NL2001722C2 - Nurse call system for use in e.g. hospital, for communication between patient and medical staff, has communication ports connected with electric wires, and message unit arranged to communicate system with chamber-controller over wires - Google Patents

Abstract

The system has a chamber-controller (1) provided with two communication ports. A processing unit is utilized for processing transmission information between the communication ports. The communication ports are connected with multiple electric wires. A message unit is arranged to communicate the system with the chamber-controller over the electric wires. A micro-controller is arranged for enabling the communication between the message unit and the chamber-controller on a communication bus. The micro-controller and the chamber-controller are communicated based on an asymmetric protocol.

Description

Multi-drop low-cost nurse call system

The present invention relates to a nurse call system.

It further relates to a peripheral and room-controller that 5 are part of such a system.

Nurse call systems are employed in most hospitals and elderly care homes. These systems are used for communication between patients and medical staff. Typically, a nurse call system comprises a room-controller which is connected to 10 several peripherals. An example of a peripheral is a unit installed in the vicinity of the patient's bed. This unit is provided with message means, such as buttons, that a patient can operate to signal a medical emergency or to ask for assistance.

15 The room-controller is installed near the room entrance. It has a first communications port enabling remote communication with the room-controller. For instance, the room-controller can be connected to a central monitoring system. From this central system, medical personnel can be 20 dispatched to the patient. It is also possible to connect a pager system such that pressing a button will automatically trigger a pager call. Several technologies for remote communication are possible such as IP-based communication, wireless communication etc.

25 The room-controller further comprises a second communications port, which allows communication with a plurality of peripherals. Communication from and to the peripheral is processed and or relayed between the first and second port of the room-controller.

2

One important aspect of a nurse call system is the ability to be able to trace the patient's call or request back to that patient. Nowadays, this is realized by having separate wiring for each peripheral activator and indicator.

5 Adding more peripherals is therefore only possible if sufficient wiring is available in, or can easily be added to, the building.

There is a continuing demand to add more functionality to the system. One of such demands is to add bi-directional 10 communication, not only to enable a voice connection between medical staff and the patient, but also to remotely configure or operate the peripherals.

An option to alleviate the wiring requirement would be to use a communication bus to which the peripherals are 15 connected. In this latter case, each peripheral is given an identity, e.g. address, and contains intelligence to distinguish messages based on this identity. The use of a communication bus instead of separate wiring reduces the costs for installing the wiring. In addition, adding more 20 peripherals to a given system is less complex.

Given current technologies, it is possible to realize very complex systems that enable a lot of functionality. For instance, wireless communication could be used for the connection between peripherals and room-controller.

25 Several requirements for the nurse call system render prior art systems or techniques unattractive. Firstly, the costs of the system, especially the peripherals, should be kept at an absolute minimum due to the large amount of peripherals required. Secondly, the power used by the system 30 as a whole should be as low as possible. Thirdly, it must be 3 possible to install the system using wiring that is already present in the building.

It is therefore an object of the present invention to provide a nurse call system that at least partly fulfills 5 the above mentioned requirements.

This object is achieved with a nurse call system as described in claim 1. According to the invention, a peripheral in the nurse call system comprises a microcontroller that is connected to the message means. The 10 micro-controller is arranged for facilitating the communication between the message means and the room-controller over the communication bus. The micro-controller and room-controller are arranged for communication based on an asymmetric protocol at voltages substantially equal to or 15 less than a nominal operating voltage of said microcontroller. In addition, the communication bus is non-terminated.

The use of low voltages, typically around 5.5V depending on the type of semiconductor technology used, 20 reduces the need for costly voltage down-conversion in the peripherals. By using an asymmetric protocol, existing wiring can be more easily used. Symmetric protocols, like RS-485 or RS-422, all rely on a minimum of four wires, i.e. supply, ground and two data lines. However, the use of an 25 asymmetric protocol in combination with low-voltage operation requires a well defined ground level. Hence, current consumption must be kept at a minimum to avoid voltage drops in both the supply and ground lines. To this end, a non-terminated communication bus has been chosen. The 30 absence of resistor termination eliminates the need for separate bus drivers in the peripherals, further reducing costs, complexity and current consumption of the system. The 4 above mentioned combination of features provides a system that can be used with existing wire structures and offers the required functionality.

