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BACKGROUND OF THE INVENTION
Target shooting is popular with bow and arrow, guns, darts and the like
both as a sport and form of amusement and with regard to guns, as a
serious means for improving shooting skills required in connection with
legitimate and worthwhile vocational pursuits such as law enforcement and
military service.
Various types of targets have been devised over the years to aid the
practitioner but none have been fully automatic.
U.S. Pat. No. 346,876 granted in 1886 on an annunciator target displayed on
a replica of the target the location of the point struck by the
projectile. Related devices accomplishing similar purposes were patented
in 1894 in U.S. Pat. No. 521,049 and in 1910 in U.S. Pat. No. 954,997. All
of these devices utilize relatively complex mechanical constructions
wherein the impact of the projectile closed an electrical switch
incorporated in the target structure. In the case of U.S. Pat. Nos.
346,876 and 954,997, a long connective cable was required between the
target and the annunciator.
Other innovations in the field include special targets with parallel
electrically conductive membranes which are either pierced by a conductive
projectile or momentarily deformed into electrical contact with each other
by the projectile, the closing of the electrical circuit in either case
being utilized to identify the location struck within a defined locational
grid. The location is then electrically recorded. U.S. Pat. No. 3,677,546
is an example of such a construction.
SUMMARY OF THE INVENTION
In accordance with the invention claimed, an improved indicating target is
provided wherein a flashing light defines the sector of the target struck
by a projectile, the indicating target automatically resetting the
indicator after a predetermined time prior to the next shot.
It is, therefore, one object of this invention to provide an improved
indicating target.
Another object of this invention is to provide an improved indicating
target wherein an electric lamp illuminates the particular sector of the
target which is struck by the projectile.
A further object of this invention is to provide an indicating target
wherein the illuminating lamp is flashed for a predetermined time for
improved visibility and recognition at relatively great distances.
A still further object of this invention is to provide an indicating target
wherein the indicating means is automatically turned off or reset after a
brief interval.
A still further object of this invention is to provide an improved
indicating target in a simple and inexpensive form which is lightweight,
compact, portable and easily maintained.
Further objects and advantages of the invention will become apparent as the
following description proceeds and the features of novelty which
characterize this invention will be pointed out with particularity in the
claims annexed to and forming a part of this specification.
BRIEF DESCRIPTION OF THE DRAWING
The present invention may be more readily described by reference to the
accompanying drawing, in which:
FIG. 1 is a perspective view of an indicating target embodying the
invention;
FIG. 2 is an exploded view showing the major mechanical parts employed in
the indicating target structure;
FIG. 3 is a cross-sectional view of the major mechanical parts shown in
their assembled relationship as viewed in the direction indicated by lines
3--3 of FIG. 2;
FIG. 4 is a schematic representation of two of the modular electronic
circuits utilized in the indicating and resetting functions incorporated
in the target structure.
FIG. 5 is a modification of the schematic representation shown in FIG. 4
illustrating a common operating circuit for all indicating and resetting
functions incorporated in the target structure.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring more particularly to the drawings by characters of reference,
FIGS. 1, 2 and 3 illustrate the indicating target structure 10 comprising
a lamp assembly 11 and a circular cluster of target sectors 12, the
cluster comprising a circular center sector 13 and six identical
surrounding pie-shaped sectors 14-19.
Lamp assembly 11 comprises a mounting plate 20 to which are mounted seven
lamps 21-27 within seven circular holes formed in plate 20. Hole 21A is
located at the center of plate 20 and the six holes 22A-27A are arranged
uniformly about the circumference of a circle concentrically located with
hole 21A.
Plate 20 may be laminated in two layers including an electrically
insulating supporting board 20A and an electrically conducting forward
surface layer 20B which is cemented to board 20A or if comprising merely a
thin surface painted thereon. Lamps 21-27 may have bell-shaped reflector
housings the openings of which rest against the rear surface of board 20A
in suitable orientation to cause their illuminating rays to be directed
forward through the seven circular holes 21A-27A.
