Synchronizing signal generator
First Claim
1. A synchronizing signal generator comprising:
- a light source means emitting a modulated light beam used for scanning;
a deflector for deflecting said modulated light beam in a predetermined direction;
a beam splitter consisting of a first diffraction grating which diffracts a portion of said modulated light beam deflected by said deflector and a base carrying thereon said diffraction grating;
a photodetector;
means for deriving a scan synchronizing signal from a synchronizing signal beam which is a portion of said diffracted beam; and
means for feeding scan signals synchronized with said synchronizing signal into said light source means.
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Abstract
In a device wherein a scanning beam from a light source is deflected by a light deflector, especially a rotatable polygonal mirror or a vibratory mirror and focused by an optical element such as a lens or the like to optically scan a surface to be scanned, thereby effecting writing and display of information, a synchronizing signal generator includes an optical system for taking out part of the scanning beam as a synchronizing beam for providing synchronism of signals in scanning. In this device, a diffraction element such as a diffraction grating or the like serving as a beam splitter for splitting the deflected beam to obtain the synchronizing beam is disposed within the deviation range of the deflected beam, and the diffracted beam exiting from the diffraction element is directed to a photodetector so as to provide a synchronizing signal. In this device, the use of the diffraction element as the beam splitter permits a wide area of the scanning beam to be split by a relatively thin member.
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Citations
17 Claims
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1. A synchronizing signal generator comprising:
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a light source means emitting a modulated light beam used for scanning; a deflector for deflecting said modulated light beam in a predetermined direction; a beam splitter consisting of a first diffraction grating which diffracts a portion of said modulated light beam deflected by said deflector and a base carrying thereon said diffraction grating; a photodetector; means for deriving a scan synchronizing signal from a synchronizing signal beam which is a portion of said diffracted beam; and means for feeding scan signals synchronized with said synchronizing signal into said light source means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A synchronizing signal generator comprising:
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a light source for emitting a scanning light beam; a deflector for deflecting said scanning light beam in a predetermined direction; a beam splitter consisting of a first diffraction grating of volume type disposed within the deviation angle range of said scanning light beam and a base carrying thereon said volume type diffraction grating; a photodetector; means for deriving said diffracted light entering said photodetector to generate a synchronizing signal; whereby said beam splitter splits the scanning beam only when the deflected beam is deflected to the timing angle and said beam is entirely transparent for any other angle of deflection. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification