WO2007146725A2 - Digitizing circuit for anti-ambient light noise - Google Patents
Digitizing circuit for anti-ambient light noise Download PDFInfo
- Publication number
- WO2007146725A2 WO2007146725A2 PCT/US2007/070576 US2007070576W WO2007146725A2 WO 2007146725 A2 WO2007146725 A2 WO 2007146725A2 US 2007070576 W US2007070576 W US 2007070576W WO 2007146725 A2 WO2007146725 A2 WO 2007146725A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- signal
- slice
- offset
- positive
- circuit
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
- G06K7/10544—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation by scanning of the records by radiation in the optical part of the electromagnetic spectrum
- G06K7/10821—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation by scanning of the records by radiation in the optical part of the electromagnetic spectrum further details of bar or optical code scanning devices
- G06K7/10851—Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/261—Amplifier which being suitable for instrumentation applications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/78—A comparator being used in a controlling circuit of an amplifier
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45138—Two or more differential amplifiers in IC-block form are combined, e.g. measuring amplifiers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45586—Indexing scheme relating to differential amplifiers the IC comprising offset generating means
Definitions
- This invention relates to optical scanning and detection systems, and has particular application in barcode scanning.
- the frequency at which the reflected light from the barcode changes is significantly greater than the frequency at which the ambient light increases and decreases, differentiation can reduce the effect of the ambient light. Or, put in another way, the ambient light will have a much lower value of derivative, than the reflected light from the barcode signal.
- FIGs. 1 and 2 show a block diagram of an existing digitizer circuit, with FIG. 2 representing the internal components of digitizer 101 of FIG. 1.
- the signal is initially compared with noise elimination levels that are larger than the noise and lower than the barcode signal.
- These outputs 201 and 202 are then fed to logic gates 203 and 204 while the first differentiated signal received is differentiated again by differentiator 205.
- the process of the existing digitizer shown in FIG. 2 is demonstrated in FIGS. 3-9, where the wave forms at the output of the various analog and digital components of FIG. 2 are indicated.
- FIG. 9 shows that the digitized signal is emitted from a flip flop 210.
- FIG. 1 is a diagram depicting a prior art signal decoding system
- FIG. 2 is a logic diagram showing the internal functions of the digitizer of FIG. 1;
- FIG. 3 depicts an exemplary signal at point a of FIG. 1;
- FIG. 4 depicts an exemplary signal at point b of FIG. 1;
- FIG. 5 depicts an exemplary signal at point c of FIG. 2;
- FIG. 6 depicts an exemplary signal at point d of FIG. 2;
- FIG. 7 depicts an exemplary signal at point e of FIG. 2;
- FIG. 8 depicts an exemplary signal at point f of FIG. 2;
- FIG. 9 depicts and exemplary signal at point g of FIG. 2;
- FIG. 10 shows an exemplary embodiment of an analog implementation of the present invention
- FIG. 11 depicts an exemplary signal at point h of FIG. 1 ;
- FIG. 12 depicts and exemplary signal at point i of FIG. 10;
- FIG. 13 depicts exemplary signals at point j of FIG. 10;
- FIG. 14 depicts an exemplary signal at point k of FIG. 10;
- FIG. 15 depicts an exemplary signal at point 1 of FIG. 10;
- FIG. 16 depicts an exemplary signal at point m of FIG. 10.
- FIGS. 17A and 17B depict an exemplary digital implementation of the present invention.
- FIG. 10 depicts an exemplary embodiment of the invention which comprises two offset blocks 401 and 402 at the input stage. Offsets 401 and 402 produce the signals 501 and 502 as designated in FIG. 13.
- the arrangement of FIG. 10 is an exemplary analog implementation of the functions discussed herein with respect to the invention, however, the same functionality may be implemented in digital form as shown in FIG. 17.
- switches 420 and 421 serve to charge and discharge capacitor 407 respectively. More specifically, when switch 420 is on and switch 421 is off, the voltage on capacitor 407 begins rising.
- Element 430 is a current regulator that limits the rate of charging or discharging, and may also be implemented as a resistor or similar component. It is noted that while a capacitor 407 is shown, other charge storage devices may be used without departing from the present invention.
- the voltage on capacitor 407 is termed a slice signal, and is depicted as 503 in FIG. 15.
- the operational amplifiers 404 and 403 serve to generate offset signals that follow the input, and thus which when combined as shown, generate the slice signal designated as 503.
- the slice signal 503 follows the positive offset signal 504, but is held just below that signal.
- the slice signal does not follow the relatively high frequencies contained within the positive offset signal as shown pictorially in FIG. 13.
- the slice signal 503 continues to follow the positive offset signal 504 as that positive offset signal rises. If the input signal crosses over the slice signal, this represents an edge in the barcode pattern.
- the output comparator 408 will reconfigure the switches 420 and 421, closing switch 421 and opening switch 420, thereby causing the slice signal to begin decreasing and to tend towards the upper part of the negative offset signal 505 as shown.