The six target sectors 14-19 are incomplete pie sections, each having been
diminished by a sector of the circular center segment 13. Center segment
13 and the six surrounding sectors 14-19 fit conformingly together
substantially filling a complete circular area but with a finite and
uniform spacing maintained between adjacent segments.
Each of the sectors 13-19 is molded from a tough and resilient but
relatively rigid translucent plastic material. Preferably a centered
circular insert 31 is provided in each sector in alignment with one of the
lamps 21-27, the insert 31 being molded from a similar plastic material
but having a higher degree of transparency than that of the surrounding
plastic material, the insert 31 thus serving as a lens for the
transmission of light from lamps 21-27.
Each of the target sectors 14-19 is secured to the forward surface of plate
20 by means of one or more flexible supports 32 and 33. Each of the
supports may be formed of a resilient material such as rubber or plastic
in a hollow cylindrical configuration as shown in FIG. 3 which deforms
temporarily under stress. As noted from the drawing, one end of each
support is secured to the rear surface of one of the target sectors 13-19
and the other end is secured to the forward surface of plate 20 by means
of a screw or other suitable fastening means. Also attached to the rear
surface of each target sector 13-19 are two spring contacts 38 and 39
which extend perpendicularly rearwardly from the rear surface of the
target sector to a point just forward of the front surface of plate 20
where each of the contacts terminates in a right angle contact tab. Slight
physical clearance is provided between contacts 38 and 39 when the segment
to which they are mounted is in a rest position, but in the presence of
vibratory motion of the segment relative to plate 20 as produced by the
impact of a projectile, at least one momentary electrical contact is made
between spring contact 38 or 39 or both and conducting surface layer 20B
of plate 20. As shown in FIG. 3, the target section 13 is displaced from
lamp assembly 11 for the sake of clarity; however, when assembled,
assembly 11 and target section 12 are close together.
The two contacts 38 and 39 on each target sector are electrically connected
together and an external electrical connection is made to each pair by one
of seven electrical conductors 41. A single electrical conductor 42 makes
electrical connection between conductive surface 20B of plate 20 and one
end of a resistor 43. Another conductor 44 is attached to the other end of
resistor 43. Two electrical conductors 45 and 46 are connected to the
terminals of each of the lamps 21-27.
Associated with each target sector 13-19 is a lamp driver circuit 50 with
two circuits 50 being illustrated in FIG. 4. Each circuit 50 comprises a
silicon-controlled rectifier 51, transistors 52 and 53, a silicon
unilateral switch 54, a capacitor 55, resistors 56-60. A battery 61, or
other suitable source of power, supplies current to all of the lamp driver
circuits 50 associated with sectors 56-60. In the specific example shown
in FIG. 4, the lamp driver circuits 50 are each connected to a different
lamp such as lamps 26 and 27 which are positioned opposite target sectors
18 and 19. Although two batteries 61 are shown in FIG. 4 for sake of
illustration, only one battery is needed for all circuits 50 utilized with
each circuit 50 connected across the same.
Silicon controlled rectifier 51 is a four layer semiconductor device having
an anode 62, a cathode 63 and a gate 64. As in the case of a conventional
diode, controlled rectifier 51 blocks current flow from cathode to anode;
it also blocks current flow from anode to cathode, however, until a
positive voltage pulse is applied from gate to cathode in the presence of
a positive anode-to-cathode voltage, in which case it switches to a low
impedance mode, readily passing current from anode to cathode. Once the
controlled rectifier has been switched to the low impedance mode, it
remains in this mode even after the positive gate voltage is removed. To
return the device to its high impedance mode in which it blocks current
from anode to cathode, it is necessary to reduce the anode to cathode
current to zero by external means and to hold the current at zero for a
finite period of time, typically 20-30 microseconds while the controlled
rectifier recovers. The General Electric Company describes the device in
detail in its several editions of its "Controlled Rectifier Manual."
Transistor 52 is an NPN semiconductor device having an emitter 65, a base
66, and a collector 67. Transistor 52 passes current from collector 67 to
emitter 65 in proportion to the current supplied from base 66 to emitter
65. If the base to emitter current is substantially in excess of that
required to allow the maximum current available from collector to emitter,
the transistor is said to be saturated and the collector to emitter
voltage drop is then typically 0.5 volts or less.
