EP1019667A1

EP1019667A1 - Arrangement on firearms used at practice shooting

Info

Publication number: EP1019667A1
Application number: EP98941932A
Authority: EP
Inventors: Siri Grundnes Holmboe; Tor Holmboe
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-09-05
Filing date: 1998-08-25
Publication date: 2000-07-19
Also published as: WO1999013286A1; NO305184B1; NO974094D0; AU9008598A; NO974094L

Abstract

The present invention relates to a device in a firearm (1A), in particular guns and light small arms, and more particularly for practice firing of such weapons, comprising a device mounted detachably on the weapon, capable when in use and by means of processable electrical signals, of identifying, selecting and verifying the extended line of sight of the weapon relative to a firing target, in particular a bull's eye, and communicating with a data processing unit which can process the electrical signals to provide an evaluation of the shot, and for the purpose of providing a device which can be fitted on the weapon for capture of relevant firing data for practice purposes, while being independent of electronic equipment at the targets or at the shooting station, it is suggested according to the invention that the device comprise a combination of optics (1), camera unit (3) and electronic image detector (2) for sequential and optionally selected electronic image formation of the weapon's relative movements and position relative to one or several bull's eye(s) in a certain space of time prior to, during and after the weapon's ignition mechanism is released, and that the data processing unit is comprised by an electronic central unit (5) detachably mounted on the weapon, arranged to process, preferably in digital form, to optionally compress and to store the image signals received sequentially from the device (1, 3, 2), in particular in the form of sight movements prior to and after the firing.

Description

ARRANGEMENT ON FIREARMS USED AT PRACTICE SHOOTING.

The scope of the invention

The present invention is a device in a firearm, especially a gun and light small arms of the kind mentioned in the preamble of the attached patent claim l.

Prior art

A device of a similar nature is known from e.g. EP 0 330 886 (Volpe) , the said publication suggesting an electronic shooting simulator which can be fitted to an ordinary gun, enabling live shots to be fired. The simulator, however, works with a so-called telecamera which constitutes an electronic camera, and the entire known device is merely arranged to take a still picture at the very moment when the shot is released. True enough, each single picture is processed and stored electronically, to be presented to the marksman on a monitor, but nevertheless as a still picture which serves to evaluate a shot fired and its pertaining point of impact.

Consequently, the said publication fails to describe any recording of the movements which the marksman makes with the weapon before, during and after the actual moment of firing the shot, nor is there any measuring made of the time space occupied by the force which the marksman exerts on the trigger.

Known from EP 0 160 123 (Kuroiwa) is a practising aid which may be attached to a gun or a pistol, so that live shots can be fired. The system relies on the use of a miniature camera attached either directly on the barrel of the gun, or only the optics are attached to the barrel of the gun, leading the picture to the camera, but here by means of a bundle of flexible optical fibres. A similar device is also known from DE 32 21 592 (Busch) where an objective is used and is connected to a camera by a bundle of flexible optical fibres several metres long.

The said solutions involving permanently fitted fibre cables are not viable as a practising aid in connection with e.g. biathlon where the marksman skier moves from one shooting station to the next, and where it is of great importance to record the movements of the weapon before, during and after the firing moment, not least in a plurality of successive shots.

From DE 28 25 836 (Borel) is also known the use of a photographic camera, but here merely one photographs is taken when the trigger is pulled, i.e. a registration is made of the point of impact which is of limited value in practice shooting.

GB 2 141 810 (Keller et al.) relates to an apparatus for the practicing of cannon gunners, where a video camera is also used and connected via a flexible bundle of optic fibres. Such an apparatus would only with difficulty be adaptable to e.g. a gun used by a biathlon marksman without considerable technical efforts.

NO patent application 78.2090 (Knight et al . ) relates mainly to a system for electronic display of hits made by live shots which entails that a certain type of microphone will need to be placed by the target. To be sure, NO patent application 78.2090 mentions video filming of what the marksman sees through his sight, namely by fitting suitable optics on the gun and connecting the optics to a video camera by means of A bundle of flexible optic fibres, which is highly impractical when the marksmen are to move from shooting station to shooting station. In the said publication there is also mention of pressure sensitive transducers, e.g. of the strain gauge type, for the purpose of measuring the pressure exerted by the marksman against four different parts of the gun butt. Mentioned is also a sensor at the trigger, yet this is only intended for recording the time taken by the marksman to increase the pulling force from the first point of pressure until release level, a parameter which is of secondary importance compared with the present invention.

