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A keyboard instrument support has a driving device to control upward and downward movement of inner tubes relative to the outer tubes and a ratchet device to retain the elevation of the inner tubes. The ratchet device includes a ratchet alternatively rotated by the driving device and a leverage to

A keyboard instrument support has a driving device to control upward and downward movement of inner tubes relative to the outer tubes and a ratchet device to retain the elevation of the inner tubes. The ratchet device includes a ratchet alternatively rotated by the driving device and a leverage to abut a ratchet tooth. Thus, after the inner tubes are elevated by the driving device, the abutment of the leverage to the ratchet retains the elevation of the inner tubes.

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What is claimed is: 1. In a keyboard instrument support having two legs horizontally separated from each other, two outer tubes respectively and obliquely extending out from distal ends of the two legs, two inner tubes slidably received in the two outer tubes respectively, two arms horizontally sep

What is claimed is: 1. In a keyboard instrument support having two legs horizontally separated from each other, two outer tubes respectively and obliquely extending out from distal ends of the two legs, two inner tubes slidably received in the two outer tubes respectively, two arms horizontally separated from each other and extending from free ends of the two inner tubes, two connecting tubes with two sliding tubes each slidably received in a corresponding one of the two connecting tubes being securely connected to outer faces of a respective one of the outer tubes and the corresponding one of the inner tubes, wherein distal ends of the two sliding tubes are securely connected to outer faces of one of the outer tubes and one of the inner tubes and each of the connecting tubes is provided with a pivotal plate having an eccentric block integrally formed with the pivotal plate and selectively extendable through the outer face of the connecting tube to engage the outer face of the sliding tube so as to limit the sliding movement of the sliding tubes inside the connecting tubes, wherein the improvements comprise: a first seat and a second seat mounted on a corresponding one of the two outer tubes and respectively composed of two plates to rotatably receive therebetween a roller with multiple bosses formed on an outer periphery of the roller to correspond to a hole adapted to be defined in each of the outer tubes and each boss being received in one of multiple adjusting holes adapted to be defined in each of the inner tubes; a first rotation tube with a first end adjacent to an outer face of the second seat and having an open second end to securely receive therein a second rotation tube having a first end adjacent to an outer face of the first seat, with the first ends of the first and second rotation tubes integrally formed with two extensions, two threaded bolts-integrally formed with each of the extensions and respectively extending through a corresponding one of the rollers sandwiched between the first and second seats; a ratchet firmly connected to the extension of the second rotation tube and selectively rotated to drive the roller in each of the first and second seats to rotate; and means for selectively driving the ratchet to rotate such that the rotation of the roller in the first and second seats lifts or retracts the inner tubes with respect to the outer tubes and the arms are able to move simultaneously to maintain the keyboard instrument placed on top of the two arms horizontal. 2. The keyboard instrument support as claimed in claim 1, wherein the ratchet further has a leverage pivotally connected to the first seat and having a projection formed on a top face of the leverage to abut a ratchet tooth of the ratchet so as to limit the rotation of the ratchet. 3. The keyboard instrument support as claimed in claim 2, wherein the leverage has a finger extending from a bottom face of the leverage to abut a first end of a spring of which a second end is securely connected to the outer face of the first seat so that the spring is able to provide a resilient force to the leverage to maintain the abutment of the projection to the ratchet tooth of the ratchet and thus the rotation of the ratchet is limited. 4. The keyboard instrument support as claimed in claim 1, wherein the driving means comprises a handle and a connector sandwiched between the handle and the ratchet to allow the threaded bolt to extend into the connector after extending through the first and second seats, the rollers respectively received in the first and second seats and the ratchet alternatively rotated beside the outer face of the first seat. 5. The keyboard instrument support as claimed in claim 3, wherein the driving means comprises a handle and a connector sandwiched between the handle and the ratchet to allow the threaded bolt to extend into the connector after extending through the first and second seats, the rollers respectively received in the first and second seats and the ratchet alternatively rotated beside the outer face of the first seat. 6. The keyboard instrument support as claimed in claim 5, wherein the connector has a securing hole defined through the connector to align with a through hole defined in the threaded bolt and allow a securing pin to extend through the securing hole and into the through hole to secure engagement between the connector and the threaded bolt. 7. The keyboard instrument support as claimed in claim 6, wherein the securing hole has a dimension larger than a dimension of the securing pin such that the securing pin is distant from a periphery defining the securing hole and the connector has a threaded bore defined in the connector to threadingly receive therein the threaded bolt of the second rotation tube such that when the handle is rotated in a first direction to drive the connector to rotate in the same direction as that of the handle, a free end of the threaded bolt at a first position is moved to a second position where the ratchet is driven to rotate by the connector and the roller is rotated to lift the inner tube relative to the outer tube. 8. The keyboard instrument support as claimed in claim 7, wherein the securing pin abuts the periphery defining the securing hole when the free end of the threaded bolt is moved to the second position such that the rotation of the handle is able to drive the ratchet to rotate in the first direction. 