Transistor 53 is a PNP semiconductor device having an emitter 68, a base 69
and a collector 70. Except for the direction of current flow, the PNP
device 53 has characteristics which are identical to those NPN devices 52.
In this case, current flow is from emitter to collector and from emitter
to base, and saturation is produced by providing emitter to base current
in excess of that current. Numerous semiconductor texts describe the
construction and characteristics of these devices, e.g. "RCA Transistor
Thyristor and Diode Manual," Technical Series SC-15, Copyright 1971 by RCA
Corporation.
Silicon Unilateral Switch 54 is a four-layer semiconductor device having an
anode 72 and cathode 73 and a gate 74. The silicon unilateral switch is
essentially a miniature controlled rectifier having an anode gate (instead
of the usual cathode gate) and a built in low voltage avalanche diode
between the gate and cathode. The silicon unilateral switch, or SUS,
blocks current from in both directions but may be switched to a low
impedance state (to pass current from anode to cathode) by applying an
anode-to-cathode voltage in excess of the breakdown voltage of the
internal avalanche diode. The device remains in the low impedance state
until anode-to-cathode current is reduced to zero by external means. For
further information on the silicon unilateral switch, see page 109 of "SCR
Manual Including Triacs and Other Thyristors," Fifth Edition, Copyright,
General Electric Co., 1972.
With reference again to FIG. 3, resistor 57, lamp 27 and controlled
rectifier 51, anode 62 to cathode 63, are serially connected across
battery 61, the negative terminal 75 of battery 61 being connected to the
cathode 63 of controlled rectifier 51 and the upper end of resistor 57
being connected to the positive terminal 76 of battery 61. In the high
impedance mode of controlled rectifier 51 or through serially-connected
lamp 27. Resistor 56 connected from gate 64 to cathode 63 of controlled
rectifier 51 bypasses leakage current flowing from anode 62 to gate 64
holding gate-to-cathode voltage at a low value, thereby preventing such
leakage current from triggering the device to its low impedance state.
Transistor 53 having its emitter connected to the upper end of resistor 57
and to positive terminal 76 of battery 61, and having its base connected
to the lower end of resistor 57 is serially connected with resistor 60 and
capacitor 55 across battery 61, the lower end of capacitor 55 being
connected to negative battery terminal 75. While controlled rectifier 51
is in its high impedance state and while there is consequently no current
through or voltage drop across resistor 57, there is also consequently no
current flow from emitter 68 to base 69 of transistor 53. For this reason,
there is essentially no current flow from emitter 68 to collector 70 of
transistor 53 or through serially-connected resistor 60 and capacitor 55.
Connected in the gate circuit of controlled rectifier 51, however, is a
network which supplies a pulse of voltage and current to gate 64 under
certain conditions. Conductor 41 which is shown in both FIGS. 2 and 3 to
be connected to spring contacts 38 and 39 of one of the target sectors
13-19 (in this case sectors 18 and 19) and is connected to gate 64 while
conductor 44 from resistor 43 is connected also to positive terminal 76 of
battery 61. It is now seen that when, in response to an impact produced by
a projectile striking the associated target sector 19, the resulting
vibration of the target sector causes a momentary electrical contact to be
made between spring contact 38 or 39 and surface layer 20B of plate 20. A
pulse of current flows momentarily from positive terminal 26 of battery 61
through conductor 44, resistor 43, conductor 42, surface layer 20B,
contact 38 or 39, conductor 41 and resistor 56 to negative terminal 75 of
battery 61.
By virtue of the current thus caused to flow through resistor 56, a
positive pulse of voltage is provided from gate 64 to cathode 63 of
controlled rectifier 51 and rectifier 51 is thus triggered to its low
impedance state whereupon a current is initiated which flows from positive
terminal 75 of battery 61 through resistor 57, lamp 27 and controlled
rectifier 51 (anode 62 to cathode 63) to negative terminal 75 of battery
61. This current flowing through lamp 27 causes it to be energized and
thus to illuminate target sector 19, thereby indicating to the marksman
that his projectile such as an arrow, bullet or dart has struck target
sector 19. Lamps 21-27 are preferably of the flashing type similar to
those used on Christmas trees wherein the internal heating of the lamp
causes a bimetal switch to be opened and closed to produce the flashing
operation. The flashing of the light is more readily distinguished by the
marksman than is a steady light, especially if the target is located some
distance away.