Summary of the invention

One aim of the present invention is to provide a device to be used as a practising aid for gun and pistol marksmen, and in particular for biathlon skier marksmen, in a simple, rational and cos -saving manner.

A further aim of the invention is to provide a device capable of measuring what movements the marksman makes with his weapon relative to the bull's eye of the target in a certain space of time surrounding the actual moment of firing, hereinafter referred to as "the sight movements" .

Yet another aim of the present invention is to provide a unit which can be attached to the actual weapon, so that the weapon becomes completely mobile, which is an advantage e.g. in connection with biathlon where the contestant varies between shooting and cross-country skiing between the various shooting stations.

An additional aim of the invention is to provide a device which is independent of additional equipment at the bull's eyes of the targets which entails that the device may be used e.g. for biathlon targets with five black bull's eyes.

Yet a further aim is to provide units which are easily replaced and adapted to each individual marksman and/or form of shooting, respectively the time and place of shooting and/or displaying.

More specifically, an aim of the invention is also to provide a device where measuring is made of the position of the weapon at the exact moment of being fired, so that the points of value / point of impact of the shot is recorded relative to the sight movement.

An additional aim of the invention is that by means of such a device it will be possible to measure also the force of pressure exerted by the marksman on the trigger of the weapon as a function of the time during the said space of time, e.h. 5 seconds, prior to the moment of firing, and 2 or more seconds after the moment of firing.

It is yet another aim of the invention to provide a special way of treating the data recorded, and also specific methods of displaying these in real time and/or later.

These and other aims are achieved by a device of the nature stated initially which is characterised by the features stated in the characterising part of the attached patent claim 1.

Additional features and advantages of the present invention will be evident from the following description, taken in conjunction with the attached figures of drawings, and also from the additional, attached patent claims .

Brief description of the f igures of the drawings

Figure 1 shows an Assembly of the most signif icant components being part of an example of an embodiment of the invention . Figures 2 is a schematic constellation of elements which may form part of a general technical solution according to the present invention.

Figure 3 is a constellation similar to that of Figure 2 wherein is shown an example of a technical realisation of some of the most important elements.

Detailed description of embodiments

Shown in Figures 1 to 3 is an example of an embodiment of the present invention.

In Figure 1 is shown a weapon (1A) , in particular a gun, comprising a device detachably fitted to the weapon, which when being used is capable of, by means of processable, electrical signals, identifying, selecting and verifying the extended sight line of the weapon relative to a firing target .

In the embodiment shown in Figures 1, 2 and 3 such a device comprises a combination of optics 1, camera unit 3 and electronic image detector 2 for sequential and optionally selected electronic imaging of the weapon's relative movements and position as regards one or several bull's eyes for a certain space of time before, during and after the firing mechanism of the weapon is released, while a data processing unit is constituted by an electronic central unit 5 detachably fitted to the weapon 1A and being arranged so that it may preferably in digital form, process, optionally compress, and store the image signals received sequentially from the device 1, 3,2, in particular in the form of sight movements before and after firing.

In the example shown the device makes use, among other things, of an electronic camera 3 with a specially designed encapsulation 3A and optics 1, which are attached to the actual weapon 1A, in parallel with the sight line, so that the bull's eye constitutes part of the image. This electronic camera may, for instance, be a video camera which will automatically take pictures continuously and generate a standard electronic video signal, e.g. CCIR composite video with 50 images per second. The relative position of the bull's eye in the picture reveals where the weapon is pointing at any given time. A series of pictures, consecutive in time, from the camera will thus contain the desired information concerning the sight movement .

The electrical signal from the camera 3 is led to the electronic signals processing unit or the central unit 5, which is also attached to the actual weapon 1A. Here the camera signal is digitized, followed by further processing and storing in the "solid state memory". This process takes place in real time, so that the processing of the signal / storing of requisite information from one image is completed before the next image arrives. The signals processing unit 5 has a sufficiently large memory (e.g. 4 Mbit) to enable it to store data from a number of images so large as to be deemed sufficient for being able to describe the movements in connection with several shots (e.g. 10) with acceptable time resolution and sufficiently length of time per shot.

