ELEVATOR SYSTEMS

Abstract

An elevator system includes a hoistway (217) including a landing (225A-225C), which includes a landing door (227A-227C), an elevator car (203), comprising an elevator car door (229), arranged to move within the hoistway (217), a first safety switch (231; 233) configured to indicate a potential hazard in the elevator system (201) and a controller (215). The controller (215) is configured, when the first safety switch (231; 233) is triggered, to stop movement of the elevator car (203) and determine whether the elevator car (203) is located anywhere within an unlocking zone (253) in the hoistway. The controller is further configured, if it is determined that the elevator car (203) is located anywhere in the unlocking zone (253), to allow the elevator car door (229) and landing door (227A-227C) to be opened.

Claims

1. An elevator system (201) comprising: a hoistway (217) comprising a landing (225A-225C) which comprises a landing door (227A-227C); an elevator car (203), comprising an elevator car door (229), arranged to move within the hoistway (217); a first safety switch (231; 233) configured to indicate a potential hazard in the elevator system (201); and a controller (215) configured, when the first safety switch (231; 233) is triggered, to: stop movement of the elevator car (203); determine whether the elevator car (203) is located anywhere within an unlocking zone (253) in the hoistway; and if it is determined that the elevator car (203) is located anywhere in the unlocking zone (253), to allow the elevator car door (229) and landing door (227A-227C) to be opened.

2. The elevator system (201) of claim 1, wherein the landing (225A-225C) comprises a landing floor (226A-226C), the elevator car (203) comprises a car floor (204), and wherein the unlocking zone (253) comprises: a first portion space (253A) within the hoistway (217) whereby, if the elevator car (203) is present therein, the car floor (204) and landing floor (226A-226C) are aligned; and a second portion of space (253B) within the hoistway (217) whereby, if the elevator car (203) is present therein, the car floor (204) and landing floor (226A-226C) are misaligned.

3. The elevator system (201) of claim 1, wherein the first safety switch (231; 233) indicates a first category of potential hazard within the elevator system (201), and wherein the elevator system (201) further comprises a second safety switch (239) configured to indicate a second category of potential hazard within the system (201), and wherein the controller (215) is configured to stop movement of the elevator car (203) when the second safety switch (239) is triggered and configured to prevent the opening of the elevator car door (229) and landing door (227A-227C) irrespective of whether the elevator car is in the unlocking zone.

4. The elevator system (201) of claim 1, wherein the triggering of the first safety switch (231; 233) indicates that the elevator car (203) is at a particular position within the hoistway (217) and wherein the controller (215) determines whether the elevator car (203) is within the unlocking zone (253) based on the triggering of the first safety switch (231; 233).

5. The elevator system (201) of claim 1, wherein the first safety switch (231; 233) is a physical switch arranged in the hoistway (217).

6. The elevator system (201) of claim 1, wherein the landing is a terminal landing (225A;225B) of the hoistway (217), and wherein the first safety switch (231; 233) is a final limit switch configured to indicate the elevator car (203) has reached a final limit of the hoistway (217).

7. The elevator system (201) of claim 1, further comprising a position reference system (243) configured to output a position of the elevator car (203) within the hoistway (217), and wherein the controller (215) is configured to determine whether the elevator car (203) is in the unlocking zone (253) using the position output by the position reference system (243).

8. The elevator system (201) of claim 7, wherein the position reference system (243) is an absolute position reference system.

9. The elevator system (201) of claim 1, further comprising a warning device (261; 265; 267) configured to generate a warning indicating that the elevator car door (229) and landing door (227A-227C) are misaligned.

10. The elevator system (201) of claim 9, wherein the elevator car (203) comprises a car operating panel (257) and the warning device (261; 265; 267) is integrally provided with the car operating panel (257).

11. A method of operating an elevator system (201), wherein the elevator system (201) comprises a hoistway (217) comprising landing (225A-225C), which comprises a landing door (227A-227C), and an elevator car (203), comprising an elevator car door (229), which is arranged to move within the hoistway (217), the method comprising: stopping movement of the elevator car (203) when a potential hazard is detected; determining whether the elevator car (203) is located within an unlocking zone (253) within the hoistway (217); and allowing the elevator car door (229) and landing door (227A-227C) to be opened if the elevator car (203) is anywhere within the unlocking zone (253).

