GB2290483A - Simulated weapon - Google Patents

Abstract

A simulated weapon (10) suitable for use as an advanced toy and in professional games and training applications comprises a directional transmitter (11, 13, 15) which emits an offensive signal simulating firing of the weapon, and an omnidirectional receiver (21) for receiving the offensive signal of another weapon. Upon registering such a received signal a reply signal is generated and broadcast by an omni-directional transmitter (22). A directional receiver (12, 14, 16) for the reply signal, sharing a common field of view with the directional transmitter, provides the weapon from which the offensive signal originated, and none other, with the powerful capability of monitoring the effect of its offensive signal. The offensive signal, can be replaced by one having a function of identity-interrogation, range-finding, or carrying voice communication. Many weapon variations are described. <IMAGE>

Description

SIMULATED WEAPON The invention relates generally to simulated weapons, and more specifically to toy weapons and games played therewith.

A simulated weapon is a device whose operation at least to some extent simulates that of an actual weapon, but without the potential for causing damage or injury. Such devices find a variety of applications, including use as toys and in sports and other leisure activities, both indoor and outdoor.

The key event to be simulated is ordinarily the firing of one or a number of projectiles, such as a bullet in the case of a gun. This is usually done by generating a signal beam, the path of the beam simulating the trajectory and the signal itself simulating the projectile. The beam is typically infrared light, though ultrasound is sometimes used.

Secondary events, such as those associated with the triggering of the weapon or the impact of a projectile on a target, can also be simulated, by means of visual and audible effects.

A considerable number of light-emitting guns or gun-like devices of this type have been proposed over the past decade or so. Certainly a lesser number have reached the stage of being manufactured, and so far market success has largely eluded the manufacturers.

In several cases, the guns were so unsophisticated that they were just not interesting to use, both to adults in their more advanced forms and to children in their simpler versions, with the result that users very quickly became bored. In addition, many of the guns were not robustly made and failed early. More advanced guns, utilising lasers, are currently available only to franchisees operating in the main at indoor leisure sites. The present versions of these laser guns are expensive. They are also reportedly of somewhat delicate construction and not wholly reliable. The indoor games are conducted in semidarkness with an artificially-created foggy atmosphere, the lasers having a purely cosmetic function which is to flash a narrow beam of laser light, seen cutting through the mist, onto a targeted player as the gun is fired.The actual bullet signal is a pulse of non-laser infrared light.

The known simulated weapons appear to fall broadly into two categories of system. In a first, the weapon equipment comprises a receiver which detects reflection from a passive reflective target of the "projectile" signal emitted by the weapon, enabling the weapon to register hits it makes on the target. In a second category, the target equipment comprises a receiver which directly detects the "projectile" signal, emitted by a weapon, enabling the target to indicate hits which it suffers, for example by producing local visual and/or audible signals of an impact. The invention is concerned particularly, although not exclusively, with this second category of simulated weapon system.

In view of the prior art, it is desirable to provide a simulated weapon of versatile function, which is reliable yet affordable, and usable in a variety of environments.

The invention is defined in the claims.

One embodiment of the invention is a hand-held or at least personally-operated weapon, specifically a gun.

Another embodiment of the invention is a selfsupporting weapon of an autonomous nature, having no or no direct human operator. In the description this weapon is called a "mine", which term is apposite in view of one of its independently inventive features.

In one aspect the invention provides what may be regarded as a "handshake" between the weapon and the target. The features and advantages are mentioned later. Briefly, the projectile transmitted by the weapon is received and processed by the target and the target transmits a message to the weapon in reply.

The process is automatic and quick, and advantageously, information as to the fate of the projectile becomes available at both the weapon and the target ends. In an exchange of fire between two weapons, where each weapon also acts as a target, the handshake is particularly convenient for scoring purposes.

Preferably, the outgoing weapon signal is transmitted directionally, that is to say practically limited to one direction and the replying target signal is transmitted or "broadcast" nondirectionally, that is to say not restricted to any particular direction. The reply signal is received directionally by the weapon which remains, at least for a short while after firing, aimed at the target.

The directional reception and timing of the reply signal ensure that only the initiating weapon will validly register the reply.

In another aspect of the invention, the same principle is exploited for a different purpose, that of establishing the identity of the target. The same hardware and the same signalling process are used; only the transmitted message or a portion thereof needs to be changed.

Preferably, in both these aspects, all messages carry an identification of the source weapon/target.

A further aspect of the invention establishes a logical or virtual range of the weapon signal which is shorter than a physical or actual range. The early part of the weapon signal is transmitted at a lower power (hence shorter range) than the later or concluding part of the signal. A condition is determined by the reception or non-reception of the early part of the signal (in addition to the later or concluding part), which depends on whether the target is within the logical range. One interesting application of this feature is the capability of registering a "miss" or "near-miss" on the target when it is beyond the logical range, whether by virtue of the weapon-to-target distance or because the target detects only the "edge" of the weapon signal beam because the weapon is poorly aimed.Here, in principle it is not necessary for the target to generate a reply, since the extent of reception of the weapon signal at the target provides novel and useful information in itself. Advantageously though the information is coded into a reply message transmitted by the target.

A still further aspect of the invention enables a voice communication facility to be provided on a gun in a unique way. A beam ordinarily modulated with the bullet signal is exploited for alternatively carrying the audio signal. This technique combines the advantages of high directionality (which is good for security of transmission and reducing power consumption) and a saving of hardware.

Many people find a conventional open gun-sight in which one must align foresight blade, backsight notch and target, difficult to use. A telescopic sight is easier, but can still be troublesome, especially for children in the case of a toy. Also, both these types of sight lose effectiveness in poor or dark light.

The invention provides a sighting device, of general application, which solves these problems. The device is used with both eyes open, does not call for a conscious short-range focusing effort on the part of the user, and works in a variety of light conditions.

We, and especially our children, live in the video age. In recent years, concern has been expressed at the lack of physical activity of many of today's youngsters, especially since habits formed in childhood tend to set the pattern for later life.

Accordingly, in the context of toys for children, it is desirable to provide a game which encourages the player or players to run around. The invention embodied by the mine meets this objective with flying colours. The mine provides a formidable opponent for a gun-carrying player. Unlike another human participant whose actions and movements are often predictable, the mine has a more erratic character.

It emits an offensive surrounding explosion signal at short range, which normally prevents the player from reaching its de-activating switch. A further obstacle is the generally random swing and fire of its cannon.

The player must not only dodge the cannon (which becomes harder to do the closer he gets to the mine), but must also shoot at the mine, for example a preset number of times, to stop the explosion, thereby removing the effective exclusion field in the near vicinity of the mine. Even then, as he dashes towards the mine switch, the explosion may suddenly reappear.

Thus, the mine combines the attractions of electronics with a real need for movement to avoid the active mine's barrage of fire if the game is to be won.

By way of example only, two principal embodiments of the invention will be described in detail with reference to the accompanying drawings in which: Fig. 1 shows a plan, a side and two end pictorial views of a gun in accordance with the first principal embodiment; Fig. 2 shows an enlargement of one of the end views of Fig. 1; Fig. 3 shows a sectional view of a sighting device provided on the gun of Fig. 1; Fig. 4A shows a sectional view of a development of the sighting device of Fig. 3; Fig. 4B shows an information display viewed through the sighting device of Fig. 4A; Fig. 5 shows a part-sectional view of a recoil mechanism provided on the gun of Fig. 1; Figs. 6 and 7 show respective side and plan pictorial views of an automatic mine in accordance with the second principal embodiment;; Fig. 8 shows another plan view of the mine with a movable turret thereof in a different position to that of Fig. 7; Fig. 9 illustrates a direction-finding function of the mine of Fig. 6; Fig. 10 is a schematic diagram of the functional components of one version of the gun of Fig. 1; Fig. 11 is a schematic diagram of the functional components of another version of the gun of Fig. 1; Fig. 12 is a schematic diagram of the functional components of the mine of Fig. 6; Fig. 13 illustrates long-range communications among two guns and a mine; and Fig. 14 illustrates short-range transmissions of a mine.

Fig. 1 shows a light emitting and receiving electronic toy gun 10. Light in the infrared, specifically near infrared region of the spectrum is used in this embodiment for the advantages of operation in a wide range of ambient light conditions, the ease of achieving directionality, the availability and reasonable cost of the necessary optical and electronic components, and of eye safety. The gun 10 comprises a moulded plastics body which incorporates a first cylindrical telescope 11 and a second cylindrical telescope 12 of a greater diameter (in this embodiment) disposed adjacently above and parallel to the first telescope 11.

The first telescope 11 has a converging lens 13 secured at its outer end (leftmost in the side view of Fig. 1). An infrared light-emitting diode (15, Fig.

10) is mounted at the inner (rightmost) end of the telescope 11 at the focal point of the lens 13. This first telescope 11 thus constitutes an emitting means for emitting, when the diode is energised, a narrow beam of infrared light in the direction in which the telescope 11, like the barrel of an actual gun, is aimed.

The second telescope 12 has a similar structure with a converging lens 14 at its outer end, except that an infrared photodetecting diode (16, Fig. 10) is instead mounted at the focal point of the lens 14.

This second telescope 12 thus constitutes a receiving means for receiving an infrared signal emitted by a second gun at which the first gun is pointed. The receiving telescope 12 has a broader response pattern than the beam pattern of the emitting telescope 11, for reasons which will become apparent.

The diodes 15, 16 are standard, low-power devices. The lenses 13, 14 are preferably plastic, e.g. acrylic.

The body of the gun includes a handle 17 in which a trigger 18 for "firing" the gun is mounted. The trigger 18 is linked to a mechanism 90 disposed beneath the body of the gun and the lower telescope 11, which needs a pump action to cock the gun before it can be fired, and which provides a recoil shock to the user on release. The mechanism 90 is described later with reference to Fig. 5. The gun may also be provided with a detachable stock (not shown) secured to the rear of the gun and held against the user's body in further imitation of an actual weapon.

A small translucent plastics dome disposed on the top and toward the front of the upper telescope 12 covers a cluster of six infrared photodetecting diodes 21 which constitute a second receiving means for infrared signals. (Four diodes 21 are shown in Fig.

10 for convenience of illustration only.) The plastics dome protects the diodes and may also serve as a light diffuser. The diodes 21 provide a wide response pattern (as compared to the directional sensitivity of the receiving telescope 12), which for convenience only will be referred to herein as "omnidirectional". A truly "omni" response will not normally be necessary (and may even be undesirable); for most applications the diodes 21 need only cover directions to the front and both sides of the gun within a reasonable range of height.

In similar manner to the omni-receivers 21 a further four domes each cover this time a pair of infrared light-emitting diodes 22. (Four of the eight diodes in total are shown in Fig. 10 for convenience of illustration only.) The emitting domes are provided two on the upper telescope 12 on the left and right sides thereof neighbouring the receiving dome 21, and two on the body of the gun on the left and right sides thereof to the rear of the telescopes 11, 12. The eight emitting diodes 22 constitute a second emitting means, for broadcasting infrared signals in a wide overall emission pattern (as compared to the directional beam of the emitting telescope 11), which again for convenience only will be referred to herein as "omnidirectional". The previous comment on the meaning of "omni" applies equally here.