This technology should not be confused with known systems which store the actual video images in analogous or digital form using for example a video cassette recorder or a PC with video editing facilities such as is known from the patent literature. These known technologies require a connection (either through a cable or by radio link) to equipment which is not fitted to the weapon in the actual firing situation.

An electronic image is made up of a rectangular matrix of image points or "pixels" . Each pixel may be imagined to consist of a numerical value, representing the colour hue of the pixel. In a black/white image it will be a matter of shades of grey. A preferred way of compressing the image information is to add together the digital values of all the pixels so that a sum is arrived at for each horizontal row and one for each vertical column which make up the image. These row and column totals may for instance be performed by hardware logics in the form of a P D circuit which will also store the result directly in a SRAM circuit.

The signals processing unit should in that case also comprise a micro computer e.g. in the form of a micro controller circuit, to administer the capture of data. It will determine, .among other things, what images from the camera are to be processed and stored. The micro computer may also handle the communication as regards the PC, e.g. in the form of standard RS232 signals.

The above mentioned way of processing the image information is not an image compressing algorithm which will substantially preserve the actual image. It will on the contrary be impossible to reconstruct the image merely on the basis of the row and column totals. In the light of this it is therefore not the case that the image itself can be said to have been stored. If, however, additional information is available to the effect that the image (the bull's eye) consists of a geometrical figure of a certain size and shape contrasting against a background of a different colour, such as e.g. a black circle against a white backdrop, it will be an easy matter to detect the relative position of the figure in the image, based on the row and column totals. This may for instance be done by the PC software in the following manner:

• All the individual (horizontal) row totals in an image will jointly form a series of numbers f_m which will vary from image to image as the weapon is being moved in the vertical direction, yet is invariant to movements in the horizontal direction. • In addition a synthesizing is made of a constant series of numbers g_q corresponding to the series of numbers of the row totals theoretically arrived at if the imagined geometrical shape had been vertically centred in the image.

• The two series of numbers will be of identical form but will generally be offset by P pixels relative to each other because the bull's eye is generally offset by P pixels relative to the vertical centre of the image. It is desired to find the vertical position P of the bull's eye.

• P is found by performing a cross- correlation between the two series of numbers f_m and g_Q. The cross- correlation may be expressed by the following general formula (as known from the subject discipline digital signals analysis) :

1 ^N φ_fAn) = lim—-—- X /_mg_m+„

This series of numbers has a maximal value for n = P which gives us the vertical position P of the bull's eye. (In practice it will suffice to let N be large enough to allow all requisite information in the two series of numbers f and g to be taken into account . )

• The horizontal position of the bull's eye can be found in the same way by cross- correlating with the series of numbers consisting of vertical column totals.

In order that the signals processing unit may be able to detect when the actual shot is being fired (or the weapon's mechanism being released without a live bullet in the chamber) , a separate sensor is needed. This sensor may e.g. be a contact microphone which has good mechanical contact with the actual weapon and is readily able to register the noise generated by the weapon's mechanism upon being released, without being affected by noise from the surroundings. The microphone may e.g. be positioned in the same encapsulation as the central unit 5 or the camera unit 3. The analogous signal from the microphone is being digitized and used by the central unit e.g. in determining what images should be processed/stored.

Provided it is not required that the practising unit could be used for dry practice but only when firing live shots, the sensor may be a miniature accelerometer which will register the recoil associated with live shots.

A preferred way of structuring the information from the camera is to store the information from the images in a ring buffer which can hold enough image data to cover the entire desired time interval in connection with one shot (e.g. X seconds prior to the moment of firing and Y seconds after the moment of firing = (X+Y) seconds in all) . Prior to the moment of firing this ring buffer will contain the most recent (X+Y) seconds at any time with information about the sight movements. At the moment when the shot is fired, the relevant "image" is marked specifically, and the system continues storing image data for a further Y seconds .

Following that the process stops, or the system starts storing data in a new ring buffer in order to keep the information associated with the next shot. To be able to keep the information from Z shots, there will in that case be a need for Z ring buffers. All ring buffers may be realised in one and the same SRAM circuit.