Once lamp 27 has been energized to indicate the particular segment which
has been struck by the bullet, it is desirable that the lamp be
extinguished by the resetting of the particular circuit 50 which has been
triggered. This implies the restoration of controlled rectifier 51 to its
high impedance state, a function which is accomplished by means of
transistors 52 and 53, silicon unilateral switch 54, capacitor 55 and
resistors 58, 59, and 60.
Transistor 52 is connected in parallel with controlled rectifier 51, its
collector 67 connected to anode 62 of rectifier 51 and its emitter 65
connected to cathode 63 of rectifier 51. It is thus possible by virtue of
the low saturation voltage of transistor 52 to divert virtually all of the
current flowing from anode to cathode of rectifier 51 and to bypass it
through transistor 52. Thus, if transistor 52 is held in a saturated
condition for 20-30 microseconds by means of a current flowing from base
66 to emitter 65, rectifier 51 will recover to its high impedance state,
and when subsequently, the base emitter current of transistor 52 is
returned to zero, the current through both rectifier 51 and transistor 52
will have fallen to zero.
It was earlier shown that no current flows through transistor 53, emitter
68 to collector 70 while controlled rectifier 51 is in its "off" or high
impedance state. While rectifier 51 is conducting, however, the voltage
drop produced across resistor 57 produces a base-emitter current in
transistor 53 causing transistor 53 to be saturated, thus causing a
current to flow from positive terminal 76 of battery 61 through transistor
53, resistor 60 and capacitor 55 to negative terminal 75 of battery 61.
This current flowing through capacitor 55 causes capacitor 55 to be
charged to a voltage having a polarity as indicated by the + sign at the
upper plate of capacitor 55. Connected serially across capacitor 55 are
silicon unilateral switch 54 and resistors 59 and 58. When the voltage
across capacitor 55 exceeds the turn-on voltage (typically 8 volts of
silicon unilateral switch 54, switch 54 switches to its low impedance or
"on" state and capacitor 55 rapidly discharges (e.g. in approximately 30
microseconds) through switch 54 and resistors 58 and 59. By virtue of the
connection of the base 66 to emitter 65 terminals of transistor 52 across
resistor 58, a major part of this discharge current flows from base 66 to
emitter 65 causing transistor 52 to be saturated and thereby diverting
current from rectifier 51 as described earlier. Once capacitor 55 has
discharged to a sufficiently low value of charge, transistor 52 turns off,
current through lamp 27 returns substantially to zero and causes
transistor 53 also to turn off. As a consequence, the source of current to
unilateral switch 54 is also cut off and switch 54 returns to its high
impedance state. Circuit 50 has thus been reset as desired and the target
is ready for the marksman's next shot.
The particular construction of the target 10 as described earlier,
incorporating plastic target sectors 13-19 is best suited for use with
rubber or plastic bullets. It is also possible, however, to utilize
appropriate target materials such as very hard rubber which are suitable
for use with low energy metal projectiles such as those used with air guns
or low powered rifles.
It will be appreciated that various changes and modifications are possible
which enhance or optimize the performance of the indicating target. It is
possible, for example, to vary the member and type of elastic supporting
elements 32,33 and to arrange them in a way which minimizes interference
between target sectors. The shapes, number and sizes of the individual
target elements may also be varied.
Fixed divider partitions may be added between target segments to prevent
the bullets or projectiles from becoming lodged between sectors. A
replaceable guard may also be placed around the target cluster 11 to catch
and retain bullets which miss the target. A foam plastic, foam rubber or a
soft compressed fiber material may be used for this purpose.
It is readily recognized that the apparatus described herein is extremely
simple and inexpensive to manufacture. It has no precision parts requiring
close mechanical tolerances. Target sectors 13-19 are easily molded from
inexpensive materials. A minimum total number of individual parts are
required.
An improved circuit 80 for the control of lamps 22-27 is shown in FIG. 5,
circuit 80 offering economy over the circuit of FIG. 4 by virtue of the
fact that the individual circuit sectors 50A of FIG. 5, one of which is
associated with each of the individual target sectors 13-19 are much
simplified with respect to the corresponding circuits 50 of FIG. 4. The
simplification is made possible through the use of a common circuit sector
81 which provides the resetting function i.e. the commutation of the
silicon-controlled rectifiers 51 of sectors 50A so that such commutating
circuitry need not be incorporated in each of the sectors 50A.
The common circuit sector 81 of FIG. 5 is energized by connection between a
positive bus 82 and a negative bus 83, positive bus 82 being connected to
positive terminal 76 of battery 61, and negative bus 83 being connected to
negative terminal 75 of battery 61.
Circuit sector 81 utilizes three PNP transistors 84, 85 and 86, an NPN
transistor 87, a silicon unilateral switch 88, a capacitor 89, and
resistors 90-100. Each of the transistors 84-87 has an emitter 101, a base
102 and a collector 103.
Each of the circuit sectors 50A utilizes a silicon-controlled rectifier 51,
one of the lamps, 22-27, two capacitors, 104 and 105 and two resistors 106
and 107. The lamps 22, 23, 24, 25, 26 or 27 are connected in parallel with
capacitor 104 and resistor 106, and the parallel network thus provided is
serially connected with the anode-cathode terminals 108 and 109
respectively of controlled rectifier 51 between a positive bus 111 and the
negative bus 83 which is common with negative bus 83 of sector 81.
Capacitor 105 and resistor 107 are connected in parallel between the gate
112 and the cathode 109 of controlled rectifier 51.
Transistor 85 of sector 81 which has its emitter 101 connected to positive
bus 82 is normally turned on by virtue of the connection of resistor 94
between its base 102 and negative bus 83 which permits an emitter-base
current to flow from base 102 through resistor 94 to negative terminal 83.
In the "on" condition, transistor 85 thus provides a low impedance
connection between positive bus 82 and serially connected resistors 98 and
99 which provide a relatively low resistance path from collector 103 of
transistor 85 to bus 111. In the normal or quiescent state with none of
the lamps 22-27 energized, bus 111 is thus at nearly the same positive
potential as bus 82 and positive terminal 76 of battery 61.
Surface layer 20B is also at the same positive potential by virtue of its
connection through resistor 100 to bus 82.
As in the case of the circuit of FIG. 4, the gate 112 of controlled
rectifier 51 is connected by means of a conductor 41 to contacts 38, 39
which, when activated by the impact of a bullet striking the associated
target sector, make contact with surface layer 20B. During such momentary
contact a gate current flows from bus 82 through resistor 100, layer 20B,
contacts 38, 39, and conductor 41 to gate 112 of controlled rectifier 51,
the amount of current flowing being limited by resistor 100.
Upon the delivery of gate current to gate 112, controlled rectifier 51 is
switched to the "on" condition whereupon a current flows from positive bus
82 through transistor 85 (from emitter 101 to collector 103), through
resistors 99 and 98 to bus 111 and thence through one of the lamps 22-27
associated with the particular activated contact 38, 39 and through the
associated controlled rectifier 51 to negative bus 83. It will be
recognized that in the usual case only one of the individual sectors, 50A
is thus activated by the impact of a single bullet or projectile.
Returning to main sector 81 it is noted that transistor 86 has its emitter
101 connected to collector 103 of transistor 85 while serially-connected
resistor 95 and capacitor 89 are connected between its own collector 103
and negative bus 83, one end of capacitor 89 being connected directly to
bus 83.
As the afore mentioned current to one of the lamps 22-27 flows through
resistor 99 a voltage drop is developed across resistor 99 having a
polarity which is positive on the left and and negative on the right as
indicated by the signs + and - shown on the drawing. Emitter 101 of
transistor 86 is seen to be connected to the positive side of resistor 99
while base 102 of transistor 86 is connected through base current limiting
resistor 97 to the negative side of resistor 99. An emitter-base current
is thus induced in transistor 86 flowing from the positive side of
resistor 99 to emitter 101, base 102 and resistor 97 to the negative side
of resistor 99, the emitter-base current thereby rendering transistor 86
conductive and causing a current to flow from collector 103 of transistor
85 through transistor 86, emitter 101 to collector 103, through resistor
95 and capacitor 89 to bus 83, said current causing capacitor 89 to be
charged. As capacitor 89 is thus charged, a positive voltage is developed
on its upper plate 113.