Although experiment has demonstrated that this particular arrangement of the locations and numbers of the omni-receivers 21 and the omni-emitters 22 is effective, alternative workable arrangements are realisable. It is technically advantageous to use just one cluster of the receiving diodes 21, since then only a single feed is necessary, which reduces noise.

The special function of the infrared light emitters and receivers on the gun will now be explained with reference to Fig. 13. For present purposes, only the two guns 10', 10" in Fig. 13 need be considered; the device 100 shown in the bottom right-hand corner of the figure should be ignored for now. The guns 10', 10'' are each constructed as already described for the gun 10 of Fig. 1.

In a game of simulated man-to-man combat, two players each hold one gun. Assume that player 1 holds gun 10' and decides to take a shot at player 2 who holds gun 10". Player 1 aims his gun 10' (by pointing the barrel-like telescopes) at player 2, and operates the trigger 18. In response, the gun 10' emits from its emitting telescope 11' a narrow beam of infrared light modulated with a data signal which effectively says "I am a bullet".Provided the aim is good and player 2 is within range, the omni-receiver 21'' on player 2's gun 10'' receives the "bullet" signal, and decodes and registers it as a hit by means of circuitry within the gun 10''. In a manner characteristic to this embodiment, in response to the recognised "bullet" signal, the gun 10'' generates and emits from its omni-emitters 22" a data signal in reply which effectively says "I am hit". This acknowledgement signal is received by the receiving telescope 12' of player l's gun 10' still pointed at the second player.The broader response pattern of the receiving telescope as compared to the beam pattern of the emitting telescope allows for some deviation of the orientation of the gun 10' between the instants of firing the "bullet" and receiving the return acknowledgement of its "impact", although the delay is small anyway, of the order of 60 ms in this embodiment.

This "answer-back" function of the gun makes both players aware immediately, by means of a display and/or other indicators, audible and visible, provided on their guns, that the second player has been hit.

And there is no room for argument; the electronics does not lie. In the applicant's knowledge, such a function has not previously been realised or even contemplated in such a simulated weapon system. In a known system corresponding to the aforementioned second category, only the equipment carried or worn by the player who has been hit produces indications of the hit, normally in the form of visual and/or audible effects. Therefore, the player who fired his weapon can only assess his performance by looking/listening out for the visual/audible effects that may be generated by the other player's equipment. The ambient noise levels and light conditions will often make such an assessment difficult, especially when there is a reasonable distance between the players.

The transient nature of the hit indications only exacerbates the situation, all of which makes cheating easy. A system has been proposed for organised leisure games in purpose-built environments, in which hit information is transmitted to a master scoreboard.

However, such a system is complex and far too expensive at least for a use-anywhere type of device such as a toy gun, since it calls for a second communication link between the players and the scoreboard computer.

The gun of the present embodiment suffers none of these shortcomings, since it provides immediate feedback to each player of his performance in the game, encouraging and motivating his active participation.

Also, the impact of a personal display or signal on the player's gun of a successful shot exceeds that of any remote scoreboard. Furthermore, the answer-back function is a powerful one whose basic principle can be modified or adopted for the communication of different types of information, whether related to or independent of the bullet/impact signalling. Some examples will be described later.

In the scenario just described with reference to Fig. 13, the gun 10' of player 1 acts as a weapon and the gun 10'' of player 2 acts as a target, in an embodiment of a simulated weapon system. If player 2 shoots back, his gun 10'' will act as the weapon and the gun 10' as the target. Although, as described, each gun 10 combines the different features which perform the functions of the weapon and of the target, that is not essential to the system principle.

The basic picture of the gun 10 will now be completed, followed by a description of the internal circuitry and an explanation of the inter-gun signalling.

The body of the gun houses a circuit board (not shown) on which are mounted transmitting and receiving circuitry associated with the emitting telescope 11, receiving telescope 12, omni-emitters 22 and omnireceivers 21, and a microprocessor 23 (see Fig. 10).

The microprocessor 23 processes data signals received by the telescope 12 and the omni-receivers 21 and command signals input by operation of the trigger 18 and other control buttons of the gun, and generates in response data signals to be emitted by the telescope 11 and the omni-emitters 22 and drive signals for a display and various devices providing visual and audible indications and effects. A suitable device for microprocessor 23 is the Hitachi type H8 processor.

In this embodiment, the display comprises a 3- or 4-digit 7-segment LED 24 provided at the back of the gun facing the user. A library of sound effects is stored in a memory 25, suitably an EPROM. The microprocessor 23 provides an address to the memory 25 to read out the stored data appropriate for a desired sound, which is then supplied as an audio signal to a loudspeaker 28 after digital-to-analogue conversion and amplification by the components 26 and 27. The loudspeaker 28 is suitably located on one side of the gun, again facing the user. The microprocessor 23 also drives a standard (camera-type) xenon flash unit 29 mounted on the top of the gun. Other visual indicators 30 to 34 provide signals to the user as the gun is operated. Control buttons including the trigger 18 and a power on/off switch are collectively referenced 35 in Fig. 10.The whole gun is powered by an internal battery (not shown) which is preferably rechargeable, for example of nickel-cadmium type.

A special sight 70 (Fig. 1) mounted atop the body of the gun aids accurate aiming of the telescope 11 by providing a red "kill" dot 72 (Fig. 2) which must be located on the target. The sight will be described later with reference to Figs. 3 and 4.

Referring to Fig. 10, all the infrared diodes 15, 16, 21, 22 operate at a wavelength of 950 nm. The operations described with reference to Fig. 13 indicate that the inter-gun communication relies on outgoing transmission from the telescope diode 15 to the omni-detectors 21 and reply transmission from the omni-diodes 22 to the telescope detector 16.

Transmission from the omni-diodes 22 to the omnidetectors 21 is not used in this embodiment, since the range would be limited by noise. However, such a type of transmission is adopted in the second principal embodiment to be described, which makes specific use of the limited range.

The emitting diodes 15 and 22 are on/off (amplitude) modulated by a signal supplied on a line 39 and 38 respectively, which signal comprises a digital data signal impressed on a high-frequency carrier signal. The carrier signal is a squarewave generated internally in the microprocessor 23. The data signal and the carrier signal output by the microprocessor are combined externally thereof by a NOR gate (not shown). In this embodiment, the data rate is 2500 bit/s. The outgoing and reply communication channels use different carrier frequencies of 34 kHz and 23 kHz respectively. The carrier frequencies and the data rate of 2500 bit/s are chosen to be deliberately different to those of 38 kHz and 1200 bit/s commonly adopted in the remote control of TV and other consumer electronics, to reduce the likelihood of interference.

The drive electronics 40 for the omni-diodes 22 uses conventional transistor switches, suitably FETs, each connected between the supply rail and ground via a bias resistor which sets the LED 22 operating current. The drive electronics 41, 43 for the telescope diode 15 is basically the same, except that the bias resistor is replaced by a circuit 43 comprising a bank of resistors (here, six) wired up in parallel and each selectable by means of a respective transistor (here, FET) switch in series with the resistor. This arrangement enables the LED 15 operating current and hence its light output power level to be set to any of a number of discrete levels, according to the states of the series-wired transistors, selected by a control signal from the microprocessor on line 37.The reason for providing for control of the power level of the telescope 11 output will be explained shortly.

Turning to the receiving circuitry, the telescope detector diode 16 and the omni-detector diodes 21 are coupled to respective pre-amplifiers 45 and 46. To reduce the noise level the pre-amplifier 46 is located with the diode 16 in the telescope 12. The outputs of the pre-amplifiers 45, 46 are fed to respective bandpass filters 47, 48 on the circuit board, which have centre frequencies equal to the two carrier frequencies 34 kHz and 23 kHz of the outgoing and reply channels and bandwidths of each 2.5 kHz. The filtered signals are combined in an additive mixer 51 to the output of which is connected an AGC circuit 52, followed by a full-wave rectifier 53 which provides the digital input to the microprocessor on line 54.

As the schematic representation suggests, the squelch circuits 49, 50 serve to selectively ground the outputs of the filters 47, 48 under the control of the microprocessor 23 so as to effectively disable the omni- and telescope receivers. These circuits 49, 50, which may be suitably realised each by a simple FET switch, are used when an outgoing message has been sent in order to alleviate the effects of cross-talk between the outgoing and reply channels and of stray pick-up due to infrared reflections. Prior to a message being sent, both switches 49, 50 are closed to switch off the two receivers and the AGC gain of circuit 52 is set to an optimum level for the expected reply. After a delay of 5 ms from the end of the outgoing message, the telescope receiver is unsquelched by opening switch 50.Meanwhile the omnireceiver continues to be held off for a further period corresponding to the length of the expected reply message plus an additional short delay. Then, the omni-receiver is unsquelched by opening switch 49. If the outgoing message is such that no reply is expected, both receivers are unsquelched 5 ms plus an additional short delay after the end of the outgoing message. Critical adjustment of the timing of these operations, which can be established by experiment, brings a dramatic improvement in performance. Without the squelch circuits 49, 50, the outgoing message is liable to upset the AGC gain because of breakthrough, which may cause a weak reply message to be lost due to the slow recovery of the AGC circuit.

The squelch circuit 55 is another transistor switch arranged to effectively switch off the audio amplifier 27, under the control of the microprocessor 23, when no sound is to be produced. This saves unnecessary power consumption due to the amplifier's standing current.

The built-in ROM of the microprocessor 23 contains a control program which generates the outgoing and reply message signals for emission, processes the received incoming and reply message signals, and controls the display and effects. It is within the ordinary skill of the programmer to write a program which implements the functions described herein.

The message signals each comprise two prefix bytes followed by one, four, or more data bytes. The RS232 serial communication standard well-known in the computer art is adopted with minor exception. Each byte consists of the sequence of 1 START bit at logical 0, 8 data bits (least significant bit first) and 1 STOP bit at logical 1. The state "logical O" corresponds to the LED 15 or 22 being powered by a squarewave signal at the appropriate carrier frequency. The state "logical 1" corresponds to the LED being unpowered.

Byte 1 (the first of the two prefix bytes) is an AGC byte whose data component has value 128, i.e.

START + 7 'o's + 1 '1' + STOP or 0000000011. This sequence gives the receiver AGC circuit 52 plenty of time to settle and suppress the background noise. At this point, the receiver is not byte-synchronised to the incoming message.

Byte 2 (the second of the two prefix bytes) is a sync byte in which the LED is unpowered for the whole byte, i.e. 10 'l's. This byte is generated by transmitting value 255 and, as an exception to the RS232 standard, briefly turning the LED modulator off to modify the START bit to a '1'. With the tail of Byte 1, the sync byte provides 12 bit periods of uninterrupted silence. The AGC "hold" time is much longer than 12 bit periods, so subsequent bytes will be received with correct sync.

These two prefix bytes always precede a data byte or sequence of data bytes.

Byte 3, the first data byte, is either a range byte, or a lead-in byte which indicates that a full message follows. The lead-in byte has value 120 (hex 78) which, like the range bytes detailed below, is chosen for its low probability of occurring in noise, which tends to appear mostly as 'l's, i.e. LED unpowered, following the initial spike which triggered the receiver. Range bytes are not transmitted with reply signals.

Byte 4 follows a lead-in byte and contains the message type ("I am a bullet", etc.) coded in the least significant 5 bits. The other 3 bits may be used for other purposes.