If a requirement is specified for the target to be of the type "dark geometrical shape against a light coloured backdrop" (e.g. a circular black bull's eye on a white background, being the most common) so that the actual bull's eye contrasts well with its background, a black- and-white camera may well be used, and the digitalization of the image information may well be performed by a one bit analogous/digital converter, so that the number "1" corresponds to a dark image pixel and the number "0" to a light one, or vice versa (this presupposes that the camera has automatic exposure control so that varying conditions of light will be of no significance) .

The following preferred example illustrates the amount of data :

• Each image pixel is represented in the form of one bit

• Each image consists of 256 x 256 = 65,536 pixels = 65,536 bit

• The image is compressed in that the pixel values are added up so that a total is reached for each line and for each column making up the image. Each total will be a number between 0 and 255 which can then be represented in one byte. Following the compression, the information from the image 4 is thus represented by: 2 x 256 Byte = 512 Byte = 4,096 bit.

• A SRAM chip organised as 512k x 8 bit = 4 Mbit thus has the capacity to store Ik = 1024 images. • At an image frequency of 25 Hz a total time interval of 41 seconds will be covered which can be distributed on the number of shots (ring buffer) desired, e.g. 10 shots, equalling abt. 4 seconds per shot.

For the purpose of measuring the force between the marksman's finger and the weapon's trigger as a function of the time, several technical solutions exist. One option is to mount the actual sensor element (or elements) permanently in the actual trigger shoe. Since the entire device is intended to be readily movable from one weapon to another, that naturally requires the weapon to be of a type where it is easy to replace the trigger shoe, without having to dismantle the entire trigger mechanism and without the assistance of experts. That is, however, the case on a great number of competition weapons. A suitable manner in which to implement this is e.g. by glueing one or several strain gauges on to the trigger shoe. The small mechanical deformations which occur in the trigger shoe on being exposed to the force from the finger causes the electrical resistance in the strain gauge (s) to be altered in a systematic manner commensurate with the size of the force applied. These changes in resistance will be transformed into electrical voltage or current which is being digitized by an appropriate analogous/digital converter. On weapons where the trigger shoe cannot readily be replaced, it is possible instead to use a miniature load cell, to be fastened in a detachable manner at the front of the trigger shoe so that the marksman's finger presses against it and not directly against the trigger shoe. Such load cells are commercially available and are generally based on strain gauges or piezo- electric crystals.

The device according to the invention thus monitors the movements which the marksman makes with the weapon in relation to the bull's eye for a certain space of time surrounding the actual moment of firing, namely the "sight movements". Monitored is in particular also at what point of the bull's eye the weapon is directed at the actual moment of firing, so that the value points / point of impact of the shot is being recorded. Also monitored is the force which the marksman exerts against the weapon's trigger as a function of the time during that same space of time. The space of time concerned may e.g. commence 5 seconds prior to the moment of firing, and continue until 2 second after the moment of firing, but this can be adjusted by the marksman himself.

The device may be used both when firing live shots and for so-called "dry practice", i.e. that the marksman aims and pulls the trigger as with an ordinary shot, but without ammunition in the weapon. The device is solely attached to the actual weapon, without the need for cables or any other connection to units not attached to the weapon in the actual firing situation. Nor is there any need for additional equipment mounted at the targets. The apparatus may be used in connection with shooting on an ordinary firing range against ordinary targets, or in connection with dry practice either against full-scale targets or against targets of a reduced size at a reduced distance. The device may be fitted in a detachable manner to an ordinary weapon so that it may readily be moved from one weapon to another. There is no need for electronic equipment at the target (s) . When the shooting is finished the device is connected to a standard PC by means of a cable, for transferring the monitored data to the PC. A special PC program will post-process the data, presenting the result graphically on the PC screen or on a PC printer. The program is furthermore capable of making a statistical analysis of the marksman, based on many shots, and can also compare different marksmen.

Because the device in the firing situation only consists of units attached to the actual weapon, the weapon is rendered completely mobile. That is a major advantage in e.g. biathlon where the contestant alternates between shooting and cross-country skiing with the gun carried on the back. The fact that e.g. the biathlon targets consist of as much as five black bull's eyes also represents no major problem, since there is no need for electronic equipment at the target ( s ) .

