Pan-Tilt Head Helical Gear Preload for Backlash and Vibration
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Solution Overview
Problem
Conventional pan and tilt mechanisms for camera units face issues with rattling and vibration due to backlash and uneven transmission torque, particularly when changing rotation speeds, leading to image blurriness and instability.
Innovation Solution
A pan or tilt head design incorporating helical gears with a biasing unit that allows the second gear to move axially, reducing backlash and uneven torque by using a coil spring to maintain contact between gears, while minimizing the impact of inertia-induced vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a timing belt is used as a rotational drive mechanism, then smooth rotational drive is enabled and backlash is removed, but the image shakes due to bending and expansion/contraction of the belt when a large lens barrel is driven or stopped at high acceleration
Solution Approach 1:
The patent replaces the timing belt mechanical system with a gear-based mechanical system. Specifically, it uses a pair of spur gears (first spur gear and second spur gear) that mesh with each other to transmit rotational force, eliminating the elastic timing belt entirely. This substitution removes the source of vibration caused by belt elasticity while maintaining smooth rotational drive capability through proper gear engagement.
Solution Approach 2:
The patent introduces a biasing member (spring) as an intermediary element between the two spur gears. This spring applies a biasing force to maintain continuous contact between the meshing teeth of the gears, ensuring smooth power transmission without backlash while avoiding the vibration issues of elastic belts. The biasing member acts as a mediator that ensures consistent gear engagement without transmitting harmful vibrations.
2Reliability
If a scissors gear configuration with strong spring biasing is used, then backlash is removed and rattling is suppressed, but large unevenness in transmission torque occurs due to gear rotation phase
Solution Approach 1:
The patent changes the key parameter of the biasing force applied to the second spur gear. Instead of using a strong spring biasing force, it employs a weak spring biasing force that is specifically designed to be insufficient for completely eliminating backlash. This parameter change allows the system to tolerate some backlash while avoiding the severe torque unevenness that would result from strong spring biasing, thereby achieving smoother transmission torque throughout the gear rotation cycle.
3Speed
If the spring biasing force is weakened to reduce transmission torque unevenness, then speed uniformity improves, but the torque generated by inertia cannot be maintained and the lens barrel shakes
Solution Approach 1:
The patent introduces a damping element that dynamically responds to the motion of the lens barrel. This damping element provides velocity-dependent resistance that automatically adjusts to the inertial forces during acceleration and deceleration. When the lens barrel experiences sudden inertial forces during high-speed operation, the damping element activates to provide additional stabilizing force, preventing shakes while allowing the weak spring biasing to maintain speed uniformity during normal operation.
4Reliability
If spur gears are used in a scissors gear configuration, then backlash can be removed, but large unevenness in transmission torque occurs causing image blurriness during constant speed rotation
Solution Approach 1:
The patent changes the biasing force parameter of the spring to a weak value, which fundamentally alters the gear engagement characteristics. Instead of forcing continuous strong contact between gear teeth, the weak biasing allows for more compliant engagement that reduces impact loads and torque fluctuations. This parameter change transforms the gear interaction from a rigid, high-impact engagement to a softer, more uniform engagement that eliminates the severe torque unevenness causing image blurriness.
Solution Approach 2:
The patent incorporates a damping element that dynamically compensates for the weak spring biasing during operation. The damping element provides velocity-proportional resistance that becomes active during rapid changes in motion, stabilizing the gear engagement and reducing vibration transmitted to the camera unit. This dynamic compensation ensures that even with weak spring biasing, the system maintains sufficient control authority to prevent image blurriness during constant speed rotation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables smooth and stable rotational drive across a wide speed range, reducing rattling and vibration, and maintaining constant rotational speed, thus preventing image blurriness during panning and tilting operations.
Implementation Method 1
a biasing unit which biases the second gear in the rotation axis direction
Implementation Method 2
a coil spring to maintain contact between gears
Implementation Method 3
the first gear, the second gear, and the third gear include helical gears
Data Source
AI summary
In order to provide a pan or tilt head and the like capable of reducing rattling or vibration when a rotation is suddenly changed while reducing the unevenness in rotational speed for smooth rotational drive, there is provided a pan or tilt head including a drive unit which rotates a camera unit in a predetermined direction, first and second gears which rotate around a predetermined rotation axis in the predetermined direction and are coaxial with the predetermined rotation axis, a third gear which meshes with the first and second gears and transmits a driving force from the drive unit, and a biasing unit which biases the second gear in the rotation axis direction, the first gear, the second gear, and the third gear includes helical gears, and the second gear is disposed to be movable in the rotation axis direction with respect to the first gear.