12. The method of claim 11, wherein the landing (225A-225C) comprises a landing floor (226A-226C), the elevator car (203) comprises a car floor (204), and wherein the unlocking zone (253) comprises: a first portion space (253A) within the hoistway (217) whereby, if the elevator car (203) is present therein, the car floor (204) and landing floor (226A-226C) are aligned; and a second portion of space (253B) within the hoistway (217) whereby, if the elevator car (203) is present therein, the car floor (204) and landing floor (226A-226C) are misaligned.

13. The method of claim 11, further comprising: determining whether the potential hazard is a first category of potential hazard or a second category of potential hazard; wherein if the potential hazard is a first category of potential hazard, allowing the elevator car door (229) and landing door (227A-227C) to be opened if the elevator car (203) is in the unlocking zone (253); and wherein if the potential hazard is a second category of potential hazard, preventing the elevator car door (229) and landing door (227A-227C) from being opened.

14. A computer program product comprising computer-executable instructions, optionally embodied in a non-transitory computer readable medium, which, when read by a machine, cause the machine to perform the method according to claim 11.

15. A computer readable medium having the computer program product of claim 14 stored therein.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Certain examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

[0042] FIG. 1 is a schematic illustration of an elevator system that may employ various examples of the present disclosure;

[0043] FIG. 2 is a schematic illustration of an elevator system in accordance with an example of the present disclosure;

[0044] FIG. 3 is schematic illustration showing the connection between various

[0045] components of the elevator system shown in FIG. 2;

[0046] FIG. 4 is a schematic illustration showing the elevator car of FIG. 2 aligned with a landing;

[0047] FIG. 5 is a schematic illustration showing the elevator car of FIG. 2 misaligned with a terminal landing and with the elevator car door and landing door closed;

[0048] FIG. 6 is a schematic illustration of the elevator car in the same position as in FIG. 5, except with the elevator car door and landing door opened;

[0049] FIG. 7 is a schematic illustration showing the elevator car of FIG. 2 misaligned with an intermediate landing with the elevator car door and landing door closed;

[0050] FIG. 8 is a schematic illustration showing the elevator car in the same position as in FIG. 7, except with the elevator car door and landing door opened;

[0051] FIG. 9 is a schematic illustration of a car operating panel including a warning device;

[0052] FIG. 10 is a flow chart illustrating a method in accordance with an example of the present disclosure.

DETAILED DESCRIPTION

[0053] FIG. 1 is a schematic illustration of an elevator system that may employ various examples of the present disclosure.

[0054] FIG. 1 is a perspective view of an elevator system 101 including an elevator car 103, a counterweight 105, a tension member 107, a guide rail 109, an elevator machine 111, an encoder 113, and a controller 115. The elevator car 103 and counterweight 105 are connected to each other by the tension member 107. The tension member 107 may include or be configured as, for example, ropes, steel cables, and/or coated-steel belts. The counterweight 105 is configured to balance a load of the elevator car 103 and is configured to facilitate movement of the elevator car 103 concurrently and in an opposite direction with respect to the counterweight 105 within a hoistway 117 and along the guide rail 109.

[0055] The tension member 107 engages the elevator machine 111, which is part of an overhead structure of the elevator system 101. The elevator machine 111 is configured to control movement between the elevator car 103 and the counterweight 105, and thus control the position of the elevator car 103 within the hoistway 117. The encoder 113 may be mounted on a fixed part at the top of the hoistway 117, such as on a support or guide rail, and may be configured to provide position signals related to a position of the elevator car 103 within the hoistway 117.

[0056] In other embodiments, the encoder 113 may be directly mounted to a moving

[0057] component of the elevator machine 111, or may be located in other positions and/or configurations as known in the art. The encoder 113 can be any device or mechanism for monitoring a position of an elevator car and/or counterweight, as known in the art.