Byte 5 is an ID byte containing an individual identity in the least significant 7 bits and a team (group) identity in the most significant bit, assigned to the gun sending the message.

Byte 6 is a check byte, the exclusive OR of Bytes 4 and 5. If the check reveals an error the whole message is ignored.

Further data bytes provide the potential for transmitting additional information, which may be useful, particularly for outgoing messages. For now, it is convenient to return to the gun-to-gun combat scenario to examine more closely the signals being exchanged.

To make full use of the hit information available to both guns thanks to the unique answer-back function, a system is desirable which can provide to each player an up-to-the-moment display of his "score". There are various possibilities, but the natural basis is to provide each player with the same initial predetermined number of points, "lives", and/ or "bullets" when the gun is switched on and to gain for hitting an opponent and to lose for being shot by him and for wasting a bullet when missing the opponent. The score may be held in the built-in memory (RAM) of the microprocessor in addition to being displayed.

This embodiment develops the basic scoring system to introduce a dynamic element to the game. Each player is initially assigned, say, 900 points and 1 point is deducted every second to provide, here, a nominal 15-minute countdown. Points are gained and lost in the same way as indicated above, but the everdiminishing score displayed continuously on the LED display 24 introduces an element of urgency and stimulates interest and participation.

The basic and the developed scoring systems are readily implemented in the control program by the ordinarily skilled programmer. In both systems, the game may be terminated either when a player loses all his points or, more preferably, at the expiry of a predetermined time-out period whereupon the currentlydisplayed score is temporarily frozen on each gun's display.

Referring again to Fig. 13, the two players switch on their guns, each of which, after a cosmetic display of a test pattern on the display 24, displays the countdown from 900 points generated by the microprocessor. The countdown may start immediately or may be initiated when the gun first emits or receives a signal. When player 1 pulls the trigger 18 on his gun 10' the microprocessor 23 generates on line 39 an outgoing message signal for emission by the telescope 11 which comprises the following sequence of bytes: Byte 1 (AGC), Byte 2 (sync), lead-in Byte 3, message type Byte 4 ("I am a bullet"), Byte 5 (sending gun's ID), Byte 6 (check). Range bytes are neglected here; the power control circuit 43 sets the bias of LED 15 so as to transmit at full power.

The 7-bit individual ID in Byte 5 may be programmed by the player, for example by depressing and holding down a control button on the gun, waiting until a desired player number has been counted on the display, and then releasing the button. However, it is convenient for the microprocessor to assign the individual ID by generating a random number either when the gun is first switched on or when it is first required to emit a message signal, whether outgoing or reply. The chances of two players being assigned the same 7-bit number in this way are not insignificant, so a routine may be included in the control program to change the ID if the processor receives a message signal containing an ID byte identical to its own.

The 1-bit team ID of Byte 5 is externally programmable by means of a wired plug 37 insertable into a socket on the gun. A miniature stereo hi-fi plug and socket are suitable.

The complete 6-byte outgoing message is received by the gun 10" via its omni-detectors 21" and the receiver constituted by the components 45, 47, 51, 52, 53. Byte 1 first sets the receiver AGC, then Byte 2 synchronises the microprocessor. The lead-in Byte 3 informs the processor that the message data follows.

Bytes 4 and 5 constitute the message and the check Byte 6 enables the processor to validate it. If the message is correctly received, it is registered by the processor 23 in gun 10'' which performs the following actions: i) the count on the display 24 is reduced by, say, 25 points; ii) a characteristic sound signal is output from the effects memory 25 to the speaker 28 to inform player 2 that he has been hit; iii) a reply message signal is generated and output on line 38 for broadcast by the omni-emitters 22''; and iv) the xenon flash 29 is activated.

Optionally, but preferably, player 2's gun is temporarily disabled from firing, for example by the microprocessor not responding to any firing command, for say two or three seconds. This provides the effect of a "stun".

The reply message signal comprises Bytes 1, 2 and 3 the same as the received message, a Byte 4 of message type "I am hit", the replying gun's ID Byte 5, and the check Byte 6.

The complete 6-byte reply message is received by the gun 10' via its receiving telescope 12' and the receiver constituted by the components 46, 48, 51, 52, 53. The microprocessor 23 in the gun 10' will only recognise a reply message which is detected within a window corresponding to an expected time of receipt plus a small margin after transmission of the outgoing message, totally about 120ms. Any reply message received later is ignored. If the message is correctly received, it is registered by the processor 23 in gun 10' which performs the following actions: i) the count on the display 24 is increased by, say, 25 points; ii) a characteristic sound signal is output from the effects memory 25 to the speaker 28 to inform player 1 that he has hit player 2; and iii) a "HIT" display panel 30 (Fig.2) is lit up or flashes for a short period.

When there are only two players, the ID Byte 5 is not strictly necessary for the bullet/hit signalling, since the other player can only be the opponent.

Nevertheless, irrespective of the number of players or weapons, the microprocessor is readily programmed to display on the display 24 the team and individual ID assigned to the source weapon of any message (outgoing or reply), since in this embodiment Byte 5 is always included. Additionally, in the case of more than two players or weapons, the scoring system may be arranged to deduct points for hitting in error a weapon assigned to the same team.

Two further unique functions which make use of the answer-back principle will now be described. The first will be called herein the "IFF mode", IFF standing for "Interrogate - Friend of Foe?". The aim is to locate another player or weapon and, if appropriate, to find out whether he or it is friendly or hostile according to the team ID of the weapon.

This function is especially useful in a darkened environment and/or a crowded battlefield scene. A remarkable feature is that it can be implemented without needing any additional communication circuitry. The exchange of signals to interrogate a weapon and receive a reply therefrom uses the same communication channels as the bullet/hit signalling.

Indeed the interrogate and reply messages are almost identical to the two 6-byte signals just described; the only difference is that the 5-bit code contained in Byte 4 is changed to one representing a message of type "Who are you?" for the outgoing signal and to one representing a message of type, here, "I am a gun" for the reply signal. Since the ID Byte 5 in the reply message informs the interrogating gun of the ID of the player/weapon located, the player's number and team ID can be displayed on the gun. In the IFF mode of operation, the SCAN button 78 (Fig. 2) on the gun is pushed and held down to command the microprocessor to generate repeatedly, say five times a second, the outgoing interrogation message. Simultaneously, the player slowly sweeps his gun over the field of interest.The same principle of telescope-to-omni outgoing transmission and omni-to-telescope reply transmission is used as for the bullet signalling.

When the gun comes to be pointed at another weapon, the interrogation message is received and processed by the other weapon, without that weapon providing any sensible signs of having been located, and a reply message is generated which includes the weapon's ID in Byte 5. In the interrogating gun, the same windowing technique described previously may be adopted so as to look for a reply message within a predetermined period after emitting each interrogation signal. The gun will be pointing at the located weapon when the reply message is received. The speaker 28 of the interrogating gun emits a distinctive sound generated using the effects memory 25, which sound may be different for friend and foe, when the reply message is validly received. At the same time, one of two visual indicators, one 31 green for friend the other 32 red for foe, is lit up.The located player/ weapon's individual ID number may also be displayed on the display 24. If a foe has been found, he can be fired at immediately without disturbing the aim of the gun. The interrogate/reply signalling is extendable to acquiring any other information about or attribute of the weapon/player which can be encoded in Byte 4 of the reply message, and Byte 7 on if needed. For example, it is possible to generate interrogate/ reply signalling for finding out the current points score of another player.

Now, an explanation of the function of "range bytes" which may be transmitted with an outgoing message signal. The word "range" is a term of convenience, since the function has wider application; a more appropriate descriptive term may be "conditiondetermining". The physical range over which the previously described message signals may be received is determined by a variety of factors, including of course the power or intensity of the transmitted light beam. Message signals, whether outgoing or reply, are always transmitted at a predetermined, "full" power, which in this embodiment provides a workable physical range of about 50 to 60 metres. According to the present function, an outgoing full power message signal is preceded by a signal portion transmitted at a predetermined power lower than full power.This is achieved by controlling the bias current to the emitting telescope LED 15 using the circuits 41, 43 already described with reference to Fig. 10. The lower power signal portion naturally has a shorter physical range. A gun which receives a full power outgoing message signal will either also detect or not detect, according to its physical range or the accuracy of the source gun's aim, the lower power signal portion which precedes it. Use is made of this information.

Consider first the bullet/hit signalling. For convenience, it is assumed here that a single range byte signal of a power of, say, 35% full power, always precedes the full power "bullet" message signal. The byte sequence of the complete signal will be: Byte 1 (35%), Byte 2 (35%), range Byte 3 (35%), Byte 1 (100%), Byte 2 (100%), lead-in Byte 3 (100%), followed by the bullet message comprising Bytes 4 to 6 (100%).

Here, the relative transmission power for each byte is given in brackets thereafter. The two prefix bytes preceding the range byte are transmitted at the same power level as the range byte in order to set the receiver AGC gain to a value appropriate for the following range byte; the same applies to the two prefix bytes preceding the bullet message bytes. The range Byte 3 itself has a predetermined value programmed in the microprocessor.

If the receiving (target) gun detects the complete signal, i.e. including the range byte, a normal hit is registered and a reply is sent in the manner already described. The reply message may include a code in Byte 4 identifying that the range byte was validly received. If the target gun detects the message signal but not the range byte, this may be registered as a "miss". A reply message may still be sent, which then includes a code in Byte 4 indicating that no range byte was received. Suitable sound effects, different from those for a hit, may be generated in both guns using the library of sounds stored in memory 25. For the firing player, the sound for a miss may have a humiliating tone.

The "miss" may arise either because the target gun was beyond the physical range determined by the range byte power level or for the reason that the firing player's aim was not good. In the latter case only the lower amplitude signal at the edge of the telescope beam from LED 15 will be picked up by the target gun's omni-receivers 21 and the range byte portion is lost in noise.

As an alternative in this present case of transmitting a single range byte, the non-detection of the range byte may be registered as a "near-miss", i.e. something akin to a grazing shot, for which a lower number of points than a normal hit may be awarded to/deducted from the players' scores and a distinctive sound generated.

Another use of the range byte is in the IFF mode where the "range" of an identified foe may be determined and displayed. A player can then decide whether it is worth trying a shot at the opponent or better to first move closer. The sending of a single range byte preceding the "Who are you?" message signal, enables a simple display of whether the target is "in range". This information, like the "miss" information in the bullet signalling is coded in the reply message Byte 4 which indicates whether or not the range byte was validly received. Therefore, one option is to indicate that the detected weapon is in range by lighting up an indicator 33 (Fig. 2) simultaneously with the friend or foe light 31 or 32.

Alternatively, although in this embodiment the ranging function is an intrinsic part of the IFF signalling, it can be presented as if it were a separate function by requiring another control to be operated after the light 31 or 32 appears and by providing a short delay before the indicator 33 lights up. A cosmetic indication of system activity may be provided in the form of a "walking" cycle of orange LEDs which runs during the delay, or indeed whenever the SCAN button is depressed.

Using a single range byte is simple and effective. Greater sophistication is available by prefacing an outgoing message signal with a sequence of range bytes of respective different codes and transmitted at respective different power levels. By using more than one range-indicating signal portion, one can define different degrees of impact of the bullet, for which different numbers of points may be awarded/deducted. The range bytes should be transmitted in order of ascending power and each prefixed by Bytes 1 and 2 transmitted at the same power level as the range byte itself. The order is important because of the action of the AGC circuit 52.

