Imaging system and method for printed circuit artwork and the like

• US 4,419,675 A
• Filed: 05/24/1979
• Issued: 12/06/1983
• Est. Priority Date: 05/24/1979
• Status: Expired due to Term

• Current Assignee: Gerber Systems Corp (Barco NV)
• Original Assignee: American Hoechst Corporation (Sanofi )
• Inventors: Norton, Lyle K., Neumann, Don B., Olson, Eric V.
• Primary Examiner(s): CARDILLO JR, RAYMOND
• Application Number:
  US06/042,133
• Time in Patent Office: 1,657 Days
• Field of Search: 358/293, 358/286, 358/296-300, 358/302, 346/108, 346/76 L, 354/3-5, 355/67-69, 428/901, 219/121 L, 219/121 LM, 219/121 LH, 219/121 LY
• US Class Current: 347/249
• CPC Class Codes: B23K 26/08 Devices involving relative movement between laser beam and workpiece
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: G06K 15/1204 involving the fast moving of an optical beam in the main scanning direction G06K15/1233 - G06K15/129 take precedence
• CPC Class Codes: G06K 15/1219 Detection, control or error compensation of scanning velocity or position, e.g. synchronisation G06K15/1223 takes precedence
• CPC Class Codes: H04N 1/047 Detection, control or error compensation of scanning velocity or position H04N1/0402 and H04N1/17 take precedence
• CPC Class Codes: H04N 1/053 in main scanning direction, e.g. synchronisation of line start or picture elements in a line
• CPC Class Codes: H04N 1/1008 with sub-scanning by translatory movement of the picture-bearing surface
• CPC Class Codes: H04N 1/1135 for the main-scan only
• CPC Class Codes: H04N 1/36 for synchronising or phasing transmitter and receiver
• CPC Class Codes: H04N 1/4015 of the reproducing head
• CPC Class Codes: H04N 2201/02416 Rotational positioning, i.e. with respect to an axis
• CPC Class Codes: H04N 2201/02439 Positioning method
• CPC Class Codes: H04N 2201/02443 using adhesive
• CPC Class Codes: H04N 2201/03108 Components of integral heads
• CPC Class Codes: H04N 2201/0471 using dedicated detectors
• CPC Class Codes: H04N 2201/04724 on a separate encoder wheel
• CPC Class Codes: H04N 2201/04725 connected to the sub-scanning drive means
• CPC Class Codes: H04N 2201/04729 in the main-scan direction
• CPC Class Codes: H04N 2201/04731 in the sub-scan direction
• CPC Class Codes: H04N 2201/04734 Detecting at frequent intervals, e.g. once per line for sub-scan control
• CPC Class Codes: H04N 2201/04736 : with varying intervals between consecutive detections
• CPC Class Codes: H04N 2201/04746 : after modulation by a grating, mask or the like
• CPC Class Codes: H04N 2201/04755 : by controlling the position or movement of a scanning element or carriage, e.g. of a polygonal mirror, of a drive motor
• CPC Class Codes: H04N 2201/04756 : by controlling the position or movement of the sheet, the sheet support or the photoconductive surface
• CPC Class Codes: H04N 2201/04772 : using a phase-locked loop
• CPC Class Codes: H04N 2201/04789 : in the main-scan direction
• CPC Class Codes: H04N 2201/04791 : in the sub-scan direction
• CPC Class Codes: H04N 2201/04794 : Varying the control or compensation during the scan, e.g. using continuous feedback or from line to line
• CPC Class Codes: H04N 2201/04798 : Varying the main-scan control during the main-scan, e.g. facet tracking
• CPC Class Codes: H05K 2203/056 : Using an artwork, i.e. a photomask for exposing photosensitive layers
• CPC Class Codes: H05K 2203/107 : Using laser light
• CPC Class Codes: H05K 2203/108 : Using a plurality of lasers or laser light with a plurality of wavelengths
• CPC Class Codes: H05K 3/0002 : for manufacturing artworks for printed circuits

Abstract

Imaging system and method suitable for producing artwork masters for use in the manufacture of printed circuit boards. A beam of coherent radiation is modulated in accordance with data from a source defining the image to be produced, and the modulated beam is scanned across an output medium to form the desired image. A reference signal is generated in accordance with the position of the beam on the output medium, and this signal is shifted forward in phase to compensate for any delay between the generation of the reference signal and the arrival of the modulated beam at the output medium.

Claims

1. In a system for use in the manufacture of printed circuit boards:

a source of data representative of artwork to be formed on the circuit boards, laser means for providing a beam of coherent radiation, means for modulating the beam in accordance with the data, means for holding an output medium in position to be scanned by the beam, means for effecting scanning of the output medium by the modulated beam to form an image of the artwork on the output beam, means for sensing the position of the beam and providing a reference signal corresponding to the position of the beam on the output medium, means responsive to the reference signal for synchronizing the modulation of the beam with the position of the beam on the output medium, and means for shifting the phase of the reference signal forward in time to compensate for any delay between the generation of the reference signal and the arrival of the modulated beam on the output medium.

2. In a method utilizing a laser beam to produce artwork for printed circuit boards, the steps of:

providing data signals defining the artwork to be produced, modulating the laser beam in accordance with the data signals, scanning the modulated laser beam across an output medium to form an image of the artwork on the output medium, monitoring the position of the beam and providing a reference signal corresponding to the position of the beam on the output medium, synchronizing the modulation of the beam in accordance with the reference signal, and shifting the phase of the reference signal forward in time to compensate for any delay between the generation of the reference signal and the arrival of the modulated beam on the output medium.

3. In a system for producing an image on an output medium:

a source of data defining the image, means for providing a writing beam of coherent radiation, means for modulating the writing beam in accordance with data signals appled thereto, means for providing a reference beam, a reference mask having alternately arrayed transparent and opaque areas, means for simultaneously scanning the writing beam across the output medium and the reference beam across the reference mask, means responsive to reference beam energy transmitted by the reference mask for providing a reference signal corresponding to the position of the writing beam on the output medium, means responsive to the reference signal for controlling the delivery of data from the data source to the modulating means to provide synchronization between the modulation of the writing beam and the position of said beam in the output medium, and means for shifting the phase of the reference signal forward in time to compensate for signal transmission delays in the system so that the data is delivered when the writing beam is exactly in the position indicated by the reference signal.

4. In a system for producing an image on an output medium:

a source of data defining the image, means for providing a writing beam of coherent radiation, means for modulating the writing beam in accordance with data signals applied thereto, means for providing a reference beam, a reference mask having alternately arrayed transparent and opaque areas, means for simultaneously scanning the writing beam across the output medium and the reference beam across the reference mask, means responsive to reference beam energy transmitted by the reference mask for providing a reference signal corresponding to the position of the writing beam on the output medium, means responsive to the reference signal for controlling the delivery of data from the data source to the modulating means to provide synchronization between the modulation of the writing beam and the position of said beam in the output medium, and means for shifting the phase of the reference signal to compensate for delays in the system so that the data is delivered when the writing beam is exactly in the position indicated by the reference signal, said means for shifting the phase of the reference signal including a phase locked loop incorporating a delay therein to effect a forward shift in the reference signal phase such that that signal appears to occur prior to the arrival of the beam at the point where the signal is generated.