US2837336A - Scoring circuit - Google Patents

Description

June 3, 1958 F. w. BROWN 7 2,837,335

SCORING CIRCUIT Filed Jan. 9. 1956 l2 son XAAAIAQW J IMFD r [III] l8 u COUNTER |4 METAL T0 40V METAL 0 SHORTING T i 6 TARGET GERMANIUM 5* move me:

RELAY 8,000.0. ZMA

INVENTOR. V

FORREST W. BROWN AGENT.

United SCORING CIRCUIT Forrest W. Brown, New Canaan, Conn., assignor to The Reflectone Corporation, Stamford, (loam, a corporation of Connecticut Application January 9, 1956, Serial No. 558,044

' Claims. (01. 273-1192.

which indicates at a remote point the number of hits.

made on a target.

Targets which are adapted to sense the passage therethrough of a bullet and score upon such an occurrence are well known in the art. Such targets are usually made of two spaced, electrically insulated electrodes as described for instance in U. S. Patents, 474,109, 2,576,960, and copending application for Letters Patent, Serial Numbers 502,447 filed April 19, 1955 and 515,032 filed June 13, 1955. A bullet passing through the target momentarily causes an electrical short circuit between the electrodes.

In connection with this type of target construction it is necessary to employ electrical scoring means. Since the passing of a bullet through the target occurs in a minute fraction of a second, the actuation of scoring relays, of counters and of other indicating means is difiicult since mechanical devices cannot readily be actuated in such a short time. In view of this difiiculty electronic means are commonly used which amplify the short signal received from the target and which in turn cause operation of the circuit components necessary for scoring indication.

The use of electronic components is made difficult and undesirable, primarily by the environmental conditions which usually prevail on open target ranges, particularly sand, dust, winds, ice, snow and rain and also by the absence of suitable electrical energy which is necessary to energize electronic amplifying devices. A source of 100 volts or better is usually required to suitably energize electronic amplifying tubes, a voltage magnitude which is not readily available from storage batteries. Still further, the fragility of electronic tubes and the absence of skilled maintenance personnel on firing ranges creates problems which seriously impair the reliability of the entire target and scoring installation.

One of the objects of this invention is therefore to provide a new and improved electrical scoring circuit which avoids one or more of the disadvantages of prior art devices.

Another object of this invention is the provision of a scoring circuit characterized by utmost simplicity and reliability.

A still further object of this invention is the provision of an electrical scoring circuit which avoids the use of electronic amplifying means and eliminates the need for electronic vacuum tubes.

A still further object of this invention is the provision of an electrical scoring circuit which will operate over a wide resistance variation of the target.

Still another and further object of this invention is the provision of a scoring circuit which in view of the absence of thermionic tubes requires but a minimum of standby power.

P ce

For a better understanding of the present invention together with other and further objects thereof reference is made to the following description taken in connection with the accompanying drawing in which:

The figure is a schematic circuit diagram of the target and scoring arrangement.

Referring now to numeral 11, a source of voltage is identified which via a resistor 12 is connected to the electrodes 13 and 14 of a target. These electrodes preferably are electrically conductive electrodes spaced from one another and which momentarily are short-circuited upon the passage of a bullet therethrough. Such targets are discussed in great detail in the references cited above. This target is connected in parallel with a scoring circuit which comprises the parallel combination of a rectifier diode 15 and electrical relay 16, both of which are serially connected with a capacitor 17. The actuation of relay 16 causes the energizing of an electrically operated indicating means, counter 18, which in its actuated position derives its power from the voltage source 11.

The operation of this circuit may be visualized as follows:

When the target is in its normal condition, i. e electrodes 13 and 14 insulated from one another, source 11 which for the purpose of illustration is assumed to be 40 volts, is applied to the target. Also capacitor 17, asstuned to be 1 mfd. is charged to the supply voltage via resistor 12, assumed to be 50 ohms. If due to rain, snow, or other environmental condition a leakage exists across the target, that is a leakage resistance across electrodes 13 and 14, electrode 13 is still maintained at a positive voltage but its magnitude is reduced by the voltage drop across the series resistor 12. The same applies for capacitor 17.

Upon the passage of a bullet through the target, capacitor 17 discharges through the pat h comprising electrode 13, electrode 14 and rectifier 15. Since the short-circuit between electrodes 13 and 14 exists for a fraction of a second only, it is important that rectifier 15 have a very low forward resistance, so that the capacitor is substantially discharged during the time the target is shorted. It has been found that this can be achieved exceedingly well for instance by the use of a germanium diflused junction diode type 1N93 commercially available from the General Electric Company, Schenectady, New York. This rectifier is characterized by an extremely low forward resistance in the order of 10 ohms under the conditions used, and by the ability of permitting the passing of a high peak forward current.

