The present invention relates to an image-exposing apparatus for a video printer, more particularly to an apparatus for recording an image obtained from an electric video signal on a photosensitive medium.
Conventionally, there have been known various methods for printing an image obtained from an electric video signal on a hard copy. For example, a photographic method has been known, which comprises the steps of converting an electric video signal into an optical image, and projecting light from said optical image on a photosensitive medium, in order to record or print an image on said photosensitive medium. As the photosensitive medium used in such photographic method, there are conventional photographic films and cycolor papers.
On the other hand, video printers utilizes a method wherein an optical image corresponding to one scanning line of an electric video signal is scanned to be recorded on a photosensitive medium. In such video printers, a cathode ray tube is generally used as a photosensitive device. In this case, an optical lens system may be used to accurately producing an optical image from the cathode ray tube on the photosensitive medium. Alternatively, a photographic method may be used, which comprises transmitting light from one pixel on the cathode ray tube to the corresponding pixel on the photosensitive medium by utilizing an optical fiber, and then contacting both ends of said optical fiber with the cathode ray tube and the photosensitive medium, respectively.
Referring to FIG. 1 there is shown typical example of a color video printer which comprises a fiber optics-cathode ray tube utilizing optical fibers. As shown in the drawing, the video printer includes a fiber optics-cathode ray tube 4 which is disposed at the front of and spaced from a photosensitive medium 1 positioned in the video printer. The fiber optics-cathode ray tube 4 comprises a cathode ray tube 2 of a conventional type and a fiber optics-face plate 3 adhered to the leading end of said cathode ray tube 2. Optical image produced on the screen of fiber optics-cathode ray tube 4 is recorded on the photosensitive medium.
In the drawing, reference numeral "5" designates a cartridge for containing the photosensitive medium 1 therein, "6", "6'", and "6" guide rollers, "7" a pressing roller, "8" a cycolor receiver paper, and "9" a heater.
However, the above-mentioned conventional apparatus requires an optical lens system or a fiber optics-cathode ray tube for accurately producing an optical image from the cathode ray tube on the photosensitive medium. As a result, there are disadvantages of increasing the overall size of the apparatus and the manufacturing cost, due to the complex construction. Particularly, when the fiber optics-cathode ray tube is used, the above-mentioned disadvantages become more serious, due to the requirement of various accessaries such as a high voltage generator, a magnetic shield, a yoke coil, and etc.