CA1115767A - Apparatus for generating electric shock pulses - Google Patents

Abstract

Abstract of the Disclosure:
An apparatus for generating electric pulses is disclosed. The apparatus comprise a gene-rator or oscillator for charging a storage capacitor and a control circuit for controlling the discharge of the capacitor through an out-put or discharge circuit which includes a con-trollable switch device and two output termi-nals or electrodes. In an embodiment, the output circuit also includes a high voltage output pulse transformer.
Whenever a load resistance exists or occurs between the two output electrodes, a particular detector current will flow through the load resistance and through a specific detector or load sensing circuit in the apparatus. This detector current indicating that an external load resistance is present, will automatically start the charging generator which then will operate to charge and recharge the storage capacitor as long as the detector current exists, i.e. 85 long as the external load is present.

Description

`` l~.lS~7 This invention relates to apparatus for generating electric shock pulses.
A known apparatus for generating electric shock pulses comprises a power source, a generator for charging a capacitor, and a control circuit for controlling the discharge at a predetermined voltage level of said capacitor through a discharge circuit including a controllable switch device and two output terminals.
In, for example, slaughterhouses, such apparatuses, designed as hand tools are used when the animals are driven from the receiving folds and into the slaughtering rooms. The hand tool is similar in shape and size to an electric torch and the two output terminals are arranged as two freely projecting electrodes at the outermost end of the tool.
In the interior of the apparatus, there is a battery-powered generator and when the two electrodes are pressed against the body of an animal, the animal is subjected to an-electric shock. In order that the apparatus does not consume significant battery power in the intervals between each use, a switch is provided which may be finger operated. Most often, the switch is, however, associated with the electrode and if so these are mounted so as !to be movable against spring forces, whereby a switch is automatically closed, when the electrodes are pressed against an animal.
Such a switch does however have a number of drawbacks, whether finger operated or electrode operated. A finger operated switch is inconvenient to use and may fatigue the user's fingers.
If, for that reason, the user omits to open the switch between each use, unnecessary consumption of battery power will result.
Furthermore, the switch is sub~ected to wear, not least because of the rather dirty surroundings, and this necessitates that a finger operated switch be arranged in a water-proof and dust-proof manner which is a problem in itself.

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In apparatuses having an electrode operated switch, the electrodes are made so that they may slide telescopically in a guide against spring forces. EIere the dirty surroundings quickly lead to functional problems due to intrusion of dirt.
More~ver, since the apparatus may well be handled rather roughly and very probably, be dropped on the floor periodically, the sliding electrodes easily become bent or dirty and get stuck~ In other words, such electrodes are very vulnerable mechanical elements.
According to the present invention there is provided an apparatus for generating electric shock pulses, the apparatus comprises a power source, a generator for charging a capacitor;
and a control circuit for controlling the discharge at a pre-determined voltage level of said capacitor through a discharge circuit including a controllable switch device and at least two output terminals, characterized by further comprising a detec tor circuit connected and arranged in such a manner that a detector current will flow from said power source and through an external load as soon as such a load occurs across said out-put terminals, said detector circuit comprising means which, responsive to said detector current, provide a starting signal for rendering said charging generator operative.
The sensing circuit in embodiments of apparatus accord-ing to the invention will automatically establish whether an external load exists between the OlltpUt electrodes, and si~-nficiant power consumption w;11 only take place when such an external Load exists. Thus the power consumption may be minim-ised and when the apparatus is used as or in a hand tool of the type mentioned aboYe, mechanical switches and movable parts may, in addition, be completely avoided, and such a tool may easily be encapsulated effectively in a water-proof and dust-proof manner.
The invention will now be described by way of examp7e .

