MULTIPLE-SCANNER CHARACTER READING SYSTEM

• US 3,582,884 A
• Filed: 01/30/1968
• Issued: 06/01/1971
• Est. Priority Date: 01/30/1968
• Status: Expired due to Term

• Current Assignee: David H Shepard
• Original Assignee: David H Shepard
• Inventors: Shepard, David H.
• Application Number:
  US04/701,670
• Time in Patent Office: 1,218 Days
• US Class Current: 382/245
• CPC Class Codes: G06F 18/00 Pattern recognition
• CPC Class Codes: G06V 30/133 Evaluation of quality of the acquired characters

Abstract

A system comprising a central station having data processing apparatus with a common data buss arrangement interconnecting a data processor with its peripheral devices including a number of incoming data buffers. A plurality of remote desk top scanner units are connected to the central station, each being arranged to receive a document bearing graphic characters and to scan the characters on the document with an optical light beam so as to sweep the character area in a series of adjacent paths. Each remote scanner has means to develop scan signals representing the light reflected from the scanned document and to produce binary code groups indicating the scan distances between certain selected events such as white-to-black transitions. The code groups from each remote scanner are transmitted to a respective data buffer at the central station and subsequently are decoded to reconstruct the original video scan data in a form suitable for deciphering by character recognition means so as to identify the individual characters of the document. The central data processing apparatus, including decoding and character recognition means, operates on a time-sharing basis to service all of the remote units.

Claims

1. The method of reading graphic characters on a document bearing characters in line format, comprising the steps of:

scanning the document in a series of consecutive closely adjacent sweeps parallel to and completely traversing the line of characters to be read, the number of such successive sweeps being sufficient to scan in their entirety all of said characters in that line;

developing from said scanning operation binary scan signals indicating the instantaneous amount of light reflected from predetermined positions along the scan path;

transmitting to a receiving station data signals corresponding to said scan signals;

storing said data signals in a buffer at said receiving station until data is accumulated representing all of said characters in said line;

reading out such accumulated data signals to produce a series of sequences of binary data bits representing a series of vertical sweeps through said characters in said line; and

analyzing said series of sequences of data bits to produce output signals identifying each of the characters in the line.

2. The method of reading graphic characters on a document bearing characters in line format, comprising the steps of:

scanning the document in a series of consecutive closely adjacent sweeps parallel to and completely traversing the line of characters to be read, the number of such successive sweeps being sufficient to scan in their entirety all of said characters in that line;

developing from said scanning operation binary scan signals indicating the instantaneous amount of light reflected from predetermined positions along the scan path;

transmitting to a receiving station data signals corresponding to said scan signals;

storing said data signals in a buffer at said receiving station until data is accuMulated representing all of said characters in said line;

reading out such accumulated data signals representing said line to produce a sequence of binary data bits;

analyzing said sequence of data bits to produce output signals identifying each of the characters in the line; and

utilizing said accumulated data to develop a visual image display of said line of characters as represented by the stored data whenever said analysis is unable to recognize any of the characters in the line.

3. The method of reading graphic characters on documents at a plurality of separated locations, each document bearing characters in line format, said method comprising the steps of:

simultaneously scanning documents at said separated locations in a series of consecutive closely adjacent sweeps parallel to and completely traversing each line of characters to be read, the number of such successive sweeps being sufficient to scan in their entirety all of said characters in each such line;

simultaneously developing from said scanning operations binary scan signals indicating the instantaneous amount of light reflected from predetermined positions along the scan paths;

simultaneously transmitting from all of said locations to a central receiving station data signals corresponding to said scan signals;

storing the data signals from each location in a respective buffer at said receiving station;

reading out any buffer in which has been accumulated data signals representing a complete line of characters to be read, thereby to produce a corresponding sequence of binary data bits;

analyzing said sequence of data bits to produce output signals identifying each of the characters in the line;

determining when any of characters cannot be identified from the read out stream of data bits; and

utilizing said accumulated data signals in the buffer to produce a visual image display of all of the characters in said line as represented by the stored data signals.

