Lens-to-Sensor Offset Assembly for Low-Power Macro Autofocus
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Solution Overview
Problem
Existing camera devices consume significant auto-focusing actuation power due to misalignment of the lens and image sensor caused by gravity and thermal shifts, especially in horizontal and macro modes, which is problematic in small form factor electronic wearable devices with limited power budgets.
Innovation Solution
The camera device is assembled with an optical axis parallel to gravity, introducing an offset to position the lens assembly at a neutral position relative to the image sensor, minimizing auto-focusing actuation power by ensuring the lens is focused at the hyperfocal or close-up distance without additional actuation, accounting for thermal effects and orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lens is positioned in horizontal posture for typical camera use, then the camera can capture images in standard orientation, but the lens is not at its hyperfocal position requiring additional auto-focusing actuation power
Solution Approach 1:
The lens assembly is pre-positioned during assembly to account for the expected horizontal orientation and thermal conditions. By performing the positioning action in advance (during assembly rather than during operation), the system eliminates the need for power-consuming auto-focusing adjustments when the device is used in its typical horizontal orientation.
Solution Approach 2:
The assembly process introduces a pre-compensation offset that counteracts the expected thermal expansion and gravitational effects before the device is operational. This preliminary anti-action prevents the lens from being out of position during normal use, thereby avoiding the need for corrective actuation.
2Ease of manufacture
If the lens is positioned for upward posture during assembly, then the assembly process is simplified, but gravity causes the carrier to shift downward requiring additional actuation power in horizontal mode
Solution Approach 1:
The lens assembly is pre-positioned during assembly to account for the expected horizontal orientation and thermal conditions. By performing the positioning action in advance (during assembly rather than during operation), the system eliminates the need for power-consuming auto-focusing adjustments when the device is used in its typical horizontal orientation.
3Adaptability or versatility
If the camera operates at higher temperatures in wearable devices, then the camera can function in various environments, but thermal shifting causes the lens to move relative to the image sensor increasing actuation power
Solution Approach 1:
The system accounts for temperature as a varying parameter by pre-positioning the lens assembly to compensate for expected thermal expansion. The assembly is calibrated at a reference temperature, and the pre-set offset ensures that even when temperature changes cause thermal expansion, the lens remains at or near the optimal focal position, minimizing actuation power requirements.
4Reliability
If the lens is positioned to account for thermal effects, then the lens remains focused at higher temperatures, but the lens-to-sensor distance changes requiring precise assembly control
Solution Approach 1:
The lens assembly is pre-positioned during assembly to account for the expected horizontal orientation and thermal conditions. By performing the positioning action in advance (during assembly rather than during operation), the system eliminates the need for power-consuming auto-focusing adjustments when the device is used in its typical horizontal orientation.
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
Reduces or minimizes auto-focusing actuation power consumption, allowing the camera device to operate efficiently in typical and macro modes with minimal power usage, suitable for small form factor electronic wearable devices like smartwatches.
Implementation Method 1
the lens assembly is assembled within the camera device to have an optical axis parallel to gravity and positioned to have an offset along the optical axis relative to a support assembly
Implementation Method 2
The second cause is a thermal shift of the lens during typical operations of the camera device. The lens design and its performance are commonly tested at a room temperature, e.g., around 23° C. However, the camera device can often operate at higher temperatures (e.g., around 45 to 50° C.)
Data Source
AI summary
Embodiments of the present disclosure further relate to a camera device assembled such that to reduce (and in some cases minimize) auto-focusing actuation power when the camera device operates in a macro mode. The camera device includes an image sensor and a lens assembly in an optical series with the image sensor. During manufacturing of the camera device, the lens assembly is assembled within the camera device to have an optical axis substantially parallel to gravity and positioned to have an offset along the optical axis. The offset is determined during manufacturing of the camera device such that, when the camera device is in the macro mode, the lens assembly is positioned at a neutral position relative to the image sensor without actuation applied to the lens assembly.