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with reference to the accompanying drawings, in which:
Figure 1 is a block diagram schematically illustrating the main parts of an apparatus according to the invention:
Figure 2 is a circuit diagram illustrating an embodiment of the apparatus according to the invention, Figure 3 is a schematic illustration of an embodiment of the apparatus according to the invention arranged as a pulse generating device for an electric wire fence; and Figure 4 is a schematic illustration of another embodi-ment of the apparatus according to the invention.
Figure 1 illustrates the basic concepts of an apparatusaccording to the invention. The main components shown are a power source (+V), a..generator 1, a capacitor C, a control circuit 2, a controllable switch device 3, a detector or load sensing circuit 4, and two electrodes or output terminals A and B.
- Referring to Figure 1, the basic operation of the illus-trated apparatus according to the invention is as follows:
When a manually operated main breaker K is closed, the apparatus is ready for use. If there is an external load across the electrodes A and B or as soon as such a load occurs, a detector current will flow from the power source, past or through the generator 1 (as shown in dotted lines), through the external load, and through the detector circuit 4 back to the power source.
Accordingly, this detector current will indicate that an external load is present between the electrodes A and B.
~ he detector current causes the detector circuit 4 to ..~ apply a pulse or signal through a connexion 5 to the` generator 1 whereby the generator 1 is actuated to charge the capacitor C. When the capacitor C has been charged to a predetermined voltage, the control circuit 2 causes the capacitor C to discharge through a switch device 3 and the external load between the electrodes A and B.
If the external load is still present after such a first ~ .

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capacitor discharge, the capacitor C is recharged and a new current shock is applied through the external load.
It wili be noted that the generator 1 is only actuated when an external load is present. If the main breaker K is closed at an earlier time, that is, when an external load is not present between electrodes A and B, nothing will happen in the apparatus. The apparatus may, however, also be construc-ed so that the generator 1 is started immediately the main breaker K is closed, whether an external load is present or not. Thereby, the capacitor C will be charged and, thus, the capacitor C remains in the charged condition until an external load occurs between the electrodes A and B, whereupon the discharge and recharging of the capacitor C take place as ex-plained above.
Apart from the above first or initial charging, if any, of the capacitor C, the generator 1 will only be started when there is an external load between the electrodes A and B which provides the detector current mentioned above. Thus significant power consumption will only take place when and while an external load is present.
Certain types of generators will, however, continue operation automatically after initial starting. If the apparatus comprises a generator of that type, the generator will continue to operate after the external load has been removed and the detector current ceases to flow. In particular, but not exclu-sively, in such cases, it is desirable that the apparatus comprises specific means for stopping the generator, when or after that the capacitor C has been charged to a predetermined value. Such means may appropriately be a part of or be com-bined with the control circuit 2 which already senses or controlsthe capacitor voltage. A stop signal connexion 6 is indicated in Figure 1.
Referring now th Figure 2, the generator of the embodiment ~, . ~ ... . .
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`illustrated is arranged as a resonance oscillator comprising resistors Rl, R2, and R3, a transofrmer TR, a transistor Tl and a diode Dl.
In the generator, the transformer TR is charged with magnetic energy while the transistor Tl is in the conducting condition. When the transistor Tl is blocked, the magnetic energy is converted into electric energy, which is stored in the capacitor C. The resistor R2 is only necessary to start the oscillator.
In Figure 2, the control circuit (2 in Figure 1) comprises resistors R5, R7 and R8, a capacitor C2 and a glow tube G. The detector or load sensing circuit (4 in Figure 1) comprises resistors R9 and R10, a transistor T4 and a resistor R4. The switch device (3 in Figure 1) is a transistor T5.
If the main breaker K in the apparatus of Figure 2 is closed while there is no load resistance RB between the elec-trodes A and B, nothing will happen in the apparatus and thus there is no power consumption.
If on the other hand, a load resistance RB is present when the breaker K is closed, or if such a resistance occurs while the breaker K is in its closed condition, a current will flow through the diode D2, a resistor R6 and the load resistance RB. This current flows on through the resistor R9 and to the base of the transistor T4. The transistor T4 will become conductive and draw current through the resistor R4 and the base of a transistor T3, which is in the input of the generator.
Thereby, the transistor T3 will become conductive and the generator will start and will continue to operate as long as the external load RB is present between the electrodes A and B.
When the generator operates, the capacitor C will be charged and in the control circuit the capacitor C2 ~ill be charged to the firing voltage of a glow tube G, which is fired thereby so that the capacitor C2 is discharged through resistors R7 and R8 and the base of transistor T5. The transistor T5 then -- , .

