[TITLE OF THE INVENTION1 A device for monitoring door status of an elevator system and a method thereof and an elevator controller using the same [TECHNICAL FILED) The present invention relates to a device for monitoring door status of an elevator system and a method thereof and an elevator controller using the same for detecting door status at each floor, especially to a device for monitoring door status of an elevator system and a method thereof and an elevator controller having a double-structured door switch (also called as a"door switch") which is turned on or off according to opening or closing of an elevator door (also called as a"door") at each floor.

[BACKGROUND OF THE INVENTION) Generally, an elevator system facilitated in a building is designed to stop its operation temporarily for the safety of users when the door at a floor of the building is open. Accordingly, the door status of opening and/or closing at each floor should be always monitored, and a status of abnormal opening and/or closing of the door or disorder or malfunctioning of the door switch (hereafter,"an abnormal status") must be detected promptly.

The conventional method for achieving the above object is described below with reference to Fig. 1. Fig. 1 shows an equivalent circuit diagram of a conventional device for monitoring door status (hereafter, called"a monitoring

device"). According to the monitoring device of the conventional elevator system, door switches 10, 12, 14 and 16 are provided on the door (not shown) of each floor.

The door switches 10,12,14 and 16 are connected with one another in series. Each of the door switches 10,12,14 and 16 is, for example, turned off when the door open, or on when the door is closed. For example, the door switch is a pair of conductors which are short-circuited when the door is closed, and open-circuited when the door is open. As mentioned before, each of the door switches 10,12,14 and 16 is connected in series with ones of the adjacent floors. One terminal of the door switch 10 of the ground floor is connected to ground, and one terminal of the door switch 16 of the top floor is connected to a power source Vcc through a pull- up resistor 3. The terminal connected to the resistor 3 in door switch 16 of the top floor is also connected to a monitoring terminal A.

According to the conventional elevator system having the door switches 10,12,14 and 16 of the structure described above, output of the monitoring terminal A is"low", when all of the door switches 10,12,14 and 16 are turned on as the doors of all floors are closed, because a current flows from the power source Vcc to the ground through the resistor 3. The output of the monitoring terminal A is"high", when at least one of the door switches 10, 12,14 and 16 is turned off as one or more of the doors is open or an abnormal status occurs to a door switch, because no current flows through the resistor 3. Therefore, the elevator stops its operation when the output is high by detecting output of the monitoring terminal A and determining whether the output is high or low.

But, according to the above described conventional structure of the door

switches connected in series, it is impossible to recognize which door is open or to which door the abnormal status occurs. Further, it is impossible to determine whether only one door is open or more than one door are open, or whether the abnormal status occurs to only one door or to more than one door.

Therefore, according to the conventional elevator system described above, there is a problem in that a human manager must check each door of each floor one by one for detecting which door has problem, and it takes much time for repairing or facilitating.

1SUMMARY OF THE INVENTION] Therefore, it is an object of the present invention to provide a device for monitoring door status of an elevator system and a method thereof and an elevator controller using the same for detecting abnormal door when an abnormal status has occurred, so that it is possible to reduce the time for repairing and facilitating.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is an equivalent circuit diagram of a monitoring device for monitoring door status in a conventional elevator system.

Fig. 2 is an equivalent circuit diagram of a monitoring device for monitoring door status according to an embodiment of the present elevator system.

Fig. 3 is a block diagram of an abnormal door detector according to an embodiment of the monitoring device shown in Fig. 2.

Fig. 4 is a flowchart showing operation of the monitoring device shown in

Fig. 2 according to an embodiment of the present invention.

Fig. 5 is a flowchart showing operation of the monitoring device shown in Fig. 2 according to another embodiment the present invention.

[BEST MODE FOR CARRYING OUT THE INVENTION] For achieving the above object, the present invention provides a device for monitoring door status of an elevator system including: at least two door switches including a first door switch, of which one terminal is coupled to a ground, and a second switch, of which one terminal is coupled to a power source via a pull-up unit, wherein the at least two door switches are serially coupled to one another, respectively provided on doors of floors, and respectively turned on or off by opening or closing the doors; at least two supplementary switching elements respectively coupled to the at least two door switches in parallel; and an abnormal door detector for detecting an abnormal status of a door of the elevator system by receiving output from a terminal, which is coupled to the pull-up unit of the second door switch, and determining which door is under the detected abnormal status by turning on and/or off at least one of the supplementary switching elements if an abnormal status is detected.

According to another aspect of the present invention, a method for monitoring door status of an elevator system, which includes at least two door switches including a first door switch, of which one terminal is coupled to a ground, and a second switch, of which one terminal is coupled to a power source via a pull-up unit, wherein the at least two door switches are serially coupled to

one another, respectively provided on doors of floors, and respectively turned on or off by opening or closing the doors; and at least two supplementary switching elements respectively coupled to the at least two door switches in parallel, including steps of receiving an output from a terminal coupled to the pull-up unit of the second door switch; detecting an abnormal status of a door of the elevator system in response to receiving the output from the terminal coupled to the pull-up unit of the second door switch; and determining on which floor an abnormal door is located by turning on and/or off at least one of the supplementary switching elements if an abnormal status is detected.

According to another aspect of the present invention, an elevator controller for controlling operation of an elevator system including: at least two door switches including a first door switch, of which one terminal is coupled to a ground, and a second switch, of which one terminal is coupled to a power source via a pull-up unit, wherein the at least two door switches are serially coupled to one another, respectively provided on doors of floors, and respectively turned on or off by opening or closing the doors; at least two supplementary switching elements respectively coupled to the at least two door switches in parallel; and an abnormal door detector for detecting an abnormal status of a door of the elevator system by receiving output from a terminal, which is coupled to the pull-up unit of the second door switch, and determining which door is under the detected abnormal status by turning on and/or off at least one of the supplementary switching elements if an abnormal status is detected.

Now, a monitoring device for monitoring door status of an elevator system and a method thereof and an elevator controller using the same according to a preferred embodiment of the present invention is described in detail with reference to the accompanied drawings.

Fig. 2 is an equivalent circuit diagram of the monitoring device for monitoring door status in an elevator system according to the present invention. A monitoring device 100 for monitoring door status of the present invention includes door switches 112,114,116 and 118, wherein each of the door switches 112, 114, 116 and 118 is provided on a door of each floor, and turned on or off by opening or closing the door. The door switches 112,114,116 and 118 are connected in series with one another. One terminal of the door switch 112 in the ground floor is coupled to ground. One terminal of the door switch 118 in the top floor is coupled to a power source Vcc through a pull-up unit 130, and the terminal is also used as a monitoring terminal A.

Besides, the monitoring device 100 of the present invention further includes two or more of supplementary switching element 122,124,126 and 128 respectively coupled to each of the door switches 112,114,116 and 118 in parallel.

According to an embodiment of the present invention, the supplementary switching element 122,124,126 or 128 may be a normal-open, or normal-off, relay. The"normal-open relay"means a relay which maintains open, or off, status in an initial and ! or a normal status. In respect to the operation and function of the supplementary switching elements 122,124,126 and 128, details are described later referring to Figs. 4 and 5.

The monitoring device 100 of the present invention further includes an abnormal door detector 110. The abnormal door detector 110 detects an abnormal status of a door of the elevator system by receiving output from the terminal A, which is coupled to the pull-up unit 130 of the door switch 116 in the top floor. If the abnormal door detector 110 detects an abnormal status, the abnormal door detector 110 determines which door ("abnormal door") is under the detected abnormal status by turning on and/or off the supplementary switching elements 122,124,126 and 128.

The abnormal door detector 110 may easily be embodied by programming a microprocessor to perform operations, which are described later in detail referring to Fig. 4 or Fig. 5. Alternatively, according to another embodiment of the present invention, the abnormal door detector 110 may also be embodied by programming a microprocessor already provided to an elevator controller (not shown) for controlling general operations of the elevator system without having a dedicated microprocessor for the abnormal door detector 110.

Further, the abnormal door detector 110 may be embodied by using discrete circuit elements, as describe below referring to Fig. 3. The abnormal door detector 110 embodied by the combination of discrete circuit elements can be implemented in a single body with the elevator controller.

Now, referring to Fig. 3, another embodiment of the abnormal door detector 110 is described in detail. The abnormal door detector 110 includes an output reader 300 for reading output of the monitoring terminal and determining whether the output is high or low.

The abnormal door detector 110 further includes a mode register 302 for setting operation of the elevator system to enter into an abnormal door detecting mode, where it is determined which floor the abnormal door is located on, if the output reader 300 determines that the output of the monitoring terminal A is high.

The abnormal door detector 110 further includes a switching element controller 304 for controlling any one, any combination or any sub-combination of the supplementary switching elements 122,124,126 and 128 provided to the doors from the lowest to the highest floors to be turned on and/or off in case the abnormal door detecting mode ("detecting mode") is activated by the mode register 302.

The abnormal door detector 110 further includes a counter 306 for counting the number of the supplementary switching elements 122,124,126 and 128 which are controlled to be turned on and/or off by the switching element controller 304, in case the detecting mode is activated by the mode register 302.

The abnormal door detector 110 further includes an abnormal floor deciding unit 308 for deciding on which floor the abnormal door is located when the output reader 300 determines that the output of the monitoring terminal A is high in case the detecting mode is activated.