The purpose of taking these measurings of sight movements and trigger force is to be able in an objective manner to characterize important aspects of the marksman's behaviour. Too wide deflections in the sight movements prior to the shot being fired may e.g. indicate an incorrect firing position, or that the marksman uses his muscles incorrectly, e.g. tension. The sight movements after the shot has been fired will in the case of live ammunition mostly be a result of the weapon's recoil, and the marksman's position and grip on the weapon. If that recoil movement varies from shot to shot, it means that the marksman is unable to handle the recoil, e.g. because his grip on the weapon is not firm enough or because the shooting position is wrong. Monitoring the trigger force shows whether the marksman has a correct pull or whether he "tucks", i.e. pulls the trigger too quickly and uncontrolled. The outcome of a "tuck" will more often than not be that the marksman makes a rapid unconscious / uncontrolled movement with the weapon so that the shot misses the bull's eye, even if the shooting position and grip are correct. These are familiar problems in all kinds of shooting with guns and pistols. Combined measuring of pulling force and sight movements will uncover and provide evidence of this interconnection to the marksman / the coach in a highly pedagogical manner. Since the device also shows the value points / point of impact, is is well suited also for dry practice.

Related devices exist in the market and in the patent literature. The most significant advantages inherent in the device concerned over those others are as follows:

• All units required in the actual situation of firing in order to capture and store the necessary data, are fitted on to the weapon. No additional electronic equipment is required at the target (ε) or at the shooting station. This means that the mobility of the weapon is not affected, and the weapon may, e.g. during biathlon, be carried along in the ski track. • The device can be used for live ammunition as well as in dry practice.

• The device also measures the force on the trigger as a function of the time. Another feature of the device is that the central unit comprises electronic elements which may comprise software for final signals processing and presentation, optionally replaceable elements which may be pre-adjusted / programmed. with various parameters adapted to the individual marksman and/or form of shooting.

Particular embodiments may then entail that the electronic elements of the central unit are designed as electronic boards or other appropriate programmable and/or information carrying units.

The device may moreover be executed in a way where the central unit is equipped to communication, e.g. via a cordless connection or cabling, with a mainframe computer located at the respective practice place, optionally at each shooting station in connection e.g. with biathlon, so that the marksman may have a presentation of the captured information i nigh on real time, immediately after each shot or series of shots .

For marksmen and coaches it may be expedient that the sight movements are displayed in two dimensions on a suitable display, and that the pertaining pressure force on the trigger is also shown two-dimensionally on the same or a similar monitor, optionally that the sight movements and the pertaining application of force on the trigger be displayed three-dimensionally, e.g. perspectively, stereoscopically or by means of colour coding.

It should be understood that the device may also comprise a third sensor 9 mounted internally in the central unit or the camera unit, and arranged so as to measure the angle accelerations as a function of the time in two different directions perpendicular to the sight line, for instance horizontally and vertically, and that electronic information concerning the acceleration in these two directions is being processed and stored in the central unit . thereby to detect the position of the sighting point relative to the images in the period of time between the point in time for each image.

The objective is thus to gather supplementary information from a two-axis accelerometer for the purpose of increasing the time resolution of the sight movement beyond the time resolution in the image information. A standard video camera, for instance, will give 50 images per second, which means 50 points for the sight movement per second. If for instance 200 accelerometer measurings are made per second, then the number of points in the sight movement can be increased to 200 per second. It is, however, important to note that the accelerometer measurings in themselves do not provide an absolute position relative to the bull's eye, but only provides the movement of the sighting point between each image. The image information therefore still remains the most important, as it provides the absolute position of the sighting point relative to the bull's eye.

Claims

P a t e n t c l a i m s

1. A device in a weapon (1A) , in particular guns and light small arms, and more particularly for practice shooting with such weapons, comprising a device fitted detachably to the weapon which is during use capable, by means of processable electrical signals, of identifying, selecting and verifying the extended line of sight of the weapon relative to a shooting target, in particular a bull's eye, and is communicating with a data processing unit capable of processing the electrical signals to provide an evaluation of the shot, c h a r a c t e r i s e d in that the device comprises a combination of optics (1) , camera unit (3) and electronic image detector (2) for sequential and optionally selective electronic image formation of the weapon's relative movements and position relative to one or several bull's eye(s) in a certain space of time prior to, during and after the firing mechanism of the weapon is released, and that the data processing unit is made up of an electronic central unit (5) fitted detachably to the weapon and arranged to process preferably in digital form,

2. A device as stated in claim 1, c h a r a c t e r i s e d in that the electronic central unit (5) is arranged to communicate with a camera unit (3) in the form of a video camera and to digitize the analogous signals from there, optionally that the electronic central unit (5) communicates with a camera unit (3) which issues digital signals.

