TILTABLE SUPPORTING DEVICE

Abstract: Tiltable supporting device with an element (7) to be positioned, for example a light source, comprising at least one arm (4) supported by a supporting means (3) in a pivot point (8) and made at least partially of a flexible material, which arm (4) is provided with the element (7) to be positioned and interacts with at least one counterweight (6). In this case the counterweight (6) has a fixed point of application on the arm (4), in such a way that said arm (4) has an equilibrium essentially in the horizontal position without friction, and during upward or downward tilting of the arm (4) through changing of deflection of the arm (4) a new equilibrium is obtained before the vertical position is reached, while means are provided to permit fixing of the arm (4) in the non-equilibrium positions and give greater ease of use.

Description: Short title: Tiltable supporting device The present invention relates to a tiltable supporting device with an element to be positioned, for example a light source, comprising at least one arm supported by a supporting means in a pivot point, and consisting of a first and a second arm part, the first arm part being provided with the element to be positioned, and the second arm part interacting with at least one counterweight. Such a tiltable supporting device is known from NL- A 91 01 899, which discloses a bearing arm, at least part of which is made of a flexible, pliable material, and in which the counterweight has a holder in which one or more elements such as balls are placed in such a way that they can be moved freely. This has made it possible for the mass centroid of the bearing arm and the pivot point to lie on a vertical line in any position of the arm. A disadvantage of this tiltable supporting device is that the freedom of movement of the freely movable counterweight in the holder can be adversely affected after some time by dust collecting on or in the holder, while the noise during movement of the counterweight will be found to be irritant. The object of the present invention is to provide a tiltable supporting device without the abovementioned disadvantages. This object is achieved by a tiltable supporting device of the abovementioned type as described in claim 1. An additional advantage is that the construction of the tiltable supporting device can be greatly simplified, which also makes it less fragile. Special embodiments are described in the subclaims. The invention is explained in greater detail below with reference to a drawing, in which: Fig. 1 shows a diagrammatic representation of a side view of a tiltable supporting device according to the invention in the form of a lamp; Figs. 2 - 7 show other embodiments of a tiltable supporting device; - 2 - Fig. 8 shows a view in perspective of a special counterweight construction; and Fig. 9 shows an embodiment according to the cascade principle. Fig. 1 shows in side view a tiltable supporting device according to the invention, in which an arm 4 is supported by a supporting means 3 in a pivot point 8. The arm 4 is formed by two arm parts 1 and 2 situated on either side of the pivot point 8. The end of the first arm part 1 bears an element 7 to be positioned, for example a lamp. The second arm part 2 has at some distance from the pivot point 8 a fixed point of application in which a counterweight 6 acts upon the arm part 2. This embodiment is such that the counterweight forms a unit with the second arm part, and in this case is placed in such a way that in an essentially horizontal position of arm 4 the centre of gravity of the arm 4 lies at such a distance below the pivot point 8 that on tilting out of this position, through extension of the arm parts, the centre of gravity of the arm 4 shifts until it lies on the vertical through the pivot point, before a vertical position is reached. In practice, what this means is that the point of application of the counterweight on the arm in the horizontal position lies below the line through the centre of gravity of the object arm and the pivot point. According to the invention, the arm 4 supported in the pivot point 8 has a position of equilibrium in three positions thereof. The new position of equilibrium or position of near-equilibrium of the arm 4 is not achieved by the solution of a freely movable counterweight, as described in NL-A 91 01 899, but is achieved according to the invention by increasing or reducing the effective length of the arm of force of an arm part. In the position of equilibrium of the arm 4 shown in Fig. 1 the pivot point lies above the centre of gravity of the assembly of the arm 4, the object to be positioned and the counterweight. The arm 4 also has two positions of equilibrium (not shown) in which the centre of gravity lies on the vertical through the pivot point 8. This is made possible through the flexibility of the arm 4, by means of which the latter acquires a downward directed deflection when the ends are loaded. The deflection is greatest when the element 7 and the counterweight 6 lie on a horizontal line. The greater the angle formed by the arm 4 with the horizontal line through