Abstract: Provided is a hollow organ model unit. The hollow organ model unit includes a base that includes a recessed part, a hollow organ model that is placed in the recessed part, a filler that is filled in the recessed part, and a sensor that performs a measurement on the hollow organ model.

Abstract: A scale balancing device for use in a universal parallel ruler device having a head, a spindle rotatably supported on a non-rotating part of the head, a scale mounting plate fixed to the lower spindle, a handle fixed to the upper spindle, and scales mounted on the scale mounting plate, the device has a first gear coaxially mounted on the spindle for rotation therewith, the weight of the scales exerting a torque on the first gear, a second gear rotatably mounted on a non-rotating part of the head and having a spring connected thereto for applying a torque to the second gear to rotate the second gear in a predetermined rotating direction, and a two-stage intermediate gear having a small gear and a large gear integrally connected and rotatably supported on a non-rotating part of the head, the second gear being in mesh with the small gear and the large gear being in mesh with the first gear, the ratio of the diameter of the first gear to the diameter of the large gear being substantially the same as the ratio of

Abstract: A scale balancing device for balancing the weight of the scales of a universal parallel ruler, the device having a head structure having the scales rotatably mounted thereon, a rotating member rotatably mounted on the head structure separate from the scales, the rotating member and the rotatable scales being rotatably interlocked, and a spring having one end rotatably connected to a point on the rotating member eccentric to the axis of rotation thereof and the other end rotatably connected to a non-rotatable part of the head structure, the spring, when the scales are rotated to a position vertically in line with the axis of rotation thereof, having substantially no tension therein and when the scales are rotated ninety degrees from such position, having tension for exerting a maximum force on the eccentric connection point on the rotating member and sufficient in magnitude and having a direction which substantially cancels out the torque on the rotating member from the weight of the scales.

Abstract: A scale balancing device for balancing the weight of a scale of a universal parallel ruler, having a head structure having a rotating scale support rotatably mounted thereon on which the scales are carried, the scale support and scales having a center of gravity when the scale is horizontal spaced horizontally from the axis of rotation of the scale support, a rotating member rotatably mounted on the head structure separate from the rotating support, the rotating member and the scale support being rotatably interlocked, an eccentric member on the rotating member, a spring member having one end connected to the eccentric member and the other end connected to the head structure and tensioned for providing a torque on the rotating member in a direction which substantially cancels out the torque on the rotating member from the weight of the scales, the point of interlocking of the rotating member and the scale support being on the side of the scale support toward the center of gravity when the scale is in the hori

Abstract: A scale balancing device for balancing the weight of the scales of a universal parallel ruler, the device having a head structure having a rotating scale support rotatably mounted thereon on which the scales are carried, a rotating member rotatably mounted on the head structure offset from the rotating support, the rotating member and the scale support being rotatably interlocked, an eccentric member movably mounted on the rotating member for movement radially of the rotating member, and a spring member having one end connected to the eccentric member and the other end connected to the head structure and tensioned for providing a torque on the rotating member in a direction which substantially cancels out the torque on the rotating member from the weight of the scales.