GB1451917A - Electrical encoder - Google Patents

Electrical encoder

Info

Publication number
GB1451917A
GB1451917A GB5640973A GB5640973A GB1451917A GB 1451917 A GB1451917 A GB 1451917A GB 5640973 A GB5640973 A GB 5640973A GB 5640973 A GB5640973 A GB 5640973A GB 1451917 A GB1451917 A GB 1451917A
Authority
GB
United Kingdom
Prior art keywords
levels
threshold
outputs
input
clockpulses
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB5640973A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Business Machines Corp
Original Assignee
International Business Machines Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Publication of GB1451917A publication Critical patent/GB1451917A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/403—Discrimination between the two tones in the picture signal of a two-tone original
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V10/00—Arrangements for image or video recognition or understanding
    • G06V10/20—Image preprocessing
    • G06V10/28—Quantising the image, e.g. histogram thresholding for discrimination between background and foreground patterns
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
    • H03M1/12—Analogue/digital converters
    • H03M1/34—Analogue value compared with reference values
    • H03M1/36—Analogue value compared with reference values simultaneously only, i.e. parallel type
    • H03M1/361—Analogue value compared with reference values simultaneously only, i.e. parallel type having a separate comparator and reference value for each quantisation level, i.e. full flash converter type

Abstract

1451917 Electrical encoder INTERNATIONAL BUSINESS MACHINES CORP 5 Dec 1973 [26 Dec 1972] 56409/73 Heading G4R A circuit for providing a digital signal 18 when an analog input 14 exceeds a threshold comprises means 21-28 for comparing the input with fixed threshold levels and means 40, 50, 60, 70, 80 for selecting one of these levels to be the threshold in dependence on the results of previous comparisons. Input 14 is derived from the scanning 11, 13 of a document 12, and the output 18 indicates the presence of a "black" or a "white" bit on the scanned document. Signal 14 is compared at 21- 27 with (increasing) voltages V1-V7 from a resistor chain 28 which provide levels 1-7 expressed as percentages of absolute black, levels 1 and 4 (10%, 24.3%) corresponding to light and dark (highcontrast) printing. The outputs from 21-27 are stored (under the control of clockpulses 17') in latches 30 from which the signals corresponding to levels 1-4 are fed to gates 41-44). The outputs from 30 also pass to circuits 70, 80 which cause counters 52, 62 to be in- or decremented by clockpulses 17". The outputs from 52, 62 are decoded and fed back to 70, 80. The most significant output bits 51, 61 of each counter are fed back to control gates 41-44: they form a Gray code sequence 00-10-11-01 which effectively identifies the output threshold with levels 1 to 4 in turn. In effect, counters 52, 62 record the numbers of certain sets of the levels which have already occurred and adjust the threshold accordingly. The decoder outputs co-operate with 70 and 80 to ensure that 52, 62 do not exceed their pre-set minimum and maximum counts, and that the level transitions occur only in the order 1-2-3-4-3-2-1.
GB5640973A 1972-12-26 1973-12-05 Electrical encoder Expired GB1451917A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US31796472A 1972-12-26 1972-12-26

Publications (1)

Publication Number Publication Date
GB1451917A true GB1451917A (en) 1976-10-06

Family

ID=23236028

Family Applications (1)

Application Number Title Priority Date Filing Date
GB5640973A Expired GB1451917A (en) 1972-12-26 1973-12-05 Electrical encoder

Country Status (4)

Country Link
JP (1) JPS4991756A (en)
DE (1) DE2363124A1 (en)
FR (1) FR2211814B1 (en)
GB (1) GB1451917A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2505479A1 (en) * 1975-02-10 1976-08-19 Siemens Ag PHASE COMPARATOR AND PROCEDURE FOR ITS OPERATION

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL203213A (en) * 1954-12-29 1900-01-01
US3662341A (en) * 1970-09-25 1972-05-09 Ibm Video-derived segmentation-gating apparatus for optical character recognition

Also Published As

Publication number Publication date
FR2211814B1 (en) 1976-06-25
JPS4991756A (en) 1974-09-02
DE2363124A1 (en) 1974-06-27
FR2211814A1 (en) 1974-07-19

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
PCNP Patent ceased through non-payment of renewal fee