Further advantages can be obtained if the room-5 controller is arranged to communicate with a plurality of peripherals connected to the communication bus and if the aforementioned protocol is a serial multi-drop protocol. In serial communication, bits are sent one-by-one, instead of multiple bits parallel. This latter parallel technique 10 requires more wires and more complex and costly electronic circuitry. In multi-drop communication, several devices, such as peripherals or room-controllers, can be simultaneously connected to the same communication bus. A process of arbitration is used to determine which device is 15 sending out information while the other devices are receiving.

The micro-controller comprises a plurality of terminals. Preferably, at least a supply terminal and an input/output (I/O) terminal of the micro-controller have a 20 low-frequent direct connection to said communication bus.

Within the context of the present invention, a low-frequent direct connection does not exclude the use of filtering at the terminals of the micro-controller, for instance to remove high-frequency components or for 25 electrostatic discharge protection.

It is also possible that the supply terminal of the micro-controller is not fed by the communication bus but by means of a separate power supply, e.g. an internal battery or by the mains network.

30 Preferably, the communication between peripheral and room-controller comprises speech. In this way, a patient can 5 talk to medical staff or vice-versa. It is convenient if the speech data is transferred over a dedicated data line in the communication bus. Such a data line is exclusively used for speech communication and not for other information related 5 for instance to the buttons on the peripheral. This means that the common ground wire must be very noise-less to avoid audible effects, hence no current consuming digital bus termination.

At this point, it should be noted that non-terminated 10 busses are prone to reflection. Consequently, the bit rate in the system is kept relatively low, at around 2kbps.

To enable identification of the peripherals such that a message can be traced back to the corresponding peripheral, it is advantageous if each peripheral is assigned a specific 15 address, and if the aforementioned protocol is frame-based. In such a frame-based protocol, each frame comprises an address field, a status message from the room-controller to a peripheral pertaining to the address in the address field, and a status message from the peripheral pertaining to the 20 address in the address field to the room-controller.

According to this frame-based protocol, the room-controller sequentially communicates with all the peripherals participating in the communication.

Preferably, the peripherals comprise switches connected 25 to the micro-controller. These switches can be operated to set an address of the peripheral. This option is less complex and less costly than for instance using techniques in which the room-controller assigns a peripheral a specific address.

30 To improve the reliability of the system and the communication, the room-controller may comprise a memory for 6 messages received from a peripheral. In addition, the room-controller may be arranged to accept a message from a peripheral only if a predetermined amount of corresponding consecutive identical messages from the peripheral have been 5 received. For instance, the room-controller can be set-up to only accept a message if this message has been received twice. In this way, disturbances, interferences and or errors in the communication can be greatly reduced. It should be obvious to the skilled person in the art, that 10 similar measures can be implemented on the peripheral side of the system.

To enable communication between the room-controller and a peripheral or a plurality of peripherals, the devices need to be synchronized. Typically, the room-controller is set-up 15 as the master device dictating the timing of the communication. In case the peripherals do not receive timing information on a dedicated line, the timing information needs to be extracted from the messages from the room-controller itself. To this end, it is advantageous if each 20 frame comprises a predetermined bit pattern and if the peripheral is arranged to synchronize with the room-controller based on this predetermined bit pattern. For instance, the peripheral can listen to the communication bus and once it has received a unique bit pattern, it can start 25 to synchronize itself with the room-controller. An example of a predetermined bit pattern is a fixed falling or rising edge.

It is convenient if each frame comprises a predetermined bit pattern for synchronizing the peripheral 30 with the room-controller before the status message from the room-controller to the peripheral, and before the status message from the peripheral to the room-controller.

7

By having the above mentioned techniques to synchronize the peripherals with the room-controller, the requirements for the internal timing circuitry in the peripheral are reduced. Consequently, the use of separate quartz crystals 5 for obtaining an accurate internal clock signal has become obsolete, which further reduces the complexity and costs of the peripheral.

If the communication comprises speech communication over a dedicated data line, it is advantageous if each frame 10 comprises a speech bit and if the peripherals and room- controller connected to the communication bus are arranged to toggle between a microphone mode and a speaker mode in response to a binary value of said speech bit.

Speech communication between room-controller and 15 peripheral can be conducted over a dedicated data line.

