A DIRECTION INDICATOR WHICH IS DISPLACEABLE ALONG A GUIDE

Abstract: There is provided an arrangement for maintaining in a first plane (1) the direction of a direction indicator (4) that is carried by a carriage (3) for parallel movement along a substantially straight guide (2) that extends parallel with said plane. The carriage (3) includes a first part (31, 32) which is guided by the guide (2; 21, 21'), and a second part (4) which carries the direction indicator (5) and which can be rotated about an axis (61) that intersects the plane (1) and that is generally perpendicular to the longitudinal direction of the guide (2). The arrangement also includes a reflector (12) which is generally perpendicular to the longitudinal direction of the guide (2) and which is mounted at an end region of the guide (2) or in the extension of said guide. The second carriage part (4) carries a light beam emitter (8) which emits generally parallel with the longitudinal direction of the guide a beam that can impinge upon the reflector (12). This second carriage part also carries a light sensor (10) which is adapted to detect a beam emitted by the emitter and reflected by said reflector (12) when said second carriage part (4) is rotated, so that the direction indicator (5) will take the same direction in the plane (1) with the various positions of displacement of the carriage along the guide (2).

Description: A DIRECTION INDICATOR WHICH IS DISPLACEABLE ALONG A GUIDE The present invention relates to an arrangement of the kind defined in the preamble of Claim 1. The invention thus relates to an arrangement that includes an elongate, generally straight guide and a carriage which is displaceably carried by the guide and, in turn, carries a direction indicator which will ideally give a uniform direction indication in all positions of the carriage along the guide, provided that there is no play between the carriage and the guide and that the guide is truly straight. The direction indicator may be a telescope, a video camera, a sight or some similar arrangement whose line of sight has a selectable angle relative to the longitudinal axis of the guide. Alternatively, the direction indicator may emit a light beam or a light disc that will mark a line, a point or a plane in space or on an underlying surface that may be parallel with the guide axis. As indicated above, one problem with an arrangement of this kind is that it is difficult to establish play-free mounting of the carriage on the guide and also to ensure that the guide is exactly straight. Wear phenomena and temperature changes and similar influences can cause corresponding problems in a system that is otherwise ideal. The object of the invention is therefore to provide an arrangement with which the aforesaid problems are avoided either totally or partially. This object is achieved with the arrangement according to the accompanying Claim 1. In one practical embodiment of the invention, the carriage includes a first part which is guided by the guide and which carries a second part which carries the direction indicator and which can be rotated relative to the first part about an axis that intersects the plane in which it is desired to maintain the direction of the indicator in different positions of displacement along the guide. The rotational axis is generally perpendicular to the longitudinal axis of the guide. A reflector positioned generally perpendicular to the longitudinal axis of the guide is provided in one end region of the guide or in the geometric extensions of the guide. The other carriage part carries a light emitter which functions to emit a light beam generally parallel with the longitudinal axis of the guide, or a light disc that can impinge on the reflector. The second carriage part also carries a light sensor which is able to detect the beam reflected by the reflector when rotating said second carriage part. This takes place when the reflected beam and the transmitted beam lie in a plane that is parallel with the ideal direction or reference direction of the guide. If there is play between the guide and the carriage and/or the guide is crooked, this can result in displacement of the carriage transversely to the reference direction, although the direction indicator can be set in one and the same direction in the various positions of carriage displacement along the guide, provided that the radius/size of the reflector is greater than said displacement. The light emitter and the light sensor will suitably lie in a plane that is perpendicular to both the first plane and the reflector plane. The second carriage part of the inventive arrangement may, of course, be rotatable in two mutually intersecting planes, so as to enable the light emitter to send a narrow beam that is reflected back to the emitter. In this case, the light sensor may comprise a ring-shaped element that concentrically surrounds the light emitter. The reflector is suitably flat and perpendicular to the reference direction of the guide. The invention will now be described by way of example and with reference to the accompanying drawings. Fig. 