[0058] The controller 115 is located, as shown, in a controller room 121 of the hoistway 117 and is configured to control the operation of the elevator system 101, and particularly the elevator car 103. For example, the controller 115 may provide drive signals to the elevator machine 111 to control the acceleration, deceleration, levelling, stopping, etc. of the elevator car 103. The controller 115 may also be configured to receive position signals from the encoder 113 or any other desired position reference device. When moving up or down within the hoistway 117 along guide rail 109, the elevator car 103 may stop at one or more landings 125 as controlled by the controller 115. Although shown in a controller room 121, those of skill in the art will appreciate that the controller 115 can be located and/or configured in other locations or positions within the elevator system 101. The controller 115 may, for example, be located remotely or in the cloud.

[0059] The elevator machine 111 may include a motor or similar driving mechanism. The elevator machine 111 may be configured to include an electrically driven motor. The power supply for the motor may be any power source, including a power grid, which, in combination with other components, is supplied to the motor. The elevator machine 111 may include a traction sheave that imparts force to tension member 107 to move the elevator car 103 within hoistway 117.

[0060] Although shown and described with a roping system including a tension member 107, elevator systems that employ other methods and mechanisms of moving an elevator car within a hoistway may employ embodiments of the present disclosure. For example, examples may be employed in ropeless elevator systems using a linear motor to impart motion to an elevator car. Examples may also be employed in ropeless elevator systems using a hydraulic lift to impart motion to an elevator car. FIG. 1 is merely a non-limiting example presented for illustrative and explanatory purposes.

[0061] FIG. 2 depicts an elevator system 201 in accordance with an example of the present disclosure. The elevator system 201 shown in FIG. 2 may employ any of the features of the elevator system 101 described above with respect to FIG. 1. The elevator system 201 comprises a hoistway 217 which comprises a lower terminal landing 225A, an intermediate landing 225B and an upper terminal landing 225C. The lower terminal landing 225A comprises a landing floor 226A and a landing door 227A, the intermediate landing 225B comprises a respective landing floor 226B and a landing door 227B and the upper terminal landing comprises a respective landing floor 226C and a landing door 227C. Whilst in the example depicted the elevator system 201 comprises three landings 225A-225C, it will be appreciated that this is just for illustration purposes and the elevator system 201 may comprise any suitable number of landings.

[0062] As depicted, an elevator car 203, which comprises an elevator car door 229, is arranged to move within the hoistway 217. The elevator car 203 comprises a car floor 204. The elevator car 203 is coupled to a tension member 207 which is coupled to an elevator machine 211 arranged at the top of the hoistway 217. The elevator machine 211 is configured to move the elevator car 217 by moving the tension member 207. A controller 215 controls operation of the elevator machine 211, the elevator car 203, including the elevator car door 229, as well as operation of the landing doors 227A-227C. The controller 215 may be distributed in any suitable manner so as to control the components of the elevator system 201.

[0063] The elevator system 201 further comprises a first safety switch 231, which is in the form of a final limit switch, arranged in the hoistway 217. As depicted, the first safety switch is located in a region of the hoistway 217 a short distance below the landing floor 226A of lower terminal landing 225A. In the example depicted, the first safety switch 231 is a physical switch which is triggered as the elevator car 203 moves into the space in the hoistway 217 where the safety switch 231 is located.

[0064] Another first safety switch 233, which is also a final limit switch, is arranged in an upper portion of the hoistway 217, a short distance above the top of the landing door 227C of the upper terminal landing 225C. Accordingly, the first safety switches 231, 233, are arranged to detect when the elevator car 203 has moved past the landing doors 227A, 227B, respectively, to a position whereby the car floor 204 and landing floor 226A, 226C are misaligned. The first safety switch 231 and the further first safety switch 233 may detect the presence of the elevator car 203 via any suitable means. For example, the first safety switches 231, 233 may comprise a mechanical element which is triggered by the elevator car 203, when the elevator car 203 reaches the respective first safety switches 231, 233.

[0065] Alternatively, the first safety switches 231, 233 may comprise a contactless means for detecting the presence of the elevator car 203. For example, the first safety switches 231, 233 may comprise an optical or magnetic detection means. The first safety switches 231, 233 may also be configured as virtual safety switches which are embedded within software within the elevator system 201, e.g. the controller 215.

[0066] The first safety switches 231, 233 are positioned in a pre-set position such that the triggering of either of these first safety switches also indicates the position of the elevator car 203 in the hoistway 217. As such, the elevator controller 215 may be able to determine whether the elevator car is within an unlocking zone based the first safety switch 231, 233 which is triggered. Triggering of the first safety switches 231, 233 indicates a first category of potential hazard in the elevator system.

[0067] As depicted, a buffer 235 is located at the bottom of the hoistway 217. Another safety switch may be arranged on the buffer 237, such that if the elevator car 203 contacts the buffer 235, the safety switch is triggered. Such a safety switch may be a first safety switch, i.e. indicate a hazard which does not alone preclude the elevator car door and landing door from being opened.

[0068] A second safety switch 239 is arranged on the roof 241 of the elevator car 203. The second safety switch 239 may be an emergency-stop switch, which can be triggered by a maintenance engineer when present on the roof 241 of the elevator car 203. Triggering of the second safety switch 239 indicates a second category of potential hazard within the elevator system whereby it is not safe for the elevator door 229 and landing door 227A-227C to be opened.

[0069] An absolute position reference system 243 is arranged on the elevator car 203. Whilst an absolute position reference system 243 is depicted and described below, it will be appreciated that any other form of position reference system may be utilised instead. The absolute position reference system 243 may, for example,

[0070] comprise an optical or magnetic absolute position reference system as described above. In such examples, a visual or magnetic code may be provided on the wall 240 of the hoistway 217 and a suitable detector for reading the code may be present on the elevator car 203. The absolute position reference system 243 may thus be capable of outputting a position of the elevator car 203 within the hoistway 217.

[0071] The first safety switches 231, 233, the second safety switch 239, and the absolute position reference system 243, may all be connected to the controller 215 via any suitable means, e.g. a wired, or wireless connection.

[0072] FIG. 3 shows a schematic illustration of the connection of some of the components of the elevator system 201. As depicted, the controller 215, indicated by the dashed line, may be subdivided into a safety controller 215A, which monitors first safety switches 231, 233, second safety switch 239 and absolute position reference system 243, and a general controller 215B which controls operation of the elevator system 201, e.g. the elevator machine 211 etc. Of course, any suitable distribution of the controller 215 may be provided as long as it is able to function in the manner described. In the example depicted, the safety controller 215A, first safety switches 231, 233, second safety switch 239 and position reference system 243 form a safety chain.

[0073] A power supply 245 provides power to the safety controller 215A. The power supply 245 may also supply power to the general controller 215B and other components of the elevator system 201. Of course, a separate dedicated power supply may be provided for each of the safety controller 215A and the general controller 215B. As depicted, the safety controller 215A is coupled to an actuator 247 on an emergency brake (not depicted) and the motor (not depicted) of the elevator machine 211. As such, the safety controller 215A is able to stop movement of the elevator car 203 through operation of the actuator 247. A human machine interface (HMI) 249 is also provided and coupled to the safety controller 215A. The HMI 249 may allow an on-site person, e.g. a maintenance engineer, to interact with the safety controller 215A. For example, it may allow a safety engineer to reset the safety controller 215A, thereby allowing the elevator car 203 to move, once any issue has been resolved.

[0074] As depicted, the first safety switches 231, 233, second safety switch 239, and absolute position reference system 243 are coupled to safety nodes 251A, 251B, 251C within the safety controller 215A. Of course the system may comprise any suitable number of safety nodes. Each of the safety nodes 251A, 251B, 251C may separately process the output from its respective safety switch 231, 233, 239, or absolute position reference system 243. The safety nodes 251A, 251B, 251C are connected within the safety controller 215A by a Controller Area Network (CAN) Bus. A CAN is not essential and any other communication means may be employed.

[0075] The safety controller 215A may store an association between the first safety switches 231, 233 and their respective positions in the hoistway, as well as the positions which define an unlocking zone for each of the landings 225A-225C. The safety controller 215A may be configured that if either of first safety switches 231, 233 is triggered, it instantly knows that the elevator car 203 will be within an unlocking zone due to the positioning of the first safety switches 231, 233. However, the safety controller 215A may also store positions which define the unlocking zone such that a position determined from a first safety switch 231, 233, or from the position reference system 243 can be compared to the positions which define the unlocking zone so as to determine whether the elevator car 203 is in an unlocking zone.