Because speech information is only from room-controller to peripheral or vice-versa but not both at the same time, arbitration is needed to assign which device is talking and which device is listening. To this end, a speech bit can be 20 part of the peripheral specific status message communicated from room-controller to peripheral. A drawback of this approach is that all peripherals need to receive this information to toggle to the correct mode before the actual speech communication can take place. It is therefore 25 advantageous if this speech bit is communicated outside of the peripheral specific status message but inside a part of the status message which is received and listened to by each peripheral.

In a possible implementation, the default setting for 30 speech is that each peripheral is by default in the speaker mode. Only when the room-controller needs to be in the microphone mode will the speech bit be changed by the room- 8 controller. Once, the room-controller releases control over the speech bit, peripherals will switch back to the speaker mode.

Next, the present invention will be described in more 5 detail using embodiments thereof which are illustrated in the accompanying figures in which:

Figure 1 illustrates a schematic overview of a room-controller connected to a plurality of peripherals;

Figure 2A and 2B shows an embodiment of a peripheral 10 and a schematic connection diagram of this peripheral, respectively.

Figure 3 shows a possible frame build-up of the protocol used for communication between room-controller and peripheral.

15 Figure 1 illustrates a room-controller 1 connected to a plurality of peripherals 2. Each peripheral 2 comprises a wall-unit 3 near the patient's bed and a module 4 that is connected to the wall-unit 3 but is more flexible. This figure shows a possible situation in which three 20 communication busses (BUS-0 20, BUS-1 21 and BUS-2 22) are present in a hospital room. To each communication bus a plurality of peripherals 2 can be connected, depending on the address structure that is used in the protocol. For now, it is assumed that the address field in the protocol 25 comprises three bits so that a total of eight peripherals 2 can be connected. Although in this figure identical peripherals 2 are shown, it is also possible to connect different devices provided that they can communicate with the room-controller 1 using the prescribed protocol. Other 30 devices are for instance a room display, card reader, duty selector switch or slave corridor lamp.

9

Given the specific address and communication bus a peripheral 2 is connected to, information sent from this peripheral 2 can be traced back to it. For instance, instead of medical personal being dispatched to a certain room, they 5 can now be dispatched to a specific peripheral 2, i.e. a specific patient.

The room-controller 1 is typically connected to a communication bus or network itself, e.g. Ethernet, wireless network etc. It could for instance be connected to a central 10 monitoring system for a given hospital department. From this system, medical staff like nurses or doctors can be dispatched to the patient and or communication can take place between medical staff and patient. Logging, which is a essential part of the system, is handled via the 15 communication bus, as well as looking up data bases for ID-cards. Another use is the remote download of software.

Figure 2A shows an embodiment of a peripheral in more detail. It comprises three push buttons, a medical emergency button 5, a medical assistance button 6, and a button 7 to 20 indicate that a nurse is present. In addition, three corresponding light emitting diodes (LEDs) 5'-7' are present.

The microphone is situated in the speaker module 9, which is a module that can be mounted directly aside of the 25 3-button peripheral and connected via a short 5-pole interconnect cable (not shown). Speech direction is preferably in control of the nurse, i.e. there is no speech switch at the patient side. These buttons, LEDs and speaker/microphone are examples of the aforementioned 30 message means.

10

Figure 2B shows a schematic connection diagram of this peripheral 2. The peripheral 2 is connected to a four wire (supply, ground, data, and speech) communication bus. A micro-controller 10 is connected to the communication bus, 5 buttons and LEDs. In addition, the micro-controller 10 comprises a speech controller 11, which controls the speaker/microphone 9. In figure 2b, the speaker/microphone 9 is drawn inside peripheral 2. This does not exclude the possibility that speaker/microphone 9 is placed externally. 10 This controller 11 is connected to the speech line of the communication bus and to a speech control signal 12 from the micro-controller 10. The latter signal is derived from the speech bit present in every frame of the communication protocol. If the speech bit is such that the peripheral is 15 in microphone mode, the speech controller 11 will activate the microphone 9. Audio signals from the microphone 9 will then be transferred to the speech line of the communication bus. This signal is preferably analog. A dedicated enable bit in the protocol will effectively switch on one or more 20 speech units at the same time and make a broadcast possible (speech from staff to patients in case of emergency situations).

