WO2011153163A2

WO2011153163A2 - Anti-backlash bracket

Info

Publication number: WO2011153163A2
Application number: PCT/US2011/038605
Authority: WO
Inventors: Gary Katsuya Ushino; Thomas Viebach; Ursula Meyr
Original assignee: 3Ality Digital, Llc
Priority date: 2010-06-02
Filing date: 2011-05-31
Publication date: 2011-12-08
Also published as: WO2011153163A3

Abstract

A device and method for improving the positional stability, preventing "backing off" from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs.

Description

ANTI-BACKLASH BRACKET

FIELD

[001] The invention pertains to the field of camera lenses and more specifically to an anti-backlash bracket for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs.

BACKGROUND

[002] Motion picture camera lenses commonly have one or more cog rings 102 to allow adjustments to be made to focus, zoom and iris positions, as can be seen in a typical camera setup 100 in Figure 1. The cog rings 102 are intended to mesh with external drive motors 104. The external drive motors 104 are commonly mounted on an iris rod 106 or 107, separate from the lens 110, with a camera lens sled clamp lock 108. In order for the lens 110 to be changed, the external drive motors 104 must be able to be engaged and disengaged from the cog rings 102. This is typically done by loosening the motor bracket clamp 108, rotating the external drive motor 104 around the iris rod 106 or 107 to either engage or disengage the motor and tightening the motor bracket clamp 108.

[003] The current practice is adequate for a single camera/single lens use. However, stereoscopic 3D generally uses two cameras and two lenses. The corresponding settings, such as, for example, focal length, for each lens pair must match as closely as possible. To achieve this goal it is necessary to mate the gears of the motor and the lens as tightly as possible to minimize gear slop when changing directions (backlash). Disadvantageously, however, simply pressing the motor drive more tightly against the lens causes undesirable friction and can push the lens out of position. Additionally, the common clamping mechanism tends to "back off from the ideal gear meshing from the centripetal force of the drive function and the high pitching moment relative to the clamping force due to the distance from the gear mating point to the clamping point. Finally, the exact clamping position will vary from lens to lens and setup to setup, which defies the use of knurled rods or pin holes.

[004] Therefore, there exists a need for a device for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs that is not associated with these disadvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

[005] These and other features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying figures where:

[006] Figure 1 is diagram of a prior art device for positioning a camera lens;

[007] Figure 2 is a side view of a anti-backlash device for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs according to one embodiment of the present invention;

[008] Figure 3 is perspective view of the anti-backlash device of Figure 2;

[009] Figure 4 is an operational diagram of the anti-backlash device of Figure 2; 21

[0010] Figure 5 is a side view of the anti-backlash device in combination with a lens according to one embodiment of the invention;

[0011] Figure 6 is a schematic drawing of the anti-backlash device according to one embodiment of the present invention; and

[0012] Figure 7 is a detailed schematic drawing of the anti-backlash device according to one embodiment of the present invention.

SUMMARY OF THE INVENTION

[0013] An anti-backlash bracket device for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs, the anti-backlash device comprising a lens motor; an anti-backlash bracket body operationally connected to the lens motor;

connection means for at least two iris rods connected to the anti-backlash bracket body; an adjustment screw shaft connected to the anti-backlash bracket body and to the at least two iris rods using a pressure means; a knob attached to a distal end of the adjustment screw for fine position adjustment; a quick release pivotally connected to the anti-backlash bracket body; a threaded cam follower physically connected to the adjustment screw shaft and operationally connected to the quick release cam; a fine adjustment connected to the adjustment screw shaft; and a lock screw connected to the anti-backlash bracket body. The quick release provides a means to quickly move the anti-backlash bracket for coarse adjustments and the fine adjustment screw provides fine adjustment of the anti-backlash bracket for moving the lens motor. The locking screw prevents the anti-backlash bracket from moving once the adjustments to the lens motor are complete.

[0014] A device for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens [0015] gears in 3D camera rigs comprising a quick release; a fine adjustment; a lock screw; and a dual locking arm.

[0016] The dual locking arm is used to keep the anti-backlash bracket stable in the horizontal and vertical planes with respect to the camera and the lenses. The anti-backlash device can further comprise quick release knobs for attaching to the camera rig.

