Mark reader with reduced trigger-to-decode response time

Abstract

Systems and methods for use with a handheld mark reader that reduce the time between activation of the reader's trigger and the reader returning a successful decode response. Image processing may be performed prior to the user actuating the trigger and thus obtaining a decodable image with reduced delay. Separate pre-trigger and post-trigger parameters may be used for image decoding. A feedback loop may be incorporated for repeated parameter updates. An adjustable lens may be utilized either with illumination OFF or ON.

What is claimed is: 
     
         1 . A handheld mark reader comprising:
 the reader having a manual trigger;   an image acquisition sensor that acquires at least one pre-trigger image of the mark prior to an actuation of the manual trigger and acquires at least one post-trigger image of the mark after the actuation of the manual trigger;   a pre-trigger calculation process that calculates, for the at least one pre-trigger image, at least one pre-trigger image parameter including at least one of a gain and a focal setting;   a decode process that decodes the at least one post-trigger image; and   a feedback process that uses the at least one pre-trigger image parameter to control at least one of a post-trigger image acquisition process and the decode process.   
     
     
         2 . The handheld mark reader according to  claim 1  wherein the feedback process comprises a pre-trigger feedback loop that determines the at least one pre-trigger image parameter prior to the actuation of the trigger. 
     
     
         3 . The handheld mark reader according to  claim 2  wherein the pre-trigger feedback loop comprises an image acquisition process, an image analysis process, and a configure pre-trigger parameters process. 
     
     
         4 . The handheld mark reader according to  claim 1  further including a post-trigger image acquisition process that uses the at least one pre-trigger image parameter to acquire the at least one post-trigger image. 
     
     
         5 . The handheld mark reader according to  claim 1  wherein the at least one pre-trigger image parameter further includes exposure. 
     
     
         6 . The handheld mark reader according to  claim 1  wherein the focal setting pre-trigger image parameter comprises an auto-focus parameter. 
     
     
         7 . The handheld mark reader according to  claim 1  wherein the focal setting pre-trigger image parameter comprises a focal setting for a liquid lens. 
     
     
         8 . A handheld mark reader for reading a mark comprising:
 a reader body supporting a manual trigger and an image acquisition sensor, the sensor configured to acquire a pre-trigger image of the mark and a post-trigger image of the mark;   a pre-trigger image acquisition process;   a first pre-trigger calculation process that calculates, for the pre-trigger image, at least one parameter of exposure and gain;   a first decode process that attempts to decode the pre-trigger image prior to operation of the manual trigger;   a post-trigger image acquisition process;   a second decode process that attempts to decode the post-trigger image; and   a feedback process that uses the first calculated at least one parameter to control at least one of the post-trigger image acquisition process and the second decode process.   
     
     
         9 . The handheld mark reader according to  claim 8  wherein an illumination source is OFF during the pre-trigger image acquisition process. 
     
     
         10 . The handheld mark reader according to  claim 8  wherein an illumination source is OFF during the pre-trigger image acquisition process and ON during the post-trigger image acquisition process. 
     
     
         11 . The handheld mark reader according to  claim 8  wherein an illumination source is turned ON prior to the pre-trigger image acquisition process. 
     
     
         12 . The handheld mark reader according to  claim 8  further including a second pre-trigger calculation process that calculates, for the pre-trigger image, at least one of contrast and sharpness. 
     
     
         13 . The handheld mark reader according to  claim 8  wherein the first pre-trigger calculation process comprises a feedback loop including an image acquisition process, an image analysis process, and a configure pre-trigger parameters process. 
     
     
         14 . The handheld mark reader according to  claim 13  wherein information from at least one of the image analysis process and the first decode process is used to optimize the post-trigger image acquisition process. 
     
     
         15 . The handheld mark reader according to  claim 13  wherein information from the first image decode process is used in a determination of a confidence level of the second decode process. 
     
     
         16 . A mark reader for decoding an image, the reader comprising:
 a body;   an imager sensor within the body, the image sensor configured to acquire a pre-trigger image of at least a portion of a mark;   the body having a manually operable trigger, the trigger configured to activate the image sensor to acquire a post-trigger image of the at least a portion of the mark;   a processor operatively coupled to the trigger and the image sensor, the processor configured to activate the image sensor prior to operation of the trigger to acquire the pre-trigger image of the at least a portion of the mark and to calculate, for the pre-trigger image acquired prior to operation of the trigger, at least one of auto-exposure, auto-gain, auto-focus, and image decode; and   the processor further configured to decode the post-trigger image acquired after activation of the trigger using at least one of the calculated auto-exposure, auto-gain, auto-focus, and image decode.   
     
     
         17 . The mark reader according to  claim 16  further including a pre-trigger feedback loop for determining pre-trigger image parameters based on a non-illuminated pre-trigger image, and a post-trigger feedback loop for calculating post-trigger image parameters based on an illuminated post-trigger image. 
     
     
         18 . The mark reader according to  claim 16  wherein the pre-trigger image parameters are used for a first post-trigger image acquisition, and the post-trigger image parameters are used for subsequent post-trigger image acquisitions. 
     
     
         19 . A method for decoding an image of a mark using a handheld mark reader, the reader including a trigger configured to initiate an acquisition of the image of the mark, the method comprising:
 a) providing a processor, the processor operatively coupled to the trigger and to an image acquisition sensor;   b) activating the processor to acquire a pre-trigger image of the mark prior to actuation of the trigger;   c) analyzing the pre-trigger image, and based on the analyzing;   d) calculating a pre-trigger acquisition parameter including one or more of a gain and a focal setting;   e) adjusting the image acquisition sensor using the calculated pre-trigger acquisition parameter;   f) repeating steps b) through e) until the trigger is actuated;   g) after the trigger is actuated, acquiring a post-trigger image of the mark using the calculated pre-trigger acquisition parameter; and   h) decoding the post-trigger image.   
     
     
         20 . The method according to  claim 19  further including turning an illumination source ON after the trigger is actuated. 
     
     
         21 . The method according to  claim 19  further including, before the trigger is actuated, determining if the pre-trigger image meets predetermined image threshold values. 
     
     
         22 . The method according to  claim 19  further including, before the trigger is actuated, attempting to decode the pre-trigger image. 
     
     
         23 . The method according to  claim 19  wherein the pre-trigger acquisition parameter includes a focal setting for an adjustable lens. 
     
     
         24 . The method according to  claim 19  wherein the pre-trigger acquisition parameter includes a focal setting for a liquid lens. 
     
     
         25 . The method according to  claim 19  wherein the pre-trigger parameter comprises an auto-focus parameter.