Portable laser diode scanning head

• US 4,897,532 A
• Filed: 01/09/1989
• Issued: 01/30/1990
• 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): Trafton, David L.
• Application Number:
  US07/295,151
• Time in Patent Office: 386 Days
• Field of Search: 250/236, 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) optical means mounted in the head for optically directing said incident laser beam along a first optical path to a scanning mirror for reflection therefrom 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;

(c) scanning means mounted in the head for moving the scanning mirror and for sweeping said incident laser beam 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; and

(e) a reciprocally oscillatable, generally concave mirror mounted with the scanning mirror for joint movement therewith and operative, when moved by the scanning means, for collecting said returning portion of said reflected laser light over the field of view, and for directing said collected returning portion to the sensor means.

2. The head as defined in claim 1, further comprising signal processing means mounted in the head for processing the analog electrical signal, and for generating a processed signal indicative of the symbol.

3. The head as defined in claim 2 further comprising manually-actuatable trigger means on the head and operatively connected to, and operative for actuating, the scanning and concave mirrors, the laser beam generating means, the scanning 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.

4. The head as defined in claim 1, wherein the scanning mirror and the concave mirror are of one-piece construction, and include a plano-convex lens constituted of a light-transmissive material and having a first outer substantially planar surface and a second outer curved surface, a first light-reflecting layer applied over a part of the first surface, and a second light-reflecting layer applied over the second surface.

5. The head as defined in claim 1, wherein the incident laser beam is non-readily visible to a user;

and further comprising means including an actuatable aiming light source mounted in the head and operative, when actuated, for generating an aiming light beam whose light is readily visible to the user; and

aiming means mounted in the head for directing said aiming light beam along an aiming light path from the aiming light source toward the reference plane and to the symbol to visibly illuminate at least a part of the symbol, said aiming light path lying within at least one of said optical paths in the portion of the latter which lies exteriorly of the head; and

wherein the concave mirror is also operative for focusing the aiming light beam and, when moved by the scanning means, for sweeping the aiming light beam over the symbol.

15. The head as described in claim 1 wherein the scanning means includes an electric motor having an output shaft, and said concave mirror and said scanning mirror are mounted for direct movement with said output shaft.

23. The laser scanning head according to claim 1, wherein the incident laser beam is non-readily visible to a user.

6. An optical component for use in optical scanning system of the type having a laser light source and a laser light sensor mounted in a lightweight handheld housing, and operative for reading indicia having parts of different light reflectivity, comprising;

(a) a reciprocally oscillatable scanning mirror for reflecting light from the light source to the indicia parts in a scan across the indicia parts, thereby reflecting light of variable light intensity off the indicia parts;

(b) a reciprocally oscillatable, generally concave collecting mirror for collecting at least a portion of the light reflected off the indicia parts, and for directing the collected portion of light to the light sensor; and

(c) drive means for jointly, reciprocally and simultaneously oscillating the scanning mirror and the collecting mirror.

7. The component as recited in claim 6, wherein the collecting mirror has an optical axis, and wherein the scanning mirror is mounted on the collecting mirror radially offset from the optical axis.

8. The component as recited in claim 6, wherein the scanning mirror is smaller than, and is mounted on, the collecting mirror.

9. The component as recited in claim 6, wherein the scanning mirror is one-piece construction with the collecting mirror.

10. The component as recited in claim 6, wherein the scanning mirror has a front surface facing the light source and covered with a light-reflecting coating, and wherein the collecting mirror has a front surface facing the light sensor and covered with a light-reflecting coating.

11. The component as recited in claim 6, wherein the collecting mirror includes a plano-convex lens constituted of a light-transmissive material, said lens having a first outer substantially planar surface on a portion of which a first light-reflecting layer is coated to constitute the planar scanning mirror, and a second outer generally spherical surface on which a second light-reflecting layer is coated to constitute the concave collecting mirror.

12. The component as recited in claim 6, wherein the collecting mirror is a spherical mirror for focusing the collected portion of light onto the light sensor.

13. The component as recited in claim 6, wherein the oscillating means includes a scanner motor having an output shaft on which the scanning and collecting mirrors are mounted, said motor being operative for reciprocally and repetitively oscillating the shaft in alternate circumferential directions over arc lengths less than 360°

and at a rate of speed on the order of a plurality of oscillating per second.

14. The component as recited in claim 6, wherein the light source is a laser source, and wherein the indicia constitute bar code symbols.

24. The optical component according to claim 6 wherein the laser source generates light that is non-readily visible to a user.

16. A lightweight, handheld laser scanner for reading bar code and generating electrical signals indicative thereof, comprising:

(a) a housing having an area for passing laser light to the bar code and for receiving reflected laser light from the bar code;

(b) a source of laser light in the housing;

(c) a sensor in the housing for receiving said reflected laser light after it has been admitted through said area and for generating a first signal representative of said bar code;

(d) a plurality of optical elements positioned in the housing generally defining an optical path between the source of laser light and said area of the housing and between said area and said sensor, the optical elements including (i) a reciprocally oscillable scanning mirror positioned for receiving laser emissions from the light source and sweeping them through said area across said bar code, and (ii) a reciprocally oscillable collecting mirror positioned for receiving said reflected laser light and reflecting it onto said sensor, said collecting mirror being generally concave, and said scanning mirror and said collecting mirror secured in a fixed physical relationship for joint movement with each other; and

(e) drive means for reciprocally oscillating said scanning mirror and said collecting mirror jointly.

17. The scanner according to claim 16 wherein said scanning mirror is relatively smaller in size than said collecting mirror and is attached to said collecting mirror.

18. The scanner according to claim 16 and including signal processing circuitry in said head for processing said first signal into a digital signal.

19. The scanner according to claim 16 wherein the collecting mirror is spherical.

20. The scanner according to claim 16 and including a trigger supported by the housing and operatively connected to said laser light source and to said drive means for initiating the scanning of said bar code.

21. The scanner as described in claim 16 wherein the drive means includes an electric motor having an output shaft, and said concave mirror and said scanning mirror are mounted for direct movement with said output shaft.

25. The laser scanner according to claim 16 wherein the source of laser light generates light that is non-readily visible to a user.

22. In a lightweight handheld laser bar code scanner for reading bar code and generating electrical signals indicative thereof, wherein the bar code scanner defines a first optical path which includes laser light passing from a laser source to a scanning mirror to the bar code where the light is reflected in a second optical path which includes a generally concave collecting mirror for receiving the reflected light and passing it for impingement on a photosensor, wherein the scanner has drive means for reciprocally oscillating the scanning mirror and for reciprocally oscillating the collecting mirror, the method of directing the laser light in said optical paths, comprising the steps of:

(a) mounting said collecting mirror and said scanning mirror in a fixed relationship with each other so that they move jointly with each other when reciprocally oscillated by said drive means, and

(b) positioning said light source, said mirrors, and said photosensor in said first and second optical paths.

26. The method of claim 22, wherein the laser light passing from a laser source is non-readily visible to a user.