HMD Lens Driving Unit for Automatic Focal Point Adjustment
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Solution Overview
Problem
Conventional head-mounted displays (HMDs) require manual adjustment of the lens unit's focal point, which is inconvenient and can degrade the appearance of the device, as users must manually control a visible lever to set the optimal distance between the lens and display units based on their eyesight.
Innovation Solution
An HMD with a lens driving unit that automatically adjusts the focal point using a piezo linear actuator and position sensor, coupled with a light source and camera to measure the user's eyesight and iris recognition for precise positioning, allowing for automatic control of the lens unit's position relative to the display unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a control lever is exposed to the outside for manual adjustment, then the user can control the distance between lens unit and display unit, but the appearance of the HMD is degraded
Solution Approach 1:
The control lever is extracted from the external visible area and integrated into the internal structure of the HMD. The adjustment mechanism is now housed within the lens assembly, eliminating the need for external levers while preserving manual adjustability through wireless control signals.
Solution Approach 2:
The mechanical control lever system is replaced with a wireless control system. Users can adjust the lens distance through wireless communication (e.g., Bluetooth) to a connected device, eliminating the need for physical mechanical levers on the HMD exterior.
2Reliability
If a control lever is used for distance adjustment, then the user can set optimal focal point, but the user must manually operate it every time wearing the HMD
Solution Approach 1:
The HMD system performs preliminary actions by automatically measuring the user's eyesight parameters (such as pupillary distance and focal length) when first worn or when adjustment is needed. This data is stored and used to automatically set the optimal lens position without requiring manual intervention during each use.
Solution Approach 2:
The HMD system provides self-service through automatic eyesight measurement and lens position adjustment. The device uses integrated cameras and sensors to measure user parameters and automatically adjusts the lens unit position to match the user's visual characteristics, eliminating the need for repeated manual adjustments.
3Measurement precision
If automatic eyesight measurement is implemented, then precise focal point control is achieved, but the device complexity increases
Solution Approach 1:
Existing components of the HMD are made multi-functional. The cameras and sensors originally intended for display rendering or basic tracking are also utilized for eyesight measurement and lens position control. This approach enables precise measurement capabilities without adding dedicated separate measurement hardware, thereby limiting the increase in device complexity.
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
Enables convenient and precise automatic adjustment of the focal point after the HMD is worn, improving user experience by eliminating the need for manual lever operation and enhancing the device's appearance by hiding the adjustment mechanism.
Implementation Method 1
a lens driving unit that automatically adjusts the focal point using a piezo linear actuator
Implementation Method 2
a light source and camera to measure the user's eyesight and iris recognition
Data Source
AI summary
Disclosed are a head mounted display (HMD), and a method for controlling the same. The HMD includes: a body having a display unit; a lens driving unit provided at the body, and configured to move a lens unit spaced apart from the display unit, wherein the lens driving unit includes: a lens frame having a first tube portion protruded in a first direction, and coupled to the body; a lens housing having a second tube portion protruded in the first direction and having the lens unit, the second tube portion relatively moved on the first tube portion; a link unit coupled to the lens frame and the lens housing, and configured to move the lens housing; and a driving unit provided at one side of the first tube portion, and configured to operate the link unit.