Counterbalanced parallel linkage supporting mechanism

Abstract: Counterbalanced parallel linkage supporting mechanism comprising a pair of interlocked parallel links (2,3), each provided on the opposite side of the center shaft (S), a weight (X) supported on one of the parallel links, a counterweight (W) supported on another parallel link for counterbalancing the weight, and a shaft bushing (5) provided on a center shaft for pivotably supporting the center shaft, the shaft bushing supported pivotably about the horizontal axis crossing square with the center shaft.

Description: Background of the Invention 1. Field of the Invention This invention relates to a mechanism for supporting a parallel linkage which is generally known as a counterbalanced parallel linkage having counterweights for supporting a weighty equipment or the like in the air. 2. Description of the Prior Art The applicant of the present invention has previously proposed a Stand Mechanism for a Medical Optical Equipment disclosed in Japanese Patent Laid-Open Publication No. 56409/1989 (EP-A-0 293 227) showing a mechanism of the conventional counterbalanced parallel linkage. The stand mechanism comprising a counterbalanced parallel linkage having a pair of parallel links, each configuration having been transformed linked with each other, supports a weighty medical optical equipment in the air. The conventional counterbalanced parallel linkage and the supporting mechanism thereof have been capable of performing the following four types of motion: 1. changing the supporting angle of the weight in the lateral direction (transformation of the parallel linkage) 2. motion of the weight in the up and down directions (vertical motion of the parallel linkage) 3. changing the supporting angle of the weight in left and right directions (pivotal motion about the center shaft of the parallel linkage) 4. motion of the weight within a horizontal plane in both back and forth and right and left directions (horizontal motion of the parallel linkage) The supporting mechanism for the conventional counterbalanced parallel linkage, however, has needed at least two counterweights, the first counterweight for the above-mentioned 1 and 3 motions, and the second counterweight for the above-mentioned 2 motion, so that naturally, all the components of the parallel linkage and the supporting mechanism for supporting the parallel linkage in total have been inevitably heavy. Especially, the second counterweight for the motion of the above 2, which is for lifting vertically up and down the whole components of the parallel linkage together with the weight, should have been considerably heavy. Therefore, conventionally, it has been inconvenient to transport and assemble the components. Summary of the Invention Accordingly, in view of the foregoing prior art, the present invention according claim 1 is directed to provide a supporting mechanism for the counterbalanced parallel linkage which facilitates a vertical motion (the above motion 2) of the weight without having the second counterweight as used to be provided in the prior art. The above and other objects, advantages, features and uses will be apparent by referring to the following description when considered in connection with the accompanying drawings. Brief Description of the Drawings Fig. 1 is a schematic perspective view of a supporting mechanism embodying a counterbalanced parallel linkage in accordance with the present invention; Fig. 2 is a side view of the parallel linkage; Fig. 3 is a side view corresponding to Fig. 2 showing the transformation of the parallel linkage; Fig. 4 is a side view corresponding to Fig. 2 showing the parallel linkage pivoting about the horizontal axis; Fig. 5 is a plan view of the parallel linkage and the supporting mechanism thereof; Fig. 6 is a plan view of the parallel linkage corresponding to Fig. 5 showing the weight transferred horizontally in the left and right directions; Fig. 7 is a plan view corresponding to Fig. 5 showing the weight transferred horizontally in the lateral direction; Fig. 8 is a front view of the parallel linkage and the supporting mechanism thereof; and, Fig. 9 is a front view corresponding to Fig. 8 showing the parallel linkage pivoting about the center shaft. Description of the Preferred Embodiments The supporting mechanism for the counterbalanced parallel linkage is provided with a shaft bushing on a center shaft of the balanced parallel linkage for pivotably supporting the center shaft, wherein the shaft bushing is supported pivotably about the horizontal axis crossing square with the center shaft. The weight supported on one of the parallel links of the parallel linkage can be lifted upward or downward by rotating the whole parallel linkage about the horizontal axis provided at the shaft bushing. Thus, the parallel linkage having a counterweight is well counterbalanced even when the parallel linkage is rotated about the horizontal axis. As the weight is lifted upward or downward in this manner without lifting the whole components vertically, the second counterweight conventionally provided can be eliminated. Referring now to the drawings, a preferred embodiment of the present invention is illustrated in Fig. 1 to Fig. 9. The direction of A, B, C, D, E and F in the drawings are referred to as front, rear, left, right, up and down, respectively in the description of the invention. S shows a center shaft which pivotally supports a main frame T at a fixture point 1. In the rear side of the center shaft S, there formed a rear parallel link 2 including the part in rear of the fixture point 1 on the center shaft S and the part lower than the fixture point 1 on the main frame T, and in the front side of the center shaft S, there formed another front parallel link 3 including the part in front of the