| 摘要 |
A changeable display includes a sheet containing a number of joined frames, each having a display on opposite sides. The sheet is wound on a pair of take-up rollers having parallel axes separated by one frame. A separate idler roller for each take-up roller is arranged so a nip is formed between each idler roller and its associated take-up roller. A motor-clutch arrangement selectively drives one of the take-up roller to transfer the sheet between the take-up rollers. Each idler roller is urged toward the periphery of the wound material on its associated take-up roller while the sheet is being transferred between the take-up rollers to maintain a constant separation nip between each idler roller and the periphery of the sheet on each take-up roller. A housing for the sheet, rollers and motor-clutch pair of includes a pair of windows on opposite sides of the sheet. The windows lie parallel and in close proximity with the sheet so light is not substantially reflected between the windows and the sheet and are mounted on pivoting panels. A bumper pad on one window urges against one side of the sheet when the panels are closed. The housing includes light diffusing, translucent surfaces through which light from lamps inside of the housing that simultaneously illuminate the opposite sides of the sheet propagates. The frames are secured together by a wire extending beyond an edge of the sheet of the last frame at each sheet end. The extending wire portion activates a microswitch to prevent winding the sheet off the take-up rollers.
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