After the bullet has passed through the target and the short circuit has disappeared capacitor 17 is slowly charged up to full voltage via the circuit comprising resistor 12, capacitor 17 and relay 1d. The relay is is a relay of the type usually employed in anode circuits of vacuum tubes having for the purpose of illustration a rating of 8000 ohms and 2 milliamperes. Vt/bile capacitor is being charged, current flows through relay 16 which actuates counter 18 to register a hit. The relay automatically disconnects the counter 18 as soon as the current through the relay coil decreases to the drop-out value and shortly thereafter capacitor 17 is fully charged so that the entire circuit is reset. The charging time of the capacitor is determined by the time constant comprising the size of the capacitor and the resistance value of the relay coil and the series resistor. From the foregoing it will be apparent that the counter is actuated not while the bullet passes through the target but during the charge time of capacitor 17 thus obtaining a greater length of time. The diode employed in the circuit requires no standby power, is extremely compact and as far as it is known has a practically unlimited life. With the values as shown it has been found that the resistance between electrodes 13 and 14 of the target may deteriorate from several thousand ohms to approximately 150 ohms without impairing the operation and reliability of the circuit.

Although the above description and drawing states certain values for the components used, it will be evident to those skilled in the art that the components may be varied within wide limits without affecting the operation and reliability of the circuit and that, the values stated are intended only for illustrative purposes.

While there has been described a certain preferred embodiment of the invention it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the field of the invention which should be limited only by the scopeof the appended claims.

What is claimed is:

1. A scoring circuit fora target having a set of spaced electrodes which become momentarily short-circuited by a bullet passing therethrough comprising; a source of voltage connected to the electrodes of said target rendering. one electrode of positive and the other electrode of negative potential; an electrical network including the winding of an electrical relay and a rectifier in parallel and a capacitor connected serially with said, rectifier and winding; said network connected in parallel with said target and said source thereby causing said capacitor to be maintained normally charged with electrical potential; said rectifier connected so as to permit passage of current therethrough from the normally positive to the normally negative target electrode via said capacitor to cause said capacitor to discharge in response to the bullet establishing a short circuit between said target electrodes; said rectifier having a sufficiently low resistance in the direction of current fiow to cause substantial discharging of said capacitor during the momentary short circuit condition across said target electrodes; said relay having characteristics such that it Will not operate in response to discharge current, and an indicating device operated in response to the current flow through the coil of said relay when said capacitor is being restored to its charged condition.

2. A scoring circuit for a target having a set of spaced electrodes which become momentarily short-circuited by a bullet passing therethrough comprising; a source of direct current voltage connected to the electrodes of said target rendering one electrode of positive and the other electrode of negative potential; an electrical network including the winding of an electromagnetic relay and a solid state rectifier in parallel and a capacitor connected serially with said rectifier and winding; said network connected in parallel with said target and said source thereby causing said capacitor to be maintained normally charged with electrical potential; said rectifier connected so as to permit passage of current therethrough from the normally positive to the normally negative target electrode via said capacitor to cause said capacitor to discharge in response to the bullet establishing a short circuit between said target electrodes; said rectifier having a sufiiciently low resistance in the direction of current flow to cause substantial discharging of said capacitor during the momentary short circuit condition across said target electrodes; said relay having characteristics such that it will not operate in response to discharge current, and an indicating device operated in response to the current fiow through the coil of said relay when said capacitor is being restored to its charged condition.

3, A scoring circuit as set forth in claim 2 wherein said rectifier is a diffused junction rectifier.

4. A scoring circuit as set forth in claim 2 wherein said indicating device is a counter.

5. A scoring circuit for a target having a set of spaced metallic electrodes which become momentarily shortcircuited by a bullet passing therethrough comprising; a

source of direct current voltage connected via a. resistor to the electrodes of said target rendering one electrode of positive and the other electrode of negative potential; an electrical network including the winding of an electromagnetic relay and a diode rectifier in parallel and a capacitor connected serially with said rectifier and winding; said network connected in parallel with said target and said source thereby causing said capacitor to be maintained normally charged with electrical potential; said rectifier connected so as to permit passage of current therethrough from the target electrodes via saidcapacitor to cause said capacitor to discharge in response to the bullet establishing a short circuit between said target electrodes; said rectifier having a sufficiently low resist ance in the direction of current flow to cause substantial discharging of said capacitor during the momentary short circuit condition across said target electrodes; said relay having characteristics such that it will not operate in response to discharge current, and an indicating device operated in response to the current flow through the coil of said relay when said capacitor is being restored to charged condition.

References Cited in the file of this patent UNITED STATES PATENTS 2,080,273 Holmes May 1.1 1937 2,146,863 Stansbury Feb. 14-, 1939 2,347,481 Hooven Apr. 25, 1944. 2,749,123 Ream June 5,, 1956 2,749,124 Ream June 5, 1956 2,749,125 Ream June 5, 1956

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