4. The method of reading graphic characters on a document bearing characters in line format, comprising the steps of:

scanning the document with consecutive, closely adjacent scanning-spot sweeps defining a series of parallel scan paths which are uniformly spaced and which completely cover the area occupied by the line of characters to be read, the center-to-center spacing between consecutive scan paths being uniform and at least approximately equal to the size of the scanning spot, the number of such successive sweeps being sufficient to scan in their entirety all of said characters in that line;

developing from said scanning operation binary scan sample signals indicating the presence or absence of character elements at uniformly-spaced sample points along each scan path, the sample points in the successive scan paths being aligned so that the scan sample signals for the complete series of scanning sweeps reflects the presence or absence of character elements at the intersections of an orthogonal matrix encompassing all of the characters to be read in the line being scanned;

transmitting to a receiving station data signals corresponding to said scan signals;

storing said data signals in a buffer at said receiving station until data is accumulated representing all of said characters in said line;

reading out such accumulated data signals representing said line of characters;

analyzing said accumulated data signals to produce output signals identifying individually each of the characters in the line;

determining when any of said characters cannot be identified by analysis of the information in said data signals; and

utilizing signals derived from said accumulated data signals to develop a visual image display of said entire line of characters as represented by the stored data signals whenever said analysis is unable to recognize any of the characters in the line.

5. A method of reading characters wherein the documents bearing characters are scanned at one location to produce scan signals which are analyzed at another location, comprising the steps of:

scanning the document in a series of closely adjacent paths by a scanning spot substantially smaller than the character height;

developing clock pulses at positions along each scan path;

producing binary video signals under control of said clock pulses to indicate the presence or absence of character elements at said positions;

storing in a buffer output signals corresponding to said video signals;

transmitting the output signals from said buffer to a remote station for analysis to determine the scanned characters; and

temporarily interrupting said scanning function whenever said buffer contains more than a predetermined amount of said output signals awaiting transmission to said remote station.

6. The method of claim 5, wherein the documents bear characters in line format, said scan paths being scanned in sequential succession parallel to and completely traversing the line of characters to be read;

said clock pulses being developed at predetermined fixed uniformly spaced positions which are identical for each scan path; and

the scanning function being interrupted by preventing the scanning spot from advancing from the scan path then being traversed to the next scan path in the sequence.

7. The method of claim 6, wherein the scanning function also is interrupted by preventing the development of any further output signals at the instant in the scan when the buffer storage exceeds the predetermined amount;

retaining in storage data identifying the part of the scan where the development of output signals stopped; and

resuming the development of output signals during a subsequent scan and at the part thereof identified by said stored data.

8. An optical character recognition system comprising:

a central station having high-speed data handling apparatus including character recognition portions organized to effect analysis of scan data to develop output signals identifying individual characters;

a plurality of optical scanning devices remote from said central station to examine documents at separate locations and provide video signals corresponding to the individual characters on the documents for the central station to analyze;

means at each scanning device to encode said video signals to provide coded scan data signals containing the original scan data but capable of transmission through a limited band-width transmission channel in less time than would be required for the transmission through such channel of said video signals;

limited band-width transmission channels operatively connected with said scanning devices to transmit said coded scan data signals to said central station;

signal storage means at said central station having a plurality of separate sections;

means at said central station coupled to said transmission channels and operable to store the coded scan data signals developed at each remote scanning device in a corresponding section of said signal storage means assigned to such remote scanning device; and

means at said central station for retrieving the coded scan data signals from said sections of said temporary storage means and for decoding said scan data signals to reconstruct the original scan data for analysis by said character recognition portions of said data handling apparatus.

9. In a character reading system of the type comprising a first station having a data processing system organized for character signal analysis and coupled to a second station comprising means to receive and support a document to be scanned;

scanning means operable to scan said document, said scanning means including means for irradiating said document and for detecting the amount of radiation reflected therefrom at the scanned regions;

advancing means to effect relative movement between said scanning means and said document in a direction perpendicular to said scan path;

actIvating means normally operative to activate said advancing means to trace successive parallel scan lines across the document;

means for developing binary signal pulses indicating the amount of radiation reflected from said document at corresponding positions along said scan lines;

means for producing data signals corresponding to said binary signals;

buffer means for storing said data signals;

transmission circuit means coupled to the output of said buffer means to direct said data signals to said first station so that the data signals may be analyzed to determine the characters on the document; and

control means operable, upon the accumulation of a predetermined amount of untransmitted data signals at said buffer means, to interrupt said activating means so as to prevent operation of said advancing means.

