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 a 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 detecting from a reflective area on a surface separate from or of the object on which area said beam is incident and from which said beam is reflected to present said symbol thereon in intercepting relationship with said beam, means for testing the presence of said reflective area on said surface separate from the object and of the object, said testing means including means for providing said beam in successive means including means for providing said beam in successive pulses of emanating light which are returned by said reflecting areas when reflected thereby, and means responses to the ratio of said pulses of emanating light to said return pulses of light for operating said reading means.
5 Assignments
0 Petitions
Accused Products
Abstract
A bar code label is read by automatically initiated scanning of the bar code symbol by a beam of light, as from a laser in a bar code scanner. Initially, the scanner is operated in a pulsed mode with low duty cycle (5%) pulses. These pulses are reflected from a reflective tape on one side of a detection zone or from an object carrying the label in 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 (ten pulses for example). 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 and 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 object 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 a object carrying a bar code label, when not scanning. The pulsing mode is used to detect the presence of a reflective tape or an object.
82 Citations
16 Claims
- 1. Apparatus for reading a 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 detecting from a reflective area on a surface separate from or of the object on which area said beam is incident and from which said beam is reflected to present said symbol thereon in intercepting relationship with said beam, means for testing the presence of said reflective area on said surface separate from the object and of the object, said testing means including means for providing said beam in successive means including means for providing said beam in successive pulses of emanating light which are returned by said reflecting areas when reflected thereby, and means responses to the ratio of said pulses of emanating light to said return 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 reflective surface defined by said object or a reflector separate therefrom along the path which is blocked by the object when reading of the symbol thereon is desired, and detecting the presence of said object or said reflector separate therefrom with the reader depending upon whether or not 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