1 is a side view of an inventive arrangement. Fig. 2 is a plan view of the arrangement, taken on the line II-II in Fig. 1. Fig. 3 is a broken side view of a guide with carriage and laser unit. Fig. 4 is a view taken on the line IV-IV in Fig. 3. Fig. 5 illustrates an alternative beam path. Fig. 2 illustrates a flat working surface 1 and a guide 2 that extends along one edge part of said surface parallel therewith. Also shown is a carriage 3 which is mounted on the guide 2 for movement therealong. The carriage 3 supports a laser unit 4 which is adapted to deliver a thin light disc 41 that defines preferably a right angle with the surface or the plane 1. The guide 2 is shown supported on posts 22 that extend up from a floor defining the surface 1. The .guide 2 may support a further carriage 3 carrying a laser unit 4. The carriage includes a path sensor which ensures that the position of the carriage 3 along the guide 2 will always be known. The carriage 3 may also include drive means 7, 71 for otorised displacement of the carriage along the guide 2. As will be seen from Fig. 4, the drive means may include a carriage-mounted motor having a drive roller 71 in contact with a rail 21. The roller 71 and the rail 21 may coact with one another through the medium of respective cogs or teeth 22. An indication of the position of the carriage 3 along the guide 2 can be obtained by detecting the number of turns of the roller 71. The carriage also carries a sensor 75 which detects a position indicator 74 carried in a specific position along the guide 21, therewith obtaining a reference relating to the position of the carriage 3 along the guide 2. The guide rails 21 are received in respective corner angles of a recess 32 in the carriage 3. As will be seen, the laser unit 4 includes a chassis 42 which carries a motor 43 that has a vertical rotatable shaft 44. In turn, the shaft 44 carries a motor 90 that functions to rotate a horizontal shaft 91 mounted on the shaft 44 and firmly connected to an underpart 52 of the laser emitter 5. The plane 41 of the laser light can be given a desired orientation relative to the chassis 42 of the unit 4, by appropriate driving of the motors 43 and 90. Fig. 4 also shows the chassis 42 supported in spaced relationship with the carriage 3 through the medium of a motor 6 that has a vertical rotatable shaft 62. The shaft 61 carries a motor 60 which functions to turn a horizontal shaft 81 mounted on the shaft 61 and firmly connected to an underpart 82 of the laser unit chassis 82. The chassis 42 has a light emitter 8 mounted on at least one of two mutually opposite sides. The emitter 8 delivers a beam 87 that is parallel with the desired path of movement of the laser unit 4 along the guide 2, i.e. parallel with the ideal longitudinal direction of the guide. The beam 87 is perpendicular to a reflector 12 located beyond an end region of the guide 2 and functions to reflect the light beam 87 back to the emitter 8. It will be seen from Fig. 4 that the emitter 8 is exposed in its centre by a known type of light sensor disc 9 and emits an output signal that is dependent on the position at which the reflected beam 8 impinges on the disc 9. The output signal from the disc 9 is conducted by a cable 14 to a control unit 15 which is adapted to control the motors 6 and 7 such as to cause the beam reflected by the mirror 12 to impinge on the disc 9 as close as possible to its centre. The power requiring arrangements, such as the laser emitter 5 and the control unit in the motor 7, may be powered by a battery 16 carried on the carriage 3. The control unit 15 may communicate with an associated remote control terminal (not shown) via a radio transmitter/receiver 18. The motors 90 and 43 may be controlled via the control unit 15. Alternatively, the motors 43 and 90 can be replaced with manually adjustable indexing or stepping arrangements provided with associated setting scales. As shown in Fig. 3, plates 9 may be disposed on mutually opposite sides of the chassis 42 and provided with central light emitters 8 whose beams are reflected back by respective mirrors 12 provided at or beyond respective ends of the guide 2. As before mentioned, the system may be used to mark corners, angles, edge lines, planes, or intersections of various orientations relative to the underlying supportive surface, although the system may, of course, also be used to measure- up corner angles, the positions of intersection points and intersection lines, measure-up the directions of edge lines, walls or corners of objects in the working area, distances between points and planes on objects in the working area, the size of a corner angle in the working area, the distance between points on a measurement scale 11 along the guide, etc. In the case of this embodiment, the setting arrangement and the carrying arrangement have been described in the form of universal joint arrangements that can be swung about two mutually perpendicular axes with the aid of associated motor means, although it will be obvious that such movements can be effected in many other known ways. As will be