Imaging Scanner Focus Plane Determination via Slit-Frame Analysis

The patent applies preliminary action by capturing an aiming pattern image before the actual barcode scanning to determine the optimal focus plane position. This preliminary focus determination allows the system to know the correct focus position in advance, eliminating the need to capture multiple image frames during the actual scanning process, thus reducing the time required for barcode decode while maintaining focus accuracy.

The patent applies self-service by enabling the imaging system to automatically determine its own optimal focus plane position by capturing an aiming pattern image and processing it to identify the focus plane. This self-determination mechanism eliminates the need for external calibration procedures or complex calibration hardware, reducing device complexity while maintaining focus accuracy.

The patent applies the intermediary principle by introducing an aiming pattern as a mediator between the rolling shutter sensor and the focus plane detection process. The aiming pattern serves as a reference object that can be captured at different focus positions, and by analyzing the sharpness of the aiming pattern lines in the captured image, the system can accurately determine the focus plane position despite the sequential row-by-row capture nature of rolling shutter sensors.