10. Apparatus as claimed in claim 9, wherein said control means also is operable to stop the development of further coded data during the remainder of a particular scanning sweep after said predetermined amount of coded data is accumulated;

said scanning means being operable to retrace said particular scanning sweep to generate coded signals corresponding to said remainder of said scanning sweep.

11. Apparatus as claimed in claim 10, including pulse-generating means for producing clock pulses at preselected uniformly spaced positions along the scanning path so as to permit developing sample pulses indicating the reflected radiation at such positions;

said positions being the same for every scan so as to assure that the retracing of any scan line will develop substantially the same sample pulses as an original scan.

12. Apparatus as claimed in claim 9, wherein the system comprises a plurality of said second stations connected to said first station by respective transmission circuit means;

each second station further including converter means responsive to the binary scan signals and operable to produce coded data signals capable of transmission with reduced band-width requirements.

13. In a character reading system of the type comprising a central station, a plurality of remote units each having means to receive a document bearing characters to be read;

scan means forming part of each remote unit and arranged to trace scan paths on the document and to produce sequential sample signals indicating the presence or absence of character elements at points along each path; and

circuit means at each of said remote units responsive to said sample signals and operable to produce corresponding output signals suitable for transmission to said central station;

that improvement wherein said system comprises;

a plurality of simultaneously operable signal channels for said remote units respectively for directing the output signals of all of said remote units concurrently to said central station;

said central station including a plurality of functionally independent and simultaneously operable temporary storage means each assigned to one of said remote units respectively;

control means at said central station for said temporary storage means, said control means including means coupled to said signal channels for directing the signals received from said channels to the respective temporary storage means assigned thereto, whereby the remote scanner units can be operated concurrently to develop and send respective output signals over the corresponding signal channels simultaneously so as to provide efficient utilization of the remote units and the signal channels; and

character recognition means at said central station operable on a time-sharing basis to receive from any one of said temporary storage means signals representing accumulated scan data for any one remote unit when such accumulated data is a predetermined increment representing at least one complete character, said character recognition means serving to analyze such signals to produce corresponding signals identifying each individual character of the scanned documents.

14. Apparatus as claimed in claim 13, wherein said circuit means at each remote unit includes coding means to convert the sequential sample signals to corresponding coded output signals containing the essence of the scan data needed for character recognition but capable of being transmitted through said signal channels in less time than would be required to transmit the data in its original sample signal form, said central station including means to decode said coded output signals and to reconstruct the original scan data in its sequential format.

15. Apparatus as claimed in claim 14, wherein said remote units include pulse generating means producing clock pulses synchronized with the scan displacement with respect to the document being read;

said coding means comprising a binary counter coupled to the output of said pulse generating means and arranged to produce a binary number corresponding to the number of clock pulses received; and

means operable by said scan means for controlling the function of said counter in response to the sensing of transitions between the presence or absence of character elements while scanning the document.

16. Apparatus as claimed in claim 13, wherein each remote scanner unit includes means defining a document receiving region having parallel sides, said scan means serving to trace scan paths extending from one side of said region to the other, whereby when the document is properly oriented in said receiving region with a line of characters extending perpendicularly to said sides said scan paths will sweep parallel to and through the line of characters to intersect each character in sequence;

said circuit means at each remote unit including means to produce signals identifying each segment of said output signals which represents the data from a full scan path;

said control means at the central station including means responsive to the signals received from said signal channels to detect when scan data representing scan paths covering a complete line of characters has been accumulated in any of said temporary storage means; and

means for directing such accumulated scan data signals to said character recognition means.

17. Apparatus as claimed in claim 16, including a graphic image display device;

means coupled to said character recognition means for sensing whenever said recognition means is unable to read a character, said sensing means serving to transmit to said image display device all of the character data signals stored in the temporary storage means containing the undeterminable character;

said display device serving to present images representing all of the stored characters in the complete line of characters.