If two range bytes of relatively high and low powers were to be sent in that order, the AGC circuit would depress the receiver gain in response to the high power signal and the following low power signal would probably not be detected because of the slow recovery of the AGC gain.

In one specific embodiment, the following six different range bytes are used: pattern code strength 1 1 0 0 0 0 0 0 1 weakest 10100000 2 10000000 3 01000000 4 00100000 5 0 0 0 1 0 0 0 0 6 strongest The optimum criterion for choosing range byte values is that they should have as many 'O's as possible, i.e. keeping the LED powered on as long as possible, particularly at high power. The strongest range byte is the one which defines the maximum measurable range, and should therefore be the one least likely to be confused with noise. By way of example, the weakest byte may be transmitted at a power level which is 1% of the full power used for the message signal, and the strongest byte at 35% thereof.

The intermediate power levels may be set to provide approximately regular range increments between successive range bytes.

The power control circuit 43 described with reference to Fig. 10 has six independently switchable resistors for setting the LED bias current. This circuit provides the potential for setting, in principle, 62 different power levels between zero and 100% (using binary-weighted resistors), which gives flexibility in varying the physical range determined by each byte since it requires only programming the microprocessor to generate a different control signal on line 37.

For the microprocessor in the receiving gun, the significant event is to register the first range byte to be validly detected ahead of the full message, i.e.

the one of the lowest power out of those range bytes received. The later range bytes of higher power should always then be received in sequence. However, if a received sequence starting from the first detected range byte is not complete, this may indicate that the first byte is invalid, in which case the range byte received next may be registered, or the processing aborted. It is not essential to send all six range bytes, provided those which are used are sent in order of ascending power. The code, indicated in the above table, for the first validly detected range byte is normally returned in the three most significant bits of Byte 4 of the reply message.

However, this is not essential; for example, when a "miss" is registered by a receiving gun, this may be signalled only to the player who was nearly hit to warn him that he is under attack. The player who fired the bullet knows he missed because he does not receive the hit indications.

In the IFF mode, the range display may comprise a line of LEDs, the number of which is lit up indicating the range. In the firing mode, the determined range may be used to decide the number of points awarded for a hit - minimum or zero points when the lowest power range byte (indicating the closest range) is received and maximum points when only the highest power range byte (indicating the farthest range) is received. Even if all six available range bytes are transmitted, the microprocessor may be programmed so as not to discriminate among them all for the purpose of allocating scores of points. The range display in the IFF mode enables a player to engage in some strategic planning, in view of the dependence of the points available on the range. It also indicates to the player his own vulnerability since is he of course within the same range of the other player.

In a further development, a condition which is registered (and, optionally, transmitted in a reply message) in response to the received range byte(s) may be determined under control of the microprocessor program. Two approaches are proposed. In a first, a degree of vulnerability to a bullet and/or the effective range is established for a player's gun ab initio by programming the gun before a game commences, as a factor of the "personality" of the player's role in the game, e.g. infantryman, artilleryman, armoured knight, etc. Secondly, the degree of vulnerability to a bullet and/or the effective range may be changed automatically as the game progresses, according to the number of bullets, points and/or lives remaining on the player's gun.

It is not essential to transmit the range- or condition-determining information portion of the signal separately from the message portion. For example, the range code may be included in the message portion and the transmission of the message portion repeated two or more times at different power levels, each time including a different range code (or none in the case of the portion transmitted at full power).

Another version of the gun 10 will now be described with particular reference to Fig. 11, in which like parts have been given the same reference numerals. This version performs all the functions already described for the gun of Fig. 10; therefore the description of those functions and the features which achieve them will not be repeated. In the gun of Fig. 11, the outgoing and reply message data signals are transmitted using carriers of 15.5 kHz and 10.4 kHz respectively, the data rate is 1000 bit/s and the receiving bandpass filters for extracting outgoing and reply signals have centre frequencies corresponding to those carrier frequencies and a bandwidth each of 1 kHz. None of these differences affects the functions, which remain the same.

The gun of Fig. 11 provides additional communication channels for carrying two-way speech and which use the same directional infrared beam of telescope 11 and non-directional infrared emission of LEDs 22 for transmission as the outgoing and reply message data signals of the "bullet" and IFF functions. The philosophy of using the same basic transmitters and receivers for all communications provides substantial savings on additional hardware.

Returning to Fig. 13, suppose that player 1, holding gun 10', wishes to speak with player 2, holding gun 10". Player 1 aims his gun at player 2, for example after having located him using the IFF scan function. Player 1 presses and holds down the CALL button 79 and speaks into the microphone 64 at the rear of his gun (see Fig. 2). He literally talks to player 2 down the infrared beam as his speech is modulated on the output of emitting telescope 11'.

The omni-receiver 21'' of gun 10'' receives and demodulates the transmitted signal which is then heard by player 2 on loudspeaker 28. When player 2 wishes to reply, he presses and holds down the REPLY button 80 on his gun and speaks into the microphone.

However, player 2 is not required to aim his telescope at player 1, since his reply transmission is emitted via the omni-emitters 22". Player l's gun, still aimed at player 2, receives the reply transmission via its telescope receiver 12', demodulates the speech signal and player 2's message is heard on loudspeaker 28.

It will be seen that the communication paths are the same as for bullet and IFF signalling, i.e.

telescope emitter to omni-receiver for outgoing and omni-emitter to telescope receiver for reply. And again different carrier frequencies are used for the outgoing and reply signals. In an environment where there are more than two players, security of the outgoing (initiating) speech transmission is assured by the directional nature of the telescope beam.

Since the reply transmission is via the omni-emitters 22", it may be received by a third player whose gun is aimed at player 2. In view of this possibility an additional security measure is provided which prevents any gun other than the one which initiated the speech link from processing the reply signal, as will be explained in the following.

Referring to Fig. 11, the speech for the outgoing transmission is fed as an audio signal to a transistor modulator circuit 65 from the microphone 64 via an amplifier 66 which is suitably an AGC amplifier. The circuit 65 also receives, on line 69, a carrier signal whose frequency is 27.8 kHz. The carrier is generated internally in the microprocessor 23 and output as a squarewave. The carrier signal is analogue amplitude modulated by the audio signal in circuit 65 and the output supplied to one input of an additive mixer 63.

The other input is coupled to the data signal line 39.

The output of the mixer 63 is applied to the drive circuit 41 for the telescope 11. The circuit 65 also serves to mute the input of audio to the telescope when the microprocessor suppresses the output of the carrier signal on line 69.

When the CALL button is depressed, in addition to generating the carrier for the audio signal, the microprocessor generates an outgoing 6-byte data message having the same basic structure as for example the previously described bullet message. Byte 4 of the message indicates that an outgoing audio transmission is being made, whereas Byte 5 contains as before the sender's ID. This "calling" message modulates the 15.5 kHz data carrier and the result is supplied to the mixer 63 on line 39. (The power control circuit 43, if fitted, is set to the full power state by the microprocessor.) The calling message signal is generated repeatedly, here once every second, for as long as the CALL button is depressed. The audio signal and the calling message signal are thus combined in the mixer 63 whose output controls the drive transistor for telescope LED 15.

In the receiving gun, the telescope beam signal emitted by the calling gun is picked up by the omnireceiver 21 and supplied simultaneously to bandpass filters 47, 57 which extract the data and audio components respectively. The calling message signal is applied to the receiving circuitry constituted by the components 51, 52, 53. The calling message is input to the microprocessor 23 on line 54. The microprocessor, on valid receipt of the calling message opens a squelch switching circuit 61 which normally suppresses the audio receiving channel input to the amplifier 27.

The audio channel bandpass filter 57 has a centre frequency corresponding to the outgoing audio carrier frequency of 27.8 kHz and a bandwidth of 3 kHz. The output of filter 57 is applied to one input of an additive mixer 59 whose output is connected to an AGC circuit 60. The AGC output is applied to the audio amplifier 27 via another additive mixer 62 whose other input is coupled to the sound effects memory 25. The loudspeaker 28 reproduces the transmitted speech.

When the REPLY button is pressed and held down on the receiving gun, a very similar process of signal generation takes place as for the outgoing signal.

Notably, however, the omni-emitter 22 is used so that the replying gun holder does not need to aim his gun at the caller. Here, the audio carrier frequency is 24.2 kHz and the data carrier frequency is 10.4 kHz.

The signal to be emitted by the LEDs 22 is generated using the components 64, 66, 36, 44 and 40, the audio carrier signal on line 68, and the signal on data signal line 38. The components 36, 44 and 40 perform the same basic functions as the components 65, 63 and 41 respectively. The microprocessor generates a reply 6-byte data message in which, analogous to the calling message, Byte 4 indicates that a replying audio transmission is being made. However, Byte 5 contains the ID of the calling gun, not the replying gun. This ID was stored in the microprocessor memory when the "calling" message signal was received. The "replying" message signal is generated repeatedly, here once every second, for as long as the reply BUTTON is depressed.The audio signal output by the circuit 36 and the replying message signal are combined in the mixer 44 whose output controls the drive circuitry 40 for the LEDs 22.

The gun which initiated the call receives the reply signal via its telescope receiver 12 and applies it to bandpass filters 48 and 58. The filter 48 extracts the data component to apply the replying message signal to the receiving circuitry constituted by the components 51, 52, 53 via the other input of mixer 51. The replying message is input to the microprocessor 23 on line 54.

The audio channel bandpass filter 58 has a centre frequency corresponding to the replying audio carrier frequency of 24.2 kHz and a bandwidth of 3 kHz. Its output is applied to the other input of mixer 59, and thence via AGC circuit 60 and mixer 62 to the amplifier 27.

The microprocessor, on valid receipt of the replying message, opens the squelch switching circuit 61 to enable the audio signal supply to amplifier 27.

It is necessary that the ID Byte 5 of the received replying message correspond to the ID of the receiving gun. Otherwise, the microprocessor does not respond and the accompanying audio does not reach amplifier 27. This function ensures that only the calling gun reproduces the replier's speech.

In each gun, whilst the CALL or REPLY button is being depressed, the audio channel squelch circuits 55, 61 are held closed to prevent audio breakthrough on the loudspeaker.

Although analogue amplitude modulation is adopted for the audio communication in this embodiment, the present state of the art is such that digital transmission of the audio signal is feasible, for example in like manner to the described data signal modulation, by using a different microprocessor and a higher data rate.

One version of the sight 70 is shown in Fig. 3.

The device comprises an elongate body 71 of hollow cylindrical form having at one closed end a point light source and at the other open end a viewing lens 77. The point light source comprises a pin-hole plate 75 having a red LED 73 mounted therebehind in a support 74. The LED 73 is aligned with the pin-hole of plate 75 along an optical axis 76 of the sight.

The lens 77 is disposed on the optical axis 76 such that its focal point is located as precisely as possible on the pin-hole of plate 75.