3. A device as stated in claims 1 or 2 , c h a r a c t e r i s e d in that the combination of optics (1) , camera unit (3) and electronic image detector (2) is built together in a separate camera housing.

. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the central unit (5) comprises electronic elements which may comprise software for final signals processing and presentation, optionally replaceable elements which may have been pre-adjusted / programmed with various parameters adapted to the individual marksman and/or form of shooting.

5. A device as stated in claims 1 or 2 , c h a r a c t e r i s e d in that the electronic elements of the central unit (5) are executed as electronic boards or other suitable programmable and / or information carrying units.

6. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the central unit (5) comprises among other things a PLD circuit for compressing image information, a micro controller for controlling, and a SRAM circuit for storage of data.

7. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the central unit (5) is executed with facilities for communication with a mainframe computer (7) . for instance via a cordless connection or cable (6) , for optionally final processing of the electronic signals and presentation on a suitable display, for instance a screen or a board or such like, be it in real time and/or at a random period of time after the shooting has been completed.

8. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the device comprises an initial sensor (4) which detects the point in time for release of the weapon's firing mechanism, irrespective of whether the weapon is loaded with live shots or not.

9. A device as stated in claim 8 , c h a r a c t e r i s e d in that the initial sensor (4] is made up of a microphone.

10. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the device comprises a second sensor (8) which is mounted in the area of the weapon's trigger, and arranged so as to be able to measure the force exerted by the marksman's finger against the trigger as a function of the time, and that electronic information concerning this event of force being exerted is processed and stored in the central unit (5) .

11. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the force monitoring sensor (8) comprises one or more strain gauges, for instance of the piezo-resistive type, which are preferably permanently mounted on a detachable trigger so that the trigger and the force monitoring sensor (8) constitute an integrated unit which may be moved from one weapon to another.

12. A device as stated in the claims 1 to 10 c h a r a c t e r i s e d in that the force monitoring sensor (8) is mounted detachably on the trigger of the weapon.

13. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the device comprises a third sensor (9) which is fitted internally in the central unit or the camera unit and is arranged to measure the angle accelerations as a function of the time in two different directions perpendicular to the line of sight, for instance horizontally and vertically, and that electronic information concerning the acceleration in these two directions is processed and stored in the central unit.

14. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the central unit (5) is executed with facilities for communication, for example via a cordless connection or cable (6) with a mainframe computer (7) located at the respective practice place, optionally at each shooting station in connection with for instance biathlon, so that the marksman may have the information captured presented in nigh on real time, immediately after each shot or series of shots.

15. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the electronic image detector (2) may be a video circuit emitting a standard video signal, so that the camera unit (3) may comprise a video camera.

16. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the central unit (5) , respectively one or several mainframe computers (7), comprise a compressing algorithm for image information which entails that the digital values of all picture points of the image are added up so that a total is arrived at for each row and a total for each column which make up the image.

17. A device as stated in claim 13 c h a r a c t e r i s e d in that the relative position of the bull's eye in the image is detected on the basis of the said row and column totals, and that the offset of the bull's eye relative to the geometrical centre of the image is calculated, this being performed by cross-correlation between the said row and column totals and known series of numbers corresponding to the geometrical shape of the bull's eye.

18. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the information from the images is stored in a ring buffer which can hold enough image data to cover the entire desired time interval in connection with one shot, and that in the central unit (5) so many ring buffers are arranged as the number of expected shots in one round.

19. A device as stated in one of the preceding claims c h a r a c t e r i s e d in that the sight movements are displayed two-dimensionally on a suitable display (7) , and that the pertaining pressure force on the trigger is also displayed two-dimensionally on the same or a similar monitor (7), optionally that the sight movements and the pertaining application of force on the trigger be displayed three-dimensionally, e.g. perspectively, stereoscopically or by means of colour coding.