GB2078353A

GB2078353A - Target with a device for the automatic determination of the position of the shot in the target image

Info

Publication number: GB2078353A
Application number: GB8118733A
Authority: GB
Original assignee: Polytronic AG
Current assignee: Polytronic AG
Priority date: 1980-06-18
Filing date: 1981-06-18
Publication date: 1982-01-06
Also published as: AT368632B; SE8103668L; FR2485181B1; FR2485181A1; DE3122287A1; GB2078353B; AU7131381A; CH647861A5; AU539054B2; ATA269781A

Abstract

The target comprises a target member (1), behind which is positioned a ricochet plate (6) made from a resonatable material, which cannot be penetrated by a shot. Sensors (11, 12, 13 and 14) are in contact with ricochet plate (6) and are connected to an electronic evaluation apparatus (15) and a following optical display (16) for determining and displaying the score and the position of the shot. This arrangement makes it possible also to determine the position of the shot of projectiles with a flight velocity in the subsonic range. <IMAGE>

Description

SPECIFICATION Target with a device for the automatic determination of the position of the shot in the target image The present invention relates to a target with a device for the automatic determination of the position of the shot in the target image by means of a group of sound wave-sensitive sensors, which assume a clearly defined position relative to a reference coordinate system and which are connected to an electronic evaluation apparatus and to a following optical display forthe determination and display of the score and the position of the shot.

In a known device of this type according to Swiss Patent 526763 a plurality of sensor pairs are arranged on the periphery of a circle concentric to the centre of the target, the two sensors of one pair being diametrically opposite to the centre of the target. The sensors assume a clearly defined position with respect to a polar coordinate system, whose origin coincides with the centre of the target image. If the sound propagation speed prevailing in the target is known, the position of the shot in the polar coordinate system can be calculated in the computer of the electronic evaluation apparatus on the basis of the time-staggered arrival of the detonation wave at the sensors of a pair of sensors.

Furthermore it is known from Swiss Patent 589 835 to arrange three acoustic sensors in the target plane in order to measure the time stagger of the arrival of the detonation wave at the sensors and calculate the position of the shot utilizing the sound propagation speed prevailing in the target.

The sound propagation speed in the vicinity of the target can be determined on the basis of the air temperature and humidity level prevailing there.

These devices have the disadvantage that they supply incorrect indications if there is a wide variation in the air temperatures and humidity levels prevailing in the target, so that no clearly defined sound propagation speed is obtained.

To take account of this the present Applicant proposes providing a further sensor for determining the position of the shot when the sound velocity is unknown and which is in addition to the number of sensors required for shot position determination when this speed is known and which is associated with the group of sensors in the target plane. As a result in the case of a mathematical evaluation of the position of the shot it is possible to ignore the average sound velocity occurring in the target between the penetration point and the acoustic transducers at the time of penetration.

However, in the case of these devices the ambient air serves as the propagation medium for the sound waves, but this can only achieve a "signal magnitude" if a sonic boom is produced with the incoming projectile. However, incoming projectiles or bullets with a flight velocity in the subsonic range, e.g. fired from small-bore weapons, only produce neutral sound waves which cannot be evaluated with the existing devices.

The problem of the present invention is to provide a target of the aforementioned type making it possible to also permit the determination of the position of the shot of projectiles arriving with a subsonic speed.

According to the invention this is achieved in that the sensors are in contact with a ricochet plate made from a resonatable material which cannot be penetrated and positioned behind the target member carrying the target image.

The target can be constructed in such a way that the preferably steel ricochet or deflecting plate is inclined relative to the target member, said member and said plate forming a downwardly opening angle.

At the bottom between the ricochet plate and the target member there is a butt. It is also advantageous if the sensor group has four sensors with preferably a piezoelectric crystal in each case. They face one another in pairs with respect to the centre of the target image, the sensors of one pair being equidistantly spaced.

In order to prevent a signal being undesirably given in the case of broken stones or ricochets between each sensor and the electronic evaluating apparatus a threshold value switch is provided.

Unlike in the prior art this measure now makes it possible to determine the position of the shot in the target image or picture even with bullets having a flight velocity in the subsonic range because now the richochet plate which, compared with air as the propagation medium for the sound waves, is acoustically much denser, acts as a sensitive conductor for the impact wave produced by the impact of the bullet.

