GB2245063A

GB2245063A - Compass

Info

Publication number: GB2245063A
Application number: GB9110313A
Authority: GB
Inventors: Raimo Raitmaa
Original assignee: SISTECO Ltd Oy
Current assignee: SISTECO Ltd Oy
Priority date: 1990-06-11
Filing date: 1991-05-13
Publication date: 1991-12-18
Anticipated expiration: 2011-05-13
Also published as: FI84756C; FI902917A7; GB2245063B; FI902917A0; FI84756B; GB9110313D0

Abstract

A compass, whereby in the frame (2) there is a compass box (1) and in it a compass rose (10). The compass box is turnable in regard to the frame and sidewards movable. The compass box is filled with a fluid and has an elastically deformable bottom plate (6). The compass is characterised in that aiming marks (not shown), a reading line 24, and the supporting point 11 for the compass rose are all at the same level. <IMAGE>

Description

Compass The invention relates to a magnetic compass, whereby there is a compass box constructed in frame and a compass rose mounted in bearings to the compass box. There are aiming marks in the frame for directing the compass and a reading mark in the box for reading the direction according to the scale in the compass rose.

Also compasses are known, whereby there is a compass box of metal fixed closed by a glass cover and fulled with liquid. The box has an elastic bottom, to which there is connected a vertical supporting point.

Supported by it there is a compass rose equipped with scale mounted in bearings. On the opposite sides of the compass rose there are aiming lines in the box. In the connection of the back aiming line there is also a reading line, at the point of which the direction is read according to the scale in the compass rose. One of the disadvantages in the compass described above is, that aiming lines, reading line and supporting point of compass rose cannot be adjusted exactly to the same level.

Now it has been invented a compass according to the claim 1, whereby the disadvantage mentioned above has been solved. Some of the advantageous embodiments of the invention are described in dependent claims.

Fig. 1 is a cross profile of a compass according to the invention.

The main parts of the compass according to Fig.

1 are compass box 1, frame 2, bottom 3 and installation ring 4.

In the compass box there is a cylinder-shaped body 5 made of antimagnetic metal, as e.g. of brass.

At its bottom it is closed by a round bottom plate 6 made of membrane-like antimagnetic metal material, which plate 6 is soldered into the body 5. There are ring-shaped folds 7 in the bottom plate 6 in order to increase elasticity of the bottom plate.

On top of the bottom plate 6 in a distance from it there is a metallic supporting plate 9 supported by a cantilever 8 in the body 5, in the middle of which plate the supporting point 11 of the compass rose 10 is attached. On top of the supporting plate 9 there is glued a cup-like, white backing plate 12 in order to create an optical contrast and support the reading line and illuminator attached to it. The backing plate 12 is made of plastic most suitable for the purpose.

There is an opening 13 in the middle of the backing plate 12 and corresponding to them openings 14 in the supporting plate 9.

On top side of the body 5 there is a sealing ring 15 and on top of it a glass plate 16. The glass plate 16 is pressed on top side against the sealing ring 15 by a metallic ring follower 17, which is attached to the body 5 by threading.

In the body 5 there is a liquid filling opening 19 closed sealingly by a screw 18. A corresponding opening 20 is to be found in the backing plate 12 at the same location.

Due to the elastic structure of the bottom plate variations in volume of liquid in box caused by variations in temperature can be compensated.

In the outer circle of ring follower 17 there is a ring-shaped cantilever 21, the top surface of which is oblique downwards and the bottom surface horizontal. On top of the ring follower 17 there is sealingly attached a plastic trail ring 22, in the inner circle of which there is a ring-shaped groove 23 at the place corresponding the one of cantilever ring 21. The trail ring 22 is elastic in a manner, that it can easily be pressed in its position. By shaping the cantilever ring 21 and ring groove 23 loosening of the trail ring has been made more difficult. In the outer circle of ring follower 17 there are in addition axial grooves and in the trail ring 22 detent pins 31 correspondingly, by which winding of trail ring in regard to ring follower is prevented.