understood, when solely the direction of the laser unit 4 in a single plane that extends, e.g., parallel with the floor 1 is of interest, rotation of the unit 4 about the axis 4 will be sufficient in this regard, therewith enabling the emitter and the sensor to be mutually separated in a plane that contains the shaft 44 and that is parallel with the ideal direction of the guide, said emitter therewith emitting a light disc in this plane. It will be also be understood that other embodiments of the invention may include a telescope, a camera, for instance a video camera, a sight or some similar arrangement as a substitute for the laser unit, so that the observation instrument will function to enable readings to be taken in certain directions or planes rather than marking corresponding directions or planes with the aid of light. For instance, there may be provided on the floor 1, along the guide 2, a measuring scale 11 with which readings or markings can be taken/made to provide an indication of the position of the carriage or the unit 4 along the guide, especially when the direction of the direction indicator 4 is perpendicular to the ideal longitudinal direction of the guide 2. The motors 43 and 90 may, of course, be replaced with manually operable setting devices. After having established the correct alignment of the unit 4 in a chosen position of displacement along the guide with the aid of said motor arrangements, said motor arrangements can be caused to set the direction indicator in a chosen direction relative to the correct, newly set direction of said unit. Fig. 4 illustrates an arrangement in which the emitter and the sensor are in coaxial alignment but on opposite sides of the part 4. Also shown is a rectangular beam path established with the aid of four mirrors 12. One side of the rectangular beam path is defined by the axes of the emitter and the sensor respectively. By placing a mirror 12, e.g., at each end-part of the guide 2 and in alignment with the sensor and the emitter respectively, and deflecting said part of the beam part to a beam part parallel therewith through the medium of a further pair of mirrors 12, there is achieved an advantage whereby the distance from the emitter to the sensor will be the same in all positions of displacement of the unit 4 along the guide. The beam path may suitably lie in one plane, for instance a vertical plane, and each mirror 12 may be adapted to deflect the beam through an angle of 90°. Thus, Fig. 4 shows that a number of stationary mirrors are able to establish a closed beam path between the emitter and the sensor, this path being equally as long in all positions of displacement of the unit 4.

Claims: CLAIMS 1. An arrangement for maintaining in a first plane (1) the direction of a directional indicator (4) carried by a carriage (3) for parallel movement along a generally straight guide (2) that extends parallel with said plane, characterised in that the carriage (3) includes a first part (31, 32) that is guided by the guide (2; 21, 21'), and a second part (4) that carries the direction indicator (5) and that is pivotal about an axis (61) which intersects said plane (1) and which is generally perpendicular to the longitudinal direction of the guide (2) ; in that there is provided at one end region of the guide (2) or its extension a reflector (12) which is generally perpendicular to the longitudinal direction of said guide; in that the second carriage part (4) carries a light beam emitter (8) which emits generally parallel with the longitudinal direction of the guide a light beam that can impinge on the reflector (12) ; and in that the second carriage part carries a light sensor (9) which is adapted to detect an emitter beam reflected by the reflector (12), by virtue of rotating said second carriage part (4) so that the direction indicator (5) will be brought to the same direction in the plane (1) with different positions of displacement of the carriage along the guide (2) . 2. An arrangement according to Claim 1, characterised in that the light emitter (8) and the light sensor (9) lie in a p l ane that is perpendicular to the reflector plane and also perpendicular to the first plane (1) . 3. An arrangement according to Claim 1 or 2, characterised in that the light emitter (8) is adapted to emit a narrow light beam; and in that the light sensor encircles the light emitter. 4. An arrangement according to Claim 3, characterised in that the second carriage part (4) is also rotatable relative to the first carriage part (31, 32) in a second plane that intersects said first plane, therewith enabling the direction indicator (5) to be positioned uniformly in space with different positions of displacement along the guide. 5. An arrangement according to any one of Claims 1-4, characterised in that the reflector (12) is perpendicular to a straight reference direction that is generally parallel with the longitudinal direction of the guide (2) .

Inventors: HEDSTROEM HANS, HEDSTROEM, HANS
Applicants: HEDSTROEM HANS, MEGASCALE AB, HEDSTROEM, HANS
Application year: 2000
Main classification: G02B27
IPC codes: G01C15