Optical scanner for reading and decoding one- and two-dimensional symbologies at variable depths of field

• US 5,786,582 A
• Filed: 12/08/1995
• Issued: 07/28/1998
• Est. Priority Date: 02/27/1992
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Fisher, Donald, Roustaei, Alexander R.
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): Rodriguez, Douglas X.
• Application Number:
  US08/569,728
• Time in Patent Office: 963 Days
• Field of Search: 235/462, 235/472, 396/98, 396/103, 396/108, 359/196
• US Class Current: 235/462.07
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10742 including a diffuser for diffusing the light from the light source to create substantially uniform illumination of the target record carrier
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/10841 Particularities of the light-sensitive elements semiconductor devices H01L
• CPC Class Codes: G06K 7/1092 sensing by means of TV-scanning

Abstract

An optical device for reading one- and two-dimensional symbologies at variable depths of field, the device including a light source for projecting an emitted light towards the two-dimensional image and an optical assembly, or zoom lens, with dual field of view capability for focusing light reflected from the framed symbology onto a CCD detector for detecting the focussed light and generating a signal therefrom. The dual field of view capability enables scanning of both wide and narrow fields of view. An apodizing filter is provided within the optical assembly to increase depth of field. Aiming of the sensor to read the symbology is facilitated by a frame locator including a laser diode which emits a beam that is modified by optics, including diffractive optics, to divide the beam into beamlets having a spacing therebetween that expands to match the dimensions of the field of view of the sensor, forming points of light at the target to define the edges of the field of view. One or two sets of diffractive optics may be provided, with one set corresponding to each position, for each of the dual field of view positions of the zoom lens.

Claims

1. An optical scanning device for reading a one- or two-dimensional symbology having a first width, said optical scanning device comprising:

at least one printed circuit board having a front edge with a second width;

a light source mounted on said at least one printed circuit board, said light source for projecting an incident beam of light onto said symbology, said incident beam of light having substantially said second width at said front edge of said at least one printed circuit board and a first height and a third width at said symbology, said third width being greater than said second width and at least as large as said first width;

an optical assembly comprising a plurality of lenses disposed on said at least one printed circuit board along an optical path for receiving and focusing light reflected from said framed symbology to obtain a focused light at a focal plane, said optical assembly having moving means for moving at least one of said plurality of lenses with respect to other lenses of said plurality to provide a variable field of view;

at least one framing means disposed on said at least one printed circuit board for framing said symbology to identify an area to be scanned by said scanner, wherein said at least one framing means comprises at least one laser diode for emitting a laser beam and at least one diffractive optic for transforming said laser beam into a plurality of diverging beamlets, said diverging beamlets having a beamlet spacing at said symbology at least as large as said first width, wherein said at least one framing means comprises a first framing means and a second framing means, the first framing means corresponding to a wide field of view and the second framing means corresponding to a narrow field of view;

a detector disposed on said at least one printed circuit board within said optical path substantially at said focal plane of said optical assembly for detecting at least a portion of said focused light within said variable field of view of said detector, said variable field of view having said first height and said third width, said detector for sensing said focused light to obtain a sensed symbology;

a processor for processing said sensed symbology to obtain an electrical signal; and

an output means for converting said electrical signal into output data.

2. The optical scanning device recited in claim 1 further comprising a blocking means for blocking light from one of the first and second framing means in response to movement of a dual position zoom lens.

3. The optical scanning device recited in claim 2 wherein said blocking means comprises a movable louver having at least two louver positions, each louver position corresponding to one zoom position of said dual position zoom lens.

4. An optical scanning device for reading a one- or two-dimensional symbology having a first width, said optical scanning device comprising:

at least one printed circuit board having a front edge with a second width;

a light source mounted on said at least one printed circuit board, said light source for projecting an incident beam of light having a first wavelength onto said symbology, said incident beam of light having substantially said second width at said front edge of said at least one printed circuit board and a first height and a third width at said symbology, said third width being greater than said second width and at least as large as said first width;

an zoom lens assembly comprising a plurality of lenses disposed on said at least one printed circuit board along an optical path for receiving and focussing light reflected from said framed symbology to obtain a focussed light at a focal plane, said zoom lens assembly having moving means for moving at least one of said plurality of lenses with respect to other lenses of said plurality to provide a variable field of view, wherein said zoom lens assembly has two zoom positions, a first zoom position corresponding to a wide field of view and a second zoom position corresponding to a narrow field of view;

at least one framing means disposed on said at least one printed circuit board for framing said symbology to substantially frame an area to be scanned by said scanner, wherein said at least one framing means comprises at least one high purity light source for emitting a high purity beam having a second wavelength different from said first wavelength and at least one diffractive optic for transforming said high purity beam into a plurality of diverging beamlets, said diverging beamlets having a beamlet spacing at said symbology at least as large as said first width, wherein said at least one framing means comprises two sets of diffractive optical elements, a first set of diffractive optical elements for generating a first set of diverging beamlets for framing said wide field of view when said first zoom position is selected and a second set of diffractive optical elements for generating a second set of diverging beamlets for framing said narrow field of view when said second zoom lens position is selected;

a detector disposed on said at least one printed circuit board within said optical path substantially at said focal plane for detecting at least a portion of said focussed light within said variable field of view of said detector, said variable field of view having said first height and said third width, said detector for sensing said focused light to obtain a sensed symbology;

a processor for processing said sensed symbology to obtain an electrical signal; and

an output means for converting said electrical signal into output data.

5. An optical scanning device as recited in claim 4 wherein said at least one framing means includes a blocking mask for blocking said first set of diverging beamlets when said second zoom lens position is selected and for blocking said second set of diverging beamlets when said first zoom lens position is selected.