the pivot point 8, the less the deflection of the arm 4 is, since the gravity component directed at right angles to the arm 4 decreases with an increasing angle. In the course of this the whole centre of gravity of the arm 4 shifts upwards. If in the horizontal position this centre of gravity lies close enough to the pivot point 8, there will be a position between the horizontal and the vertical position of the arm 4 in which the centre of gravity of the arm 4 and the pivot point 8 coincide, and the arm 4 thus acquires a new position of equilibrium. An explanation for this is that, when there is a change of position, the arm acquires a different curvature, with the result that the centre of gravity of the arm as a whole shifts relative to the pivot point. The deflection is greatest in the horizontal position, so that on tilting out of this position the centre of gravity moves closer to the pivot point. The smaller the distance from the pivot point to the centre of gravity in the horizontal position, the quicker the distance will become zero. On further tilting out of this high or low position of equilibrium, the centre of gravity shifts to above the pivot point, and the arm acquires a tendency to tilt over. Fig. 2 shows an embodiment in which a cable 20, one end of which is connected to the counterweight, and the other end to the arm part 1, is guided over a swivelling wheel 19 situated above the pivot point and fixed to the supporting means, and in which the point of application of the cable on the arm in the horizontal position lies above the line through the centre of gravity of the object arm and the pivot point. Through the tilting out of the horizontal position the arm becomes more extended, with the result that, with a changing angle of the application force, such a change occurs in the effective arm of force that at a certain point in time a new equilibrium is produced. The smaller the distance from the point of application in the horizontal position to the line through the centre of gravity of the object arm and the pivot point, the smaller will be the angle at which this equilibrium will occur. Such a construction will mean that the necessary horizontal space can be reduced considerably. Fig. 3 shows an embodiment in which a second arm situated below the first arm and in the same plane as the first arm is rotatably connected to the supporting means. In this case the counterweight acts upon the second arm in a point which in approximately the horizontal position of the first arm and the second arm lies at some distance below the horizontal line through the pivot point of the second arm, and a cable is stretched more or less vertically between the second arm and the second arm part of the first arm. The advantage of this is that an upright con- struction will consequently have less of a tendency to fall over, since the counterweight can be placed close to the base. Fig. 4 shows an embodiment in which the counterweight 6 acts, by means of the cable 9, hanging freely on the arm part 2 of the arm 4, in a point which lies at some distance below the line through the mass centroid of the first arm part and the pivot point. The freely hanging counterweight can have the disadvantage that it starts to rock during pivoting or tilting of the arm, and an upright construction can easily fall over. That is why in the modified embodiment of Fig. 5 the cable 9 runs over a swivelling wheel 18 disposed below the pivot point on the supporting means, with the result that the counterweight is guided along the supporting means 3. This greatly reduces the rocking. Given a certain desired range, the point of application of the counterweight must lie lower as the cable runs less vertically. An additional advantage can be that the higher up the swivelling wheel is placed the lower need be the mass of the counterweight. A change in the mass of the object can be compensated for by shifting the swivelling wheel. In the embodiment shown in Fig. 6 the counterweight 6 is connected by means of a cable to the second arm part, the counterweight 6 being guided slidably over the supporting means 3, or being guided along the supporting means 3 by means of a holder fixed on the supporting means. As in the case of the previous embodiment, in this case also the point of application of the counterweight must lie lower as the cable runs less vertically. By comparison with the design according to NL-A 91 01 899, the design according to the present invention has one more degree of freedom, because the counterweight is not fixed in such a way that it can move. The construction can be made suitable for a variable load by making the counterweight movable. When, for example, the object is a paint sprayer which acquires a lower mass during use, the counterweight must be moved during use a little closer to the pivot point at least at intervals, in order to permit more pleasant working. However, this is not sufficient, since the arm will deflect less at a lower load, with the result that the mass centroid of the arm moves to a higher position. The counterweight consequently has to move to a lower position, in order to place the mass centroid at a great enough distance from the pivot point. In Fig. 7 the object has a variable mass, and the counterweight is movably fixed to an angular second arm part in such a way that when there is an increase in the moment exerted on the first arm part the counterweight shifts further away from the pivot point and at the same time reaches a position so much higher up that the fall in the mass centroid of the arm as a result of the greater deflection of the arm is at least largely compensated for as a result. Also the situation can be envisaged where an object of constant mass is fixed by means of an antenna-like construction, so that the arm length of the first arm part is variable. A flexible arm part to which the counterweight is fixed has an upward curvature when the arm part bearing the object has an ergonomically justified downward curvature. An upwardly directed arm part which is loaded at the end will have the tendency to tilt sideways. Fig. 8 shows a part of a tiltable supporting device according to the invention, in which from some distance from the point of application onwards the cable is split into two equal parts 21 and 23, the ends of which act upon two bars 22 of equal length placed in the point of application at right angles to the arm. The lateral stability is considerably improved by this, because the tilting tendency cannot be followed, since when there is a very small sideways tilt the load of the pulling cable part is reduced and that of the other part is increased. The tilting tendency is automatically compensated for in this way. The centre of gravity of the arm 4 in every position in the range between the positions of equilibrium lies near the vertical through the pivot point. This makes it possible with little friction to fix the position of the arm 4 in or around the pivot point 8. Even in a small range beyond the extreme positions of equilibrium, this friction is sufficient to position the arm. Due to the low friction, it is also possible with little effort to set the supporting device according to the invention in another position. The friction can be applied to parts moving relative to each other during tilting. If the position of the arm is such that the latter lies outside the range, the centre of gravity lies beside the vertical through the pivot point and above the arm, so that the arm 4 then has the tendency to run through to the vertical position. In order to prevent the arm from running through, the device can be provided with limiting means, which limit the angular travel of the arm, and thus fix the effective range. For example, in Fig. 1 it is possible to fit on the arm part 1 near the pivot point 8 a limiting means 13 projecting from the arm 4, and on the arm part 2 a limiting means 14 likewise projecting near the pivot point 8. The maximum angular travel of the arm 4 can be set with the aid of these limiting means. In Fig. 4 a limiting means 11, 12 is fixed on the arm part 2 on either side of the point of application of the cable 9. When the arm 4 assumes a position lying in the desired range, the cable 9 is not in contact with a limiting means. However, if the position of arm 4 is such that the cable 9 comes to rest against a limiting means 11 or 12 , a new point of application of the counterweight on the arm part 2 is produced as a result, and a new moment occurs, which moment forces the arm 4 to assume a position which is again in the desired range. The limiters are preferably resilient and can be fixed at various points on parts which move relative to each other during the tilting. With the compensation mass 5 shown on the arm 4 in Fig. 1 it is possible to ensure that the centre of gravity of the arm 4 and the pivot point 8 come slightly closer together. The result of this is that the upper and lower positions of equilibrium shift to a position closer together, so that the range becomes smaller. A part of the counterweight can also be fitted so that it is slidable along the arm, as a result of which the height of the range can be set, or there can be compensation for a slightly heavier or lighter lamp. In order to adjust the angle or the height of the range, (the point of application of) a part of the counterweight can be placed so that it is movable relative to the arm, and a swivelling wheel can be placed so that it is movable relative to the supporting means. Although in Fig. 1 the supporting means 3 is in the form of an upright placed on a base, on which upright the pivot point 8 lies at one end, the supporting means 3 can also be a construction which is suitable for fixing to a ceiling or to a wall. In all cases the supporting means can consist of a tubular element which is fixed in such a way that it is pivotable about a vertical spindle. In this way the means fixed to the supporting means pivot with the arm in the vertical plane. The invention is extremely well suited for placing a second supporting device according to one of the preceding claims at the position of the object to be positioned. Fig. 9 shows a standard lamp with three interconnected arms which are pivotable in the vertical and the horizontal plane.

Claims: C L A I M S 1. Tiltable supporting device with an element to be positioned, for example a light source, comprising at least one arm supported by a supporting means in a pivot point and made at least partially of a flexible material, said arm being provided with the element to be positioned and interacting with at least one counterweight, characterized in that the counterweight has a fixed point of application on the arm, in such a way that said arm has an equilibrium essentially in the horizontal position without friction, and during upward or downward tilting of the arm through changing of deflection of the arm a new equilibrium is obtained before the vertical position is reached, while means are provided to permit fixing of the arm in the non- equilibrium positions and give greater ease of use. 2. Supporting device according to claim 1, charac¬ terized in that the arm consists of a first and a second arm part, the first arm part being provided with the element to be positioned, and the counterweight forming a unit with the second arm part and being placed in such a way that in an essentially horizontal position of the arm (4) the centre of gravity of the arm (4) lies just below the pivot point (8) , at such a distance that on tilting out of this position, through extension of the arm parts, the centre of gravity of the arm (4) shifts to a position in the pivot point before a vertical position is reached. 3. Supporting device according to one of the preceding claims, characterized in that a cable acts upon the first arm part in a point at some distance above the line through the mass centroid of the first arm part and the pivot point, which arm part is fixed to the end of the counterweight, which cable is guided over a swivelling wheel situated above the pivot point and fixed to the supporting means, and in which the point of application of the cable on the arm in the horizontal position lies above the line through the centre of gravity of the object arm and the pivot point. 4. Supporting device according to one of the preceding claims, characterized in that a second arm situated below the pivot point in the same plane as the first arm is rotatably connected to the supporting means where the counterweight acts in a point which in approximately the horizontal position of the first arm and the second arm lies at some distance below the line through the pivot point of the second arm parallel to the line through the mass centroid of the first arm part and the pivot point of the first arm, and a cable is stretched more or less vertically between the second arm part of the first arm and the second arm. 5. Supporting device according to one of the preceding claims, characterized in that the counterweight acts, by means of a cable, on the second arm part in a point which in a more or less horizontal position lies at some distance below the line through the mass centroid of the first arm part and the pivot point. 6. Supporting device according to claim 3 or 5, characterized in that the cable runs over a swivelling wheel disposed below the pivot point on the supporting means, with the result that the counterweight is guided along the supporting means. 7. Supporting device according to one of claims 3, 5 or 6, characterized in that the counterweight connected to the cable is guided slidably over the supporting means, or is guided along the supporting means by means of a holder fixed on the supporting means. 8. Supporting device according to one of the preceding claims, characterized in that the object has a variable mass, or the arm length of the first arm part is variable, and in that the counterweight is movably fixed to an angular second arm part in such a way that when there is an increase in the moment exerted on the first arm part the counterweight shifts further away from the pivot point and at the same time reaches a position so much higher up that the fall in the mass centroid of the arm as a result of the greater deflection of the arm is at least largely compensated for. 9. Supporting device according to one of the preceding claims, characterized in that from some distance from the point of application onwards the cable is split into two equal parts, the ends of which act upon two bars of equal length placed in the point of application transversely to the arm. 10. Supporting device according to one of the preceding claims, characterized in that friction is produced between parts moving relative to each other during tilting. 11. Supporting device according to one of the preceding claims, characterized in that preferably resilient limiting means are provided which can be fixed at various points on the construction. 12. Supporting device according to one of the preceding claims, characterized in that a part of the counterweight or the point of application thereof is disposed so that it is movable relative to the arm, and a swivelling wheel is disposed so that it is movable relative to the supporting means. 13. Supporting device according to one of the preceding claims, characterized in that the supporting means consists of a tubular element which is fixed in such a way that it is pivotable about a vertical spindle. 14. Supporting device according to one of the preceding claims, characterized in that the object to be positioned comprises a second supporting device according to one of the preceding claims.

Inventors: EILERING JOHANNES HERMANUS, EILERING, JOHANNES, HERMANUS
Applicants: EILERING JOHANNES HERMANUS, EILERING, JOHANNES, HERMANUS
Application year: 1995
Main classification: F21V21
IPC codes: F21S6, F21V21