Evaluation of eye response using a wearable display with automatic interpupillary distance adjustment

In this study, we introduce a design for a near-eye, wearable display (HMD: head mounted display) that can automatically control the user's interpupillary distance (IPD). In addition, we demonstrate a test-bed module for the wearable AR display based on proposed design. Both the adjustment accuracy and the viewing effect through distance matching between the user's eyes are evaluated by the user's experience in actual wearing of the module. We demonstrate that the distance between the left and right eye pupils can be measured and adjusted using a set of IR camera sensors and a micro-actuator module that we proposed. A half-mirror unit to be mechanically controlled for each eye is designed to combine the image displayed from the projector and an image taken by the IR camera, leading to fine adjustment of the user's IPD. A set of images taken by the IR camera sensors is image-processed in real time to determine each pupil's position with high accuracy under infrared light illumination. Based on the measured information, a micro-actuator module we fabricated for the test bed can automatically adjust the binocular distance to fit each viewer's IPD. The maximum movement distance of each micro-actuator motor is ±10 mm with precision control of at least 0.5 mm. It takes about 18 seconds to calculate the user's IPD from two IR photographs and then to accurately adjust the actual binocular distance of the module that the participant wears. Using the demonstrated test bed, a total of 50 subjects participated to confirm the accuracy in the automatic IPD adjustment with an error of 0.25% as well as the improvement of the displayed image quality and 3D immersive experience.