ADAPTIVE MULTIPLE SPEED FACSIMILE SYSTEM

• US 3,646,256 A
• Filed: 03/24/1970
• Issued: 02/29/1972
• Est. Priority Date: 03/24/1970
• Status: Expired due to Term

• Current Assignee: V V S Energy Patent Fund Incorporated
• Original Assignee: David Schiff, Eugene Mogul, Gerald W. Jacob, Ira Kamen, Malcolm Reader, Paul Z. Boros
• Inventors: Boros, Paul Z., Kamen, Ira, Jacob, Gerald W., Mogul, Eugene, Schiff, David, Reader, Malcolm
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Leibowitz, Barry
• Application Number:
  US05/022,231
• Time in Patent Office: 707 Days
• Field of Search: 178/6,DIG.3,6.6 179/15,55,15BV,15BW
• US Class Current: 358/438
• CPC Class Codes: H04N 1/17 the scanning speed being dependent on content of picture

Abstract

A facsimile transmitter comprises means for scanning a document to produce signals corresponding to the dark and light areas of the document. Those signals are transferred to the receiver at one of two predetermined rates-fast or slow-depending on the content of the document. If desired, the rate of scanning may also be varied according to that content. Signals having a low information value are thereby transmitted at a higher rate than signals having a high information content.

Claims

1. A system for transmitting signals derived by the scanning of a document or the like having light and dark areas thereon, said system comprising means including a control terminal and a signal terminal for deriving at said signal terminal data signals at one of two discrete levels corresponding respectively to the dark and light areas on the document, an output terminal, signal storing means having input and output stages, said output stage being coupled to said output terminal, means coupled to the signal terminal of said data signal deriving means for selecting one of a first and second different data rates, said second data rate being a multiple of said first data rate, means coupled to the signal terminal of said signal deriving means for applying said data signals to the input stage of said storing means at the selected one of said first and second rates, and means coupled to said rate selecting means and said storage means for reading out the previously stored data signals from said output stage of said storing means to said output terminal at the selected one of said first and second rates simultaneous with the application of said data signals to the input stage of said storing means at said selected one of said first and second rates.

2. The system of claim 1, in which said signal-deriving means comprises means for scanning the document with a beam, and means in operative optical communication with said scanning means for producing said data signals, said system further comprising means coupled to said rate determining means and said scanning means for operating said scanning means at one of first and second different rates.

3. The system of claim 2, in which said rate selecting means comprises first and second sources of timing signals at said first and second rates respectively, means for counting a predetermined number of said data signals at one of said levels, and gating means operatively controlled by said counting means for applying one of said first and second timing signals to said signal storing means for determining the rate of signal readout therefrom.

4. The system of claim 3, in which said scanning rate means comprises second counting means receiving input signals at one of said first and second rates, and scan signal generating means coupled to said second counting means for producing scanning signals at a rate corresponding to the rate of said input signals.

5. The system of claim 4, in which said second counting means is also effective when a second predetermined number of input signals is applied thereto to produce an end of line signal for controlling the position of said document.

6. The system of claim 4, further comprising means for sensing the completion of the scanning of a line, and means responsive to said line completion sensing means for initiating scanning on the succeeding line on the document at the faster one of said first and second rates.

7. The system of claim 6, in which said rate determining means further comprises means for delaying by a predetermined period the changeover in said data transferring rate from said first rate to said second rate and vice versa.

8. The system of claim 7, in which said storing means comprises a first number of data storing units, and said counting means comprises a second number of stages, said delay period being determined by the difference between said second and first numbers.

9. The system of claim 8, further comprising means for generating a three-level output signal corresponding to the selected data transfer rate and level of the transmitted data signal.

10. The system of claim 7, comprising means for generating a unique sequence of signals at first and second levels whenever a predetermined one of said first and second data transferring rates is selected.

11. In combination with the system of claim 10, a facsimile receiver coupled to said transmitter output terminal and comprising second scanning means, and means responsive to signals derived from said transmitting system for operating said second scanning means at the selected one of said first and second rates.