[0076] Operation of the elevator system 201 according to an example of the present disclose will now be described with reference to FIGS. 4-8. FIG. 4 is a view of the elevator system 201, depicted in FIG. 2, focussing on the lower terminal landing 225A. In the illustration shown in FIG. 4, the elevator car 203 is at a position within the hoistway 217 whereby it is aligned with the lower terminal landing 225A such that the car floor 204and landing floor 226A are fully aligned. When in this position, assuming that the second safety switch 239 has not been triggered, then the elevator car door 229 and landing door 227 will be free to be opened and closed in the normal manner

[0077] Whilst the safety switch 231 has not been triggered in the position shown in FIG. 4, another safety switch within the elevator system 201 could be triggered whilst the elevator car 203 is in this position. For example, a first safety switch indicating that the elevator car 203 has been overloaded with passengers may be triggered. If such a safety switch is triggered, the controller 215 may determine whether the elevator car 203 is within an unlocking zone 253. In the example depicted, the unlocking zone 253 is depicted as a vertical region within the hoistway 217 wherein if the bottom 255 of the elevator car 203 is within this unlocking zone 253, then it will be possible to open the elevator door 229 and the landing door 227A, of course depending on which safety switch has been triggered. As depicted, the unlocking zone 253 incorporates a first portion of space 253A within the hoistway 217 whereby the car floor 204 and landing floor 226A are aligned, and further includes a second portion of space 253B within the hoistway 217 whereby the car floor 204 and landing floor 226A will be misaligned. As depicted, the first portion of space 253A has a small extent in the vertical direction. Accordingly, the car floor 204 and landing floor 226A may be considered to be aligned even when they are actually misaligned by a small amount. For example, the first portion of space 253A may extend 20 mm in the vertical direction and be positioned such that the car floor 204 and landing floor 226A can be offset by up to 10 mm above or below one another, and still be considered to be aligned. The unlocking zone 253 need not necessarily be defined based on a reference point on the bottom 255 of the elevator car 203 and may instead be defined based on any other suitable reference point of the elevator car 203.

[0078] In the position depicted in FIG. 4, the bottom 255 of the elevator car 203 is clearly within the unlocking zone 253 and thus the elevator door 229 and landing door 227A, whilst depicted as closed, may be opened. In the situation depicted in FIG. 4, as no safety switch has been triggered which indicates a position of the elevator car 203, the position of the elevator car 203 may be determined using the position reference system 243 and this position may be used by the controller 215 to determine whether the elevator car 203 is in the unlocking zone.

[0079] With the elevator car 203 in the position shown in FIG. 4, a passenger may board the elevator car 203. Once the passenger has boarded, the controller 215 may instruct the elevator machine 211 to begin hoisting the elevator car 203 upwards in the hoistway 217. However, in some instances, the elevator machine 211 may fail and as a result the elevator car 203 may drop a small amount in the hoistway 217.

[0080] This is depicted in FIG. 5. As shown in FIG. 5, the elevator car 203 has moved past the landing floor 226A of the lower terminal landing 225A such that the car floor 204 and landing floor 226A are no longer fully aligned. The elevator car door 229 and landing door 227A are still closed at the instant in time depicted in FIG. 5. As illustrated, the bottom 255 of the elevator car 203 is adjacent the safety switch 231 such that the safety switch 231 is triggered. As a result, the controller 215 (not visible in this Figure), stops any further movement of the elevator car 203. This may be achieved by the safety controller 215A triggering operation of the actuator 247 which operates a safety brake (not shown) on the elevator car 203 as well as a brake on the motor of the elevator machine 211.

