Device for operating display members at signs

A driving device for operating signs for consecutive, repeated presentation of a series of images, the driving device comprising:

• elongate display members (2) operated through pairs of gear wheels (9, 10), the gear wheels (9, 10) having conical teeth (11 and 12 respectively);
• a driving gear wheel (9) in each pair of gear wheels, the driving gear wheels being mounted on a drive shaft (6);
• and
• a driven gear wheel (10) in each pair of gear wheels (9, 10), the driven gear wheel (10) being operatively connected with the elongate display members (2),
• the driving gear wheel (9) having a gear sector (14) occupying a periphery of the driving gear wheel (9) such that, during each revolution of the drive shaft (6), the driving gear wheel (9) is rotated a number of degrees depending on the number of sides of the elongate display members (2),
• the drive shaft (6) having a lock means (15) provided to cooperate with a member (16) centered with the driven gear wheel (10) and non-rotatably connected with the driven gear wheel (10), the lock means (16) being located in a locking position for blocking the driven gear wheel (10) against rotation immediately after the gear sector (14) of the driving gear wheel (9) is no longer engaging the driven gear wheel (10), the lock means (16) leaving the locking position for permitting rotation of the driven gear wheel (10) just before the gear sector (14) of the driving gear wheel (9) engages the driven gear wheel (10),
• the lock means (15) comprising a first lock means member in the shape of a cam disk (17) protruding radially from the drive shaft (6),
• the member (16) having a number of side surfaces (18) for cooperation with the cam disk (17),
• the number of side surfaces (18) on the member (16) being directly proportional to the number of sides on the elongate display members (2),
• the cam disk (17), in the locking position, cooperating with one of the side surfaces (18) on the member (16) such that the driven gear wheel (10) is blocked against rotation and displacement of the gear sector (14) of the driving gear wheel (9) and the driven gear wheel (10) relative to each other in a first direction along the longitudinal direction of the drive shaft (6),
• the lock means (15) further comprising at least one second lock means member (19, 23, 24, 28) for at least preventing displacement of the gear sector (14) of the driving gear wheel (9) and the driven gear wheel (10) relative to each other in at least a second direction opposite the first direction along the longitudinal direction of the drive shaft (6).