JP4649105B2 - Load mounting device and mounting load support method - Google Patents

Description

  The present invention relates to a load mounting technique, and more particularly to a load balance technique for an apparatus that mounts an object that moves up and down, and more particularly, it is effective when applied to a load balance mechanism of a camera mounting apparatus used for video shooting. Technology.

  For example, a camera used when producing a television program is mounted on a camera-mounted device called a pedestal in order to enable free video shooting in various postures. The pedestal is composed of a cart with wheels attached to the floor, a bamboo shoot-like cylinder attached to the cart, and a table disposed on the upper part of the cylinder.

  A TV camera is mounted on the platform via a pan head. The TV camera needs to be moved up and down in order to photograph a subject, and this up and down movement is performed by a cameraman extending and contracting a bamboo shoot-like cylinder.

  In this pedestal, the camera is placed at an arbitrary position in the vertical direction by expanding and contracting the cylinder while the camera is mounted, but even if the cameraman releases his hand from the pedestal in that state, the cylinder does not move It is required to stop at that position. Dynamically speaking, even if the cylinder is expanded and contracted in a state where the camera is mounted, it is required that the pressing force by the mounting load and the force by which the cylindrical body pushes up the camera are balanced at an arbitrary position.

  A mechanism using a gas pressure spring is known as a balance mechanism of a reference technique for realizing this. The gas pressure spring includes a cylindrical cylinder, a piston, and a piston rod connected to the piston, and gas is sealed in an airtight chamber constituted by the cylinder and the piston. In this balance mechanism, the pressure of the gas in the hermetic chamber gives an ascending force to the piston, and the ascending force balances the weight of the cylindrical body and the mounted load via the piston rod. However, such simple gas pressure springs have the following technical problems.

  That is, when the mounting load is moved downward, the cylinder also moves downward, the piston moves downward via the piston rod, and the airtight chamber volume is reduced. As a result, the pressure of the gas in the hermetic chamber increases and the ascending force due to the gas pressure increases. On the other hand, when the mounting load is moved upward, the volume of the hermetic chamber decreases and the ascending force also decreases. As a result, when the mounting load moves up and down, the ascending force due to the air pressure spring is not constant, and there is a technical problem that the ascending force due to the air pressure spring and the loading load are balanced only at one place in the vertical direction.

  As a countermeasure, the technique of Patent Document 1 has been disclosed. This technology installs a disc with an eccentric and variable radius on the piston rod, hangs a wire on the disc, fixes one end to the carriage, and connects the other end to the mounting load to mount the displacement of the piston rod. It is configured to transmit to the load. And by appropriately setting the radius change such as the eccentric amount of the disk, even if the gas pressure in the hermetic chamber changes within the range of vertical movement of the loading load, it tries to keep the force balanced to the loading load constant. Is.

However, the above-described prior art has another technical problem as follows.
In other words, the disk is directly attached to the piston, and the wire hung on the disk directly drives the mounting body or the cylindrical body constituting the multistage extension column that supports the mounting load. For this reason, the moving amount of the cylinder, the moving amount of the piston, and the circumferential length of the disc are closely related, and the size of the disc must be extremely limited.

  Further, since the wire is placed on the outer periphery of the disk, the disk is rotated by the frictional force between the wire and the outer periphery of the disk, and slipping is likely to occur. If slippage occurs between the wire and the outer circumference of the disk, there is a technical problem that the amount of rotation of the disk is reduced and the load balance is distorted.

  In addition, the disc is usually installed inside the column cylinder and moves with the piston. For this reason, the disc must be smaller than the cross-sectional dimension of the cylinder, and there is a design difficulty that there should be no obstacle in the moving range.

Japanese National Patent Publication No. 11-502600

An object of the present invention is to provide a load mounting technique with less restrictions on the device structure and design specifications.
Another object of the present invention is to provide a load mounting technique capable of maintaining stable load balance control.

