Patent ID: 8578854

Claim:
An apparatus comprising: a flatbed or drum surface configured to have a photo-curable printing plate placed thereon with a mask covering a surface of the plate in order to cure the plate by exposing the plate to UV radiation; a light tunnel of at least four light reflective walls having a uniform polygonal cross-section and a length; and a UV light source comprising an LED or an array of LEDs located at or near one end, called the source end of the light tunnel and arranged in operation to produce UV light radiation to the inside of the light tunnel towards the other end of the light tunnel, called the plate end, including towards the reflective inner surfaces of the walls, such that UV light entering the light tunnel towards an inner reflective surface of a wall is reflected off the inner reflective surface so that the UV light can emerge from the plate end with divergence, wherein the UV light source has a power sufficiently high to emerge from the plate end with an intensity of at least 19 mW/cm 2 ; wherein the combination of the light tunnel and the UV light source forms a light exposure unit producing UV light emerging from the plate end at the intensity of at least 19 mW/cm 2 , wherein the exposure unit is located with the plate end over and near at least part of the surface of the flatbed or drum, and wherein after the photo-curable printing plate and the mask covering the surface of the plate are placed on the surface of the flatbed or drum, the exposure unit is operative to cure the plate by exposure through the mask to UV light radiation exiting the plate end at a sufficiently high exposure, with sufficient divergence as a result of the light tunnel being sufficiently long, and for a time sufficient to cure the plate that is exposed to the UV light radiation to obtain broader support shoulders for halftone dots on the cured plate than if the UV light source was used without the light tunnel.