Portable optical reader with motion sensing system and method

• US 5,736,725 A
• Filed: 07/09/1996
• Issued: 04/07/1998
• Est. Priority Date: 08/30/1994
• Status: Expired due to Term

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Norand Corporation (Baker Hughes Company)
• Inventors: Danielson, Arvin D.
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): Le, Thien Minh
• Application Number:
  US08/677,155
• Time in Patent Office: 637 Days
• Field of Search: 235/462, 235/472, 235/463, 235/454, 235/470, 235/469
• US Class Current: 235/462.11
• CPC Class Codes: G06K 2207/1011 Aiming
• CPC Class Codes: G06K 7/10693 for omnidirectional scanning
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners

Abstract

A portable terminal unit of tablet configuration contains an optical reader for scanning two-dimensional information on a target area. The terminal unit has an optical window near an underside thereof and contains an optical reader having a given depth of field and field of view at a given range from the window. The apparatus includes a ranger for operably determining the range of the target area from the terminal unit and a controller for operably controling activation of the reader. The controller may be configured to permit activation of the reader as: the target area is spaced within a certain tolerance range about an optimal focal length from the reader; the target area is spaced within the depth of field of the reader and motion of the terminal unit relative to the target area is halted; or the target area is spaced within the depth of field of the reader and motion of the terminal unit relative to the target area is reversed.

Claims

1. A terminal unit capable of imaging optical indicia located on a target surface, comprising:

a) an optical reader having a known depth of field;

b) a housing with an optical window for permitting light to enter said housing and be received by said optical reader;

c) a range finder for determining distance to the target surface; and

d) a motion detection system for determining whether the distance to the target surface is changing;

activation of said optical reader being permitted if said motion detection system determines that the distance to the target surface is not changing and said range finder determines that the target surface is within said optical reader'"'"'s depth of field.

2. A terminal unit capable of imaging optical indicia located on a target surface, comprising:

a) an optical reader having a known depth of field and an optimal focus length defining an optimal focus location;

b) a housing with an optical window for permitting light to enter said housing and be received by said optical reader;

c) a range finder for determining distance to the target surface; and

d) a motion detection system for registering a change in the distance to the target surface;

activation of said optical reader being permitted if said motion detection system determines that the target surface is moving away from the optimal focus location and said range finder determines that the target surface is within said optical reader'"'"'s depth of field.

3. A terminal unit capable of imaging optical indicia located on a target surface, comprising:

a) an optical reader having a known depth of field and an optimal focus length defining an optimal focus location;

b) a housing with an optical window for permitting light to enter said housing and be received by said optical reader;

c) a range finder for determining distance to the target surface; and

d) a motion detection system for determining whether the distance to the target surface is changing;

activation of said optical reader being permitted if said range finder determines that the target surface has moved within a given tolerance range about the optimal focus location, the given tolerance range having been selected to fall within said optical reader'"'"'s depth of field.

4. A method for imaging optical indicia contained on a target surface, comprising the steps of:

a) determining the distance to the target surface;

b) determining whether the distance to the target surface is changing; and

c) permitting activation of an optical reader, to capture an image of the target surface, if it is determined that the distance to the target surface is not changing and that the target surface is within the optical reader'"'"'s depth of field.

5. A method for imaging optical indicia contained on a target surface, comprising the steps of:

a) determining an optimal focus location for an optical reader having a known depth of field and an optimal focus length;

b) determining the distance to the target surface;

c) determining whether the distance to the target surface is changing; and

d) permitting activation of the optical reader, to capture an image of the target surface, if it is determined that a target surface is moving away from the optimal focus location and that the target surface is within the optical reader'"'"'s depth of field.