公开(公告)号：US20020179713A1

公开(公告)日：2002-12-05

申请号：US10201224

申请日：2002-07-22

申请人： Welch Allyn Data Collection, Inc.

发明人： John A. Pettinelli ,  Dennis W. McEnery ,  Robert C. Gardiner ,  Thomas W. Karpen

IPC分类号： G06K007/10 ,  G06K007/14

CPC分类号： G06K7/10584 ,  G06K7/10752 ,  G06K7/10851

摘要： An exposure control apparatus for use with optical readers, such as bar code readers, which utilize photosensitive image sensors. An illumination signal generating circuit generates an illumination signal having a magnitude that varies in accordance with the illumination level at the image sensor. A window detecting circuit samples the illumination signal during a predetermined part of each scan to determine whether the illumination signal is within the window, has exited the widow, or has re-entered the window. Exposure control circuitry uses the output of the window detecting circuit to control which of a plurality of the subdivisions of the exposure control range of the image sensor will be used. Changes in exposure time are made only between adjacent subdivisions of the exposure control range. Together with a predetermined hysteresis between the exit and re-entry thresholds of the window, the latter changes stabilize the operation of the reader by reducing exposure control nullhuntingnull.

摘要翻译： 一种用于光学读取器的曝光控制装置，例如利用光敏图像传感器的条形码阅读器。 照明信号发生电路产生具有根据图像传感器的照度的变化的幅度的照明信号。 窗口检测电路在每次扫描的预定部分期间对照明信号进行采样，以确定照明信号是否在窗口内，已经退出遗ow，或者已经重新进入窗口。 曝光控制电路使用窗口检测电路的输出来控制将使用图像传感器的曝光控制范围的多个细分中的哪一个。 曝光时间的变化仅在曝光控制范围的相邻细分之间进行。 与窗口的出口和重入阈值之间的预定滞后一起，后者通过减少曝光控制“搜索”来改变读者的操作。