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US 8,006,905 B2Granted
Method of reducing noise in an optically read image using an optical collection device
AssigneeIntermec IP Corp.
InventorsDenis Jolivet, Alain Gillet
Life of this patent
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Abstract
A system and method of reading an indicia and rejecting ambient light is disclosed. An imaging signal and an ambient signal are received by the system where the imaging signal corresponds to indicia information and a first portion of the ambient light, and the ambient signal corresponds to a second portion of the ambient light. The imaging signal and the ambient signal are mathematically manipulated to subtract the contribution of the first portion of the ambient light from the imaging signal.
Claims19
A system, comprising:
- a light source configured to illuminate a first area, wherein the first area includes at least an indicia to be read, and ambient light is present on and around the indicia;
- and
- a subsystem, wherein the subsystem comprises:
- a first sensor having a first active area;
- one or more additional sensors each having one or more second active areas, wherein the one or more additional sensors together have a total active area;
- a collection optics configured to focus an image:
- a first light reflected from the first area onto the first active area of the first sensor, wherein the first reflected light includes a first portion of ambient light and light reflected from the indicia, and the first active area converts the first reflected light to a first electric current, and
- a second portion of ambient light from the one or more additional areas near the indicia onto the one or more second active areas of the one or more additional sensors, wherein the one or more second active areas convert the second portion of ambient light to one or more second electric currents;
- and
- a first circuit configured to produce an output current by subtracting a sum of all the second electric currents times a multiplier from the first electric current, wherein the multiplier is based at least upon a ratio of the first active area and the total active area.
7 more elements
A system, comprising:
- a laser source;
- a scanning optics configured to raster scan an output from the laser source over an indicia to be read;
- an imaging optics configured to:
- image the raster-scanned indicia onto a primary sensor having a two-dimensional active area, wherein the image of the raster-scanned indicia includes a first background light from a first area near the indicia, and
- image one or more secondary areas near the indicia onto one or more secondary sensors;
- the primary sensor configured to convert the image of the raster-scanned indicia from the first area to a first electrical signal, wherein the primary sensor is located in an image plane of the imaging optics;
- and
- the one or more secondary sensors having one or more secondary active areas configured to:
- receive a second background light from the one or more secondary areas near the indicia, and
- convert the second background light to one or more second electrical signals, wherein the one or more secondary sensors do not receive light reflected from the indicia;
- and
- a circuit configured to:
- sum the one or more second electrical signals,
- weight the sum based at least upon a ratio of the two-dimensional active area and the one or more secondary active areas, and
- subtract the weighted sum from the first electrical signal.
12 more elements
A system, comprising:
- a light source means configured to illuminate a first area, wherein the first area includes at least a bar code to be read, and ambient light is present on and around the bar code;
- and
- two subsystems, wherein each subsystem comprises:
- a collection optics configured to focus an image:
- a first light reflected from the first area onto a first active area of a first light sensing means, wherein the first reflected light includes a first portion of the ambient light and light reflected from the bar code, and
- a second portion of ambient light reflected from one or more additional areas near the bar code onto two additional light sensing means, wherein the one or more additional areas do not overlap the first area;
- the first light sensing means configured to convert the first reflected light to a first electric signal;
- the two additional light sensing means configured to convert the second reflected light to two second electric signals, wherein the two additional light sensing means each have a second active area that is substantially half of the first active area, a first one of the additional light sensing means is positioned above the first light sensor, and a second one of the additional light sensing means is positioned below the first light sensing means;
- and
- a circuit configured to mathematically manipulate the first and second electric signals to produce an output signal that filters the second electric signals from the first electric signal.
7 more elements
A method of reading an indicia and rejecting ambient light, comprising:
- receiving an imaging signal and an ambient signal, wherein the imaging signal corresponds to indicia information and a first portion of ambient light, and the ambient signal corresponds to a second portion of ambient light;
- mathematically manipulating the imaging signal and the ambient signal to subtract a contribution of the first portion of ambient light from the imaging signal;
- storing the output signal in a memory.
Dependencies are inferred from the claim text.