[0017] A method for using a device for improving the positional stability, preventing

"backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs. First, loosening the anti-backlash threaded nut lens motor clamp. Then, sliding the lens motor onto the anti-backlash bracket motor receiver. Next, locking the lens motor in the vertical position desired for good lens gear contact using the threaded nut. Then, loosening the lower lock screw. Next, positioning the lens motor bracket to achieve alignment of the lens motor to the lens gear. Then, backing off the upper screw knob and pulling the lens motor away from the lens if there is no clearance with the lens and the lens motor. Next, repeating these steps until the desired clearance has been achieved. Then, turning the upper adjustment screw to move the lens motor gear toward the lens gear, where the lens motor gear is aligned with the lens gear to be engaged and the quick release lever is in the closed position. Next, rotating the lens gear back and forth while simultaneously turning the upper adjustment screw toward full engagement as the gears of the anti -backlash bracket begin to make contact. Then, stopping the adjustment when all gear slop or backlash is removed. Repeating these steps for each lens motor attached to the camera rig. Optionally, the user can open the quick release lever to pull back the lens motor. Additionally, the user can loosen the anti-backlash motor bracket from the lens and repeat these steps if a binding condition is suspected or has occurred. DETAILED DESCRIPTION

[0018] The anti-backlash bracket was developed to fill the need of extreme accuracy of lens motor position during a shoot in 3D. Filming in 3D requires that lens motor position in relation to lens gear engagement does not change once all look up tables (LUTs) have been loaded. Once set, the position and changing backlash associated with long duration shooting should remain constant or unchanging during an event until the motor is manually loosened or otherwise deliberately moved by a user.

[0019] According to one embodiment of the present invention, there is provided an anti-backlash device for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs. According to another embodiment of the present invention, there is provided a method for using the anti-backlash device for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs. In one embodiment, the method comprises, providing a device according to the present invention.

[0020] All dimensions specified in this disclosure are by way of example only and are not intended to be limiting. Further, the proportions shown in these Figures are not necessarily to scale. As will be understood by those with skill in the art with reference to this disclosure, the actual dimensions of any device or part of a device disclosed in this disclosure will be determined by its intended use.

[0021] Methods, systems and devices that implement the embodiments of various features of the system will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the system and not to limit the scope of the invention. Reference in the specification to "one embodiment" or "an embodiment" is intended to indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least an embodiment of the invention. The appearances of the phrase "in one embodiment" or "an embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0022] Throughout the drawings, reference numbers are re-used to indicate correspondence between referenced elements. In addition, the first digit of each reference number indicates the figure where the element first appears.

[0023] As used in this disclosure, except where the context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and

"comprised" are not intended to exclude other additives, components, integers or steps.

[0024] In the following description, specific details are given to provide a thorough understanding of the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments may be practiced without these specific detail. Well-known circuits, structures and techniques may not be shown in detail in order not to obscure the embodiments. For example, circuits may be shown in block diagrams in order not to obscure the embodiments in unnecessary detail.

[0025] Also, it is noted that the embodiments may be described as a process that is depicted as a flowchart, a flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be rearranged. A process is terminated when its operations are completed. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination corresponds to a return of the function to the calling function or the main function.

[0026] According to one embodiment of the present invention, there is provided a device for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs.

[0027] Referring now to Figure 2, there is a side view of an anti-backlash device 200 for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs according to one embodiment of the present invention. As can be seen the anti-backlash device comprises means for mounting the bracket to two or more iris rods 106 and 107. Multiple mounting points to the iris rods 106 and 107 provide greater stability for the lens motor 104. Also, the anti-backlash device has a quick release cam 204 feature that allows the quick, gross movement of the lens motor 104 in or out of position for lens changes etc. A threaded cam follower locking rod 210 applies pressure to an adjustment screw shaft 212 preventing movement of the lens motor 104. The adjustment screw shaft applies pressure to the iris rods 106 and 107 using pressure means, such as, for example, a brass pressure ring or other means that will be apparent to with skill in the art with reference to this disclosure. Additionally, there is a fine adjustment 206 to precisely engage the lens motor gear to the lens gear. Finally there is a lock screw 208 that secures the position of the anti-backlash bracket 200 to the iris rods 106 and 107 and the anti-backlash bracket 200 lens motor 104 position.

[0028] Referring now to Figure 3 there is shown a perspective view of the anti- backlash device of Figure 2. The quick release cam 204, adjustment screw 206 and the locking screw 208 can be seen in a perspective view. As can be seen, the quick release 204 is pivotally attached to the anti-backlash bracket 200 provides a means to quickly move the anti-backlash bracket for coarse adjustments. The adjustment screw 206provides fine adjustment and the locking screw 208 prevents the anti-backlash bracket from moving once the adjustments are complete. [0029] Referring now to Figures 4 and 5 there are shown operational diagrams of the anti-backlash device of Figure 2 using a front view and a side view of the anti-backlash device 200 in combination with a lens 110. First, the anti-backlash bracket threaded nut lens motor clamp 208 is loosened. Then, the lens motor 104 is slid onto the anti-backlash bracket motor receiver 202 and using the threaded nut, lock the lens motor in the vertical position desired for good lens gear contact. Next, the lower lock screw 208 is loosened and the lens motor bracket is positioned laterally to achieve alignment of the lens motor 110 to the lens gear 102. Then, if there is no clearance with the lens 110 and the lens motor 104, the user can back off the upper screw knob 206 and pull the lens motor away from the lens. Continue this procedure until the desired clearance has been achieved. Optionally, the user can open the quick release lever 204 to pull back the lens motor. Next, with the lens motor 104 gear aligned with the lens gear 102 to be engaged and the quick release cam 204 lever is in the closed position, the upper adjustment screw 206 is turned to move the lens motor 104 gear toward the lens gear 102. Then, as the gears of the anti-backlash bracket begin to make contact, the lens gear 102 is rotated back and forth while simultaneously turning the upper adjustment screw 206 toward full engagement. The user will be able to see, hear and feel the gear lash of the gear engagement while it is still loose and sloppy. The gear slop condition will lessen the engagement of the gears when the adjustment screw 206 is tightened. Next, the adjustment is stopped when all gear slop or backlash is removed. Over-tightening will result in the undesirable condition of binding. This binding condition can cause rough, uneven movement or even full stop of the motor as well as excessive wear on the lens cams, lens bearings, lens motor bearings and lens motor overheating. If a binding condition is suspected or has occurred, loosen the upper adjustment screw 206 and pull back lens motor 104 from lens gear 102 and repeat the steps above. Finally, repeat the steps for each lens motor. [0030] Referring now to Figure 6 there is shown a schematic drawing of the anti- backlash device according to one embodiment of the present invention. As can be seen the anti-backlash bracket comprises a quick release mechanism pivotally attached to the anti- backlash bracket and the adjustment screw shaft. A knob is attached to an end of the adjustment screw for fine position adjustment.