According to a first aspect of the present invention, a mounting table on which an object is mounted and a mounting table are engaged with the mounting table, and the mounting table can be raised and lowered within a predetermined stroke range by a gas elastic force. A gas spring supported by the gas spring and the gas spring is provided so as to be interposed in the path of the linkage cable and to be rotatable around a ring axis, and the first linkage on the gas spring side of the linkage cable is provided. When the cable and the second linkage cable on the mounting table side are fixed to one side and the other side of the wheel shaft and the mounting table is raised and lowered, the load mounted on the mounting table at an arbitrary position and the stroke The rotational axis generated by the tension generated in the first linkage cable and the tension generated in the second linkage cable by the tension generated in the first linkage cable so as to balance the elastic force of the gas spring changed by The rotational moment generated around It was lance, provided with a support power adjustment mechanism that allows a constant supporting force is transmitted to the mounting table side, wherein the first linkage rope has one end locked to the side of the gas spring, the second The linkage cable has one end locked on the mounting table side, and the support force compensation mechanism has a round disk with the other end of the first linkage cable fixed, and the winding radius of the first linkage cable is constant, A non-circular disk fixed coaxially to the circular disk and having the other end of the second cooperative cable fixed, and a winding radius of the second cooperative cable changing so as to compensate for a change in the elastic force And a load mounting device characterized by comprising:

A second aspect of the present invention is a mounting load supporting method for supporting a mounting table on which an object is mounted in a predetermined stroke range by a resilient force of a gas spring via a linkage cable so as to freely move up and down. Independently of the gas spring, a support force compensation mechanism is provided so as to be interposed in the path of the linkage cable and rotatable around the wheel shaft, and the support force compensation mechanism is provided on the gas spring side of the linkage cable. The first linkage cable and the second linkage cable on the mounting table side are fixed to one side and the other side of the wheel shaft, and when the mounting table is raised and lowered, the load mounted on the mounting table at an arbitrary position And the rotational moment generated around the wheel axis by the tension generated in the first linkage line and the tension generated in the second linkage line so that the elastic force of the gas spring that changes with the stroke is balanced. Around the wheel axis The rotational moment to balance, and transmits a constant supporting force on the mounting table side, wherein the first linkage rope has one end locked to the side of the gas spring, the second linkage cord one end to the mounting table side The other end of the first linkage cable is fixed, and the supporting force compensation mechanism is fixed coaxially to the true disk having a constant winding radius of the first linkage cable. And the other end of the second linkage rope is fixed, and the winding radius of the second linkage rope changes so as to compensate for the change in the elastic force. Provide a method of supporting the load.

  According to the present invention described above, since the supporting force compensation mechanism is provided independently of the gas spring, an eccentric disk that causes restrictions on the device structure and dimensions is fixed on the gas spring side as in the past. Therefore, it is possible to compensate for the elastic force of the gas spring, and it is possible to provide a load mounting device with less restrictions on the device structure and dimension setting.

  In addition, the support force compensation mechanism has a structure in which the linkage cable is fixed, so that the linkage cable does not slip during operation, and there is no load balance compensation error due to the occurrence of the slip. It becomes possible to maintain the load balance control.

  ADVANTAGE OF THE INVENTION According to this invention, a load mounting apparatus with few restrictions on an apparatus structure, a design specification, etc. can be provided. Further, it is possible to provide a load mounting technique capable of maintaining stable load balance control.

Hereinafter, embodiments of the present invention will be specifically described.
(Embodiment 1)
FIG. 1 is a conceptual diagram showing an example of a configuration of a pedestal that is an embodiment of a load mounting device according to the present invention. The pedestal 20 of the present embodiment includes a cylindrical body 1 that can move up and down, a mounting table 10 attached to the upper end of the cylindrical body 1, a basic cylinder 13 through which the cylindrical body 1 is inserted, and wheels 17 for moving on the floor. A carriage 14 that supports the base cylinder 13, a gas spring 15 mounted inside the carriage 14, a circular pulley 7, a wheel shaft 16 (supporting force compensation mechanism), and a cylinder-side wire 2 (second linkage cable), a spring side It is composed of a wire 5 (first linkage cable).

