Portable laser diode scanning head

• US 4,816,660 A
• Filed: 05/19/1988
• Issued: 03/28/1989
• Est. Priority Date: 02/28/1985
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Barkan, Edward, Swartz, Jerome, Metlitsky, Boris, Barkan, Eric F., Shepard, Howard M., Krichever, Mark J.
• Primary Examiner(s): Pitts, Harold I.
• Application Number:
  US07/196,021
• Time in Patent Office: 313 Days
• Field of Search: 235/467, 235/472
• US Class Current: 235/462.21
• CPC Class Codes: G06K 2207/1011 Aiming
• CPC Class Codes: G06K 7/10633 by oscillation
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners

Abstract

A portable laser diode scanning head, aimable at each symbol to be read, emits and receives non-readily-visible laser light, and is equipped with a trigger-actuated aiming light arrangement for visually locating and tracking each symbol. A compact laser diode optical train and an optical folded path assembly, as well as an interchangeable component design and an integral window construction for the head also are disclosed.

Claims

1. In a laser scanning system for reading symbols, a laser scanning head comprising:

(a) means including an actuatable laser light source mounted in the head and operative, when actuated, for generating an incident laser beam;

(b) optic means mounted in the head for optically forming and directing said incident laser beam along a first optical path toward a reference plane located exteriorly of the head, and to a symbol located in a working distance range in the vicinity of the reference plane, thereby reflecting off the symbol reflected laser light, at least a returning portion of which travels along a second optical path away from the symbol back toward the head,

said optic means including a focusing lens and an aperture stop located in the first optical path in the immediate vicinity of the focusing means between the laser light source and the symbol and operative for focusing the incident laser beam to have a beam cross-section of a predetermined size within the working distance range, said aperture stop having a cross-section which is smaller than the beam cross-section at the aperture stop to permit a portion of the incident light beam to pass through the aperture stop en route to the symbol, said cross-section of the aperture stop directly determining said predetermined size of the beam cross-section, said aperture stop being bounded by a blocking wall for obstructing the remaining portion of the incident light beam from passing through the aperture stop en route to the symbol;

(c) scanning means mounted in the head for scanning the symbol in a scan across the symbol, said returning portion of said reflected laser light having a variable intensity over the scan;

(d) sensor means mounted in the head for detecting the variable intensity of said returning portion of said reflected laser light over a field of view, and for generating an electrical analog signal indicative of the detected variable light intensity;

(e) said scanning means being operative for scanning at least one of said incident laser beam and the field of view;

(f) signal processing means mounted in the head for processing the analog electrical signal, and for generating a processed signal indicative of the symbol; and

(g) manually-actuatable trigger means on the head and operatively connected to, and operative for actuating, the laser beam generating means, scanning means, sensor means and signal processing means to initiate a reading of the symbol upon manual actuation of the trigger means by the user, said trigger means being actuatable for each symbol to be read, each symbol in its respective turn.

2. The head as recited in claim 1, wherein the incident laser beam has a non-radially symmetrical cross-section, and wherein the aperture stop has a radially symmetrical cross-section and modifies the non-radially symmetrical beam cross-section to one which is radially symmetrical at the reference plane.

3. The head as recited in claim 1, wherein the incident laser beam has a non-radially symmetrical cross-section, and wherein the aperture stop has a non-radially symmetrical beam cross-section to one which is of a predetermined non-symmetricity at the reference plane.

4. An optical system for distinguishing different light-reflective indicia portions from each other, comprising:

(a) means including a laser light source for generating a wide-angle laser beam; and

(b) optic means for optically forming and directing the laser beam along an optical path to different light-reflective indicia portions for reflection therefrom, said optic means including focusing means and an aperture stop located in the optical path in the immediate vicinity of the focusing means between the laser light source and the light-reflective indicia portions for focusing the laser beam to have a beam cross-section of a predetermined size within a working distance range, said aperture stop having a cross-section which is smaller than the beam cross-section at the aperture stop to permit a part of the beam to pass through the aperture stop en route to the indicia portions, said cross section of the aperture stop directly determining said pre-determined size of the beam cross-section, said aperture stop being bounded by a blocking wall for obstructing the remaining part of the beam from passing through the aperture stop en route to the indicia portions.

5. The optical system as recited in claim 4, wherein the laser beam has anon-radially symmetrical cross-section, and wherein the aperture stop has a radially symmetrical cross-section and modifies the non-radially symmetrical beam cross-section to one which is radially symmetrical at the reference plane.

6. The optical system as recited in claim 4, wherein the laser beam has a non-radially symmetrical cross-section, and wherein the aperture stop has a non-radially symmetrical cross-section and modifies the non-radially symmetrical beam cross-section to one which is of a predetermined non-symmetricity at the reference plane.

7. The optical system as recited in claim 4, wherein the focusing means includes a single focusing lens, said aperture stop being located downstream of the lens.

8. The optical system as recited in claim 7, wherein the laser light source is a solid-state diode, and the optical means further includes means for adjustably and jointly positioning the lens and the aperture stop at a predetermined spacing from the diode, and locating the lens at the aperture stop at said spacing.

9. The optical system as recited in claim 4, wherein the focusing means includes a single focusing lens having a spherical surface.

10. The optical system as recited in claim 4, wherein the focusing means includes a single focusing lens of plano-convex configuration.

11. The optical system as recited in claim 4, wherein the focusing means includes a single focusing lens having a flat surface.

12. The optical system as recited in claim 4, wherein the focusing means includes a single spherical focusing lens of plano-convex configuration.

13. The optical system as recited in claim 4, wherein said cross-section of said aperture stop is circular.

14. The optical system as recited in claim 4, wherein said cross-section of said aperture stop is rectangular.

15. The optical system as recited in claim 4, wherein said cross-section of said aperture stop is oval.

16. An optical system for distinguishing different light-reflective indicia portions from each other, comprising:

(a) means including a laser light source for generating a laser beam; and

(b) optical means for directing the laser beam along an optical path to light-reflective indicia portions for reflection therefrom, said optical means including an aperture stop located in the optical path between the laser light source and the light-reflective indicia portions for modifying the laser beam to have a beam cross-section of a predetermined size within a working distance range, said aperture stop having a substantially rectangular cross-section which is smaller than the beam cross-section at the aperture stop and a numerical aperture value below 0.05 to permit a part of the beam to pass through the aperture stop and to directly determine said predetermined size of the beam cross-section, said aperture stop being bounded by a blocking wall for obstructing the remaining part of the beam from passing through the aperture stop en route to the indicia portions.

17. The optical system as recited in claim 16, wherein the laser beam has a non-radially symmetrical cross-section, and wherein the aperture stop has non-radially symmetrical cross-section and modifies the non-radially symmetrical beam cross-section to one which is of a pre-determined non-symmetricity at the reference plane.

18. The optical system as recited in claim 16, wherein the laser light source generates a wide-angle laser beam, and wherein the optical means includes focusing means in the immediate vicinity of the aperture stop.

19. The optical system as recited in claim 18, wherein the focusing means includes a single focusing lens, said aperture stop being located downstream of the lens.

20. The optical system as recited in claim 19, wherein the laser light source is a solid-state diode, and the optical means further includes means for adjustably and jointly positioning the lens and the aperture stop at a predetermined spacing from the diode, and locating the lens at the aperture stop at said spacing.