HAND-SUPPORTABLE PLANAR LASER ILLUMINATION AND IMAGING (PLIIM) BASED CAMERA SYSTEM CAPABLE OF PRODUCING DIGITAL LINEAR IMAGES OF A OBJECT, CONTAINING PIXELS HAVING A SUBSTANTIALLY UNIFORM WHITE LEVEL INDEPENDENT OF THE VELOCITY OF THE OBJECT WHILE MANUALLY MOVING SAID FILM BASED CAMERA SYSTEM PAST SAID OBJECT DURING ILLUMINATION IMAGING OPERATIONS

• US 6,953,152 B2
• Filed: 05/17/2002
• Issued: 10/11/2005
• Est. Priority Date: 06/07/1999
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Zhu, Xiaoxun, Knowles, C. Harry, Au, Ka Man, Ghosh, Sankar, Schnee, Michael D., Tsikos, Constantine J.
• Primary Examiner(s): Le, Thien M.
• Application Number:
  US10/151,743
• Publication Number:
  US 20030042315A1
• Time in Patent Office: 1,243 Days
• Field of Search: 23546201-46248, 235/472.01, 235/472.02, 235/472.03, 235/454, 235/455, 235/470, 235/494
• US Class Current: 235/462.01
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• CPC Class Codes: G02B 19/0052 the light source comprising a laser diode coupling into light guides using intermediate optical elements G02B6/4204; semiconductor lasers having optical devices external to the laser cavity H01S5/005
• CPC Class Codes: G02B 19/0085 for use with both a detector and a source , e.g. in a transceiver, G02B19/009, G02B19/0095 take precedence
• CPC Class Codes: G02B 19/009 for use with infrared radiation
• CPC Class Codes: G02B 19/0095 for use with ultraviolet radiation
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 27/095 Refractive optical elements
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G06K 7/10 by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
• CPC Class Codes: G06K 7/10594 Beam path
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/146 the method including quality enhancement steps
• CPC Class Codes: G06Q 10/00 Administration; Management
• CPC Class Codes: G06Q 30/00 Commerce
• CPC Class Codes: G06V 20/62 Text, e.g. of license plates, overlay texts or captions on TV images
• CPC Class Codes: G06V 30/144 using a slot moved over the image; using discrete sensing elements at predetermined points; using automatic curve following means
• CPC Class Codes: H01S 5/005 Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping H01S5/026, H01S5/18388 take precedence
• CPC Class Codes: H01S 5/02325 Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence

Abstract

A hand-supportable planar laser illumination and imaging (PLIIM) based camera system for producing digital linear images of a object within a working range, having a substantially uniform white level independent of the velocity of the object. The hand-supportable PLIIM based camera system comprises a PLIIM based imaging system having a linear image detection array with a field of view (FOV), a planar laser illumination array (PLIA) with a plurality of laser diodes arranged in a linear array for producing a planar laser illumination beam (PLIB) coplanar with the FOV, and a micro-controller for controlling the operation of the PLIIM based imaging system. An object velocity measurement subsystem is mounted within its hand-supportable housing, for determining the velocity of the object relative to the hand-supportable housing and generating object velocity data indicative of the determined velocity of the object. During object illumination and imaging operations, the micro-controller uses the object velocity data compute the optical power which each laser diode must produce in order that each digital image of the object, formed by illuminating the object with the computed optical power, will have substantially the same white intensity level independent of the velocity of the object relative to the PLIIM-based imaging system. The computed optical power value(s) are transmitted to the micro-controller, and the micro-controller uses the computed optical power value(s) to drive each laser diode so that it produces a planar laser illumination beam having the computed optical power level with the FOV. By virtue of the present invention, the planar laser illumination beam illuminates the object, and the PLIIM-based imaging system automatically produces a digital image of the moving object, with pixels having a substantially uniform white level, independent of the velocity of the object. Such image characteristics enables simpler and more reliable image processing in applications such as, for example, optical character recognition (OCR) processing, where image pixels having a substantially uniform white level, and a uniform aspect-ratio, are often desired or required.

Claims

1. A hand-supportable planar laser illumination and imaging (PLIIM) based camera system having a working range and for producing digital linear images of a object, containing pixels having a substantially uniform white level, said hand-supportable PLIIM based camera system comprising:

a hand-supportable housing having a light transmission aperture;

a PLIIM-based linear imaging subsystem mounted within said hand-supportable housing, and having

planar laser illuminalion array (PLIA) including a plurality of laser diodes for producing and projecting a planar laser illumination beam (PLIB) through said light transmission aperture, so as to illuminate an object as said hand-supportable housing is manually moved past the object during object illumination and imaging operations, and

an image formation and detection (IFD) module having a linear image detection array and imaging forming optics for providing said linear image detection array with a field of view (FOV) which is projected through said light transmission aperture, and along which digital linear images of illuminated portions of said object can be detected,

wherein said PLIB and FOV are arranged in a coplanar relationship along the working range of said PLIIM based camera system so that the PLIB illuminates primarily within said FOV of the IFD module;

an object velocity measurement subsystem disposed within said hand-supportable housing, for determining the velocity of the object relative to said hand-supportable housing and generating control data indicative of the determined velocity of the object;

a micro-controller, mounted within said hand-supportable housing, for controlling the operation of said PLIIM-based linear imaging subsystem, in response to control data generated by said object velocity measurement subsystem,

wherein said micro-controller

(1) uses said object velocity data to compute the optical power which each laser diode in said PLIIM-based linear imaging subsystem must produce in order that each digital linear image capture by said PLIIM-based linear imaging system will have pixels with a substantially uniform white level, independent of object velocity; and

(2) generates and transmits control signals to said laser diodes in order to control the operation thereof so that said PLIIM-based linear imaging subsystem produces digital linear images of said object, wherein the pixels in each said digital image have a substantially uniform white level independent of the measured object velocity.

2. The hand-supportable PLIIM based camera system of claim 1, wherein said object velocity measurement subsystem comprises:

means for projecting and scanning a light beam along the surface of said object;

means for receiving and detecting light reflected from said object;

means for generating an electrical signal representative of characteristics of said detected light;

means for processing said electrical signal to determine velocity of the object relative to said hand-supportable housing; and

means for generating object velocity data indicative of the determined velocity of the object.

3. The hand-supportable PLIIM based camera system of claim 2, wherein said object velocity measurement subsystem comprises:

mean for producing a pair of laser scanning beam which are projected outside of said hand-supportable housing at different angles so as to scan the surface of said object, and produce reflected light signals which are detected and processed so as to determine the velocity of the object being illuminated and imaged; and

mean for generating object velocity data indicative of the determined velocity of the object.

4. The hand-supportable PLIIM based camera system of claim 2, wherein said object velocity measurement subsystem comprises:

means for producing a pair of amplitude modulated (AM) laser scanning beams which are projected at different angles outside of said hand-supportable housing at different angles so as to scan the surface of said object, and produce reflected light signals which are detected and processed so as to determine the velocity of the object being illuminated and imaged; and

means for generating object velocity data indicative of the determined velocity of the object.

5. The hand-supportable PLIIM based camera system of claim 1, wherein said micro-controller comprises a programmed microprocessor.