Connected across capacitor 89 is a series network comprising silicon
unilateral switch 88 and resistors 92 and 93, the anode 114 of silicon
unilateral switch 88 being connected directly to upper plate 113 of
capacitor 89, its cathode 115 connected directly to one end of resistor
93, and resistor 92 being connected between the other end of resistor 93
and the lower plate 116 of capacitor 89 which is also connected to
negative bus 83.
When the charge developed across capacitor 89 reaches a voltage level
sufficient to turn on unilateral switch 88 a discharge current flows from
positive plate 113 through serially connected switch 88 and resistors 93
and 92 to negative plate 116. A part of this discharge current is diverted
through the base-emitter junction of transistor 87 which has its base 102
connected to the upper positive end of resistor 92 and its emitter
connected to the lower end of resistor 92. Transistor 87 is thereby
rendered conductive and by virtue of the connection of its collector 103
to base 102 of transistor 84 through a current-limiting resistor 91, an
emitter-base current is caused to flow from base 101 to emitter 102 of
transistor 84 through resistor 91 and collector 103 to emitter 101 of
transistor 87 to negative bus 83. Said emitter-base current renders
transistor 84 highly conductive and because transistor 84 is connected
directly across the emitter-base junction of transistor 85, the
emitter-base current of transistor 85 is reduced essentially to zero so
that transistor 85 is turned off and the supply of current to the
energized lamp and associated controlled rectifier of the activated sector
50A is momentarily interrupted. During said momentary interruption the
previously conducting controlled rectifier recovers to its high impedance
state. When the discharge of capacitor 89 is completed base drive to
transistor 87 and hence to transistor 84 reduces to zero, and transistor
85 is restored to its "on" state. The entire circuit 80 is thus restored
to its quiescent condition in readiness for the subsequent operation.
As transistor 85 is restored to its "on" state, the abrupt rise of voltage
on bus 111 has a tendancy to cause controlled rectifiers 51 to be turned
on. Such erratic turn-on is prevented by the connection of capacitor 105
and resistor 107 between gate 112 and cathode 109.
In some cases it is desired to employ a type of lamp 22-27 which flashes by
means of an internal switch which interrupts continuity through the lamp
by thermal action. Such interruption would cause the commutation of
controlled rectifier 51 were it not for resistor 106 connected in parallel
with the lamp, the resistor providing continuity of current to the
controlled rectifier during the open condition of the internal lamp
switch. Capacitor 104 suppresses electrical noise across the lamp during
flashing which otherwise also produces erratic operation of controlled
rectifier 51.
Further simplification of the circuit 80 is possible through the use of
such a lamp with an internal or external thermally operated switch to
interrupt lamp current and through the utilization of such current
interruption as the means for commutating the controlled rectifier.
If such a means is employed it is possible to omit all curcuit elements
within sector 81 with the exception of battery 61 and resistors 98 and 100
together with the elimination of resistors 106 across capacitors 104 of
the sectors 50A. The left-hand end of resistor 98 would then connect
directly to bus 82 as indicated by broken line 120. Operation then occurs
as follows: Controlled-rectifier 51 is turned on as before by gate current
flowing in response to the activation of contacts 38, 39. Lamp current
flows through controlled rectifier 51 until interrupted by the thermal
switch, said interruption commutating the controlled rectifier and
resetting the circuit for the next operation.
If desired, a large target of the type disclosed may be used for golf with
the golfer, off at a distance, driving the ball into the target thereby
indicating the accuracy of his drive.
Although but one embodiment of the present invention has been illustrated
and described, it will be apparent to those skilled in the art that
various changes and modifications beyond those already suggested may be
made therein without departing from the spirit of the invention or from
the scope of the appended claims.
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