Image analysis – Image sensing
Reexamination Certificate
1997-10-17
2001-10-02
Couso, Jose L. (Department: 2621)
Image analysis
Image sensing
C382S313000
Reexamination Certificate
active
06298175
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to stationary position type optical readers and particularly to an object sensing system for a stationary position type optical reader.
2. Background of the Prior Art
Many available stationary position optical readers, typically termed “presentation scanners” are configured to operate in a continuous scan mode; that is they continuously capture and attempt to decode bar code symbols without regard to whether a symbol-bearing substrate is in the field of view.
A continuous scan operating configuration requires repetitive illumination flashing of an LED array in the case of an image sensor based optical reader and repetitive laser scanning in the case of a laser scan engine based optical reader. Repetitive flashing illumination or laser scanning requires a high level of energy consumption and can result in premature component degradation. Furthermore, the repetitive illumination or laser scanning has been observed to be highly distracting to users of such optical readers configured to continuously scan image data.
U.S. Pat. No. 5,550,366 describes a system for automatically activating image scanning in a portable bar code reader when the presence of a bar code in a target area is detected. However, the detection of a bar code in the target area is carried out on a period basis and requires activation of a high radiance source of illumination. Accordingly, the system is not responsive in real time to an object being moved into the field of view of the reader, and the high radiance illumination required for operation of the system remains a source of distraction.
There is a need for a fixed position optical reader which automatically reads indicia on objects presented to the reader without continuously scanning images when objects are not present in the field of view of the reader's imaging assembly.
SUMMARY OF THE INVENTION
According to its major aspects and broadly stated the present invention is a stationary position optical reader having incorporated therein a sensor system for sensing the presence of an object in the field of view of the optical reader.
Optical readers of the type in which the present invention may be incorporated include an imaging assembly which is directed toward a stationary target location. The imaging assembly may be image sensor based or laser scan engine based and may be adapted to capture images in 1 or 2 dimensions.
The system of the invention includes an optical reader specially configured for use in the system including an imaging assembly, and a light source positioned opposite the imaging assembly so that the light source directs light toward the imaging assembly.
A presentation area is defined between the imaging assembly of the reader and the light source. When an object, such as a symbol-bearing substrate is presented to the presentation area, the imaging assembly's view of the light source is blocked, thereby decreasing the amount of light received by the imaging assembly from the light source.
According to the invention, light generated by the light source is caused to be emitted according to a predetermined pattern or timing sequence. In one embodiment, light is caused to be selectively emitted by the light source during alternating image data frame capture periods of the reader.
The image data that is captured by the reader will reveal the predetermined pattern of light emitted by the light source in the case that there is no object in the presentation area defined by the light source. However, if an object is present in the presentation area then light emitted the light source will be at least partially blocked by the object, and consequently the image data capture will not reveal the pattern of light emitted by the light source to the same extent (if at all) that the image data reveals the pattern when there is no object in the presentation area.
The reader of the invention is configured to sense the presence of an object in the presentation area by detecting for the light pattern emitted by the light source. If the pattern is detected, then the condition is indicated that no object is present in the presentation area. If the pattern is not detected, then the condition is indicated that an object is present in the presentation area.
Operation of the reader is made responsive to the detection of a light pattern. If the reader does not detect the predetermined pattern of light emitted from the light source (indicating the condition that an object is present in the presentation area) then the reader is made to operate in an active operating state wherein the illumination source of the reader illuminates scenes at standard radiance illumination and executes a decoding algorithm wherein the reader attempts to decode for any unknown symbol which may be in the field of view. If the reader does detect the predetermined pattern of light emitted by the light source (indicating the condition that an object is not in the presentation area) the reader is made to operate in an inactive operating state. In an inactive operating state, the reader's illumination source may be deenergized, and the full scale decoding algorithm executed during the active operating state may be deactivated.
The detection light source of the system which emits light according to a predetermined pattern emits light of lower radiance than that emitted by the reader's illumination source during an active operating state. Accordingly, the system does not emit potentially distracting high radiance light when there is no object in the presentation area.
These and other details, advantages and benefits of the present invention will become apparent from the detailed description of the preferred embodiment hereinbelow.
REFERENCES:
patent: 4882629 (1989-11-01), Faulkerson et al.
patent: 5039847 (1991-08-01), Morii et al.
patent: 5268564 (1993-12-01), Metlitsky et al.
patent: 5410141 (1995-04-01), Koenck et al.
patent: 5513017 (1996-04-01), Knodt et al.
patent: 5537003 (1996-07-01), Bechtel et al.
patent: 5550366 (1996-08-01), Roustaei
patent: 5557091 (1996-09-01), Krummel
Husssey Robert M.
Longacre Jr. Andrew
Couso Jose L.
Dang Duy M.
Wall Marjama & Bilinski
Welch Allyn Data Collection Inc.
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