Now, the operation of the monitoring device 100 of an elevator system of the present invention is described in detail with reference to Figs. 4 and 5. Fig. 4 is a flowchart showing operation of the monitoring device shown in Fig. 2 according to an embodiment of the present invention. Fig. 5 is a flowchart showing operation of the monitoring device shown in Fig. 2 according to another embodiment the

present invention. Fig. 4 shows operations of the abnormal door detector 110 which is embodied by programming a microprocessor provided to the elevator controller or a dedicated additional microprocessor. Fig. 5 shows operations of the abnormal door detector 110 which is embodied by the combination of discrete circuit elements as shown in Fig. 3.

Referring to Fig. 4, when each door of each floor is normally closed, the output of the monitoring terminal A is low because a closed circuit is established from the power source Vcc to the ground via the pull-up unit 130. In this case, the on or off statuses of the supplementary switching elements 122,124,126 and 128 do not give any effect to the output of the monitoring terminal A.

However, in case one or more of the door switches 112,114,116 and 118 is/are turned off due to the abnormal status of a door of any floor, the output of the monitoring terminal A becomes high, and it can be recognized that a door is under an abnormal status by maintaining all of the supplementary switching elements 122,124,126 and 128 to be open (off). Therefore, as mentioned above, it is preferable to use a normal-open relay, but the present invention is not limited to this.

Firstly, when electric power is applied to the monitoring device 100 of an elevator system in present invention and operation of the monitoring device 100 is started, the abnormal door detector 110 monitors the output of the monitoring terminal A (S402). If it is determined that the output of the monitoring terminal A is low, the elevator system is maintained to be in a normal operation. However, if the output of the monitoring terminal A is high (S404), the operation enters into

the abnormal door detecting mode for detecting which floor the abnormal door is located on (S406). The reason for entering into the abnormal door detecting mode is to indicate that the output of the monitoring terminal A of this mode is for detecting on which floor the abnormal door is located and different from one of a normal operation.

Next, the output of the monitoring terminal A is made to be low by turning on all supplementary switching element 122,124,126 and 128 of every floor. Next, the supplementary switching element 122 on the ground floor is turned off (S410), and the output of the monitoring terminal A is checked. In case the output is determined to be high (S414), it is determined that an abnormal status occurs to the door of the floor of which the supplementary switching element 122 is switched off (S416). Then, the supplementary switching element 122 is turned on again (S418).

But, if the output of the monitoring terminal A is determined to be low in the step S414, since the door of which the supplementary switching element 122 is currently turned off is in normal operation status, the step S418 is performed again to turn on the supplementary switching element 122 again.

Next, it is determined whether or not the supplementary switching element 122 currently turned on is that of the top floor (S420). If it is determined that the supplementary switching element 122 currently turned on is not that of the top floor, the supplementary switching element 124 of the next floor is turn off (S422).

And then, the steps from S412, where output of the monitoring terminal A is checked, to S420 are performed again.

The above described steps are repeated until the supplementary switching element 128 of the top floor is tested, and then all supplementary switching element 122,124,126 and 128 are turned off again (S424). Then, the abnormal door detecting mode is ended (S426), and operation control is returned to the normal mode.

Therefore, according to the above described method, it is possible to quickly confirm on which floor the abnormal door is located when an abnormal status occurs.

Now, referring to Fig. 5, operations shown in Fig. 5 are generally similar to those of Fig. 4, except that the steps S406, S416 and S422 are respectively substituted by steps S506, S516 and S522. According to the present embodiment shown in Fig. 5, there is no microprocessor as mentioned above because the abnormal door detector 110 includes circuit elements like the counter 306, etc. The general operations are similar to those shown in Fig. 4, and only the differences will be described in detail.

First, the step S506 of Fig. 5 corresponds to the step S406 of Fig. 4. The counter 306 resets its variables to be zero when the mode register 302 reports the start of the detecting mode. The switching element controller 304 recognizes a floor where a door to be controlled according to the count of the counter 306 is located. For example, if the count of the counter 306 is zero, the supplementary switching element 122 of the ground floor is controlled. If the count of the counter 306 is larger than zero, a door located on an upper floor indicated by the count of the counter 306. Detailed numerical value of the floor is dependant on the structure

of the building, such as the number of the basement floors, and the details are omitted because it is a simple matter of design selection.

Next, step S516 of Fig. 5 corresponds to the step S416 of Fig. 4. In the step S516, the abnormal floor deciding unit 308 confirms the abnormal floor using the count of the counter 306 and information of the building.

Next, step S522 of Fig. 5 corresponds to the step S422 of Fig. 4. In the step S522, the supplementary switching element of next floor is turned off and the count of the counter 306 is increased by one (1).

[INDUSTRIAL APPLICABILITY] According to the present invention, it is possible to reduce time and effort for repairing and/or constructing an elevator system in a building by promptly detecting a floor on which an abnormal door is located when an abnormal status has happened to the elevator door.