The sight 70 is mounted on top of the body of the gun with its optical axis 76 substantially aligned with the direction of the beam emitted by the telescope 11. In use, the LED 73 is continuously powered and produces by means of the pin-hole plate 75 and the lens 77 a bright red spot of light 72 in the operator's field of view as the gun is aimed, the spot 72 coinciding with the centre of the footprint of the beam of emitting telescope 11. The operator keeps both eyes open, one aligned with the sight, and concentrates his focus on the target, effectively at infinity, the spot 72 appearing automatically clear and sharp in his field of view. Advantageously, no short-range focusing effort is necessary. Moreover, this sight is usable in both dark and light conditions.

For optimum aim, the point light source provided by pin-hole plate 75 needs to be seen through the viewing lens 77 along the optical axis 76. If the pin-hole is sufficiently small and accurately located with respect to the lens, the "kill dot" 72 will only be visible under this condition. However, it may be convenient to superimpose a circular sighting ring on the view of the lens 77, either provided on a supporting sleeve which slips over the end of the sight in front of the lens or printed or etched directly on the lens. Then, the aim is good when the red spot 72 appears within the sighting ring. A further solution is to dispose two apertured plates within the body of the sight, the first closer to the lens and at the focal point thereof, the second farther from the lens and associated with the LED like components 75, 73.The apertures of the two plates are arranged coincident with the optical axis, whereby the red spot 72 will only appear when the angle of view is such that the apertures are mutually aligned.

The size of the closer aperture sets the tolerance.

The sighting device is broadly applicable to any object which needs to be aimed by an operator, including an actual weapon.

According to a preferred feature of the gun 10 the state of the LED 73 is controlled by the microprocessor 23. When the IFF scan function is operated, the normally continuously-powered red LED may be made to flash when an enemy player or weapon is detected and extinguished when a friendly player or weapon is detected. Further, there may be an indication when a detected foe is within range. More preferably, the red LED 73 is replaced by a multicolour LED and controlled so that the colour of the aiming spot 72 changes according to the detection of a friend or a foe. For example, the LED may ordinarily display a neutral orange or yellow colour, changing to red for detection of an enemy and green for a friend. The red dot may flash when the enemy is within hitting range. The use of the sight LED in this way may either supplement or replace the indicators 31, 32, 33.

A preferred modification of the sight 70 develops further the last-described features by incorporating one or more visual indicators and/or displays within the sight, for viewing through the lens 77. Fig. 4B shows an exemplary display arrangement provided within the sight by mounting miniaturised components on or adjacent the pin-hole plate 75. As shown in Fig. 4A, the components 81 are viewable through apertures 82 in the plate 75. (In the version of the sight having two plates, the components are mounted on or adjacent the plate closer to the lens.) The components surround but do not obstruct the central area where the aiming light spot 72 is generated.Fig. 4B shows a 3-digit 7-segment display 24, a HIT panel 30 which lights up red when a hit is scored, an IFF panel 86 which flashes green when the IFF function is operating, a range display 33 comprising an arrow-shaped dimly lit panel having five yellow lights which flash in sequence when a target is being scanned for range, and a dimly lit orange panel 88 and corresponding line of five orange lights 87 for indicating a current number of lives of the gun. In addition, the aiming spot 72 shows red for foe and green for friend during IFF scanning, and turns yellow when a scanned target is within range. All of these components may either supplement or replace the corresponding ones already described as provided elsewhere on the gun.

Like the aiming spot 72, the in-sight display features appear in the user's field of view as he aims the gun. This provides the player with an immediate indication of his status (score, lives) and of the operation of the gun, without any need to break from his aiming concentration.

The mechanism 90 associated with the trigger 18 is shown in detail in Fig. 5. A weight 101 is mounted in a housing 92 attached to the underside of the gun so as to be slidably movable within the housing against the action of two tension springs 93. A projecting member 94 fixed to and extending from one end of the weight 101 comprises a rod which terminates in a cone-shaped piece whose base diameter exceeds that of the rod. The rear of the housing 92 contains a spring-mounted plate 95 which rides over the cone surface and catches the neck of the projecting member 94 when the weight is forced to the back of the housing, to hold the mechanism in the cocked condition.

A rod 96 is screwed into the other end of the weight and projects through an opening at the front of the housing. The mechanism is cocked by pushing the rod 96 into the housing. A hand grip member 91 (Fig.

1) is supported on the lower telescope 11 so as to be slidably movable thereon. A second rod 97 is fixed in the hand grip member 91 and aligned with the rod 96 within a sleeve 99 also secured to the member 91.

Thus, pulling the hand grip member back first brings the second rod 97 into contact with the rod 96, then drives the rod 96 into the housing 92 to prime the mechanism. A compression spring 98 acts between the end of the housing and the sleeve 99 to bias the handgrip 91 to the forward position. The member 91 is then automatically returned to the forward position once the mechanism has been cocked and the member 91 released. The member 91 is gripped to steady the gun when aiming.

The trigger 18 is mechanically coupled to the plate 95 so that operating the trigger displaces the plate sufficiently to disengage the projecting member 94, upon which action the weight is returned rapidly to the uncocked position. At this instant, the rod 96 collides with the second rod 97 within the sleeve 99 to produce the recoil shock. Simultaneously, an electrical contact is made or opened to supply a "gun fired" command to the microprocessor 23.

The trigger is constrained from being operated unless the mechanism 90 is cocked, so that a player cannot operate the trigger to fire the gun repeatedly in quick succession.

Other devices for producing the same effect of a recoil shock are possible including one which uses a solenoid mechanism. In a gun intended particularly for the adult leisure market a device utilising compressed air or carbon dioxide from a rechargeable cylinder is favoured.

Figs. 6 to 8 show a light emitting and receiving electronic toy mine 100, which is used in a game involving an exchange of "fire" between the mine and at least one gun 10 of the type described above.

Although in the following reference will be made to the Fig. 10 version of the gun, the Fig. 11 version is equally usable in principle with the mine. As described herein a player does not talk to the mine using the voice communication feature of the gun, but the possibility is not excluded.

The mine 100 has a moulded plastics body which is given a military appearance by being coloured green or khaki, and liberally covered in cosmetic rivets. The body comprises a base 110 having four legs 114 which extend horizontally at right angles to each other and which each terminate in a foot 116 in the form of a short cylinder stood on its end. The feet and/or legs may be adjustable to steady the mine when it is placed on an uneven surface. A turret 112 is mounted on the base 110 so as to be freely rotatable through 3600 in the horizontal plane. The turret houses a centrallyfixed DC motor (150, Fig. 12) whose shaft end or a member attached thereto fits in a slot of complementary shape in the base so that when the motor is powered the turret rotates.The turret is further supported by four circumferentially-oriented and freely-rotatable wheels mounted in the base which engage the underside of the turret. The turret also houses the electronics for controlling the mine and a power source in the form of a rechargeable, e.g.

nickel-cadmium, battery. This arrangement is preferred since then no electrical connections are required between the turret and the base.

An infrared light-emitting gun or cannon 111 is mounted horizontally on the turret. The cannon 111 rotates with the turret and is directed radially with respect to the rotation axis. Two different orientations of the cannon are shown in Fig. 7 and 8.

The construction of the cannon 111 is basically the same as that of the telescope 11 of the gun 10 in terms of its function, although it differs cosmetically. Diametrically opposite the firing end of the cannon 111, a seat 118 is provided for a game character doll who, when seated, gives the impression of an operator of the cannon. A red LED 117 on the end of the cannon warns of the cannon being operated.

A 7-segment LED 124 and a group of control buttons 135 are provided on the side of the turret.

The top of the turret includes, in ascending order, a light-receiving section 119 housing infrared photodetecting diodes 121, a light-emitting section 120 housing beneath a plastics dome infrared lightemitting diodes 122, and a game START/STOP button 125 which is depressed to activate/de-activate the mine.

The light-emitting section 120 also includes beneath the dome a xenon flash unit (129, Fig. 12). Four red LEDs 126 circumferentially distributed below the light-receiving section 119 indicate a state of the light-emitting section 120.

Referring to Fig. 12, a comparison with Fig. 10 reveals the degree of functional identity of the mine and the gun. The description of the mine will concentrate on the differences vis-a-vis the gun, referring where appropriate to the detailed description of the gun to avoid repetition.

The cannon 111 functions just like the emitting telescope 11 of the gun to fire 6-byte "bullet" signals which may be received by the omni-receiver 21 of a player's gun. The message type Byte 4 identifies the signal as representing a bullet fired by the cannon. The ID Byte 5 carries a team ID assigned to the mine by a programming plug 142 inserted into an external socket on the mine. The carrier frequency of the bullet signal is 34 kHz. Like a gun bullet, the cannon bullet may be preceded by one or more range byte signals, each comprising Byte 1, Byte 2 and the range Byte 3, enabling the mine to score a near-miss or a miss on a player.

The drive electronics and control for the cannon LED 115 is the same as the gun, but the optics is arranged to produce a broader beam than the gun, basically because the mine is autonomous and does not have the benefit of a human to aim the cannon.

Instead, the cannon 111 moves with the turret 112 under a control applied to the motor 150. The motor drive circuit 151 receives from the microprocessor a digital signal on line 156 which determines the direction of rotation and an analogue signal on line 157, converted by D/A 155, which determines the speed.

The movement of the cannon is normally random, either "hard" (i.e. genuine) random or "pseudo-random" (where the cycle is too long to be learned), producing unpredictable durations of pause and changes of direction. In some games, the pauses may be as long as one or a few minutes, giving the impression that the mine is inactive before the cannon unexpectedly comes to life. A preferred mode of operation is for the cannon to emit a burst of bullet signals at the end of a swing as the cannon slows to a standstill through an angle of about 450 after the motor has stopped.

When hit by the mine, the gun receives the cannon bullet signal via the receiver constituted by components 21, 45, 47, 49, 51, 52, 53. The hit is registered by the microprocessor 23 which deducts a predetermined number of points from the gun score in its internal memory and changes the score displayed on the 7-segment display 24 accordingly. The xenon flash and an audible effect are produced on the gun. The microprocessor 23 is programmed such that on registering the cannon bullet signal, no reply is generated, the mine having no receiver for a reply.

The mine itself suffers a hit when it detects a "bullet" fired from a player's gun. When the mine is hit by a gun bullet the random motion of the cannon is interrupted and the cannon is driven to a determined orientation to return fire. How this directionality is achieved will now be described.

Fig. 9 is an explanatory plan view of the lightreceiving section 119. It has four photodetecting diodes 121a to 121d arranged in a special configuration which divides the reception area around the mine into eight distinct angular sectors. Four circuit boards 131 on which the diodes are mounted are supported vertically in a plastic moulding so that the diodes face out perpendicularly to the four sides of an effective square formed by the boards. In the open, the diodes have a very broad field of view characteristic. The configuration of the lightreceiving section is such that the angle of view of each diode in the horizontal plane is restricted to the sides by the structure of the moulding.The components of the moulding which determine the angle of signal reception are, for each diode, two vertical partition walls 130 extending from behind the board 131 (whose side edges abut the walls) and two vertical pillars 132 formed at the outer edges of the walls.

The restricted angle of view of each diode is 135 , so that the four diodes in combination provide an all-round receptivity to signals reaching the mine from any direction, the receiving sectors of adjacent diodes overlapping at their sides.

