Method of producing a halftone picture by vibrating light source

Claim 1

A method for producing a half-tone picture on a photosensitive material, wherein the halftone dots are produced along a line of an arbitrary screen angle with respect to a scanning direction, comprising the steps of: forming a spot of light on the surface of the material; causing a motion of the material relative to the spot in a scanning direction; vibrating the spot to and fro along a vibration direction which is at a substantial angle to the scanning direction through a certain vibration width about a central point, the vibration center; and controlling the amplitude of the vibration width and the position of the vibration center by guiding the center of the vibration along a line substantially equal to the screen angle with respect to the scanning direction so that the spot exposes areas on the photosensitive material which form half-tone dots, as the material moves relative to the spot in the scanning direction.

Claim 2

A method for producing a half-tone picture on a photosensitive material, wherein the halftone dots are produced along a line of an arbitrary screen angle with respect to a scanning direction, comprising the steps of: forming a spot of light on the surface of the material; causing a motion of the material relative to the spot in a scanning direction; vibrating the spot to and fro along a vibration direction which is at a substantial angle to the scanning direction through a certain vibration width about a central point, the vibration center; and controlling the amplitude of the vibration width and the position of the vibration center by guiding the center of the vibration along a line substantially equal to the screen angle with respect to the scanning direction so that the spot exposes areas on the photosensitive material which form half-tone dots, as the material moves relative to the spot in the scanning direction.

Claim 7

A method as in any of claims 1-5, wherein the spot is vibrated by an optical inclinator element which is controlled by a frequency-modulated signal.

Claim 8

A method as in any of claims 1-5, wherein the brightness of the spot is controlled to be according to the vibration width by an optical modulator element which is controlled by an amplitude modulated signal.

Claim 10

A method as in any of claims 1-5, wherein the spot is controlled by an optical inclinator/modulator element which is controlled by a signal, the frequency of the signal controlling the optical inclinator/modulator element to vibrate the spot, and the amplitude of the signal controlling the optical inclinator/modulator element to control the brightness of the spot according to the vibration width.

Claim 11

The method as in any of claims 1-5, wherein the material also moves, in a direction perpendicular to the scanning direction, relative to the spot, at a speed which is low relative to the motion along the scanning direction.