In figure 3, an embodiment of a frame 13 of the communication protocol is illustrated. The room controller 25 sends data and the peripheral listens in time-window 30. The first bit is a zero; it is preceded by a falling edge 14. After detection of this falling edge 14, the peripheral will measure the bit time of the first bit, i.e. the start bit. From this measured bit time it deduces the sample times 30 needed for sampling the following fifteen bits. The second bit in the frame guarantees a one after the start bit. This bit is followed by the speech bit. The speech bit indicates the direction of the speech communication. The following 11 three bits represent the address field of the peripheral the communication is directed to. It should be noted at this point that every peripheral, once synchronized, reads the speech bit and the address field. The address field is 5 followed a frame bit to limit the amount of possible consecutive one's that can occur in a valid frame. This is important to avoid incorrect synchronization as will be discussed later on. Following the frame bit, there are eight status bits that represent the status message from the room-10 controller to the peripheral. After this, a parity bit is used to check the integrity of the message received so far. Next, three bits are used to indicate the boundary between the status message from the room-controller to the peripheral and the status message from the peripheral to the 15 room-controller. Firstly, a stop bit is used that is always zero. Secondly, a frame bit is used to guarantee a one after the stop bit. The peripheral uses the rising edge 15 generated by the stop and frame bits to re-synchronize with the room-controller. After having received the frame bit, 20 the peripheral seizes control over the communication bus (RC listens, peripheral answers in time-window 31). It should be noted that it is only the peripheral corresponding to the address in the address field that is able to seize the communication bus. Finally, a start bit that is always zero 25 is used to indicate the start of the status message from the peripheral to the room-controller. The start bit can also be used for another measurement of the bit time. Following the start bit, eight status message bits are sent to the room-controller. These bits are followed by a parity bit and a 30 frame bit, the latter being always one.

At several places in the frame, parity bits and frame bits with a fixed value are incorporated. Using these bits, the integrity of the message can be checked. If errors in 12 the message are found, the message can be discarded, either by the room-controller or by the peripheral. Additionally or alternatively, the peripheral can consider itself to be out-of-sync with the room-controller.

5 In figure 2B line A is a supply line, line B is a data line and line C is a speech line.

Referring back to figure 2B, the status message from the room-controller to the peripheral could for instance comprise information on the LEDs, whereas the status message 10 to the room-controller could comprise information on the status of the push buttons, e.g. whether they have been activated or not. As an example, consider the situation in which a patient presses the emergency button 5. This will trigger a signal to the micro-controller. A status message 15 will be send accordingly. Once the room-controller has received this message and determined that the emergency button 5 has been pressed, it can send a status message back to the peripheral that will activate the LED 5' above the emergency button. This way, the patient receives information 20 that the message has reached medical staff and or is properly processed by the system. Alternatively or additionally, the processing of the signal can be done by a central monitor system behind the room-controller. At the same time, the LEDs could also be used to indicate the 25 presence of the buttons in the dark. Different lighting levels or states can be used to differentiate between a lighting function and a signaling function.

It should be clear to the skilled person in the art, that various message can be sent back and forth between 30 room-controller and peripheral. Other medical equipment such as infusion pumps and ventilators could be connected. In addition, the individual bits in the message can relate to 13 individual buttons or LEDs or other message means, but they can also form a symbol. For instance, having seven message bits allows for 128 different symbols, which can represent an ASCII character. These symbols could represent different 5 instructions or messages for the peripheral or room- controller. To distinguish between a status message and an ASCII symbol bit 7 can for instance be used.

Referring to figure 3, the synchronization of the peripheral to the room-controller will be explained next.

10 Firstly, it should be noted that in a communication bus which is connected to the maximum amount of peripherals, in this case eight, frames directed to the different peripherals follow each other directly in time. In a communication bus that is not completely occupied, there 15 will be a time-window in which the room-controller sends out a message to a peripheral that is not connected. All connected and synchronized peripherals will receive the address field and speech bit, but will not listen and react to the remainder of the message from the room-controller, 20 nor will they send back their message status. As a result, all the bits corresponding to the status message from the unsynchronized or unconnected peripheral to the room-controller will be idle. It is advantageous, if the communication protocol is such that if no peripherals are 25 present or active, the lines are at a high logical level, e.g. one.

Secondly, the peripheral has its own internal clock.

Due to mismatch in oscillator frequency between the room-controller and the peripherals, the correct bit time is not 30 known by the peripheral.