[0031] Referring now to Figure 7 there is shown a detailed schematic drawing of the anti-backlash device according to one embodiment of the present invention. As can be seen the anti -backlash bracket in this embodiment comprises a dual locking arm to keep the anti- backlash bracket stable in the horizontal and vertical planes with respect to the camera and the lenses. The bracket can comprise quick release knobs for attaching to the camera rig.

[0032] Although the present invention has been discussed in considerable detail with reference to certain preferred embodiments, other embodiments are possible. Therefore, the scope of the appended claims should not be limited to the description of preferred embodiments contained in this disclosure. All references cited herein are incorporated by reference in their entirety.

Claims

What Is Claimed Is

1. An anti-backlash bracket device for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs, the anti-backlash device comprising:

a) a lens motor;

b) an anti-backlash bracket body operationally connected to the lens motor; c) connection means for at least two iris rods connected to the anti-backlash bracket body;

d) an adjustment screw shaft connected to the anti-backlash bracket body and to the at least two iris rods using a pressure means;

e) a quick release pivotally connected to the anti-backlash bracket body;

f) a threaded cam follower physically connected to the adjustment screw shaft and operationally connected to the quick release cam;

g) a fine adjustment connected to the adjustment screw shaft; and

h) a lock screw connected to the anti-backlash bracket body.

2. The anti-backlash device according to claim 1, where the quick release provides a means to quickly move the anti-backlash bracket for coarse adjustments.

3. The anti-backlash device according to claim 1, where the fine adjustment screw provides fine adjustment of the anti-backlash bracket for moving the lens motor.

4. The anti-backlash device according to claim 1, where the locking screw prevents the anti-backlash bracket from moving once the adjustments to the lens motor are complete.

5. The anti-backlash device according to claim 1 further comprising a knob attached to a distal end of the adjustment screw for fine position adjustment.

6. A device for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs, the anti-backlash device comprising:

a) a quick release;

b) a fine adjustment;

c) a lock screw; and

d) a dual locking arm.

7. The anti-backlash device according to claim 6, where the dual locking arm is used to keep the anti-backlash bracket stable in the horizontal and vertical planes with respect to the camera and the lenses.

8. The anti-backlash device according to claim 7, where the bracket can further comprise quick release knobs for attaching to the camera rig.

9. A method for using a device for improving the positional stability, preventing "backing off from standard operating forces and minimizing backlash without adding force or friction to lens gears in 3D camera rigs, the method comprising the steps of:

a) providing the device of claim 1 ;

b) loosening the anti -backlash threaded nut lens motor clamp;

c) sliding the lens motor onto the anti -backlash bracket motor receiver; d) locking the lens motor in the vertical position desired for good lens gear contact using the threaded nut;

e) loosening the lower lock screw;

f) positioning the lens motor bracket to achieve alignment of the lens motor to the lens gear;

g) backing off the upper screw knob and pulling the lens motor away from the lens if there is no clearance with the lens and the lens motor;

e) repeating steps e) through g) until the desired clearance has been achieved; f) turning the upper adjustment screw to move the lens motor gear toward the lens gear, where the lens motor gear is aligned with the lens gear to be engaged and the quick release lever is in the closed position;

g) rotating the lens gear back and forth while simultaneously turning the upper adjustment screw toward full engagement as the gears of the anti-backlash bracket begin to make contact;

h) stopping the adjustment when all gear slop or backlash is removed;

j) repeating steps b) through h) for each lens motor.

10. The method of claim 9, where the user can optionally open the quick release lever to pull back the lens motor in step g).

11. The method of claim 9, further comprising the step of loosening the anti-backlash motor bracket from the lens and repeat steps e) through h) if a binding condition is suspected or has occurred.