Arrangement for the point- and line-wise recording of image info

Details Arrangement for the point- and line-wise recording of image info Arrangement for the point- and line-wise recording of image info

1981-08-21

1984-03-27

Henry, Jon W.

Illumination

Supported by vehicle structure

Condition responsive

350321, 362 32, G02B 502, G02B 2700

Patent

active

044390220

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The invention relates to electronic reproduction technology, particularly to the recording of image information on a light-sensitive recording medium for the production of printing surfaces by means of a ray beam emerging from a light conductor, said ray beam being imaged onto the recording medium through a diaphragm and a lens.


UNDERLYING PRIOR ART

In an electronic reproduction device, a master for gaining an image signal is opto-electronically scanned point- and line-wise. An optical recording element generates a light beam whose luminosity is controlled by the image signal. The light beam exposes a light-sensitive medium (film) point- and line-wise, said medium, for example, being disposed on a rotating recording drum.
A traditional recording element consists, for example, of a stationary, modulatable laser light source whose light is coupled into an optical light conductor (fiber optical waveguide, optical waveguide) in order to conduct it to the recording location. The light emerging from the light conductor illuminates a diaphragm which, with the assistance of a lens, is imaged onto the recording medium as an exposure point. For the purpose of line-wise exposure, the light conductor including the diaphragm and lens are moved axially along the recording drum.
Usually, a multi-mode fiber optical waveguide is employed in such an optical recording element, since, given a monomode waveguide it is very difficult because of its small core diameter to stably couple the light proceeding from a laser light source into a monomode waveguide.
A multimode waveguide, however, has the disadvantage that the light distribution at its exit surface is non-uniform because of the modes forming in the waveguide and additionally changes given a mechanical motion of the waveguide. Thereby, the diaphragm is not uniformly illuminated and the exposure point on the recording medium exhibits a corresponding, inhomogeneous light distribution. As a result, the exposure of the recording medium is also streaky, this having a significantly negative effect on the reproduction quality. A further disadvantage consists therein that the parameters such as exit surface and exit aperture of the waveguide are very difficult to match to the various diaphragm diameters and to the aperture of the lens without light loss.


DISCLOSURE OF THE INVENTION

It is therefore the object of the invention to specify an optical recording element for electronic reproduction devices in which the diaphragm is always homogeneously illuminated in order to produce a streak-free recording and in which only slight light losses occur.
The object is inventively achieved in that a scatter medium (6) for dividing the ray beam (3, 4, 5) into beams with the angle of dispersion (.beta.) of divergent partial ray beams or secondary ray bundles is disposed between the exit surface (2) of the light waveguide (1) and the diaphragm (17) and a focusing lens (13) is disposed between the scatter medium (6) and the diaphragm (17); in that the spacings (l.sub.1, l.sub.2) on the optical axis (15) between the exit surface (2) of the light waveguide (1) and the scatter medium (6) as well as between the scatter medium (6) and the focusing lens (13) are dimensioned in such manner that the focusing lens (13) superimposes all secondary ray bundles or partial ray beams (7, 8, 9) in one plane (16) with a spacing (l.sub.3) to the focusing lens (13), whereby the diaphragm (17) is disposed around the plane (16) in a superimposition area (18) of the partial ray beams (7, 8, 9); and in that the spacings (l.sub.4, l.sub.5) between the diaphragm (17), lens (19) and recording medium (20) are dimensioned in such manner that the aperture of the diaphragm is imaged on the recording medium (20) in a desired scale through the lens (19) with the focal length f.sub.2.
It is preferably provided that the spacings (l.sub.2, l.sub.3, l.sub.4) between the scatter medium (6), focusing lens (13) and lens (19) are dimensioned in such manner that the image (CD) of the scatter medium (6) is image

REFERENCES:
patent: 3600568 (1971-08-01), Weyrauch
patent: 3725574 (1973-04-01), Gast
patent: 3887262 (1975-06-01), Blau, Jr. et al.
patent: 3997240 (1976-12-01), Kebabian
patent: 4253724 (1981-03-01), Minaura et al.
Hans-Georg Unger-Optische Nachrictentechnik, Elitera-Verhs, Berlin, 1976, pp. 13-31.

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