[0081] FIG. 6 depicts the elevator car 203 in the position shown in FIG. 5 as the controller 215 continues to operate. In this example, as it is the first safety switch 231 which has been triggered, and not the second safety switch 239, the elevator door 227A and landing door 229 are not necessarily prevented from being opened. As the first safety switch 231 has been triggered, the controller 215 may then determine whether the elevator car 203 is in the unlocking zone 253 based on a position known from the triggering of the first safety switch 231. As depicted, the bottom 255 of the elevator car 203 is within the unlocking zone 253, specifically in the second portion of space 253B. As a result, the controller 215 allows the elevator car door 229 and the landing door 227A to be opened. Advantageously, despite the misalignment, any passengers are still able to leave the elevator car 203, and trapping of the passengers is avoided. If, however, it was determined that the elevator car 203 was not within the unlocking zone 253, the controller 215 would prevent the opening of the landing door 229 and landing door 227A.

[0082] In the example above, when determining whether the elevator car 203 is within the unlocking zone 253, the position of the elevator car 203 within the hoistway may be determined using the first safety switch 231 and/or a position output by the absolute position reference system 243, as explained previously.

[0083] FIG. 7 depicts the situation whereby the elevator car 203 has travelled within the hoistway 217, has passed the intermediate landing 225B to a position whereby the car floor 204 and landing floor 226B are misaligned, and has been stopped. The elevator car 203 may have been travelling to the intermediate landing 225B, and thus a virtual safety switch (not depicted) within the elevator system 201, which operates based on a position detected of the elevator car 203, may have been triggered due to an apparent malfunction of the elevator system 201. When in this position, the elevator car door 229 and landing door 227B will initially be closed.

[0084] The virtual safety switch may be a first safety switch, i.e. indicate a first category or potential hazard.

[0085] As depicted in FIG. 8, the absolute position reference system 243 may be used to determine the position of the elevator car 203 within the hoistway. The absolute position reference system 243 may be capable of providing a highly accurate position of the elevator car 203 within the hoistway 217. In the example depicted in FIG. 8, the bottom 255 of the elevator car 203 is only a short distance from the intermediate landing 225B and is thus within the unlocking zone 253, specifically it is within the second portion of space 253B of the unlocking zone 253. The controller 215 may thus conclude that the elevator car 203 is within the unlocking zone 253. As such, the controller 215 may allow the elevator car door 229 and landing door 227B to be opened (as depicted in FIG. 8). Any passengers within the elevator car 203 may then be free to leave the elevator car 203 and the unnecessary trapping of the passengers is avoided even at the intermediate landing 225B.

[0086] If, in any of the examples described above, it was determined that the elevator car 203, specifically the bottom 255 thereof, was not in the unlocking zone 253, then the controller 215 may prevent the opening of the elevator car door 229 and landing doors 227A-227C. Similarly, if, in any of the examples described above, the second safety switch 239 is triggered, instead of, or in addition to any of the first safety switches 231, 233, then the controller 215 would instead prevent the opening of the elevator car door 229 and at least the relevant landing door 227A-227C. As such, the elevator car 203 would remain in the state shown in FIGS. 5 and 7 whereby the elevator car door 229 and landing door 227A, 227B remains closed. Whilst this would cause the passengers to remain trapped in the elevator car 203, it may ensure the safety of the passengers in the presence of the second category of potential hazard. The elevator car door 229 and landing door 227A-227C would remain closed until appropriate action is taken, e.g. by a maintenance engineer resetting the safety controller 215A through use of the HMI 249.

[0087] FIG. 9 depicts a car operation panel (COP) 257 which may be present inside the elevator car 203. The COP 257 comprises an input means in the form of destination buttons 259 which a user may select in order to input a destination floor.

[0088] The COP 257 further comprises display panel 261 on which a visual warning 263 may be displayed. The visual warning 263 comprises the text “MIND THE STEP” as well as a warning image illustrating a person tripping over. Of course any other suitable visual warning 263 may be displayed. The COP 257 also comprises a light 265. In the case of misalignment between the car floor 204 and landing floors 226A-226C, the light may flash to issue a warning to the passenger within the elevator car 203. The COP 257 further comprises a speaker 267. The speaker 267 may be used to issue an audible warning of the misalignment between the car floor 204 and landing floors 226A-226C. Whilst the COP 257 illustrated comprises three different forms of means for generating a warning, the COP 257 may comprise any number and combination of suitable warning means. The COP 257 may be configured to output the warning when the elevator car door 229 and respective landing door 227A-227C is opened.

