 
42 and 61 
States 
______________________________________ 
passes ON ground ON charge OFF 
through 92 
blocked by 
OFF positive OFF discharge 
ON 
disk 91 
______________________________________ 
Inasmuch as in FIG. 2, switch Q5 is analogous to switch Q3 of FIG. 1,but is 
complementary thereto, the functions will be exactly opposite when circuit 
20e is used with the FIG. 2 configuration to those shown in the foregoing 
logic table for use with the FIG. 1 configuration. That is, all functions 
shown when light beam 94 is blocked occur as shown when the light beam 
passes through apertures 92, and vice-versa. 
Referring to FIG. 5, the system illustrated is identical to the system as 
discussed in connection with FIGS. 1 or 2, except that logic means 20 of 
FIG. 1 and logic means 20a of FIG. 2 is replaced by logic means 20f. Such 
logic means 20f employs an angular modulated oscillator wherein such 
oscillator 105 is modulated by virtue of a variable capacitor being driven 
by distributor shaft 10. Such capacitor comprises a rotatable plate 101 
having protrusions 102 regularly spaced at the periphery of plate 101 and 
having a single fixed plate 103 connected to oscillator 105. Plate 101 is 
at ground potential since it is attached to shaft 10 which is grounded. 
Oscillator 101 provides a positive going signal output imposed upon 
junction 107 of the logic circuit 20f whenever a protrusion 102 is driven 
past fixed plate 103. More details concerning this modulation method is 
available in U.S. Pat. No. 4,122,815 which was incorporated by reference. 
Logic circuit 20f has a bias resistor 106 connected between base of 
transistor Q7 at 107 and ground so as to maintain the base at ground 
potential until such time as a positive signal from oscillator 101 drives 
the base sufficiently positive to cause base current to flow and hence to 
cause collector current to flow and Q7 to conduct. The collector of Q7 has 
resistor 108 connected between it and junction 15 which is at positive DC 
potential. The emitter of Q7 is at ground potential, so that when junction 
107 is biased positive due to a signal at 107 from oscillator 105, base 
current and hence collector current flows and places the Q7 collector and 
junction terminals 47 at ground potential, thereby causing Q3 to conduct 
and the Q transistors and Q2 to remain in their OFF states, and windings 
42 and 61 to be charged. When no signal from oscillator 105 is present at 
junction 107, the base of Q7 will be at ground potential and no base 
current or collector current will flow to maintain Q7 in its OFF state, 
thereby causing the collector of Q7 and junction terminals 47 to be at 
positive DC potential and Q3 to be switched to its OFF state and the Q 
transistors to their oscillatory state and Q2 to its conductive state. The 
following table expresses the logic performed by the FIG. 5 configuration 
when used in conjunction with FIG. 1 circuit: 
______________________________________ 
Q2 
Oscillator 
Potential 
State Potential 
State 
Windings 
and Q 
105 at 107 of Q7 at 47 of Q3 
42 and 61 
States 
______________________________________ 
angularly 
positive ON ground ON charge OFF 
modulated 
not ground OFF positive 
OFF discharge 
ON 
modulated 
______________________________________ 
Inasmuch as in FIG. 2, switch Q5 is analogous to switch Q3 of FIG. 1, but 
is of complementary type semiconductor, the functions will be exactly 
opposite when circuit 20f is used with FIG. 2 configuration to those shown 
in the foregoing logic table for the FIG. 1 configuration. That is all 
functions shown when oscillator 105 is angularly modulated will be 
represented in such logic table by the functions opposite the condition 
for the not modulated case, and vice-versa. 
Referring to FIGS. 6 through 10, photographic results of the system 
performance in terms of waveforms of current i.sub.1 through primary 61 
and voltage e.sub.1 across such primary 61, constitute the oscilloscopic 
current and voltage patterns, and include a photograph of the arcs fired 
by the system. In conjunction with these photographs, primary current 
i.sub.1 was measured using a calibrated 50 megahertz oscilloscope made by 
Hewlett-Packard Company, by measuring the voltage across a high power 
one-ohm resistor inserted in series with primary 61. The voltage was 
measured across such primary using the same calibrated oscilloscope. FIG. 
