1. Field of the Invention
The invention relates to a time switch whereby the on and off states of internal contact points control the operation of an electrical load according to a time schedule.
2. Description of the Background Information
A conventional time switch, such as the type described in Japanese Kokai (laid open) Patent S63-29427, includes a modular structure assembled from a motor that rotates at a uniform speed, a ratchet gear driven by a gearwheel transmission powered by the motor, and a first gear that meshes with the ratchet gear. The time switch also includes a sub-dial that rotates clockwise at a rate of one revolution per hour relative to the rotation of the ratchet gear, a gear that meshes with a second gear attached to the rotating shaft of the sub-dial, a dial that rotates clockwise once during a 24-hour period relative to the rotation of the sub-dial, a scheduling clip with a finger that projects from the circumference of a dial used to set a desired operating time schedule, and an internal contact point activating mechanism that opens and closes the contact points through contact with a contact element that is freely settable to a desired time. In the time switch of Japanese Kokai (laid open) Patent S63-29427, the ratchet gear, which is rotatably driven by motor torque supplied through the gearwheel transmission, rotatably drives the sub-dial through the sub-dial shaft. Although the dial is rotationally driven by meshing with the second gear on the sub-dial shaft, the sub-dial shaft rotates only in one direction due to the ratchet mechanism formed by the first gear and ratchet gear at the rotating sub-dial shaft. As a result, even though the sub-dial can be turned manually to set the time, it can only be turned in one direction, thereby making it time-consuming to set the time. For example, when changing the time schedule due to the enactment of daylight savings time, it would be easy to turn the sub-dial back one hour from a current setting of 7 o'clock to a 6 o'clock setting. Because the sub-dial can only be turned in the clockwise direction, however, it must be advanced 23 hours to effect the desired time change. As a result, changing the time becomes a time-consuming operation.