Lens Drive Brake Control for Power and Speed Trade-offs
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Solution Overview
Problem
Existing lens drive systems face inefficiencies in power consumption and drive time due to repeated stopping and starting of electric power supply, especially when lens drive is restarted immediately after being stopped, leading to increased power consumption and communication overhead between camera body CPU and lens CPU.
Innovation Solution
A lens device with a brake part that short-circuits coils to stop the electric motor, allowing controlled braking based on brake ON/OFF information in movement commands, enabling quick lens positioning and reducing unnecessary power usage by maintaining motor energization without braking after reaching the target position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If electric power supply is uniformly stopped when AF control is stopped to prevent increase in power consumption and damage to device due to heating, then power consumption is reduced and device damage is prevented, but the lens drive time is increased due to repeated stopping and starting of power supply
Solution Approach 1:
The patent applies local quality by differentiating the power supply control for different parts of the system. Instead of uniformly stopping power to all circuits, the invention selectively maintains power supply to the motor while stopping power to other AF-related circuits. This localized approach allows the motor to remain ready for immediate operation without the need for full system re-initialization, thus reducing lens drive time while still achieving power consumption reduction and preventing device damage.
2Loss of energy
If electric power supply is uniformly stopped when AF control is stopped, then power consumption is reduced, but communication overhead between camera body CPU and lens CPU increases due to repeated drive commands and state notifications
Solution Approach 1:
The patent applies preliminary action by maintaining the motor in a ready state with continuous power supply during AF control stops. This preliminary preparation ensures that when a new AF drive is required, the motor can immediately execute the drive command without waiting for power re-initialization. This eliminates the need for repeated communication cycles between the camera body CPU and lens CPU, thereby reducing communication overhead while maintaining low power consumption for other circuits.
3Reliability
If brake part is activated every time lens drive is completed to stop the motor, then motor stopping is achieved, but drive time increases when subsequent drives are initiated immediately due to re-energization requirements
Solution Approach 1:
The patent applies dynamics by making the brake activation conditional rather than uniform. The brake part is activated only when specified in the drive command, not automatically after every drive completion. This dynamic control allows the system to adapt to different operational scenarios: when continuous drives are needed, the brake remains inactive to maintain motor energization and enable immediate subsequent drives; when stopping is required, the brake is activated to provide reliable motor stopping. This resolves the contradiction between reliable stopping control and minimized drive time.
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
This solution allows for faster and more efficient lens drive operations by preventing prolonged braking and re-energization cycles, thus reducing power consumption and drive time, even when subsequent drives are initiated immediately after completion.
Implementation Method 1
a brake part for short-circuiting coils in the electric motor to stop the electric motor
Data Source
AI summary
The present invention provides a lens device, a drive method, a recording medium, and an image capturing device. According to an aspect of the present invention, in an one-sided drive mode which allows the lens to move beyond a target position, and then to move in a reverse direction and stop at the target position, the control part controls the lens on the basis of the brake ON/OFF information so that when the lens is temporarily stopped, braking by the brake part is not applied, and only when the lens is stopped at a final target position, braking by the brake part is applied.