Cancelling noise caused by the flicker of ambient lights
First Claim
1. A barcode scanning device comprising:
- a light source configured to emit a beam of light;
a first sensor configured to detect a first optical signal indicative of light reflecting off of a barcode, the reflected light originating from the light source and from at least one ambient light source in the vicinity of the barcode scanning device;
a second sensor configured to detect a second optical signal indicative of light originating from the at least one ambient light source;
a noise cancelling circuit configured to obtain a noise-cancelled scanning signal from the first and second optical signals; and
a mirror having an aperture in the center of the mirror, wherein the first sensor is configured to sense light illuminating through the aperture and the second sensor is configured to sense light reflected off of the mirror.
1 Assignment
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Accused Products
Abstract
Systems and methods for cancelling noise caused by the flicker of ambient lights are provided. Such noise cancelling systems and methods may be incorporated in a laser-based barcode scanning device. In one example, a barcode scanning device includes a light source, a first sensor, a second sensor, and a noise cancelling circuit. The light source is configured to emit a beam of light. The first sensor is configured to detect a first optical signal indicative of light reflecting off of a barcode. The reflected light may originate from the light source and from at least one ambient light source in the vicinity of the barcode scanning device. The second sensor is configured to detect a second optical signal indicative of light originating from the at least one ambient light source. The noise cancelling circuit is configured to obtain a noise-cancelled scanning signal from the first and second optical signals.
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Citations
20 Claims
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1. A barcode scanning device comprising:
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a light source configured to emit a beam of light; a first sensor configured to detect a first optical signal indicative of light reflecting off of a barcode, the reflected light originating from the light source and from at least one ambient light source in the vicinity of the barcode scanning device; a second sensor configured to detect a second optical signal indicative of light originating from the at least one ambient light source; a noise cancelling circuit configured to obtain a noise-cancelled scanning signal from the first and second optical signals; and a mirror having an aperture in the center of the mirror, wherein the first sensor is configured to sense light illuminating through the aperture and the second sensor is configured to sense light reflected off of the mirror. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A laser scanning apparatus comprising:
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a housing; a laser source configured to emit a beam of laser light to be scanned across a barcode; a first photodiode disposed in the housing, the first photodiode configured to detect a first optical signal indicative of reflected light originating from the beam of laser light and ambient light originating from at least one ambient light source; a noise cancelling circuit configured to provide at an output thereof a noise-cancelled scanning signal derived from the first optical signal and a second optical signal indicative of the ambient light originating from the at least one ambient light source; and a mirror having an aperture in the center of the mirror, wherein the first photodiode is configured to detect light illuminating through the aperture. - View Dependent Claims (12, 13)
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14. A noise cancellation circuit comprising:
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at least one optical sensor configured to detect a first optical signal in a first stage and detect a second optical signal in a second stage; a differential amplifier configured to subtract the second optical signal from the first optical signal to thereby remove a noise component from the first optical signal; a notch filter; and a frequency matching circuit; wherein the first optical signal includes a laser scanning component and the noise component, the noise component corresponding to ambient light from at least one ambient light source; wherein the second optical signal includes the noise component; and wherein the differential amplifier is configured to output a noise-cancelled scanning signal. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification