There is disclosed an elevator with an electronic safety system
which dispenses with dedicated hardware, which is simple and
has high availability, and in which software processing load
is reduced. The elevator with an electronic safety system
includes a rotary encoder that outputs pulse signals
corresponding with movement of a car as encoder signals and
an electronic safety controller having a first CPU and a second
CPU to which the encoder signals are input respectively. The
first and second CPUs compute speed and position data of the
car and their computation results are compared with each other
and, accordingly, the electronic safety controller decides
whether abnormality occurs. Car speed and position data
computed in multiple cycles are transferred between the first
and second CPUs by serial communication and compared. If such
data is beyond an allowable error range set beforehand, the
electronic safety controller decides that abnormality occurs.

WHAT IS CLAIMED IS:
1. An elevator with an electronic safety system comprising
a rotary encoder that outputs pulse signals corresponding with
movement of a car as encoder signals and an electronic safety
controller having a first CPU and a second CPU to which the
encoder signals are input respectively, wherein the first and
second CPUs compute speed and position data of the car and their
computation results are compared with each other and,
accordingly, the electronic safety controller decides whether
abnormality occurs,
wherein car speed and position data computed in a plurality
of cycles are transferred between the first and second CPUs
by serial communication and compared and, if such data is beyond
an allowable error range set beforehand, the electronic safety
controller decides that abnormality occurs.
2. The elevator with an electronic safety system according
to claim 1, wherein the first and second CPUs compute speed
data for each cycle and determination is made as to whether
current speed data, speed data as of one cycle ago, and speed
data as of two cycles ago fall within respective allowable error
ranges.
3. The elevator with an electronic safety system according
to claim 1, wherein, if the speed data is beyond the allowable
error range set beforehand and if a maximum value of the speed
data computed in a plurality of cycles is at or more than a
predefined speed, the electronic safety system makes emergency
stop of the car.
4. The elevator with an electronic safety system according
to claim 1, wherein, if the speed data is beyond the allowable
error range set beforehand and if a maximum value of the speed
data computed in a plurality of cycles is less than a predefined
speed, the electronic safety system stops the car at the nearest
floor.
5. The elevator with an electronic safety system according
to claim 1, wherein a period of the cycle is determined from
rated speed data during booting.
6. The elevator with an electronic safety system according
to claim 1, wherein car speed and position data as of two cycles
ago is stored and the electronic safety system stops the car
when it has been decided that abnormality occurs and indicates
a floor at which the car stopped to users (passengers), based
on the stored data.
7. The elevator with an electronic safety system according
to claim 1, wherein acceptance signal data signifying whether
or not initialization has finished in each CPU is added to data
that is communicated between the first and second CPUs by serial
communication.
8. The elevator with an electronic safety system according
to claim 1, wherein sequential number data that is incremented
each time data is transmitted, so that the receiving side can
determine whether or not the data is updated by referring to
it, is added to data that is communicated between the first
and second CPUs by serial communication.
9. An elevator with an electronic safety system,
substantially as herein described with reference to
accompanying drawings and examples.