IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0740155
(2000-12-19)
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우선권정보 |
EP-0830798 (1999-12-24) |
발명자
/ 주소 |
- Piva, Marco
- Bianchi, Maurizio
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출원인 / 주소 |
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대리인 / 주소 |
Lerner, David, Littenberg, Krumholz &
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인용정보 |
피인용 횟수 :
1 인용 특허 :
10 |
초록
▼
The method for compensating undesired variations in an electrical signal generated by a sensor of an optical code reader comprises the steps of generating an envelope signal starting from the electrical signal generated by the sensor and normalizing the electrical signal with respect to the envelope
The method for compensating undesired variations in an electrical signal generated by a sensor of an optical code reader comprises the steps of generating an envelope signal starting from the electrical signal generated by the sensor and normalizing the electrical signal with respect to the envelope signal. Preferably, the envelope signal is filtered with a low-pass filter before being normalized so as to eliminate steps and edges which may cause distortions during normalization, and the normalized signal is amplified in a controlled way so as to supply an output signal ranging between two values having preset amplitudes. Normalization is carried out by dividing, point by point, the electrical signal by the envelope signal, in the case of continuous analog processing; alternatively, in presence of discrete-time signals, normalization is carried out by subtracting the envelope signal from the electrical signal.
대표청구항
▼
1. A method for compensating undesired variations in an electrical signal generated by a sensor of an optical code reader, comprising:generating an envelope signal starting from said electrical signal; normalizing said electrical signal with respect to said envelope signal to obtain a normalized sig
1. A method for compensating undesired variations in an electrical signal generated by a sensor of an optical code reader, comprising:generating an envelope signal starting from said electrical signal; normalizing said electrical signal with respect to said envelope signal to obtain a normalized signal; and amplifying said normalized signal in a controlled way to supply an output signal of preset amplitude. 2. The method according to claim 1, further comprising the step of filtering said envelope signal with a low-pass filter before said step of normalizing.3. The method according to claim 1, wherein said step of normalizing comprises the step of dividing said electrical signal by said envelope signal.4. The method according to claim 1, wherein electrical signal, said envelope signal, and said normalized signal are continuous-time signals.5. The method according to claim 3, wherein said step of normalizing comprises the step of summing a reference value to said envelope value and said electrical signal.6. The method according to claim 1, wherein said step of normalizing comprises the step of subtracting said envelope signal from said electrical signal.7. The method according to claim 1, wherein said electrical signal, said envelope signal, and said normalized signal are discrete-time signals.8. The method according to claim 6, further comprising the step of delaying said electrical signal before subtracting said envelope signal from said electrical signal.9. A method for compensating undesired variations in an electrical signal generated by a sensor of an optical code reader, comprising the steps of generating an envelope signal starting from said electrical signal, normalizing said electrical signal with respect to said envelope signal to obtain a normalized signal, and amplifying said normalized signal in a controlled way to supply an output signal of preset amplitude, wherein said step of amplifying in a controlled way comprises the steps of: detecting a peak value of said normalized signal; selecting a gain-control signal as a function of said peak value; and multiplying said normalized signal by said gain-control signal.10. A device for compensating undesired variations in an electrical signal generated by a sensor of an optical code reader, said device having an input terminal receiving said electrical signal, the device comprising an envelope-generating stage receiving said electrical signal and generating an envelope signal, a normalization stage normalizing said electrical signal according to said envelope signal and outputting a normalized signal, and an amplification stage for amplifying said normalized signal in a controlled way to supply an output signal of preset amplitude.11. The device according to claim 10, further comprising a low-pass filter arranged downstream of said envelope-generating stage.12. The device according to claim 10, further comprising a controlled-gain amplifier means for receiving said normalized signal and generating an output signal ranging between a first preset and a second preset amplitude value.13. The device according to claim 10, wherein said envelope-generating stage and said normalization stage are continuous-time circuits.14. The device according to claim 10, wherein said envelope-generating stage comprises a peak-detecting circuit and said normalization stage comprises an analog divider circuit.15. The device according to claim 13, further comprising a first subtracting node for subtracting a reference value from said electrical signal, and a second subtracting node for subtracting said reference value from said envelope signal.16. The device according to claim 10, wherein said envelope-generating stage and said normalization stages are circuits operating in discrete-time mode.17. The device according to claim 10, wherein said normalization stage comprises a subtracting node for subtracting said envelope signal from said electrical signal.18. The device according to claim 17, further comprising a delay line arranged between said input terminal and said subtracting node.19. A device for compensating undesired variations in an electrical signal generated by a sensor of an optical code reader, said device having an input terminal receiving said electrical signal, the device comprising an envelope-generating stage receiving said electrical signal and generating an envelope signal, a normalization stage normalizing said electrical signal according to said envelope signal and outputting a normalized signal and a programmable-gain amplifier means connected to an output of said normalization stage and having a control input receiving an amplification control signal; peak-detecting means receiving said normalized signal and outputting a peak-amplitude value of said normalized signal; and selecting means generating said amplification control signal as a function of said peak-amplitude value.20. The device according to claim 19, wherein said peak-detecting means comprise a peak detector and a memory element, that are cascade-connected; and said selecting means comprise memory-correlation means storing different values of said amplification-control signal as a function of intervals of said peak-amplitude value of said normalized signal.21. An optical code reader comprising:a sensor having an output supplying an electrical signal representative of the luminosity detected by the sensor; a device for compensating undesired variations of said electrical signal by generating an envelope signal starting from said electrical signal and normalizing said electrical signal with respect to said envelope signal to obtain a normalized signal, said device being connected to said output of said sensor; and an amplifier connected to said device, said amplifier for amplifying said normalized signal in a controlled way to supply an output signal of preset amplitude.
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