Weight-balancing Arrangement At Vertically Displaceable Instrument Tables For Ophthalmological Apparatus Or The Like

Abstract

A weight-balancing arrangement on essentially vertically displaceable instrument tables for ophthalmological apparatus or the like which includes a pull rope connected with a spring and engaging at the apparatus support approximately in the centroidal axis thereof to counteract the weight; the drawing direction of the spring extends in an approximately horizontal plane while the rope is connected at one end with a downward extension of the apparatus support and over a section thereof is guided by way of reversing rollers in the direction of movement of the apparatus support.

Description

The present invention relates to a weight-balancing arrangement at essentially vertically displaceable instrument tables for ophthalmological apparatus or the like, with a pull rope connected with a spring and engaging at the instrument support approximately in the axis of gravity thereof.

It is known in the prior art to provide a weight-balancing or weight-compensating arrangement at instrument tables for ophthalmological apparatus, which permits a height adjustment of the instrument table that is balanced as much as possible as regards weight. For that purpose, a compression or draw spring was provided heretofore, which is arranged is proximity to the guide elements of the instrument table. Such spring must possess as flat as possible a spring characteristic in order that the weight of the instrument table with the attached ophthalmological instruments or apparatus is at least approximately uniformly balanced over the adjusting path. The prerequisite of the flat characteristics of the spring results structurally in a very long spring that can be constructively accommodated only relatively poorly. The arrangement of the bulky balancing spring in the axis of gravity of the table, which is desirable for the reduction of friction losses on the inside of the guide means of the instrument table, cannot be attained in practice.

It is an object of the present invention to provide a weight-balancing arrangement which permits by an extremely flat spring characteristic, a far-reaching weight-balancing over the entire adjustment path of the instrument table, yet has dimensions which do not impair the overall structure of the instrument table. In particular, the weight-balancing arrangement should possess slight dimensions in the vertical direction and should not require more space in the vertical direction than corresponds to the adjusting path of the instrument table. Additionally, the influence of the friction at the guide elements of the instrument table should be limited far-reachingly.

The underlying problems are solved according to the present invention in that the draw direction of the spring extends in an approximately horizontal plane and in that a downwardly directed extension is arranged at the instrument support within the area of its axis of gravity, with the free end of which is connected the pull rope guided over a section thereof in the direction of movement of the apparatus support with the aid of reversing rollers.

For the purpose of achieving a particularly flat characteristic of the spring arrangement, a spiral spring may be provided as draw spring, whose movable end is connected by way of a rotating shaft with a drum, on which is wound an end section of the pull rope.

Insofar as a constant draw force in the rope is desired, a conventional arrangement may be provided between the spring and the pull rope which converts the spring force variable as a function of the path into a constant draw force of the rope. For example, a rope disk with an eccentric abutment or engaging surface for the pull rope may be utilized for that purpose. The abutment surface is then to be so dimensioned that the radius thereof effective at the pull rope increases with the effective spring force.

In order to enable an adaptation of the force of the weight-balancing arrangement acting on the instrument table to the instrument and apparatus attachments with different weight, the prestress of the spring may be adjustable. For example, with the use of a spiral spring, this spring may be arranged in a cylindrical spring housing and may be connected to the spring housing with one end thereof. This spring housing may then be constructed rotatable about its axis and lockable.

Accordingly, it is an object of the present invention to provide a weight-balancing arrangement for instrument tables, especially for opthalmological apparatus, which avoids by simple means the aforementioned shortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in a weight-balancing arrangement for vertically displaceable instrument tables, for example, for ophthalmological apparatus, which permits a relatively compact construction minimizing friction losses and assuring an extraordinary flat spring characteristic.

A further object of the present invention resides in a weight-balancing arrangement of the type described above which insures a far-reaching weight equalization over the entire adjusting path of the instrument table without increasing the dimensions of the installation or of the overall construction of the instrument table.

Still another object of the present invention resides in a weight-balancing arrangement for instrument tables which not only achieves all of the aforementioned aims and objects in a completely satisfactory manner, but also permits adjustment of the weight-balancing arrangement to compensate for the attachment of instruments of different weight.

These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one embodiment in accordance with the present invention, and wherein:

The single FIGURE is a somewhat schematic cross-sectional view through a weight-balancing arrangement of an instrument table for ophthalmological apparatus or the like in accordance with the present invention.