Considering the diode 121a, the lines 133, 134 drawn on Fig. 9 define the limit of the intrusion of the fields of view, respectively, of the neighbouring diodes 121d and 121b into the field of view of the diode 121a. The lines 135, 136 drawn parallel to the line 133, 134 and through the diode 121a define the boundaries of a central 450 sector of the diode 12la's 1350 field of view. A signal arriving at an angle within this central 450 sector will be received exclusively by the diode 121a.On the other hand, a signal arriving at an angle within the 450 sector bounded by line 133 and the limit of the diode 12 la's field of view at line 137, will be received both by diode 121a and its neighbour 12 it. Similarly, a signal arriving at an angle within the 450 sector bounded by line 134 and the limit of the diode 12 la's field of view at line 138, will be received by diodes 121a and 121b. The same analysis applies to the other three diodes. Thus, the light-receiving section 119 has eight angular receiving sectors of 450 extent and an incoming signal can be located in one sector by identifying the one or two diodes which detect it.

Upon such location, since the orientation of the cannon is fixed with reference to the light-receiving section, the microprocessor 123 knows the angle through which the turret must be rotated to point the cannon in the sector of the hit detected by the mine, and can control the motor 150 accordingly.

The process of determining which of the diodes 121 detect(s) the received signal will be explained with reference to Fig. 12. The outputs of the diodes 121a to 121d, after amplification by respective preamplifiers 145a to 145d, are applied in parallel to a receiver constituted by the components 149, 147, 152, 153, of which components 147, 152, 153 correspond to those referenced 47, 52, 53 in the gun. The four parallel input channels into the receiver include respective switching circuits 146a to 146d, suitably MOSFET switches, which are controlled by signals output by the microprocessor on lines 148a to 148d.

In normal operation the switches 146 are all closed.

A bullet signal, and optionally an IFF signal, emitted by the gun 10 includes a seventh, directionfinding byte whose data value is zero, i.e. continuous carrier transmission. The microprocessor 123 in the mine receives the first six bytes of the bullet (or IFF) signal in the normal way and with the switches 146 all closed. The message Byte 4 indicating the nature of the incoming signal informs the microprocessor that it must perform a directionfinding operation during Byte 7. Coincident with the timing of Byte 7, the microprocessor selectively opens and closes the switches 146 in the following way.

During the first data bit of Byte 7, the switch 146a is closed and the switches 146b to 146d are open.

During the second data bit, the switches 146a and 146b are both closed whilst the ones 146c and 146d are open. During the third data bit the switch 146b only is open, and so on in an eight-stage cycle in which the output of each diode is sampled individually and so is the output of each pair of adjacent diodes. The order of the cycle and starting point is arbitrary.

The result is that the direction-finding Byte 7 applied to the microprocessor 123 on line 154 is converted to an 8-bit code which is unique to the sector in which the signal is received. The eight possible codes are recognized by the microprocessor which is programmed to generate the control signals appropriate for rotating the turret through the smaller of the available angles to orientate the cannon within the identified sector. The microprocessor also generates a stream of cannon bullet message signals which are fired by the cannon either as it swings through the determined sector or when it reaches, say, the centre position therewithin.

The pillars 132 of the light-receiving section are adapted to receive a plate-like shutter which can be manually inserted in front of one or more of the diodes 121. This restricts the angular range of reception making it more difficult to score points by hitting the mine. Alternatively, and less visibly, one or more of the receiving sectors may be effectively rendered non-receptive electronically using the switches 146. This may be done without any indication to the player and the diode or diodes may be switched off in a random manner using the control signals on lines 148, to greatly increase the challenge.

It will be seen then that not only firing a gun bullet at the mine, but also making an IFF scan on the mine may result in the cannon swinging around to fire at the player's gun.

Next, the light-emitting section 120. A translucent plastics dome protectively covers a cluster of ten infrared LEDs 122 mounted on a circuit board in a ring in which they are evenly spaced circumferentially and face radially outwards. The emission pattern of each diode corresponds broadly to a cone of 350 angle, whereby the 10 LEDs together broadcast an applied signal substantially uniformly all around the mine in azimuth within a limited range of elevation angle. Since the mine will usually be placed on the ground, it is preferable to direct the LEDs somewhat upwardly to make the best use of the available coverage and to avoid wasting energy on the ground. The drive electronics 140 for the omni-LEDs 122 is the same as described for the gun.However, the frequency of the squarewave carrier signal output by the microprocessor is selectively one of 23 kHz and 34 kHz according to the type of the data signal to be broadcast, as explained in the following.

A characteristic function of the mine of this embodiment is that it can emit, by means of its lightemitting section 120, an "explosion" of bullets in all directions, which are receivable by the omni-receiver 21 of a gun within range of the explosion. The use of omni-to-omni transmission from mine-to-gun limits the range to a circle of a few metres' radius. The explosion bullet signal has the same basic 6-byte structure as the cannon bullet signal. However, the message type Byte 4 is different for these two types of projectile, so that the gun microprocessor 23 distinguishes between them to deduct a greater number of points for a validly registered explosion bullet than a cannon bullet. An explosion bullet may be worth 100 points (seconds) and a cannon bullet 25.

The explosion broadcast emits the explosion bullet signal, say, once every second. Thus, a player within range will very quickly suffer a potentially fatal loss of points on his gun when the omni-emitter 120 is active. The effect is to establish an effective exclusion area in the vicinity of the mine, this "force field" ordinarily preventing a player from approaching the mine to slam down the game START/STOP button 125 to win the game.

The explosion signals are transmitted on a carrier of 34 kHz, necessary for reception by the receiving circuitry coupled to omni-receiver 21 of the gun. Since the telescope receiver of the gun operates at 23 kHz carrier, the gun is not affected by the explosion signal when it is aimed at the mine from significantly outside the omni-to-omni range. (The telescope-to-omni range gun-to-mine is about 50 to 60 metres.) The gun does not reply to a hit from the mine explosion, although it does trigger the xenon flash 29 and produce a sound effect on the loudspeaker 28. The short-range, i.e. omni-to-omni, communication from the mine to the gun is illustrated in Fig. 14.

A secondary function of the omni-emitter 120 is to broadcast a reply message signal at 23 kHz carrier, in response to a gun bullet hitting the mine or an IFF scan by a gun. In either case, the outgoing transmission by the gun may include one or more range bytes; the mine will return in Byte 4 of the reply message a code for the lowest power range byte received by the mine, for the purposes of determining a near-miss or a miss, or the range of the mine. A hit or a scan on the mine is registered just the same as on another gun. The IFF scan may identify the mine as such and whether it is a friend or foe according to the respective team IDs assigned to the mine and the enquiring gun. The long-range communications, i.e.

telescope-to-omni and vice versa and cannon-to-omni, between the gun and the mine are illustrated in Fig.

13.

A further function of the mine's omni-emitter 120 is to broadcast signals to the guns at the start and finish of a game, upon operation of the button 125; see Fig. 14. This and other features of the operation of the mine will be illustrated by describing a simple game involving the mine and two guns/players.

Initially, the guns and the mine are switched on and the game program is selected on the mine's LED display 124 by pressing an adjacent control button until the desired program number is displayed. The different programs provide varying levels of difficulty. With both players within the "force field" range of the mine, the game START button on the mine is depressed. Upon this action, the chosen game program is transmitted by the mine's omni-emitter 120 to both guns. Also, there starts a ten-second countdown simultaneously on the mine and the guns, which is signalled by bleeps from the electronic sounder 128 of the mine and sound effects on the loudspeakers 28 of the guns. The players retire at speed to a distance of about 50 metres to get out of range of the mine's cannon. The game start signal has initialised the scores displayed on the two guns to 900.At the end of the countdown the mine becomes active and the gun scores begin to diminish at a rate of 1 point per second. The mine starts producing repeated explosions, indicated by the constant illumination of its four LEDs 126. The cannon 111 of the mine is also active exhibiting random rotations and pauses and randomly emitting bursts of cannon bullets, the latter indicated by flashing of the LED 117 on the end of the cannon. The mine also emits bleeps from the sounder 128 when the cannon is firing.

The players must move to avoid being hit by the cannon. However, since the cannon-to-gun firing range is approximately the same as the gun-to-mine firing range, they must risk being hit by the cannon in order to shoot the mine. The players must also try to avoid the return fire of the cannon when they are successful in hitting the mine. A hit on the mine produces a flash from the xenon 129 beneath dome 120 and an accompanying scream from the sounder 128. The sound and indication of a hit is produced on the firing player's gun. Similarly, when a player's gun is hit by the mine cannon the usual effects are produced on the gun. The number of points gained or lost for each action are one of the factors determined by the game program. Whilst the scores on the players' guns are constantly updated on the display 24, the mine itself has no visible scoreboard.Nevertheless, the mine has a score held in the memory of microprocessor 123. The mine's initial score set at the start of the game increases with time, so that in effect the mine becomes stronger. Points are deducted from the mine's internal score for every hit which it suffers. The points score of the mine is not affected by any hits which the cannon scores on the guns, since the guns do not reply to cannon bullets. The end aim of the game is for the players to reduce the internal score of the mine to below a predetermined threshold or to zero by scoring a number of successive hits on the mine. The effect of reducing the mine's score in this way is to temporarily kill the mine explosion, indicated by the LEDs 126 being extinguished. This provides an opportunity for the players to rush toward the mine and operate the game STOP button 125. However, the dead period of the "force field" is of an unpredictable duration, so that a player may be caught in an explosion before reaching the button 125.

Operation of the STOP button ends the game and causes the mine to emit via the omni-emitter 120 a bonus points signal which is received by any player within the omni-to-omni range. The bonus points are added to the score on the player's gun.

In addition, or as an alternative, to interrupting or stopping its emission of the explosion signal, the mine may change the emission in other ways in response to being fired at by a gun. For example, the power level of the explosion signal may be increased or reduced, the rate of repetition of the explosion projectile signal may be changed, and/or the directional range of the explosion signal may be varied by powering selected ones only of the LEDs 122.

Numerous variations to this basic theme are possible. In the simplest scenario, there is just one gun/player against the mine. In the described game, the two players may be assigned the same team ID, or belong to different teams in which case they can score additional points by firing at each other. A gun or a mine may also be assigned a "no team" ID. There are no limits to the number of guns and mines which may be deployed making full use of the team IDs freely assignable to all weapons. Programming possibilities include making a weapon respond falsely to an IFF scan, i.e. signalling that the player is a friend when he is in fact a foe (a "Quisling" character), or not responding at all, i.e. being effectively invisible (an "Invisible Man").

The functions of the cannon and the explosion transmitter are substantially independent; their combination in the mine is not essential.

It will be noted that each of the described data signals (gun bullet, cannon bullet, explosion projectile, interrogation, etc.) has a respective predetermined duration.

In this specification, the use of the word "toy" shall not imply any restriction on the age of the user.

The invention may be used indoors and outdoors.

In its various aspects, the invention may be embodied in specific forms other than those described without departing from its scope. The variations mentioned briefly herein are necessarily nonexhaustive. Although the specific embodiments of the invention described herein have been developed for the toy and leisure markets, the invention is not limited to any particular application.