In the backing plate 12 there is formed a reading line 24 at the level of the compass rose 10.

The edge of the compass rose 10 is transparent and the scale on it as well as the reading line 24 are illuminated by a beta emitter 25 which acts as illuminator.

The compass frame is closed in its bottom by a foot plate, in which there is a spring device 26 responding to the elastic bottom plate 6 in the compass box.

On top side of the compass frame a plastic installation ring 27 holds the compass box vertically in its position, the installation ring 27 being attached to the frame by screws. The inner diameter of the installation ring 27 at the point of the compass box is a little bit bigger than the outer diameter of the compass box. The compass box is adjusted in the installation ring 27 through the frame by three screws 28 located in the ring circle in a-120 -distance from each other, and after adjusting the installation ring is locked by a suitable glue in a trail ring. Thus when directing the compass the box can be concentrated exactly in a manner, that the aiming lines (not shown) on the opposite sides of the shaft in the frame, the supporting point 11 of the compass rose and the reading line 24 are exactly at the same vertical level.The screws 28 are located at the point of ring 21 and groove 23 as to make sure further that they stay in their position.

The front aiming line has been formed in a swinging cover of the frame. As the back aiming line on the other hand acts a chain link located in the frame in a prism device 32 on the opposite side. With help of the prism device 32 the reading line 24 and the scale in the compass rose as well the front aiming line can be followed through the chain link simultaneously. Thus the direction of the aimed target can be defined exactly.

Ih the locking ring 27 there are axial openings and in the inner edge of the trail ring 22 surface there is a small ring-shaped hole 29. Through the openings between the locking ring 27 and the trail ring 22 can be dropped e.g. suitable dissolvent for adhering the rings together. Through the hole 29 the dissolvent then spreads evenly around the entire circle.

In the edge of the installation ring 27 there is a metallic reinforcing edge 30.

As to manufacturing technique the compass structure is quite simple. It additionally provides a further advantage in a manner, that all compass parts, also the ones inside of the compass box, are easy to change. A special advantage is, that the radioactive radiator is easy to change.

Claims

1. Compass, whereby there is a frame with aiming marks on it and in the frame a liquid-filled compass box having a transparent cover and elastic bottom and in the box a compass rose (10) mounted in bearings supported by a supporting point and having a magnetic needle, c h a r a c t e r i z e d in that the compass box (1) is detachable from the frame (2) and horizontally turnable in regard to it and horizontally movable according to the line leading through the aiming marks in a manner, that when directing the compass, the aiming marks supporting point and reading line can be adjusted exactly to the same level.

2. Compass as set forth in claim 1 or 2, c h a r a c t e r i z e d in that the location of the compass box is sidewards adjustable by screws (28).

3. Compass as set forth in claim 1 or 2, c h a r a c t e r i z e d in that there is a trail ring (22) connected to the compass box, by which ring the box after having been directed is locked to the frame.

4. Compass as set forth in claim 3, c h a r a c t e r i z e d in that the locked trail ring (22) is detachable from the frame and the box.

5. Compass as set forth in one of the claims 1-4, c h a r a c t e r i z e d in that a transparent cover (16) is detachably attached to the box by a follower ring (17).

6. Compass as set forth in one of the claims 1-5, c h a r a c t e r i z e d in that in the frame there is a bottom part, where there is a spring device (26) responding to the box bottom (6).

7. Compass as set forth in one of the claims 1-6, c h a r a c t e r i z e d in that in the box on top of the elastic bottom (6) in a distance from it there is a supporting plate (9), in which the bearing journal of the compass rose is attached and through which there is a liquid connection to the bottom.

8. Compass as set forth in claim 7, c h a r a c t e r i z e d in that in the box beneath the compass rose there is a backing plate (12) for creating an optical contrast, through which plate there is a liquid connection to the bottom.