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becomes conductive and the capacitor C is able to discharge through the resistor R6 and the external load resistance RB.
When the load resistance RB is removed, the generator may in principle continue to operate, since it is self-supplying via the feedback winding. In order to stop the generator, there is inserted a transistor T2 between the base and the emitter of the transistor Tl.
When the load resistance RB is removed, the control circuit will continue to apply pulses through the glow tube G
10 and thereby to the base of transistor T2. Thus the transistor ;~-T2 will become saturated so that the potential of the base of the transistor Tl will fall to a level so low that the generator will stop.
The diode D2 is only necessary in order to start the generator in the case that the capacitor C has been completely discharged. Simultaneously, the diode D2 serves to block for high voltage on the output. -In some cases, as already mentioned, the generator maystart at once when the brea~er K is closed, regardless of whether there is an external load between the electrodes A and B
or not. To that end, a capacitor may, for example as indicated in dotted lines in Figure 2, be connected as a shunt across the transistor T3. This capacitor will be charged to the battery voltage and provide a charging pulse to start the generator. -If no load resistance is present between the electrodes A and B, the generator will stop in the same manner as explained above, since the shunt capacitor remains fully charged and the transis-tor T3 is blocked. `
In the embodiment of Figure 2, the presence of the load resistance RB between the electrodes A and B will, accordingly,at any time provide a current through the detector or load sensing circuit. This detector current will, via the detector circuit transistor T4, result in the transistor T3 which serves as a controlled switch device in the input of the generator, ~. .

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~.157~;7 being rendered conductive and being maintained conductive when and as long as the detector current exists, that is as long as the external load RB is present.
The embodiment according to Figure 2 is suitable for use as or in an electric shock generator designed as a battery powered hand tool (a so-called electric driver), since the power consumption is minimized and since there is no need of a hand or electrode operated switch means, including vulnerable movable components. Moreover~ the tool may be effectively encapsulated in a dust-proof and damp-proof housing.
Moreover, embodiments of apparatus according to the invention are also suitable for use as the pulse generating device for an electric wire fence, as indicated schematically in Figure 3.
In that case, one of the electrodes A or B is connected to ground, whereas the other electrode B or A is connected to the fence wire. The generator will be able to charge the -capacitor up to a voltage of 5,000 volts and an output pulse transformer is not necessary. The switch device 3 should be a high voltage switch for example a reed-relay.
Figure 4 shows schematically a further embodiment of the apparatus according to the invention. Components or parts corresponding to similar components in Figure 1 or 2 have been assigned the same reference designations.
In Figure 4, the generator 1 and the control circuit 2 are only shown as respective blocks as in Figure 1, but the generator and/or the control circuit may be arranged as shown and explained in connexion with Figure 2.
Although only illustrated in Figure 4 as comprising an adjustable resistance R9 and a transistor T6, the detector or load sensing circuit (4 in Figure 1) may also be arranged as illustrated and explained in connexion with Figure 2. However, the transistor T6 should, preferably, have a large current gain.
A so-called Darlington configuration transistor arrangement is : . . . ~.
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suitable as the transistor T6.
The essential difference relative to the Figure 2 embodiment resides in the fact that in Figure 4, a particular output circuit has been provided including a high voltage pulse transformer T~p. The output circuit further includes a capacitor C3 and a diode D3. The diode D3 and the capacitor C3 are arranged to block off the direct current from the battery Vb so that this current is conducted through the external load resis-tance RB, if or when such a load is present. The diode D3 and the capacitor C3 of the output circuit may, accordingly, be considered as being a part of the detector or load sensing circuit (4 in Figure 1).
The diode D3 may be Dmitted, but in that case, the capacitor C3 would have to be inconveniently large in order to render the pulse voltage drop thereacross negligible.
In Figure 4, the controllable or voltage-controlled switch device (3 in Figure 1) is comprised by a thyristor Th. -Moreover, the generator input or starting transistor T3 in the Figure 2 embodiment has been replaced by an electromagnetic ~0 relay switch KRe. A proper on/off effect as provided by the relay switch KRe is desirable as far as the starting circuit for the generator 1 is concerned. However, if desired or appropriate, the starting pulse or signal for the generator may also be provided by a starting circuit including transistors.
Referring to Figure 4, the embodiment shown operates as follows:
When the resistance between the electrodes A and B is large, for example when no external load resistance RB is present, the direct current which is able to flow from the battery Vb, via the diode Dl, through the secondary winding of the pulse transformer TRp, and through the load resistance RB to the base of transistor T6, will be small or zero, and will not be suffic-ient to bring the transistor T6 into saturation.
However, with decreasing resistance between the electrodes . ~ ,. ..