An exemplified embodiment of the invention is described in non-limitative manner hereinafter relative to the drawing, which diagrammatically shows a target according to the invention.

The represented target with a device for the automatic determination of the position of the shot in the target image A comprises a disk-like arrangement with in this case a rectangular target member 1 on whose front is provided a sheet with a circular target image A, whilst its back carries a not shown sheet with a target image B showing a figure. Target member 1 is in this case surrounded by an outer frame 3 and is supported thereon by means of a central horizontal spindle 4.

The target member 1 can be tilted vertically by 180" in the direction of arrow 5 about spindle 4 in such a way that the back target image is brought into the target plane.

Such a changeable target is described in detail in the Applicant's GB Patent no . . (Application no.

8101025) and requires no more detailed explanation here. This is particularly the case in view of the fact that such a target is not necessary and the inventive concept can also be realized on conventional fixed or vanishing targets.

According to the invention a ricochet or deflection plate 6 is positioned behind the target member 1 and with respect to the latter is inclined in such a way that both plate 6 and member 1 form a downwardly opening angle.

Ricochet plate 6 is made from a reasonatable material, which cannot be penetrated by the projectile, e.g. steel and serves both as a propagation medium for the impact wave produced by the impact of a projectile and as a reflector for the striking projectilewhich is deflected by it into a butt 7, as indicated by the dotted-line projectile trajectory 8.

Butt 7, which can be a conventional sand-filled trough, tray or the like is preferably located on the ground between ricochet plate 6 and target member 1.

In order to determine the position of the shot in the target image a plurality of sound wave-sensitive sensors 11, 12, 13 and 14 is used, which are in contact here with ricochet plate 6 and are positioned in such a way that they face one another in pairs with respect to the centre of the target image, sensors 11 and 12 or 13 and 14 of one pair being equidistantly spaced. For example these sensors can be formed by piezoelectric crystals.

Sensors 11,12, 13 and 14are connected by means of leads 9, which appropriately incorporate not shown threshold value switches, as well as amplifying means 14to an electronic evaluation apparatus 15 and a following optical display 16, which determine and display the score and the position of the shot.

Such an arrangement for determining the position of the shot in the target image is described in detail in the Applicant's aforementioned Swiss Patent, so that further comments here are unnecessary. The aforementioned Patent also shows that the sensors also assume a clearly defined position in another arrangement, eg. in a row, with respect to a Cartesian coordinate system or a polar coordinate system.

Said Patent also explains how the score and the position of the shot can be determined therefrom, so that once again no information on this need be provided.

However, it is pointed out that the distortions resulting from the inclined position of the ricochet plate 6 between the position of a score Tin the target image or the impact point T1 on plate 6 can be used as a constant in the equations.

If the richochet plate allows different propagation speeds for the impact waves in the vertical or horizontal direction this can be taken into consideration.

Claims

1. Target with a device for the automatic determination of the position of the shot in the target image by means of a group of sound wave-sensitive sensors, which assume a clearly defined position relative to a reference coordinate system and which are connected to an electronic evaluation apparatus and to a following optical display for the determination and display of the score and the position of the shot, characterized in that the sensors (11, 12, 13, 14) are in contact with a ricochet plate (6) made from a resonatable material which cannot be penetrated and positioned behind the target member (1 ) car rying the target image (A).

2. Target according to claim 1, characterized in thatthe ricochet plate (6) is made from steel.

3. Target according to claims 1 or 2, characte rized in that the ricochet plate (6) is inclined relative to target member (1), plate (6) and member (1) forming a downwardly opening angle.

4. Target according to claim 3, characterized in that a butt (7) is provided on the ground between ricochet plate (6) and target member (1).

5. Target according to claim 1, characterized in that each of the sensors (11, 12, 13, 14) comprises a piezoelectric crystal.

6. Target according to claim 1, characterized in that the group of sensors has four sensors (11, 12, 13, 14), which face one another in pairs with respect to the centre of the target image, the sensors (11, 12 or 13,14) of one pair being equidistantly spaced.

7. Target according to claim 1, characterized in that a threshold value switch is provided between each sensor (11,12, 13, 13, 14) and the electronic evaluation apparatus (15).