Cleaning device of ray transmission window incorporated into optical selector

In an optical selector wherein articles are conveyed downwardly past an optical selection means, light rays transmitted through a window impinge on the articles as they are moving downwardly, detecting the quantity of light reflected by the article, comparing the quantity of light reflected with a quantity of light reflected by a standard article, and using a blast of air to remove an article which is not selected, the improvement comprising a cleaning device for the window, said cleaning device comprising:

• a dust preventing cabinet having an opening through which said light rays are transmitted;
• a transparent window movably mounted over said opening of said dust prevention cabinet, said window having an upper part and a lower part;
• means for moving said window in a direction parallel to the surface plane of said window, said moving means connected to said window;
• a dust scraper in a fixed position so as to be in constant contact with a surface of said window;
• a linear guide supporting said window and along which said window is moved linearly;
• a fixing member to which said linear guide is fixed;
• a spring disposed between said fixing member and said window, and
• a pulling-out means connected to said window for providing a pulling force to move said window downwardly along said guide, said window being moved upwardly under the force of said spring.