A photographic camera 12 (object) is mounted on the pedestal 20 via a platform 11 on the mounting table 10.
The wheel shaft 16 includes a coaxial non-circular cam 3 and a disk 4 provided independently of the gas spring 15 and is fixed to the carriage 14 via a support column 16a.

The gas spring 15 includes an airtight chamber 18 in which gas is sealed, a piston 8 that moves in the airtight chamber 18 in the axial direction, and a piston rod 6 having one end fixed to the piston 8. A circular pulley 7 is rotatably fixed to the other end of the piston rod 6 and is configured to move up and down together with the piston 8.
In the present embodiment, a reservoir tank 21 is provided, and the reservoir tank 21 and the airtight chamber 18 are connected by an air pipe 22. The reservoir tank 21 is attached to suppress the pressure fluctuation when the pressure fluctuation is large according to the volume fluctuation of the hermetic chamber 18 due to the vertical movement of the piston 8, but is not essential in the present invention.

  One end of the cylindrical body side wire 2 is fixed to the lower end of the cylindrical body 1, and is fixed to one place around the non-circular cam 3 of the wheel shaft 16 via the relay pulley 9 at the upper end portion of the basic cylinder 13. One end of the spring-side wire 5 is fixed to the carriage 14 and is fixed to one place around the disc 4 (the winding radius R of the spring-side wire 5) of the wheel shaft 16 via the circular pulley 7.

  The winding radius r of the cylindrical body wire 2 in the non-circular cam 3 of the wheel shaft 16 (the point that the cylindrical body wire 2 is separated from the peripheral edge of the noncircular cam 3 when the noncircular cam 3 is rotated by θ (rad)) The distance from the center of the non-circular cam 3 is changed in accordance with the rotation angle θ of the non-circular cam 3.

Hereinafter, an example of the operation of the present embodiment will be described.
For example, when the cylinder 1 moves downward, the cylinder-side wire 2 rotates the non-circular cam 3 of the wheel shaft 16 in the arrow direction (counterclockwise). By this rotation, the disk 4 also rotates in the same direction, and the spring-side wire 5 is wound around the disk 4. When the spring side wire 5 is wound up, the circular pulley 7 attached to the piston rod 6 of the gas spring 15 is pushed down by the spring side wire 5, and the piston 8 is pushed down via the piston rod 6 of the gas spring 15. (Pressing force F).

  A gas having a pressure p is sealed in the hermetic chamber 18 of the gas spring 15, and a piston push-up force Q (= p × A; A: cross-sectional area of the cylinder (hermetic chamber 18)) and a push-down force F are generated by this pressure. Balanced.

Now, considering the balance of forces, the push-up force Q causes a tension of Q / 2 on the spring-side wire 5 (when the spring-side wire 5 is parallel to the stroke of the piston rod 6). On the other hand, a tension W due to the mounting load is generated in the cylinder-side wire 2. If r is determined so as to change according to the change of θ so that the moment R × Q / 2 for rotating the wheel shaft 16 by Q / 2 and the moment W × r × cos θ by the tension W are equal. The mounting load is balanced with the pushing force Q of the gas spring 15 at an arbitrary position in the vertical direction.
Here, r is the distance between the point where the cylindrical body wire 2 is separated from the peripheral edge of the noncircular cam 3 and the center of the noncircular cam 3 when the noncircular cam 3 is rotated by Θ, and θ is the noncircular cam of the cylindrical body wire 2. 3 is an angle formed by a horizontal line and a line connecting a point away from the periphery of 3 and the center of the non-circular cam 3.

Here, Q = p × A, but p varies depending on the position of the piston 8 in the hermetic chamber 18, and the rotation angle of the non-circular cam 3 is determined by the position of the piston 8. Here, if the rotation angle of the non-circular cam 3 from when the cylinder 1 is raised to the ascent limit to when it is pushed down to an arbitrary position is Θ,
h = ∫f (r, Θ) rdΘ (1)
However, h is the distance by which the cylinder 1 was pushed down.

