System for automatically reading symbols, such as bar codes, on objects which are placed in the detection zone of a symbol reading unit, such as a bar code scanner
First Claim
1. Apparatus for reading symbols on an object for obtaining information with respect thereto which comprises means for reading said symbols in response to the reflection of a beam of light emanating therefrom, means for presenting a reflective area on a surface thereof on which area said beam is incident and rom which said beam is reflected unless intercepted by said object to present said symbol thereon in intercepting relationship with said beam, means for testing for the presence of said object including means for providing said beam in successive pulses of emanating light which are returned by said reflecting area when reflected by said reflective area, and means responsive to the ratio of a plurality of said successive pulses emanating light to a plurality of said successive returned pulses of light for operating said reading means.
5 Assignments
0 Petitions
Accused Products
Abstract
A bar code label is ready by automatically initiated scanning of the bar code symbol by a scanner on a stand. Light is reflected back to the scanner as from the bars of a code being scanned. Initially, the scanner is operated in a pulsed mode with low duty cycle (5%) pulses. These pulses are reflected from a reflective area unless an object is inserted and blocks the beam path. Then (because the beam is not scanning across the code) the reflected pulses (which are detected much like the bars and spaces of the code) are not detected. The ratio of the number of generated pulses to the reflected pulses is computed for a succession of pulses. If this ratio exceeds two (i.e., that the number of effective bars is less than the number of generated pulses during the succession), then the presence of the object is detected. The system, implemented in an application program in the microprocessor controller of the bar code scanner, initiates scanning of the bar code. Upon the detection of the code (a good read) or under conditions where the label is removed before a good read, or is not removed after a good read, the scanning mode is discontinued and the pulsing mode is again initiated. The pulsing mode is initiated continually to test for the presence of an object carrying a bar code label, when not scanning.
133 Citations
16 Claims
- 1. Apparatus for reading symbols on an object for obtaining information with respect thereto which comprises means for reading said symbols in response to the reflection of a beam of light emanating therefrom, means for presenting a reflective area on a surface thereof on which area said beam is incident and rom which said beam is reflected unless intercepted by said object to present said symbol thereon in intercepting relationship with said beam, means for testing for the presence of said object including means for providing said beam in successive pulses of emanating light which are returned by said reflecting area when reflected by said reflective area, and means responsive to the ratio of a plurality of said successive pulses emanating light to a plurality of said successive returned pulses of light for operating said reading means.
- 13. The method for detecting the presence of an object having a symbol representing information concerning the object in the path of light from a beam projected from a symbol reader unit which comprises the steps of pulsing the light beam, directing the pulsing light beam toward a reflector along a path into which is blocked by the object when reading of the symbol thereon is desired, and detecting with the reader when a first number of pulses in said succession directed towards said reflector exceeds a second number of pulses in said succession reflected from said reflector.
Specification