[0089] FIG. 10 is a flow chart which illustrates a method in accordance with an example of the present disclosure. The method will be described with reference to the elevator system 201 described above. As depicted, the method is started at step S1. At this point, the elevator car 203 may be moving though the hoistway 217. At step S2, the method includes determining whether a potential hazard has been detected. A potential hazard may be detected, for example, based on the triggering of a first safety switch 231, 233 or a second safety switch 239. When a potential hazard is detected, the method proceeds to step S3 whereby the elevator car 203 is stopped from moving in the hoistway 217. This may involve stopping of the elevator machine 211, e.g. by engaging a brake thereon, and/or engaging a safety brake on the elevator car 203 itself. The method then proceeds to step S4 whereby the type of potential hazard is assessed. In the example depicted, it is determined which type of safety switch has been triggered. If a second safety switch 239 is triggered, i.e. a second category of potential hazard is detected whereby the elevator door 229 and landing doors 227A-227C cannot be safely opened, the method proceeds to step S5 whereby the car door 229 and landing doors 227A-227C are prevented from being opened.

[0090] However, if at step S4 it is determined that a first safety switch 231, 233 has been triggered, i.e. indicating a first category of potential hazard which does not necessarily prevent the elevator door and landing doors 227A-227C from being

[0091] opened, and that no second safety switch 239 has been triggered, the method proceeds to step S6. At step S6, it is determined whether or not the elevator car 203 is within the unlocking zone 253. Determining whether the elevator car 203 is within an unlocking zone 253 may comprise determining whether the elevator car is anywhere within a first portion of space 253A whereby the car floor 204 and landing floor 226A-226C are aligned or within a second portion of space 253B whereby the car floor 204 and landing floor 226A-226C are misaligned. If the elevator car 253 is not within the unlocking zone 253, then it is concluded that it is not safe for the elevator car door 229 and the respective landing door 227A-227C to be opened, and the method proceeds to step S5 whereby the elevator car door 229 and landing door 227A-227C are prevented from being opened. If, however, the elevator car 203 is determined to be within the unlocking zone 253, the method proceeds to step S7 whereby the elevator door 229 and respective landing door 227A-227C is allowed to be opened. If the elevator door 229 and the respective landing door 227A-227C are misaligned, then the method proceeds to step S8 whereby a warning is issued informing the passenger of the misalignment before and/or after the elevator door 229 and landing door 227A-227C have been opened. Once the elevator car doors 229 and landing doors 227A-227C have been opened and the passengers have been able to leave the elevator car 203, the method ends at step S10.

[0092] If the elevator car door 229 and the landing doors 227A-227C are prevented from being opened at step S5, the method may then proceed to end at step S10. In this instance, a maintenance engineer may have to take appropriate action, e.g. to make the elevator system 201 safe so that the elevator car 203 can be moved and/or so that the passengers can leave the elevator car 203.

[0093] If, at step S2, whereby it is determined whether a hazard is detected, no hazard is detected, the method proceeds to step S9 whereby the elevator car 203 is allowed to continue moving to its target landing 225A-225C. Once the elevator car 203 has arrived at its target landing 225A-225C, assuming no other hazards are present, the elevator door 229 and the respective landing door 227A-227C is allowed to open in step S7. The method may then proceed directly to step S10, skipping step S8 where a misalignment warning is issued, and the process is ended.

[0094] In the example depicted above, the method comprises analysing the type of safety switch which has been triggered in step S4. However, in some examples, this may be optional and the method may proceed from step S3 where the elevator car 203 is stopped directly to step S6 where it is determined whether the elevator car 203 is in the unlocking zone 253. As such, steps S4 and S6 may be omitted. Such a method may be utilised when only one category of hazard is indicated by the elevator system, e.g. when the elevator system only comprises first safety switches. Similarly, the step S9 of issuing a warning is optional and may be omitted.

[0095] Accordingly, it will be appreciated by those skilled in the art that examples of the present disclosure provide an improved elevator system and method which is capable of minimising the instances whereby passengers are trapped inside an elevator car. While specific examples of the disclosure have been described in detail, it will be appreciated by those skilled in the art that the examples described in detail are not limiting on the scope of the disclosure.