fixture point 1 on the center shaft S and the part upper than the fixture point 1 on the main frame T. The rear parallel link 2 and the front parallel link 3, having more members than the front link 2, both comprise longitudinal members and lateral members, each continually maintaining parallel, respectively. At the front end of the front parallel link 3, a weight X is supported so as to position just above an extension L of the center shaft S, while, at the rear end of the rear parallel link 2, a counterweight W is provided for counterbalancing the weight of the weight X. The front parallel link 3 and the rear parallel link 2 sharing the center shaft S and the main frame T, transform interlocked with each other by changing the angle formed by the center shaft S and the main frame T. The parallel linkage 4 comprising two parallel links 2 and 3 is supported by a shaft bushing 5 provided just in rear of the fixture point 1 on a center shaft S. More particularly, the center shaft S is pivotably supported by the shaft bushing 5, so that both of the two parallel links 2 and 3 are rotatable about the center shaft S in the direction G as shown in Fig. 1. Further, the shaft bushing 5, being pivotable about a horizontal axis P crossing square with the center shaft S, is pivotably joined to an extremity 6a of the first horizontal arm 6 which is movable within the horizontal plane about a base end 6b as an axis. Furthermore, the base end 6b of the first horizontal arm 6 is pivotably joined to an extremity 7a of the second horizontal arm 7 which is movable within the horizontal plane about a base end 7b attached to a base 8. The operation of the parallel linkage and the support mechanism thereof will now be described hereinafter. Change of the supporting angle by the lateral motion of the weight (Fig. 3) The supporting angle of the weight X on the lateral plane viewed from a point L' on the extension L of the center shaft S can be varied by the transformation of a pair of interlocked parallel links. Thus, when the weight is a surgical microscope or the like, the observation angle can be selectively changed with the focus upon the fixed point L'. The transformation of the parallel linkage 4 does not affect the balance maintained between the weight X and the counterweight W. Vertical motion of the weight (Fig. 4) Conventionally, the vertical motion has been conducted by lifting up or down the whole parallel linkage 4, however, according to the present invention, the weight X can be lifted up or down by pivoting the parallel linkage 4 about the horizontal axis P provided at the shaft bushing 5. The turning motion of the parallel linkage 4 doesn't affect the parallel linkage 4 being counterbalanced as a whole. Horizontal motion of the weight (Figs. 6 & 7) The weight X can be translated horizontally in the left and right directions as shown in Fig. 6 and horizontally in the back and forth directions as shown in Fig. 7 by changing the crossing angle of the first and the second horizontal arms 6 & 7 or by pivoting the second horizontal arm 7 about the base 8, as the first and the second horizontal arms 6 & 7 are pivotally connected to support the whole parallel linkage 4. Change of the supporting angle by the longitudinal motion of the weight (Fig. 9) The supporting angle of the weight X in the longitudinal direction can be changed by pivoting the whole parallel linkage 4 about the center shaft S in the direction G. In this case, too, the parallel linkage 4 is kept counterbalanced. Effects caused by the invention As explained in the foregoing description, the counterbalanced parallel linkage supporting mechanism according to the present invention can transfer the weight supported on one end of the parallel link of the parallel linkage vertically upward or downward by pivoting the whole parallel linkage about the horizontal axis provided at the shaft bushing. Accordingly, there needs no such second counterweight as conventionally provided to lift the parallel linkage vertically upward or downward. Counterbalanced parallel linkage supporting mechanism comprising a pair of interlocked parallel links, each provided on the opposite side of the center shaft, a weight supported on one of the parallel links, a counterweight supported on another parallel link for counterbalancing the weight, and a shaft bushing provided on a center shaft for pivotably supporting the center shaft, the shaft bushing supported pivotably about the horizontal axis crossing square with the center shaft.

Claims: A counterbalanced parallel linkage supporting mechanism, comprising: a pair of interlocked parallel links, each provided on the opposite side of a center shaft, a weight supported on one of said parallel links and a counterweight supported on another parallel link for counterbalancing the weight of said weight and a shaft bushing (5) which is provided on said center shaft for pivotably supporting said center shaft, said shaft bushing being supported pivotably about a horizontal axis crossing square with said center shaft, a horizontal arm (7) having base ends (7a) and (7b), which is provided swingable within a horizontal plane about said base end (7b), which is pivotable to said base (8); an arm (6) having base ends (6a) and (6b), which is provided swingable within a horizontal plane about said base end (6b), which is pivotably joined to said base end (7a); the shaft bushing (5) being pivotably joined to said base end (6a) to pivot about said horizontal axis, and the center shaft (S) being a common shaft of said parallel linkages (2) and (3) being turnably supported in said shaft bushing (5).

Inventors: NAKAMURA KATSUSHIGE, NAKAMURA, KATSUSHIGE
Applicants: MITAKA KOKI KK, MITAKA KOHKI CO., LTD.
Application year: 1990
Main classification: F16M11
IPC codes: F16M11, A61B19, G12B9, G02B21