In regions where earthquakes occur frequently as in Japan, elevators have come into widespread use which have the function of performing earthquake emergency return operations in the event of the occurrence of an earthquake in response to the shakes of buildings, i.e., the operating condition of seismic sensors. Incidentally, the above-described seismic sensor is constituted by a two-dimensional accelerometer and the like installed in an elevator machine room and the like, and when shakes of not less than a prescribed value have been sensed by such a seismic sensor as this, for example, a car is stopped at the nearest floor and control is performed thereafter so as to perform a door opening action.
As conventional techniques for an elevator having the function of such an earthquake emergency return operation, there has been proposed, for example, a technique in which a first seismic sensor that detects the shakes of a prescribed high level and a second seismic sensor that detects the shakes of a prescribed low level are provided and an earthquake emergency return operation that responds to the level of shakes is performed when each of the seismic sensors has gone into action. In such an elevator as this, a car is stopped when the first seismic sensor has gone into action. When the second seismic sensor has gone into action, first, the car is stopped at the nearest floor and the inspection of a safety circuit is automatically performed after a lapse of a predetermined time at which the termination of the earthquake is expected. And the elevator is returned to a normal operation under prescribed conditions when no abnormality is discovered in the inspection of the safety circuit (refer to Patent Document 1).
As conventional techniques for an elevator that performs control operations in response to the shakes of a building, there has also been proposed a technique in which an undulatory energy sensor capable of detecting a plurality of strong-wind levels and a controller that controls the elevator on the basis of an output signal from this undulatory energy sensor are provided and a rational control operation that responds to the actual shakes of the building during strong winds is performed. In such an elevator as this, a strong-wind signal indicating that a strong wind has been detected and a plurality of signals indicating the levels of strong winds are output from the undulatory energy sensor to the controller. And the controller that has received each of the signals performs, on the basis of these signals, control operations, such as a deceleration operation, a wait at an intermediate floor and a stop, according to the levels of strong winds (refer to Patent Document 2, for example).
Incidentally, with the tendency toward higher-rise buildings equipped with elevators, recent years have seen reports to the effect that even when shakes against which earthquake emergency return operations are to be performed are not detected by the above-described seismic sensor in the event of the occurrence of a relatively large earthquake in a remote district, long members of an elevator, such as traveling cables and compensating ropes, swing, collide against the equipment in a shaft, and are caught in such equipment. This is because buildings vibrate at a long period due to an earthquake occurring in a remote district, and if the travel of a car is continued in this state, there is a possibility that damage, such as traveling cables and the like being cut and broken equipment in a shaft, occurs.
For this reason, at present, endeavors are being made to develop a new-type seismic sensor that is different from conventional seismic sensors, i.e., a long-period seismic sensor capable of detecting long-period components of the shakes (vibrations) of a building.
There have been trials and proposals to take effective measures against earthquakes before the arrival of a principal motion of the earthquake by distributing an emergency earthquake prompt report to various places immediately after the occurrence of an earthquake by using the Internet and satellite communication on the basis of the information from seismometers (seismic sensors) installed all over Japan. The above-described emergency earthquake prompt report is composed of various kinds of information, such as the occurrence time of the earthquake, the scale of the earthquake, the epicenter, and time allowances until the arrival of a principal motion of the earthquake. The distribution of the above-described emergency earthquake prompt report is based on the technical background that with the recent high-speed, large-capacity designs of general public circuits, high-speed digital circuit networks to realize the Internet and the like have been widely built, permitting high-speed, real-time transmission of information. Incidentally, because the above-described emergency earthquake prompt report is distributed after the occurrence of an earthquake, this report cannot be effectively used in the case of the occurrence of an inland earthquake. However, when a relatively large earthquake has occurred in a remote district, it takes a certain time for a principal motion to arrive after the receipt of an emergency earthquake prompt report. Therefore, if this emergency earthquake prompt report can be effectively used, it is possible to prevent earthquake disasters.
As conventional techniques for an elevator that uses such an emergency earthquake prompt report, there have been proposed techniques that involve receiving an emergency earthquake prompt report, which includes the epicenter of an earthquake and the occurrence time of the earthquake, predicting the arrival time of seismic waves at the present location from the received emergency earthquake prompt report, and controlling earthquake emergency return operations of elevators on the basis of this prediction (refer to Patent Document 3, for example).
Patent Document 1: Japanese Patent Laid-Open No. 60-204588
Patent Document 2: Japanese Patent Laid-Open No. 5-319720
Patent Document 3: Japanese Patent Laid-Open No. 2004-224469