# US 2019/0168995 A1 · Elevator safety system, elevator system and method of operating an elevator system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0168995 A1 - Document ID: US20190168995A1 - Status: Published application - Kind: A1 - Application number: 16/190,440 - Filed: 2018-11-14 - Published: 2019-06-06 - Earliest claimed: 2017-12-01 - Assignees: Otis Elevator Company - Applicants: Otis Elevator Company - Inventors: Andreas Tutat; Helge Krambeck - Web page: https://patentgrep.com/patent/US20190168995A1 ## CPC - B66B 5/0031: {for safety reasons} - B66B 1/3453: {Procedure or protocol for the data transmission or communication} - B66B 13/22: Operation of door or gate contacts - B66B: ELEVATORS; ESCALATORS OR MOVING WALKWAYS ({apparatus for raising or lowering persons on theatrical stages or the like A63J5/12} ; funicular railbound systems with rigid ground-supported tracks and cable traction, e.g. cliff railways, B61B9/00; arrangements of ammunition handlers in vessels B63G3/00; hoists, lifts, or conveyors for loading or unloading in general B65G; braking or detent devices controlling normal movements of winding drums or barrels B66D; ship-lifting devices E02C; garages for many vehicles with mechanical means for lifting vehicles E04H6/12; hoists for feeding ammunition or projectiles to launching apparatus or to loading mechanisms F41A9/00) ## Abstract An elevator safety system comprises a plurality of door safety units, each door safety unit; a communication bus connecting the plurality of door safety units; a control unit connected to the communication bus for allowing communication between the plurality of door safety units and the control unit; and at least one position sensor configured for providing information about the current position of an elevator car within a hoistway. Each door safety unit is assigned to an elevator hoistway door and configured for monitoring a condition of the assigned elevator hoistway door. The control unit is configured for polling door safety units included in a subset S1, S2) of the door safety units which are located within a predetermined distance (D1, D2) from the current position of the elevator car. ## Claims ### Claim 1 Elevator safety system comprising: a plurality of door safety units (12), each door safety unit (12) assigned to an elevator hoistway door (10) and configured for monitoring a condition of the assigned elevator hoistway door (10); a communication bus (16) connecting the plurality of door safety units (12); a control unit (13) connected to the communication bus (16) for allowing communication between the plurality of door safety units (12) and the control unit (13); and at least one position sensor (19) configured for providing information about the current position of an elevator car (6) within a hoistway (4); wherein the control unit (13) is configured for polling door safety units (12) included in a subset (S1, S2) of the door safety units (12) which are located within a predetermined distance (D1, D2) from the current position of the elevator car (6); and for polling door safety units (12) which are not included in said subset (S1, S2) less frequently or not at all. ### Claim 2 (depends on 1) Elevator safety system according to claim 1, wherein the control unit (13) is configured for periodically polling the door safety units (12) included in the subset (S1, S2) of door safety units (12) with a frequency (f) of 10 Hz to 30 Hz, in particular with a frequency (f) of 20 Hz. ### Claim 3 (depends on 1) Elevator safety system according to claim 1, wherein the control unit (13) is configured for polling the door safety units (12) included in the subset (S1, S2) of door safety units (12) exclusively. ### Claim 4 (depends on 1) Elevator safety system according to claim 1, wherein the control unit (13) is configured for polling the door safety units (12) not included in the subset (S1, S2) less frequently than the door safety units (12) included in the subset (S1, S2) of door safety units (12). ### Claim 5 (depends on 4) Elevator safety system according to claim 4, wherein the control unit (13) is configured for polling the door safety units (12) included in the subset (S1, S2) of door safety units (12) with a first frequency (f1), and wherein the control unit (13) is configured for polling the door safety units (12) not included in the subset (S1, S2) with a second frequency (f2) which is lower than the first frequency (f1). ### Claim 6 (depends on 1) Elevator safety system according to claim 1, wherein the control unit (13) is configured for polling door safety units (12) included in a first subset (S1) located within a first predetermined distance (D1) from the current position of the elevator car (6) more frequently than door safety units (12) included in a second subset (S2) located between the first predetermined distance (D1) and a second predetermined distance (D2) larger than the first predetermined distance (D1) from the current position of the elevator car (6), wherein the control unit (13) in particular is configured for not polling door safety units (12) not included in any of the subsets (S1, S2). ### Claim 7 (depends on 1) Elevator safety system according to claim 1, wherein the predetermined distance (D1, D2) is selected such as to include a predetermined number of landings (8) ahead of and/or behind the current position of the elevator car (6), wherein the predetermined number of landings (8) in particular is any of two, three, four or five landings (8) ahead and/or behind the current position of the elevator car (6). ### Claim 8 (depends on 1) Elevator safety system according to claim 1, further comprising a sensor (19, 25) configured for determining a direction of movement of the elevator car (6); wherein the control unit (13) is configured for polling more door safety units (12) located ahead of the moving elevator car (6) than door safety units (12) located behind the moving elevator car (6). ### Claim 9 (depends on 1) Elevator safety system according to claim 1, wherein the predetermined distance (D1, D2) depends on the speed of the elevator car (6), wherein the elevator system (12) in particular comprises a speed sensor (25) configured for detecting the speed of the elevator car (6). ### Claim 10 (depends on 1) Elevator safety system according to claim 1, wherein the door safety units (12) are configured for sending an alarm signal via the communication bus (16) in case a predetermined event is detected. ### Claim 11 (depends on 1) Elevator safety system according to claim 1, wherein the communication bus (16) is a field bus, in particular a CAN bus. ### Claim 12 (depends on 1) Elevator system (12) comprising: a hoistway (4) extending between a plurality of landings (8) and having a plurality of elevator hoistway doors (10); an elevator car (6) configured for moving along the hoistway (4) between the plurality of landings (8); and an elevator safety system according to claim 1. ### Claim 13 (depends on 12) Elevator system (12) according to claim 12, wherein the control unit (13) is configured for stopping any movement of the elevator car (6) in case an alarm signal is transmitted via the communication bus (16) and/or a polled door safety unit (12) does not respond in due time. ### Claim 14 (depends on 12) Elevator system (12) according to claim 12, wherein the position sensor (19) comprises a car component (21a) attached to the elevator car (6) and/or a hoistway component (21b) located within the hoistway (4). ### Claim 15 (depends on 1) Method of operating an elevator safety system according to claim 1, wherein the method includes polling door safety units (12) included in a subset (S1, S2) of the door safety units (12) which are located within a predetermined distance (D1, D2) from the current position of the elevator car (6) and polling the door safety units (12) which are not included in said subset less frequently or not at all.