Optical read-write system with electronically variable image size

• US 4,233,636 A
• Filed: 07/03/1978
• Issued: 11/11/1980
• Est. Priority Date: 07/03/1978
• Status: Expired due to Term

• Current Assignee: Gerber Systems Corp (Barco NV)
• Original Assignee: Eocom Corporation
• Inventors: Harbaugh, Steven K., Hoogerbrugge, Gary H.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Orsino, Jr., Joseph A.
• Application Number:
  US05/921,763
• Time in Patent Office: 862 Days
• Field of Search: 358/287, 358/77, 358/140, 358/180, 343/5 SC
• US Class Current: 358/480
• CPC Class Codes: H04N 1/3875 combined with enlarging or reducing enlarging or reducing per se H04N1/393
• CPC Class Codes: H04N 1/3935 with modification of image resolution, i.e. determining the values of picture elements at new relative positions

Abstract

Disclosed is an optical read-write system including a first laser scanner for linearly scanning an object and generating a digital signal for the line scan. The digital signal is stored in a buffer at a read clock rate which is correlated to the scan of the first laser scanner. The digital signal is read-out of the buffer at a write clock rate and is applied as a control signal for a second laser scanner which linearly scans an image plane to develop an image. The second scanner scans at the same scan rate and distance as the first scanner, and the size of the image compared to the object size is determined by the differential of the read clock rate and the write clock rate.

Claims

1. An optical read-write system for scanning an object and reproducing an image which may vary in size from said object comprising:

first laser means for linearly scanning an object at a scan rate and a photo multiplier tube for generating an electrical image signal for each scan,

means for generating a read clock signal having a read frequency and generating a write clock signal having a write frequency, said means for generating a read clock signal and a write clock signal including

a source of a reference signal,

a phase comparator for receiving said reference signal and a feedback signal and producing a control voltage based on a comparison of said reference signal and said feedback signal,

a voltage controlled oscillator having a control terminal, means connecting said control voltage from said phase comparator to said control terminal whereby said oscillator generates a pulse signal at a frequency dependent on said control voltage,

pulse removal means connected to receive said oscillator signal and controllable to produce an output signal in which a variable number of pulses of said oscillator signal may be removed,

frequency divider means connected to receive said output signal from said pulse removal means and produce a divider output signal at a frequency lower than said oscillator signal frequency,

means for applying said divider output signal to said phase comparator as said feedback signal, said write clock signal being derived from said oscillator signal and said read clock signal being derived from said output signal produced by said pulse removal means,

means for storing said electrical image signal at said read frequency in synchronization with the scan of said means for optically scanning, and

second laser means for receiving said stored electrical image signal and linearly scanning at said scan rate for displaying an image at said write frequency.

2. An optical read-write system as defined by claim 1 wherein said read clock signal is generated for each scan of said first laser and said write clock signal is generated for each scan of said second laser, and including means for delaying the start of said write clock signal whereby said generated image is centered in the scan of said second laser.

3. An optical read-write system as defined by claim 1 and further including encoder means for generating a control signal for controlling said pulse removal means whereby a number of pulses are removed from said oscillator signal for a desired percentage of shrinkage in size of said image.

4. An optical read-write system as defined by claim 3 wherein said pulse removal means removes N pulses from every 1,000 pulses of said oscillator signal where N=10 (shrink percentage).

5. An optical read-write system for scanning an object and reproducing an image which may vary in size from said object comprising:

first means for optically scanning an object and generating an electrical image signal for each scan,

means for generating a read clock signal having a read frequency and generating a write clock signal having a write frequency, said means for generating a read clock signal and a write clock signal including

a source of a reference signal,

a phase comparator for receiving said reference signal and a feedback signal and producing a control voltage based on a comparison of said reference signal and said feedback signal,

a voltage controlled oscillator having a control terminal, means connecting said control voltage from said phase comparator to said control terminal whereby said oscillator generates a signal at a frequency dependent on said control voltage,

pulse removal means connected to receive said oscillator signal and controllable to produce an output signal in which a variable number of pulses of said oscillator signal may be removed,

frequency divider means connected to receive said output signal from said pulse removal means and produce a divider output signal at a frequency lower than said oscillator signal frequency,

means for applying said divider output signal to said phase comparator as said feedback signal,

said write clock signal being derived from said oscillator signal and said read clock signal being derived from said output signal produced by said pulse removal means,

means for storing said electrical image signal at said read frequency in synchronization with the scan of said means for optically scanning, and

scanning means for receiving said stored electrical image signal and displaying an image at said write frequency.

6. An optical read-write system as defined by claim 5 and further including encoder means for generating a control signal for controlling said pulse removal means whereby a number of pulses are removed from said oscillator signal for a desired percentage of shrinkage in size of said image.

7. An optical read-write system as defined by claim 6 wherein said pulse removal means removes N pulses from every 1,000 pulses of said oscillator signal where N=10 (shrink percentage).

8. An optical read-write system as defined by claim 5 wherein said means for storing said electrical image signal comprises first and second random access memories operably connected whereby one of said random access memories can receive a signal for storage while the other one of said random access memories is providing a signal to said means for displaying an image.

9. An optical read-write system as defined by claim 8 wherein said means for storing further includes multiplexer means connected to said first and second random access memories for alternately providing a signal from each of said random access memories to said means for displaying an image.

10. An optical read-write system as defined by claim 8 and further including a random access memory address means whereby a stored signal can be read out serially in a forward direction and serially in a reverse direction whereby said means for displaying an image can generate read-right and read-wrong images of said object.

11. An optical read-write system as defined by claim 8 wherein said means for optically scanning an object scans a linear distance of D mils and has a resolution of 1 mil, and said first and second random access memories each has a storage capacity of at least D bits.

12. An optical read-write system as defined by claim 11 wherein said means for optically scanning comprises a first laser which linearly scans at a fixed scanning rate and said means for generating an electrical image signal comprises a photomultiplier tube.

13. An optical read-write system as defined by claim 12 wherein said means for receiving said stored signal comprises a second laser which linearly scans simultaneously as said first laser scans at a scanning rate equal to the scanning rate of said first laser.