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` 1~ 1S'7~7 A and B, the base current of the transistor T6 will increase, whereby the collector current will increase which, in turn, will cause the relay switch KRe to close at a certain time.
The generator 1 will now operate and charge the cap-acitor C to a predetermined value, whereafter the control device2 will fire the thyristor Th. Thereby~ the capacitor C will dis-charge through the primary winding of the pulse transformer TRp, and a high voltage pulse will be generated in the secondary winding of the pulse transformer TRp.
With the diode D3 and with a properly polarized second-ary winding in the pulse transformer TRp, the positive portion of the high voltage pulse will flow through the load resistance RB and back through the diode D3, whereas the negative pulse ;
portion will be shunted via capacitor C3.
The generator 1 will continue to operate and the apparatus will generate repeated high voltage pulses across the load resistance RB as long as the resistance value thereof is sufficiently low.
The embodiment of Figure 4 is suitable for use both as a pulse generator device for electric wire fences and as or in a hand held driver tool without vulnerable movable mechanical components, and it may be effectively encapsulated in a dust-proof and damp-proof housing.
The advantage of embodiments of apparatus according to the invention as regards low power consumption will be most outstanding in conne~ion with battery-powered apparatuses.
However, there is nothing to prevent the apparatus according to the invention being provided with other types of power sources.

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Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. An apparatus for generating electric shock pulses comprising a power source, a generator for charging a capacitor, and a control circuit for controlling the discharge at a predetermined voltage level of said capacitor through a dis-charge circuit including a controllable switch device and at least two output terminals, characterized by further comprising a detector circuit connected and arranged in such a manner that a detector current will flow from said power source and through an external load as soon as such a load occurs across said output terminals, said detector circuit comprising means which, responsive to said detector current, provide a starting signal for rendering said charging generator operative.

2. The apparatus as defined in claim 1 further charac-terized in that said starting signal providing means comprise a switch device which is rendered conductive by said detector current and which thereby applies a closing signal to a switch device associated with the input of said charging generator, whereby said input switch device is kept closed as long as said detector current exists.

3. The apparatus as defined in claim 2, further charact-erized by a capacitor connected in a shunt over said generator input switch device for further enabling said generator to initially charge said capacitor regardless of whether a load is connected to said output terminals.

4. The apparatus as defined in claim 2, further charact-erized in that said generator input switch device is an electro-magnetically operated relay switch.

5. The apparatus as defined in claim 4, further charact-erized in that said control circuit comprises means for stopping said charging generator, when said capacitor has been charged to a predetermined voltage level.

6. The apparatus as defined in any of claims 1, 2 or 3, further characterized in that said control circuit comprises means for stopping said charging generator, when said capacitor has been charged to a prederermined voltage level.

7. The apparatus as defined in claim 4, characterized in that said discharge circuit further comprises a high voltage output pulse transformer.

8. The apparatus as defined in any of claims 1, 2 or 3, characterized in that said discharge circuit further comprises a high voltage output pulse transformer.

9. The apparatus as defined in claim 5, wherein said discharge circuit further comprises a high voltage output transformer.