Also,
2 × x = R × θ (2)
It is. However, R is the radius of the disc 4 and x is the descending distance of the piston 8.
Furthermore, from Boyle's law (established for absolute pressure)
(P + p _k ) {A × (L ₀ −x) + V} = (p ₀ + p _k ) × (A × L ₀ + V)
... (3)
It is. However, A is related to the cross-sectional area of the hermetic chamber 18, and p ₀ and A × L ₀ are related to the pressure (gauge pressure) and volume of the hermetic chamber 18 when the cylinder 1 is raised to the ascending limit. Further, _{p k} is atmospheric pressure, V is a total volume of the reservoir tank 21 and the air pipe 22.

Accordingly, the moment balance relationship described above R × Q / 2 = W × r × cos θ (4)
From the equations (2) and (3), the winding radius r of the non-circular cam 3 is
r = R × p × A / 2 × W × cos θ
= {R × A / (2 × W × cos θ)}
_{× {(A × L 0 +} V) × (p 0 + p k) / (A × (L 0 -x) + V) -p k}
... (5)
Is a function of θ expressed as

  Then, if the winding radius r of the non-circular cam 3 is determined so that the above equation (5) is satisfied in the entire range of h (that is, the rotation angle Θ), the tension W and the gas due to the loading load in the entire range. The push-up force Q by the spring 15 can be balanced.

  According to the compensation mechanism for the wheel shaft 16 of the present embodiment, the end portions of the spring-side wire 5 and the cylinder-side wire 2 are respectively fixed to predetermined positions around the disc 4 and the non-circular cam 3 of the wheel shaft 16. Therefore, the spring-side wire 5 and the cylinder-side wire 2 do not slide on the disc 4 or the non-circular cam 3. Therefore, the movement amount of the spring-side wire 5 and the cylinder-side wire 2 is accurately converted (transmitted) into the rotation amount of the non-circular cam 3, and there is an advantage that the balance is not lost as in the prior art, and it is always stable. Balance operation is performed.

  Further, since the circular pulley 7 only transmits the displacement and thrust of the piston rod 6 to the spring side wire 5, the size can be freely determined without any restriction on the size of the diameter, and the non-circular cam 3 of the wheel shaft 16 is Independent of the gas spring 15, it is fixed to the carriage 14 with a column 16 a, and even if the piston rod 6 or the cylinder 1 moves up and down, it only rotates and does not move up and down. There is an advantage that there are almost no spatial restrictions, and the degree of freedom of mechanism design and operation specification determination is greatly increased.

  Further, since the non-circular cam 3 that winds the cylinder-side wire 2 and the disc 4 that winds the spring-side wire 5 in accordance with the vertical movement of the piston rod 6 and the cylinder 1 are different, the amount of movement of the cylinder 1 The non-circular cam 3 and the disc 4 can be freely combined in accordance with the combination of strokes of the piston 8 of the gas spring 15, so that a great design restriction can be eliminated and the degree of freedom in design can be further increased. There is.

  As a result, the operation of the pedestal 20 on which the camera 12 is mounted can be stabilized, the degree of freedom in structural design and operation design can be greatly improved, and various shapes and operation specifications can be realized.

(Embodiment 2)
The present invention is not limited to using the non-circular cam in the wheel shaft 16 of the first embodiment as the support force compensation mechanism, and the following cone may be used instead of the non-circular cam. .

  FIG. 2 is a diagram for explaining the shape of the portion of the wheel shaft 16 in the second embodiment. In other words, the wheel shaft 16-2 of the second embodiment is fixed coaxially with the cone 19 having a helical thread groove 19a formed on the surface in place of the non-circular cam 3 described above. It consists of a disc 4.

In this case, as the cylinder 1 moves downward from the upper limit position, the cylinder-side wire 2 is wound along the spiral groove 19 a of the cone 19, but is perpendicular to the rotation axis of the cone 19. The radius d of the cross section changes with the rotation (change in Θ) so as to satisfy W × d = R × Q / 2, and the balance of the mechanical force is as described in the first embodiment. Is the same. Therefore, also in the case of the second embodiment, the load applied to the cylinder 1 is balanced at an arbitrary position of the stroke of the cylinder 1.
As a result, the same effect as in the first embodiment can be obtained.

