Video clock signal generator in an optical scanner in which a mask including a linear scale provides timing for controlling the amplitude of a vibrating mirror

• US 5,668,644 A
• Filed: 03/29/1995
• Issued: 09/16/1997
• Est. Priority Date: 11/07/1991
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Okugawa, Hisashi, Kuroiwa, Yoshinori, Nishida, Hiroshi
• Primary Examiner(s): Rogers, Scott A.
• Application Number:
  US08/412,911
• Time in Patent Office: 902 Days
• Field of Search: 358/480, 358/494, 358/474, 358/497, 358/481, 359/214, 359/215, 359/213, 359/212, 359/197, 359/566, 359/569, 250/235, 250/237 G, 250/237 R, 346/107.3, 346/107.5, 347/259, 347/260, 347/243
• US Class Current: 358/480
• CPC Class Codes: H04N 1/0283 in combination with a light deflecting element, e.g. a rotating mirror
• CPC Class Codes: H04N 1/0402 Scanning different formats; Scanning with different densities of dots per unit length, e.g. different numbers of dots per inch (dpi); Conversion of scanning standards H04N1/00283 takes precedence; picture signal circuits for modification of image resolution H04N1/3935, H04N1/40068
• CPC Class Codes: H04N 1/0411 in the main scanning direction
• CPC Class Codes: H04N 1/0426 using different sized scanning elements, e.g. reproducing different sized dots
• CPC Class Codes: H04N 1/0446 Varying the modulation time or intensity
• CPC Class Codes: H04N 1/0452 mounted on the same support or substrate
• 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 1/1135 for the main-scan only
• CPC Class Codes: H04N 2201/02439 Positioning method
• CPC Class Codes: H04N 2201/0471 using dedicated detectors
• CPC Class Codes: H04N 2201/04732 Detecting at infrequent intervals, e.g. once or twice per line for main-scan control
• CPC Class Codes: H04N 2201/04734 Detecting at frequent intervals, e.g. once per line for sub-scan control
• 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 2201/04768 Controlling the frequency of the signals
• CPC Class Codes: H04N 2201/04794 Varying the control or compensation during the scan, e.g. using continuous feedback or from line to line

Abstract

A video clock signal generator comprises: a light beam source; a mask having opposite ends spaced by a predetermined distance; a vibration scanner for reflecting the light beam and forming a light spot vibrating on the mask beyond the opposite ends thereof; a detector for generating an output signal representing optical information from the mask; a counter for counting a time required for the light spot to cross the opposite ends of the mask based on the output signal of the detector; and a control unit for controlling an amplitude of the scanner mirror in accordance with the time counted by the counter.

Claims

1. A video clock signal generator comprising:

means for supplying a light beam;

a mask having opposite ends spaced by a predetermined distance;

a vibration scanner for reflecting the light beam and forming a light spot vibrating on the mask beyond the opposite ends thereof;

a detector for generating an output signal representing optical information from the mask;

a counter for counting a time required for the light spot to cross the opposite ends of the mask based on the output signal of the detector; and

means for controlling an amplitude of the scanner mirror in accordance with the time counted by the counter;

wherein said mask includes a linear scale having a plurality of gratings arranged at a predetermined pitch in a direction of vibration of the light spot, and said video clock signal generator further comprises processing means for generating the video clock signal in accordance with optical information from the linear scale.

2. A video clock signal generator comprising:

a plurality of linear scales of different lengths each having a plurality of gratings arranged longitudinally;

means for selectively positioning the linear scales on an optical axis;

beam supply means for supplying a beam for forming a light spot on the selected linear scale;

a vibration scanner for vibrating the light spot on the linear scale in the direction of array of the gratings; and

means for controlling the amplitude of the vibration scanner in accordance with the length of the selected linear scanner.

3. A video clock signal generator according to claim 2 wherein said linear scales include a plurality of scale patterns of different lengths arranged on a scale plate.

4. A video clock signal generator according to claim 2 wherein the numbers of gratings of the linear scales are equal to each other and pitches of the gratings are different from scale to scale.

5. A video clock signal generator according to claim 2 wherein said amplitude control means includes means for prestoring amplitude data for each linear scale, and means for driving the vibration scanner in accordance with the amplitude data of the selected linear scale read from the prestore means.

6. An optical scanning image input device comprising:

a plurality of linear scales of different lengths each having a plurality of gratings arranged longitudinally;

means for selectively positioning the linear scales on an optical axis;

beam supply means for supplying a beam for forming a light spot on the selected linear scale;

a vibration scanner for vibrating the light spot on the linear scale in the direction of array of the gratings;

means for controlling the amplitude of the vibration scanner in accordance with the length of the selected linear scanner;

means for generating the video clock signal based on the optical information from the linear scale;

means for generating an image signal synchronized with the vibration scanner mirror; and

means for forming an image from the image signal and the video clock signal.