Portable laser diode scanning head

• US 5,075,538 A
• Filed: 10/16/1989
• Issued: 12/24/1991
• 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., Adelson, Alexander M., Krichever, Mark J.
• Primary Examiner(s): Trafton, David
• Application Number:
  US07/421,589
• Time in Patent Office: 799 Days
• Field of Search: 235/467, 235/472, 350/6.6
• US Class Current: 235/462.36
• 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. An embodiment that employs a Fresnel optical element and an embodiment that discloses a curved scanning/connecting mirror are also disclosed.

Claims

1. 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, compromising;

(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 Fresnel collecting mirror for collecting a 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 Fresnel collecting mirror.

2. The component as recited in claim 1, wherein the Fresnel collecting mirror has an optical axis, and wherein the scanning mirror is mounted on the Fresnel collecting mirror.

3. The component as recited in claim 1, wherein the scanning mirror is smaller than, and is mounted on, the Fresnel collecting mirror.

4. The component as recited in claim 1, wherein the scanning mirror is one-piece construction with the Fresnel collecting mirror.

5. The component as recited in claim 1, wherein the scanning mirror has a front surface facing the light source and covered with a light-reflecting coating, and wherein the Fresnel collecting mirror has a front surface facing the light sensor and covered with a light-reflecting coating.

6. The component as recited in claim 1, wherein the oscillating means includes a scanner motor having an output shaft on which the scanning and Fresnel 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 oscillations per second.

7. The component as recited in claim 1, wherein the light source is a laser source, and wherein the indicia constitute bar code symbols.

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

9. A lightweight, handheld laser scanner for reading indicia and generating electrical signals indicative thereof, comprising:

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

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 indicia;

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 oscillatable scanning mirror positioned for receiving laser emissions from the light source and sweeping them through said area across said indicia, and (ii) a reciprocally oscillatable Fresnel collecting mirror positioned for receiving said reflected laser light and reflecting it onto said sensor, wherein the scanning mirror and the Fresnel collecting mirror are secured in a fixed physical relationship for joint movement with each other; and

e) drive means for reciprocally oscillating the scanning mirror and the Fresnel collecting mirror jointly.

10. The scanner according to claim 9 wherein the scanning mirror is relatively smaller in size than the Fresnel collecting mirror and is attached to the Fresnel collecting mirror.

11. The scanner according to claim 9 and including signal processing circuitry in said head for processing said first signal into a digital signal.

12. The scanner according to claim 9 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 indicia.

13. The scanner as described in claim 9 wherein the drive means includes an electric motor having an output shaft, and the Fresnel collecting mirror and the scanning mirror are mounted for direct movement with said output shaft.

14. The scanner as described in claim 9 wherein the indicia comprise bar code.

15. The laser scanning head according to claim 9, wherein the incident laser beam is non-readily visible to a user.