  In addition, this invention is not limited to each above-mentioned embodiment, A various change is possible in the range which does not change the summary. That is, the present invention can be widely applied to a configuration provided with a support force compensation mechanism that is provided independently of the gas spring and is fixed to the linkage cable that links the gas spring and the load.

  The present invention is not limited to the mounting of an object such as a camera, but can be widely applied to a technique that requires a smooth lifting operation that is balanced with a mounting load.

It is a conceptual diagram which shows an example of a structure of the pedestal which is one Embodiment of the load mounting apparatus which implements the mounting load supporting method of this invention. It is a conceptual diagram which shows an example of a part of structure of the pedestal which is other embodiment of the load mounting apparatus which implements the mounting load supporting method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylindrical body 2 ... Cylindrical side wire 3 ... Non-circular cam 4 ... Disc 5 ... Spring side wire 6 ... Piston rod 7 ... Circular pulley 8 ... Piston 9 ... Relay pulley 10 ... Mounting stand 11 ... Pan head 12 ... Camera 13 ... basic cylinder 14 ... bogie 15 ... gas spring 16 ... wheel shaft 16-2 ... wheel shaft 16a ... column 17 ... wheel 18 ... airtight chamber 19 ... cone 19a ... spiral groove 20 ... pedestal 21 ... reservoir tank 22 ... air pipe

Claims (2)

A mounting table on which an object is mounted;
A gas spring that is engaged with the mounting table via a linkage cable, and supports the mounting table in a predetermined stroke range so as to be movable up and down by a gas elastic force;
Independently of the gas spring, it is provided so as to be interposed in the path of the linkage cable and to be rotatable around a wheel shaft. Among the linkage cables, the first linkage cable on the gas spring side and the mounting table side are provided. When the second linkage cable is fixed to one side and the other side of the wheel shaft, and the mounting table is raised and lowered, the load mounted on the mounting table at an arbitrary position and the gas spring that changes according to the stroke The rotational moment generated around the axis of the wheel shaft by the tension generated in the first linkage cable and the rotation moment generated around the axis of the wheel shaft by the tension generated in the second linkage cable are balanced so that the elastic force is balanced. And a support force compensation mechanism for transmitting a constant support force to the mounting table side,
Equipped with,
One end of the first linkage cable is locked to the gas spring side, one end of the second linkage cable is locked to the mounting table side, and the support force compensation mechanism is connected to the other end of the first linkage cable. Is fixed, and the winding radius of the first cooperative rope is fixed, and the other end of the second cooperative rope is fixed coaxially to the true disk, and the change in elasticity is fixed. A load mounting device comprising: a non-circular disk in which a winding radius of the second cooperative rope changes so as to compensate for A mounting load supporting method for supporting a mounting table on which an object is mounted in a predetermined stroke range by a resilient force of a gas spring via a linkage cable,
Independently of the gas spring, a support force compensation mechanism is provided so as to be interposed in the path of the linkage cable and rotatable around the wheel shaft, and the support force compensation mechanism is provided on the gas spring side of the linkage cable. The first linkage cable and the second linkage cable on the mounting table side are fixed to one side and the other side of the wheel shaft, and when the mounting table is raised and lowered, the load mounted on the mounting table at an arbitrary position And the rotational moment generated around the wheel axis by the tension generated in the first linkage line and the tension generated in the second linkage line so that the elastic force of the gas spring that changes with the stroke is balanced. Balance the rotational moment generated around the wheel axis, and transmit a certain support force to the mounting table.
One end of the first linkage cable is locked to the gas spring side, one end of the second linkage cable is locked to the mounting table side, and the support force compensation mechanism is connected to the other end of the first linkage cable. Is fixed, and the winding radius of the first cooperative rope is fixed, and the other end of the second cooperative rope is fixed coaxially to the true disk, and the change in elasticity is fixed. And a non-circular disk in which the winding radius of the second linkage cable changes so as to compensate for the load.