14

Due to the large number of consecutive one's, the synchronization starts with the peripheral detecting a given amount of one's and then wait for the falling edge of the start bit to start the synchronization process. The 5 threshold value for the number of one's depends on the maximum difference between the oscillator frequency of the room-controller and the peripheral. It should not be set too low in order to avoid synchronization in an occupied time slot. However, if the oscillator frequency of the peripheral 10 is relatively low (high bit time) and the threshold value also high, the necessary number of consecutive high bits will most likely never be reached.

The peripheral can determine the bit time by measuring the time in between the falling edge 14 and the first frame 15 bit which is always high.

Once a peripheral is synchronized, it can use the second start bit, following the second rising edge 15, to re-synchronize and or the re-measure the bit time.

Because the bit time is known, the peripheral is able 20 to correctly detect the falling edge 14 of the start bit pertaining to the next status message from the room-controller .

Because the communication bus is not terminated by resistors, reflections limit the bit rate that can be used 25 in this system or protocol. The bit time in figure 3 is roughly 0.5mS, resulting in a bit rate of about 2kbps. It should be obvious to those skilled in the art that other bit rates can be used depending on the particulars of the network such as the used wiring, the distance in between the 30 room-controller and the peripherals, and the number of peripherals .

15

It should be obvious to those skilled in the art, that several modification, changes, and or additions can be made to the embodiments described above without departing from the scope that is defined by the following claims.

5

Claims (14)

A nurse calling system, the system comprising: a plurality of electrical wires; a room controller provided with a first and second communication port, and processing means for processing and forwarding information between said first and second communication port, said second communication port being connected to said plurality of electrical wires, and wherein said first communication port enables remote communication with said room controller; A peripheral apparatus comprising message means, wherein said message means are adapted to communicate with said room controller over said plurality of electrical wires; Characterized in that said peripheral device further comprises a micro-controller connected to said message means, said micro-controller being adapted to enable said communication between said message means and said room controller over a communication bus formed by said plurality of electrical wires, said micro-controller and said room controller being adapted for communication based on an asymmetric protocol at voltages substantially equal to or less than a nominal operating voltage of said micro-controller, and wherein said communication bus is not terminated. 2. Nurse calling system according to claim 1, wherein said room controller is adapted to communicate with a plurality of said peripherals connected to said communication bus and wherein said protocol is a serial multi-drop protocol. A nurse calling system according to claim 1 or 2, wherein said micro-controller comprises a plurality of 10 terminals of which at least one power supply terminal and an input / output (I / O) terminal have a low-frequency direct connection to said communication bus. A nurse calling system according to any one of claims 1-3, wherein the micro-controller comprises a plurality of terminals of which at least one input / output (I / O) terminal has a low-frequency direct connection to said communication bus. 20 A nurse calling system according to any of claims 1-4, wherein said communication between said peripheral device and said room controller comprises speech. The nurse calling system according to claim 5, wherein said communication bus comprises a data line dedicated to said speech communication. 7. Nurse calling system according to any of claims 1-6, wherein each peripheral device is assigned a specific address, and wherein said protocol is based on frames, wherein each frame of said protocol comprises an address field, a status message of said room controller at a peripheral device regarding the address in said address field, and a status message from said peripheral device regarding the address in said address field to said room controller. 5 8. Nurse calling system according to claim 7, wherein said peripheral device comprises switches connected to said micro-controller, said switches being operable to set an address of said peripheral device. 9. Nurse calling system according to claim 7 or 8, wherein said room controller comprises a memory for messages received from a peripheral device, said room controller being adapted to accept a message from said peripheral device only if a predetermined number corresponding consecutive identical messages have been received from said peripheral device. 20 10. Nurse calling system according to claim 9, wherein said frames comprise predetermined bit patterns and wherein said peripheral device is adapted to synchronize with said room controller based on said predetermined bit pattern. 11. Nurse calling system according to claim 9, wherein said frames comprise a predetermined bit pattern for synchronizing said peripheral device with said room controller for said status message from said room controller to said peripheral device, and for said status message from said peripheral device to said room controller. A nurse calling system according to any of claims 7-11, wherein said communication between said peripheral device and said room controller comprises speech and wherein said communication bus comprises a data line dedicated to said speech communication, wherein each of said frames comprises a speech bit, wherein peripheral devices and room controller connected to said communication bus switch between a microphone and speaker mode in response to a binary value of a speech bit. A room controller according to any one of claims 1-12. A peripheral device according to any one of claims 1-12. 20 25