It is proposed that a weapon, particularly a gun, may be remotely "programmable" in terms of at least one of its identity, score, number of lives, etc. The programming is achieved using a data signal emitted either by a programming gun, in which case the signal may be emitted directionally, the programming gun being aimed at the intended recipient, or by a programming transmitter provided in the vicinity of the field of play, in which case the signal may be broadcast and include an identifying code of the intended recipient. Signalling techniques such as those described herein are applicable, including the transmission of an acknowledgement signal by the receiving gun. The programming gun preferably has the same structure as the described guns, only the control program (or the part of it which is used) being different.The programming gun may be carried by a "medic" character who is able to fire new lives to a player (who may be a team mate), or by an "ammocarrier" character who can transmit a fresh supply of bullets in the same manner. The programming transmitter may be used in the mine-gun game to transmit the game program.

Although the gun has been described as a selfcontained device, it may be convenient to provide the non-directional emitters and receivers or some of them on apparel such as a helmet, vest, Sam Browne belt or wrist/arm-band worn by the gun-holder and connected to the body of the gun. This type of arrangement may provide a more realistic need to aim at a player rather than his gun and may also reduce the opportunity for cheating by covering up sensors or emitters. The function of the overall weapon is, however, not affected in any way.

A preferred sound effect to be produced by the effects memory 25 of the gun is one which mimics a heartbeat. This sound is emitted continuously whilst the gun is in operation, the rate and/or volume of the heartbeat increasing noticeably when the gun suffers a hit, a near-miss or a miss. In one implementation, the heartbeat (e.g. one complete beat) is "recorded" in the memory at three different volume levels. In normal operation, the lowest volume recording is read out and reproduced at a first rate. The middle volume recording is read out and reproduced at a second, higher rate when a near-miss or a miss occurs, and the highest volume recording is read out and reproduced at a third, highest rate, when the gun suffers a hit.

Thus, the rate of the heartbeat is determined by how frequently the recording is read out of memory. The second and third conditions are maintained for a short period, after which the normal heartbeat is restored.

Clearly, there are further possibilities, such as slowing down (and finally stopping) the heartbeat as the gun runs out of lives.

The Fig. 10 version of the gun may be simplified and its cost reduced by replacing the components 25 to 28 and 55 by an electrical sounder like the one 128 of the mine, producing a more limited range of sound effects. Equally, the effects memory and associated components of the gun may be incorporated in the mine to provide a greater diversity of sound effects.

The use of synthesised speech is also possible in both the gun and the mine to indicate verbally the occurrence of the various events. No hardware changes are needed, only a data table in the existing memory.

The loudspeaker 28 of the gun may be replaced or supplemented by headphones to be worn by the player.

A helmet may incorporate the headphones and a microphone for sound effects and voice communication.

Laser devices may replace the LEDs 15, 22, 115, 122. The use of infrared light is not essential to the invention. Nor is the invention limited to the use of electromagnetic radiation; for example ultrasound may be used. The described modulation technique for data signalling is one of several possibilities which include pulse position modulation, phase modulation and frequency modulation. Also, a combination of different types of modulations may be employed.

The mine may be made self-mobile by providing one or more motorised wheels on the base, for moving and steering the mine either under the control of the microprocessor/game program or by remote control. Such mobility adds to the challenge of avoiding the mine's cannon fire and explosion field; it also brings the capability of the mine of charging towards a player whose gun it has detected.

Claims (144)

1. A game comprising a mine device which broadcasts a repeating explosion-simulating signal, and a gun device which transmits a bullet-simulating signal, wherein the mine device includes means for receiving and responding to the bullet signal and the gun device includes means for receiving and responding to the explosion signal.

2. A game according to claim 1, wherein the range of the bullet signal exceeds the range of the explosion signal.

3. A game according to claim 1 or 2, wherein the mine device includes a manually-operable switch for stopping the transmission of the explosion signal.

4. A game according to any of claims 1 to 3, wherein the gun device includes an electronic scoreboard and the score is reduced in response to explosion signal reception.

5. A game according to any of claims 1 to 4, wherein the mine device changes its emission of the explosion signal in response to bullet signal reception.

6. A game according to claim 5, wherein the mine device interrupts or stops its emission of the explosion signal in response to bullet signal reception.

7. A game according to claim 5 or 6, wherein the mine device changes the power level of its emission of the explosion signal in response to bullet signal reception.

8. A game according to any of claims 5 to 7, wherein the mine device changes the rate of its repetition of the explosion signal in response to bullet signal reception.

9. A game according to any of claims 5 to 8, wherein the mine device changes the directional range of its broadcast of the explosion signal in response to bullet signal reception.

10. A game according to any of claims 5 to 9, wherein the mine device includes an electronic scoreboard, the score is reduced in response to bullet signal reception, and the mine device changes its emission of the explosion signal in dependence upon the score of the mine device.

11. A simulated weapon comprising emitting means for broadcasting a first data signal representing a projectile, which is receivable substantially all around the weapon in the vicinity of the weapon.

12. A simulated weapon according to claim 11, wherein the emitting means is arranged to emit the first data signal repeatedly and intermittently.

13. A simulated weapon according to claim 11 or claim 12, comprising second emitting means for emitting a second data signal representing a projectile, which is receivable within a limited angular range about the weapon.

14. A simulated weapon according to claim 13, wherein the second emitting means is arranged to emit the second data signal substantially directionally.

15. A simulated weapon according to claim 14, including control means for changing the direction of emission of the second emitting means.

16. A simulated weapon according to claim 15, wherein the control means is arranged to change the direction of emission of the second emitting means at irregular intervals.

17. A simulated weapon according to claim 15 or claim 16, wherein the change of direction is random.

18. A simulated weapon according to any of claims 13 to 17, wherein the receivable range of the second data signal exceeds that of the first data signal.

19. A simulated weapon according to any of claims 13 to 18, wherein the second emitting means is arranged to emit the second data signal at irregular intervals.

20. A simulated weapon according to claim 19, wherein the times of emission of the second data signal are random.

21. A simulated weapon according to any of claims 13 to 20, wherein the second emitting means is arranged to emit the second data signal in bursts.

22. A simulated weapon according to any of claims 11 to 21, comprising receiving means for receiving a data signal transmitted by another simulated weapon.

23. A simulated weapon according to claim 22, wherein the receiving means is receptive to a said data signal irrespective of its originating direction.

24. A simulated weapon according to claim 22 or claim 23, wherein the receiving means is alternatively selectively receptive to a said data signal according to its originating direction.

25. A simulated weapon according to any of claims 22 to 24, including means for controlling the emission of the first data signal in response to the detection of one or more said data signals.

26. A simulated weapon according to any of claims 22 to 25, as appendant to claim 13 or any claim dependent thereon, including means for controlling the emission of the second data signal in response to the detection of one or more said data signals.

27. A simulated weapon according to claim 26, as appendant to claim 15, wherein the control means for changing the direction of emission of the second emitting means is responsive to the detection of a said data signal.

28. A simulated weapon according to any of claims 22 to 27, wherein the receiving means includes means for determining within which one of a plurality of angular sectors about the mine a detected said data signal has been received.

29. A simulated weapon according to claim 28, as appendant to claim 27, wherein the control means is arranged to change the direction of emission of the second data signal to within the determined sector, upon detection of a said data signal.

30. A simulated weapon according to claim 29, wherein the second emitting means is arranged to emit a burst of second data signals within the determined sector.

31. A simulated weapon comprising emitting means for broadcasting in the vicinity of the weapon a signal simulating an explosion, receiving means for receiving a signal simulating a projectile, and processing means for generating a score, wherein the processing means reduces the score in dependence upon the reception of the projectile signal.

32. A simulated weapon according to claim 31, wherein the emission of the explosion signal is terminated or interrupted when the score is reduced to below a predetermined value.

33. A simulated a weapon according to claim 31 or claim 32, wherein the processing means, in the absence of said reception of the projectile signal, increases the score.

34. A simulated weapon according to claim 33, wherein the increase of the score is continuous, subject to a predetermined maximum.

35. A simulated weapon according to any of claims 31 to 34, wherein the processing means reduces the score by a predetermined value for each detected projectile signal.

36. A game comprising the simulated weapon of any of claims 31 to 35 and at least one simulated gun which emits on command the projectile signal.

37. A game according to claim 36, wherein the gun includes receiving means for receiving the explosion signal.

38. A game according to claim 37, wherein the gun includes processing means for generating a gun score and the gun processing means reduces the gun score in dependence upon the reception of the explosion signal.

39. A game according to claim 38, wherein the gun processing means reduces the gun score by a predetermined value for each detected explosion signal.

40. A game according to claim 38 or claim 39, wherein the gun processing means, in the absence of said reception of the explosion signal, reduces the gun score.

41. A game according to claim 40, wherein the reduction of the gun score is continuous, subject to a predetermined minimum.

42. A game according any of claims 36 to 41, wherein the weapon transmits a reply signal to the gun upon reception by the weapon of the projectile signal.

43. A game according to claim 42, wherein the reply signal is transmitted by said emitting means.

44. A game according to claim 42 or claim 43, wherein the gun processing means increases the gun score upon receipt of the reply signal.

45. A game according to any of claims 36 to 44, wherein the transmission range of the projectile signal from the gun to the weapon exceeds the transmission range of the explosion signal from the weapon to the gun.

46. A simulated weapon comprising emitting means for emitting an offensive signal and receiving means for receiving a signal simulating a projectile, wherein the emitting means changes the nature of its emission in dependence upon the reception of the projectile signal.

47. A simulated weapon according to claim 46, wherein the offensive signal is a regularly repeated data signal, and the change of nature comprises a change in the rate of repetition of the data signal.

48. A simulated weapon comprising means for emitting an omnidirectional explosion-simulating signal and means for emitting a unidirectional projectile-simulating signal.

49. A simulated weapon according to claim 48, comprising means for receiving a bullet-simulating signal.

50. A simulated weapon according to claim 49, wherein at least one of the two emitting means is responsive to a received bullet-simulating signal to affect its emitted signal.

51. A simulated weapon according to claim 50, wherein the omnidirectional emitting means is arranged to stop or suspend its emission of the explosionsimulating signal in response to reception of a bullet-simulating signal.

52. A simulated weapon according to claim 50 or 51, wherein the unidirectional emitting means is arranged to change the direction of its emission in response to reception of a bullet-simulating signal.

53. A simulated weapon according to any of claims 49 to 52, wherein the receiving means defines a plurality of receiving sectors.

54. A simulated weapon according to claim 53, including processing means for identifying the receiving sector which receives a bullet-simulating signal.

55. A simulated weapon according to claim 54, as appendant to claim 52, wherein the unidirectional emitting means changes the direction of its emission, in response to a received bullet-simulating signal, so as to lie within the identified receiving sector.

56. A simulated weapon according to any of claims 53 to 55, including means for rendering one or more of the receiving sectors non-receptive to the bullet-simulating signal.

57. A simulated weapon according to any of claims 48 to 56, wherein the unidirectional emitting means has the form of a gun or cannon.

58. A simulated weapon according to claim 57, wherein the gun or cannon is rotatable in azimuth to change its direction of emission.

59. A simulated weapon according to claim 57 or claim 58, wherein the motion of the gun or cannon is normally random or pseudo-random.

60. A simulated weapon which emits a signal simulating a projectile and changes the direction of the emission randomly.

61. A simulated weapon which emits a signal simulating a projectile and changes the time of the emission randomly.

62. A simulated weapon which emits a signal simulating a projectile and changes the direction of the emission in response to a received second signal.

63. A simulated weapon according to claim 62, wherein the changed direction corresponds substantially to that of the received second signal.