12. The system of claim 1, in which said signal rate selecting means comprises first and second sources of timing signals at said first and second rates respectively, means for counting a predetermined number of signals at one of said levels, and gating means operatively controlled by said counting means for applying one of said first and second timing signals to said storing means for determining the rate of signal transfer therefrom.

13. The system of claim 2, further comprising means for sensing the completion of the scanning of a line, and means responsive to said line completion sensing means for initiating scanning on the succeeding line on the document at the faster one of said first and second rates.

14. The system of claim 12, in which said predetermined number of signals is equal to the ratio of the higher one of said first and second rates to the lower one of said first and second rates.

15. The system of claim 1, in which said rate-determining means further comprises means for delaying by a predetermined period the changeover in said data-transferring rate from said first rate to said second rate and vice versa.

16. The system of claim 15, in which said storing means comprises a first number of data storing units, and said counting means comprises a second number of stages, said delay period being determined by the difference between said second and first numbers.

17. The system of claim 1, comprising means for generating a rate command signal consisting of a unique sequence of signals at first and second levels whenever a predetermined one of said first and second data transferring rates is selected, and means for combining said two level rate command signal with said rate command signal at said output terminal.

18. The system of claim 17, in which said predetermined one of said rates is the faster of said rates.

19. In combination with the system of claim 18, a facsimile receiver coupled to said transmitter output terminal and comprising second scanning means, and means responsive to said unique rate command signal derived from said transmitting system for operating said second scanning means at the selected one of said first and second rates.

20. In combination with the system of claim 2, a facsimile receiver coupled to said transmitter output terminal and comprising second scanning means, and means responsive to signals derived from said transmitting system for operating said second scanning means at the selected one of said first and second rates.

21. The system of claim 1, in which said data signal deriving means comprises means for scanning the document, means for sensing the reflected beam from the document and for producing a corresponding analog signal, means coupled to said analog signal producing means for producing from said analog signal a binary signal at two discrete different levels, and signal conditioning means including logic means coupled to said binary signal producing means for sensing whenever the period of said binary signal at one of said discrete levels is below a predetermined minimum resolution value, and means coupled to said sensing means for expanding the duration of said binary signal to a conditioned signal of said minimum resolution duration at said one of said discrete levels.

22. The system of claim 2, in which said scanning means comprises a cathode-ray tube having deflection means, and further comprising means for providing an unblanking signal to said tube, a power supply for said tube, means for providing a deflection signal to said deflection means, and gating means having inputs coupled to said unblanking signal providing means and said deflection signal providing means, and an output coupled to said power supply, and effective upon receiving predetermined signals from each of the former to deactuate the latter.

23. A method for transmitting a copy of an image from an image transmitter to an image receiver, said method comprising the steps of at said transmitter, sequentially scanning substantially equal linear portions of the image to produce a series of image data signals at one of two binary levels, respectively corresponding to the dark and light portions of the iMage, the number of said image data signals derived from each one of said linear portions being substantially equal, processing said image data signals to generate a fast or a slow scanning rate command signal consisting of a predetermined two-level unique combination of signals at the same levels as said image data signals upon the sensing of a predetermined consecutive number of said image data signals of one of said binary levels that may appear at any arbitrary location in said series of said image data signals, said predetermined number of image data signals being less than the number of said image data signals produced by scanning one of said linear portions, interposing said unique two level scanning rate command signal into said series of image signals to produce a single train of two-level signals in which said two-level scanning rate command signal appears within said signal train when said predetermined consecutive number of image data signals is sensed, and transmitting the combined two-level rate command and image signal train;

and at the receiver, sensing from the received two-level signal train the transmitted scan rate command signal, and thereafter processing the received image signals at a fast or slow scanning rate corresponding to the sensed scanning rate command signal.

24. The method of claim 23, further comprising the step of scanning at said transmitter the image at the selected one of said rate command signals.

25. The system of claim 21, in which said signal conditioning means further comprises second logic means coupled to the output of said first-mentioned logic means for sensing the duration of said binary signal at the other of said discrete levels below a second minimum resolution value, and means for deriving from said below minimum duration signal a conditioned signal at said second minimum resolution duration at said other of said discrete levels.