Patent ID: 8245935
Filing Date: 2012-08-21
Classification: G02B,G06K

Abstract:
1. An electro-optical reader for reading a symbol, comprising: a light source for emitting a light beam along a path; a light separator for separating the light beam from the light source into a major light fraction projected towards the symbol and a minor light fraction reflected away from the light separator; an optical assembly including a variable focusing element for focusing the major light fraction of the light beam between a range of working distances in which the symbol to be read is located along the path; a controller for controlling the variable focusing element to have different focusing states, one of the focusing states being a reference focusing state in which the variable focusing element is operative for focusing the major light fraction at a reference focal plane; and a detector assembly at the reference focal plane for detecting all amount of the minor light fraction of the light beam reflected from the light separator, and for generating a self-calibration signal indicative of the reference focusing state when a predetermined amount of the minor light fraction has been detected, the controller being operative for processing the self-calibration signal to determine the reference focusing state for the variable focusing element during reading.