- the slice signal is greater than the input signal, then it follows slowly, at a constant rate, at the lowest level of the positive offset signal 504. However, when the input signal goes above the slice signal, the slice signal then tends toward the positive most portion of the negative offset signal, and follows that negative offset signal at a constant rate. In each case, the relatively high frequencies that do not represent the ambient light are not followed by the slice signal. Each time the slice signal crosses the input signal, a barcode edge is detected.
- the slice signal follows the slow changes in the input signal, it is not influenced by large ambient light, and thus, can detect the barcode pattern even in the presence of large ambient light.
- FIG. 17 depicts a digital version of a similar circuit implemented in the analog domain and shown in FIG. 10.
- the operational amplifiers are replaced with logic gates, and latches are utilized to digitally implement the analog functions.
- the arrangement of FIG. 17 operates as best shown in the drawing accompanying said FIG. 17. Specifically, the slice data will essentially follow the lower part of the positive offset signal, or the upper part of the negative offset signal, as before. However, the analog components have been replaced with digital domain components as shown, such as latches, delays, and OR function gates.
- Din is added to either + offset or -offset, depending upon whether the output 1720 is high or low, respectively. This process creates the digital equivalent of the offset signals shown in FIG. 13. Specifically, the +offset and -offset values are programmable constants, typical values of which are approximately 10-30 percent of the value of the input signal.
- the Din input to delay 1701 is always a fixed amount separated from the Offset data shown.
- the selector 1707 adds or subtracts alpha to the HoldData signal as shown. This creates the slice data. When the output is low, the alpha is subtracted from the slice data. This value will be slightly above the offset data signal, resulting in the latch 1702 being disabled. As a result, the same HoldData will remain in the next clock cycle, with the slice data then decrementing by alpha once again. This state will continue, as shown to the left of point A in graph 1730, with the Slice Data thus decrementing substantially linearly while the -offset data stays just below the Slice Data as shown.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE112007001396T DE112007001396T5 (en) | 2006-06-08 | 2007-06-07 | Digitizing circuit for anti-pollution light |
JP2009514525A JP5084826B2 (en) | 2006-06-08 | 2007-06-07 | Information extraction method and information extraction circuit |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/449,514 US7503497B2 (en) | 2006-06-08 | 2006-06-08 | Digitizing circuit for anti-ambient light noise |
US11/449,514 | 2006-06-08 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2007146725A2 true WO2007146725A2 (en) | 2007-12-21 |
WO2007146725A3 WO2007146725A3 (en) | 2009-01-29 |
Family
ID=38832682
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2007/070576 WO2007146725A2 (en) | 2006-06-08 | 2007-06-07 | Digitizing circuit for anti-ambient light noise |
Country Status (4)
Country | Link |
---|---|
US (1) | US7503497B2 (en) |
JP (1) | JP5084826B2 (en) |
DE (1) | DE112007001396T5 (en) |
WO (1) | WO2007146725A2 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7633320B2 (en) * | 2007-06-29 | 2009-12-15 | Kabushiki Kaisha Toshiba | Comparator circuit |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4517455A (en) * | 1982-10-04 | 1985-05-14 | Texas Instruments Incorporated | Dual peak detector |
US20060083037A1 (en) * | 2004-07-27 | 2006-04-20 | Silicon Laboratories Inc. | Digital PWM controller with efficiency optimization as a function of PWM duty cycle |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6031678A (en) * | 1983-07-30 | 1985-02-18 | Tohoku Richo Kk | Binarization circuit |
JPS63311489A (en) * | 1987-06-13 | 1988-12-20 | Tohoku Ricoh Co Ltd | Bar-code reader |
JPH04277931A (en) * | 1991-03-05 | 1992-10-02 | Japan Radio Co Ltd | Adaptive identification level discriminating circuit |
DE69941090D1 (en) * | 1998-09-14 | 2009-08-20 | Datalogic Scanning Inc | PROCESS FOR FAST EDGE DETECTION, RESISTANT TO HIGH INTERSYMBOL FAULT |
-
2006
- 2006-06-08 US US11/449,514 patent/US7503497B2/en not_active Expired - Fee Related
-
2007
- 2007-06-07 WO PCT/US2007/070576 patent/WO2007146725A2/en active Application Filing
- 2007-06-07 JP JP2009514525A patent/JP5084826B2/en not_active Expired - Fee Related
- 2007-06-07 DE DE112007001396T patent/DE112007001396T5/en not_active Withdrawn
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4517455A (en) * | 1982-10-04 | 1985-05-14 | Texas Instruments Incorporated | Dual peak detector |
US20060083037A1 (en) * | 2004-07-27 | 2006-04-20 | Silicon Laboratories Inc. | Digital PWM controller with efficiency optimization as a function of PWM duty cycle |
Also Published As
Publication number | Publication date |
---|---|
DE112007001396T5 (en) | 2009-04-23 |
WO2007146725A3 (en) | 2009-01-29 |
JP5084826B2 (en) | 2012-11-28 |
US20080121712A1 (en) | 2008-05-29 |
JP2009540442A (en) | 2009-11-19 |
US7503497B2 (en) | 2009-03-17 |
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