Referring now to the single FIGURE of the drawing, the apparatus support 1, 3, 4 is displaceably guided on a vertical guide column 5 with the aid of a guide bush 2. The guide column 5 is fixedly arranged in a base plate 6. A vertically downwardly directed extension 7 is arranged at the lower cantilever arm 1 of the apparatus support; the pull rope 9 is secured at the free end 8 of the extension 7. The pull rope 9 is guided within the area of the extension 7 in the direction of movement of the apparatus support 1, 3, 4 with the aid of the reversing roller 10. From the reversing roller 10, the pull rope 9 leads by way of a further reversing roller 11 onto an eccentric rope drum 12 which is connected by way of the rotating shaft 13 with the inner end of a spiral spring 14. The outer end of the spiral spring 14 is connected with the cylindrical spring housing 15. The spring housing 15 is rotatable and adjustable by conventional means about the axis 13. The spindle arrangement 16 of conventional construction serves in the usual manner for the fine height adjustment of the apparatus. Since the spindle arrangement 16 is known as such, a detailed description thereof is dispensed with herein.

By reason of the arrangement of the extension 7 approximately in the centroidal axis of the entire vertically adjustable instrument support 1, 3, 4, no tilting moment occurs between the guide bush 2 and the guide column 5 so that the arrangement operates practically without friction.

The horizontally arranged spiral spring 14 occupies only a slight amount of space in the vertical direction which does not influence the remaining constructive design and configuration of the apparatus support. Possibly the spring arrangement may also be arranged on the inside of the base plate 6. The use of, for example, a spirally shaped rope drum 12 in conjunction with a spring housing 15 adjustable in the circumferential direction permits a sensitive matching with a very fine-feel of the constant lifting force of the balancing arrangement to the prevailing weight of the apparatus support in connection with different apparatus attachments.

While I have shown and described only one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art, and I therefore do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

Claims

What I claim is:

1. A weight-balancing arrangement on essentially vertically displaceable instrument tables for ophthalmological apparatus or the like, with pull rope means operatively connected with a spring means and engaging at an apparatus support means approximately in its axis of gravity and counteracting the weight thereof, characterized in that the stressing direction of said spring means is arranged in an approximately horizontal plane and in that a downwardly directed extension is arranged at the apparatus support means within the area of the axis of gravity thereof, said rope means being operatively connected with the free end of said extension.

2. An arrangement according to claim 1, characterized in that the draw direction of the spring means extends in the approximately horizontal plane.

3. An arrangement according to claim 1, characterized in that said rope means over a section thereof is guided substantially in the direction of movement of the apparatus support means with the aid of reversing roller means.

4. An arrangement according to claim 3, characterized in that a spiral spring is provided as said spring means.

5. An arrangement according to claim 4, characterized in that the movable end of the spring means is operatively connected with the rope means by way of a converting means converting the variable spring force into a constant draw force of the rope means

6. An arrangement according to claim 5, characterized in that said converting means includes a rope disk with spirally shaped engaging surface for the rope means.

7. An arrangement according to claim 6, characterized in that the spiral spring is arranged in a spring housing and is connected with one end thereof wit said housing, and in that said spring housing is adjustable about its axis of rotation.

8. An arrangement according to claim 7, characterized in that said spring housing is of substantially cylindrical shape.

9. An arrangement according to claim 8, characterized by means for adjusting the prestress of said spring by rotating said spring housing to a predetermined initial prestress position and locking said housing in said position.

10. An arrangement according to claim 1, characterized in that a spiral spring is provided as said spring means.

11. An arrangement according to claim 1, characterized in that the movable end of the spring means is operatively connected with the rope means by way of a converting means converting the variable spring force into a constant draw force of the rope means.

12. An arrangement according to claim 11, characterized in that said converting means includes a rope disk with spirally shaped engaging surface for the rope means.

13. An arrangement according to claim 10, characterized in that the spiral spring is arranged in a spring housing and is connected with one end thereof with said housing, and in that said spring housing is adjustable about its axis of rotation.

14. An arrangement according to claim 13, characterized in that said spring housing is of substantially cylindrical shape.

15. An arrangement according to claim 14, characterized by means for adjusting the prestress of said spring by rotating said spring housing to a predetermined initial prestress position and locking said housing in said position.

16. An arrangement according to claim 14, characterized in that the movable end of the spring means is operatively connected with the rope means by way of a converting means converting the variable spring force into a constant draw force of the rope means.