1. Field of the Invention
The present invention is directed to devices for reading out a latent image from a luminescent storage screen, and in particular to such a device wherein the screen is scanned by a beam line-by-line, with the screen being advanced by a conveyor system for each line scan.
2. Description of the Prior Art
It is known in the art to latently store x-ray images in a luminescent storage screen. Such images are read-out of the storage screen by scanning the screen line-by-line with a scan beam of a radiation source which induces stimulation of the phosphor layer of the screen. The screen is induced to luminesce pixel-by-pixel. It is also known to advance the storage screen for each line scan, and to collect the light emitted by the luminescing screen over the entirety of its surface.
Such a read-out system is described in European application No. 0 098 596, wherein the storage screen additional includes a layer of magnetic material, and the screen is held on a continuous belt by a magnetic force. The belt has magnets integrated therein, which hold the storage screen on the belt by interaction with the layer of magnetic material. In another embodiment disclosed in this European application, a magnetic is provided which is disposed beneath the belt, so that the screen is pressed against the belt due to the force from the magnet. This type of apparatus, however, requires relatively complex manufacturing techniques, and it is difficult to precisely position the storage screen using this device, because the belt must be flexible so as to be entrainable around the turning rollers, and thus fluctuations in height occur during the forward feed of the belt.