9. The keyboard instrument support as claimed in claim 7, wherein a gap is defined between the free end of the threaded bolt and a bottom face of the threaded bore when the handle is rotated in a second direction opposite to the first direction to drive the free end at the second position to the first position where the ratchet is released from rotation and the inner tube is retracted inside the outer tube. 10. The keyboard instrument support as claimed in claim 8, wherein a gap is defined between the free end of the threaded bolt and a bottom face of the threaded bore when the handle is rotated in a second direction opposite to the first direction to drive the free end at the second position to the first position where the ratchet is released from rotation and the inner tube is retracted inside the outer tube. 11. The keyboard instrument support as claimed in claim 10, wherein the ratchet has a first cup formed on an outer face of the ratchet and the connector has a second cup formed on the inner face of the threaded bore to correspond to and engage with the first cup when the free end of the threaded bolt is moved from the first position to the second position and disengage with the first cup when the free end of the threaded bolt is moved from the second position to the first position. 12. A keyboard instrument support comprising: two Z-shaped brackets with a distance apart from each other; at least one connecting tube connecting the two brackets together and having a sliding tube slidably received in the connecting tube to adjust the distance between the two brackets, wherein each bracket has an outer tube and an inner tube slidably received in and extending out of the outer tube; a first seat and a second seat mounted on a corresponding one of the two outer tubes and respectively composed of two plates to rotatably receive therebetween a roller with multiple bosses formed on an outer periphery of the roller to correspond to a hole adapted to be defined in each of the outer tubes and each boss being received in one of multiple adjusting holes defined in each of the inner tubes; a first rotation tube with a first end adjacent to an outer face of one plate of the second seat and an open second end to slidably receive therein a second rotation tube having a first end adjacent to an outer face of the first seat, with the first ends of the first and second rotation tubes integrally formed with two extensions, two threaded bolts integrally formed with the two extensions and extending through the rollers sandwiched between the first and second seats; means for ratcheting elevation of the inner tubes relative to the outer tubes; and means for alternatively driving the ratcheting means to rotate such that the rotation of the rollers in the first and second seats lifts or retracts the inner tubes with respect to the outer tubes and two arms are able to move simultaneously to maintain the keyboard instrument placed on top of the two arms horizontal. 13. The keyboard instrument support as claimed in claim 12, wherein the ratcheting means comprises: a ratchet alternatively rotated in a first direction to elevate the inner tube relative to the outer tube and having multiple ratcheting teeth formed on an outer periphery of the ratchet; a leverage pivotally connected to the outer face of the first seat and having a projection formed on a top face of the leverage to correspond to and abut a corresponding one of the ratcheting teeth to limit the rotation movement of the ratchet; and a spring having a first end securely connected to the outer face of the first seat and a second end abutted to a finger extending downward from the leverage so that the leverage is able to maintain abutting the ratchet. 14. The keyboard instrument support as claimed in claim 12, wherein the driving means comprises a handle and a connector sandwiched between the handle and the ratchet to allow the threaded bolt to extend into the connector after extending through the first and second seats, the rollers respectively received in the first and second seats and the ratchet alternatively rotated beside the outer face of the first seat. 15. The keyboard instrument support as claimed in claim 14, wherein the connector has a securing hole defined through the connector to align with a through hole defined in the threaded bolt and allow a securing pin to extend through the securing hole and into the through hole to secure engagement between the connector and the threaded bolt. 16. The keyboard instrument support as claimed in claim 15, wherein the securing hole has a dimension larger than a dimension of the securing pin such that the securing pin is distant from a periphery defining the securing hole and the connector has a threaded bore defined in the connector to threadingly receive therein the threaded bolt of the second rotation tube such that when the handle is rotated in a first direction to drive the connector to rotate in the same direction as that of the handle, a free end of the threaded bolt at a first position is moved to a second position wherein the ratchet is driven to rotate by the connector and the roller is rotated to lift the inner tube relative to the outer tube. 17. The keyboard instrument support as claimed in claim 16, wherein the securing pin abuts the periphery defining the securing hole when the free end of the threaded bolt is moved to the second position such that the rotation of the handle is able to drive the ratchet to rotate in the first direction. 18. The keyboard instrument support as claimed in claim 16, wherein a gap is defined between the free end of the threaded bolt and a bottom face of the threaded bore when the handle is rotated in a second direction opposite to the first direction to drive the free end at the second position to the first position where the ratchet is released from rotation and the inner tube is retracted inside the outer tube. 19. The keyboard instrument support as claimed in claim 17, wherein a gap is defined between the free end of the threaded bolt and a bottom face of the threaded bore when the handle is rotated in a second direction opposite to the first direction to drive the free end at the second position to the first position where the ratchet is released from rotation and the inner tube is retracted inside the outer tube. 20. The keyboard instrument support as claimed in claim 19, wherein the ratchet has a first cup formed on an outer face of the ratchet and the connector has a second cup formed on the inner face of the threaded bore to correspond to and engage with the first cup when the free end of the threaded bolt is moved from the first position to the second position and disengages with the first cup when the free end of the threaded bolt is moved from the second position to the first position.