2 and FIG. 2a configurations were used for these tests. A four port 
conventional distributor was driven by means of its shaft 10, to provide 
timing by the cam actuated contactor pair in such distributor as shown in 
FIGS. 2 or 2a. 
The amplitudes of the voltages e.sub.1 measured were substantially of the 
same peak-to-peak value of 1300 volts, and only the photograph of e.sub.1 
corresponding to the i.sub.1 condition of FIG. 7 is illustrated in FIG. 8 
as exemplary. 
FIG. 6 illustrates the actual current i.sub.1 under condition when Q2 of 
FIG. 1 or Q4 of FIG. 2 are not in circuit, showing the energy stored in 
the transformer of circuits 40 or 40a being released between igniter 
firing periods as well as during igniter firings. Such condition is 
eliminated by the use of Q2 or Q4 in their respective circuits as seen 
from i.sub.1 current in FIG. 7 which does not have the stored energy 
released between igniter firing periods, and likewise the corresponding 
voltage e.sub.1 shown in FIG. 8 is free from such energy flow between 
igniter firing periods. FIG. 9 shows the condition wherein neither Q2 nor 
Q4 are in their respective circuits and jumper wire 56 is removed so that 
capacitor 55 is added to the series circuit that includes the ignition 
transformer primary winding, and it may be seen from current waveform 
therein that no energy is released during periods between igniter firings. 
It has been pointed out previously that the amplitudes of currents i.sub.1 
are not the only consideration, and notwithstanding the larger current 
obtained under conditions of FIG. 9, the conditions giving rise to FIG. 7 
current, though lower in amplitude, provide better firing or igniter arc 
performance than those of FIG. 9. 
It should also be noted, that FIG. 6 condition represents usable circuit 
performance since the energy between firing cycles was insufficient to 
cause pre-ignition. A simple test was made by rotating distributor shaft 
10 by hand to note that there is sufficient time or angle spacing between 
successive igniter positions along the locus of the distributor rotor when 
no firing occurs which is indicative that no energy transfer will actually 
occur under FIG. 6 condition in between the desired firing periods for the 
igniters. 
FIG. 10 is an actual photograph of the firing arcs experienced under the 
FIG. 7 current and FIG. 8 voltage condition. There is no appreciable 
difference in the arc intensity when examined under the FIG. 6 condition. 
However, under the FIG. 9 condition, the arcs were lesser in quantity than 
seen in FIG. 10, but each individual arc thereof appears to be slightly 
thicker than the arcs comprising FIG. 10 though lesser in number than the 
quantity of arcs of FIG. 10. It would therefore appear that the number of 
arcs correlate with the number of cycles one can count in the current 
waves, and consequently the number of cycles in the current wave of FIG. 6 
or FIG. 7 is substantially greater than the number of cycles in the 
current wave of FIG. 9. Hence, the fact that the current wave of FIG. 7 
for example only has an amplitude of 3.3 amperes whereas the current wave 
of FIG. 9 has an amplitude of 5 amperes is not conclusive of a better 
system represented by FIG. 9, since the effective duty cycle, that is the 
portion of the firing time when arcs occur is far greater in the FIG. 7 
situation than in the FIG. 9 situation, and the FIG. 7 situation will 
probably yield a greater total firing energy per firing cycle than the 
FIG. 9 situation. 
It should also be noted that when observing the arcs, there appeared to be 
a very high increase in arc velocity as interpreted from the audible arc 
firing noise of the FIG. 6 or FIG. 7 current situation, compared with the 
lower noise level in the FIG. 9 current situation which also may have 
bearing upon the energy levels of the respective arcs produced.