64. A simulated weapon comprising emitting means for emitting a first data signal and receiving means for receiving a second data signal emitted by another simulated weapon in response to reception of the first data signal.

65. A simulated weapon according to claim 64, including registering means for registering a received second data signal.

66. A simulated weapon according to claim 65, wherein the registering means registers only a second data signal which is received within a predetermined interval after the emission of the first data signal.

67. A simulated weapon according to any of claims 64 to 66, wherein the emitting means emits the first data signal substantially directionally.

68. A simulated weapon according to any of claims 64 to 67, wherein the receiving means has a substantially directional sensitivity.

69. A simulated weapon comprising emitting means for emitting a first data signal, receiving means for receiving a said first data signal emitted by another simulated weapon, processing means for processing the received first data signal and generating a second data signal in response to the processing, and emitting means for emitting the generated second data signal.

70. A simulated weapon according to claim 69, wherein the receiving means has a substantially nondirectional sensitivity.

71. A simulated weapon according to claim 69 or claim 70, wherein the emitting means broadcasts the second data signal substantially non-directionally.

72. A simulated weapon comprising in combination the features of the weapon defined by any of claims 64 to 68 and the features of the weapon defined by any of claims 69 to 71.

73. A simulated weapon according to any of claims 64 to 72, wherein the first data signal includes an identification assigned to the source weapon.

74. A simulated weapon according to any of claims 64 to 73, wherein the second data signal includes an identification assigned to the source weapon.

75. A simulated weapon according to claim 73 or claim 74, wherein the identification includes a group identity.

76. A simulated weapon according to any of claims 73 to 75, wherein the identification includes an individual identity.

77. A simulated weapon according to any of claims 64 to 76, wherein the first data signal represents a projectile and the second data signal represents an acknowledgement of an impact.

78. A simulated weapon according to any of claims 64 to 76, wherein the first data signal represents an interrogation and the second data signal represents a reply.

79. A simulated weapon according to claim 78, as appendant at least to claim 65 and claim 74, wherein the registering means includes indicating means for indicating the identification of the replying weapon.

80. A simulated weapon according to claim 79, as appendant to claim 75, wherein the indicating means includes means for producing a visual signal of a colour according to the group identity.

81. A simulated weapon according to any of claims 64 to 80, wherein the transmissions of the first and second data signals are distinguishable by the receiving means.

82. A simulated weapon according to claim 81, wherein the first and second data signals are transmitted using carrier signals of different frequencies.

83. A simulated weapon according to any of claims 64 to 82, wherein the first and second data signals are digital.

84. A simulated weapon according to any of claims 64 to 83, wherein the first data signal has a predetermined duration.

85. A simulated weapon according to any of claims 64 to 84, wherein the second data signal has a predetermined duration.

86. A simulated weapon system comprising a weapon and a target, said weapon having first emitting means for emitting a first data signal and second receiving means for receiving a second data signal, said target having first receiving means for receiving said first data signal and second emitting means for emitting said second data signal, said target including processing means for processing said received first data signal and generating said second data signal for emission, in response to the processing.

87. A simulated weapon system according to claim 86, wherein the first data signal comprises data representing a projectile and the second data signal comprises data representing an impact of the projectile.

88. A simulated weapon system according to claim 86, wherein the first data signal comprises data representing an interrogation of the target as to an attribute of the target and the second data signal comprises data representing a reply to the interrogation.

89. A simulated weapon system according to claim 88, wherein said attribute is an identification assigned to the target.

90. A simulated weapon system according to any of claims 86 to 89, wherein the first emitting means emits the first data signal substantially directionally and the first receiving means has a substantially non-directional sensitivity.

91. A simulated weapon system according to any of claims 86 to 90, wherein the second emitting means broadcasts the second data signal substantially nondirectionally and the second receiving means has a substantially directional sensitivity.

92. A simulated weapon comprising the features of said weapon according to any of claims 86 to 91, and further comprising means for registering a received second data signal.

93. A simulated weapon comprising said first emitting means of said weapon and the features of said target, according to any of claims 86 to 91.

94. A simulated weapon comprising transmitting means for emitting a first data signal comprising a sequence of portions, wherein means are provided for controlling the power with which the signal is transmitted so as to transmit different portions of the signal at different power levels.

95. A simulated weapon according to claim 94, wherein at least one of said portions includes data for determining a respective signal transmission condition, said one portion being transmitted at a unique power level.

96. A simulated weapon according to claim 94 or 95, wherein the signal includes at least one condition-determining portion and a data portion, the condition-determining portion being transmitted at a lower power level than the data portion.

97. A simulated weapon according to claim 96, wherein the signal includes a plurality of conditiondetermining portions defining respective conditions, transmitted at different power levels in order of increasing transmission power.

98. A simulated weapon according to claim 96 or claim 97, wherein the or each condition-determining portion of the signal precedes the data portion.

99. A simulated weapon according to any of claims 94 to 98, wherein the first data signal represents a projectile.

100. A simulated weapon according to any of claims 94 to 98, wherein the first data signal represents an interrogation.

101. A simulated weapon according to any of claims 94 to 100, comprising processing means which generates the data signal for transmission, wherein the processing means also generates a control signal for controlling the transmission power.

102. A simulated weapon comprising receiving means for receiving a first data signal emitted by the weapon defined by any of claims 94 to 101, and registering means adapted to register selectively one of a plurality of conditions according to the detected portion or portions of said signal.

103. A simulated weapon according to claim 102, as appendant to any of claims 96 to 101, wherein the registering means registers the one said condition according to whether or not the condition-determining portion of said first data signal is validly detected in addition to the data portion, in the case that the signal includes only one condition-determining portion, or according to the condition-determining portion of the lowest transmission power which is validly detected in addition to the data portion, in the case that the first data signal includes more than one condition-determining portion.

104. A simulated weapon according to claim 103, as appendant to claim 99, wherein the registered one condition identifies a degree of the impact of said projectile.

105. A simulated weapon according to claim 104, wherein one registrable condition identifies a miss by the projectile.

106. A simulated weapon according to claim 104, wherein one registrable condition identifies a nearmiss by the projectile.

107. A simulated weapon according to claim 103, as appendant to claim 100, wherein the registered one condition identifies a range of the interrogated weapon with respect to the interrogating weapon.

108. A simulated weapon according to any of claims 102 to 107, comprising transmitting means for responding to a received said first data signal, by emitting a second data signal which includes a representation of the registered one condition.

109. A simulated weapon which comprises in combination the features of the weapon defined by claims 94 to 101 and the features of the weapon defined by claims 102 to 108.

110. A simulated weapon according to any of claims 94 to 101 and 109, wherein the power controlling means comprises a circuit for controlling the bias applied to a radiating means of the first data signal transmitting means.

111. A simulated weapon which comprises means for transmitting a beam carrying an audio signal in the direction in which the weapon is aimed.

112. A simulated weapon which emits on command a beam of radiation modulated by a data signal representing a projectile, wherein means is provided for alternatively modulating said beam with an audio signal.

113. A simulated weapon according to claim 111 or claim 112, wherein the audio signal is derived from speech input by the operator of the weapon.

114. A simulated weapon according to any of claims 111 to 113, wherein the transmission of the audio signal is accompanied by a second data signal.

115. A simulated weapon according to claim 114, wherein the second data signal is transmitted intermittently during the audio transmission.

116. A simulated weapon according to claim 114 or claim 115, wherein the second data signal uses a carrier of different frequency than that of the audio signal.

117. A simulated weapon according to any of claims 114 to 116, wherein the second data signal includes data signalling the accompanying audio transmission.

118. A simulated weapon according to any of claims 111 to 117, wherein the beam comprises infrared light.

119. A simulated weapon according to any of claims 111 to 118, comprising means for alternatively transmitting said audio signal non-directionally.

120. A simulated weapon according to claim 119, as appendant to any of claims 114 to 117, wherein the second data signal is different for the directional and non-directional transmissions of the audio signal.

121. A simulated weapon according to claim 120, wherein the second data signal which accompanies the non-directional transmission of the audio signal includes data identifying the intended receiver of the transmission.

122. A simulated weapon according to any of claims 119 to 121, wherein the directional and nondirectional transmissions of the audio signal use carriers of different frequencies.

123. A simulated weapon according to any of claims 119 to 122, wherein the non-directional transmission comprises infrared light.

124. A simulated weapon comprising means for emitting and detecting a data signal representing a projectile, wherein means is provided for generating a sound effect of a heartbeat.

125. A simulated weapon according to claim 124, wherein the generating means is adapted to change the rate of the generated heartbeat.

126. A simulated weapon according to claim 125, wherein the rate of the heartbeat is increased when a said data signal is detected.

127. A simulated weapon according to any of claims 124 to 126, wherein the generating means is adapted to change the volume of the generated heartbeat.

128. A simulated weapon according to claim 127, wherein the volume of the heartbeat is increased when a said data signal is detected.

129. A sighting device for an object which needs to be aimed at a target by an operator, comprising an elongate body, an electrically-powered point light source disposed at one end inside the body, and a lens mounted at the other end of the body spaced from the point light source substantially by its focal length, for providing a spot of light in a field of vision of the operator when viewing the device with one eye and keeping both eyes open.

130. A sighting device according to claim 129, including display means mounted within the body of the device and viewable through said lens for providing in the field of vision of the operator a display of one or more operating conditions of the object.

131. A simulated weapon which emits on command a directional beam carrying a signal representing a projectile, the weapon including a sight for aiming the weapon, the sight comprising an electricallypowered light source and means for producing therefrom a spot of light in the user's field of vision, when aiming the weapon, which coincides with the footprint of the beam.

132. A simulated weapon according to claim 131, including means for controlling the state of the light source according to a condition determined by the weapon.

133. A simulated weapon according to claim 132, wherein the controlling means is responsive to a data signal received from an object at which the weapon is aimed.

134. A simulated weapon according to claim 132 or claim 133, wherein the light source is adapted to emit selectively light of one of a plurality of colours, the controlling means determining the emitted light colour.

135. A simulated weapon which emits on command a directional beam carrying a signal representing a projectile, the weapon including a sight for aiming the weapon, the sight including display means disposed within the body of the sight and viewable when using the sight, the display means providing a display of one or more operating conditions of the weapon.

136. A simulated weapon according to claim 135, wherein the display means includes a display of a score.

137. A simulated weapon according to claim 135 or claim 136, wherein the sight provides a coloured light spot in the field of vision of the user to be located, when aiming the weapon, on an intended target.

138. A simulated weapon substantially as hereinbefore described with reference to Figs. 1 and 10 of the accompanying drawings.

139. A simulated weapon substantially as hereinbefore described with reference to Figs. 1 and 11 of the accompanying drawings.

140. A simulated weapon substantially as hereinbefore described with reference to Figs. 6 to 8 and 12 of the accompanying drawings.

141. A sighting device substantially as hereinbefore described with reference to Fig. 3 of the accompanying drawings.

142. A sighting device substantially as hereinbefore described with reference to Fig. 4A of the accompanying drawings.

143. A game substantially as hereinbefore described comprising two simulated weapons each according to claim 138 or claim 139.

144. A game substantially as hereinbefore described comprising a simulated weapon according to claim 138 or claim 139 and a simulated weapon according to claim 140.