DESC:Technical Field of Invention
The invention, in general, relates to an SOS system for vehicles, and in particular to detection of multiple SOS switches though analogue voltage output.
Background of Invention
Nowadays vehicles employ an SOS system, which is a switch based solution for notifying a third party in case of an emergency. Emergency scenarios may be, for instance, traffic accident, driver or co-passenger misbehaviour, or any other problem. The third party may be a control-centre, police, authorities, friends, or family. To put it differently, in case of an emergency, the SOS system is known be utilized to contact the emergency services and pinpoint user’s location through satellite navigation, such as GPS, thereby allowing emergency services to respond as quickly as possible.
Certain type of SOS system activate automatically depending upon the current situation (e.g gas sensors, smoke sensors). Other category is ‘manually-actuated switches’, wherein the SOS switch can be pressed to manually activate the SOS system.
Within the conventional SOS switching based mechanisms, it is hard to detect false alarms or defective-switching elements. More worrisome is the fact that the malfunction of SOS switches jeopardizes safety of a passenger, since the passenger is all-together rendered unable to communicate emergency situations. The passenger remains oblivious of the fault state of the SOS switches and ends up actuating the faulty switch multiple times without any success, despite the fact the other SOS switches in the vehicle may be functioning right.
Accordingly, despite the state of art techniques for SOS technology, there remains a scope for substantial improvement.
Summary
This summary is provided to introduce a selection of concepts in a simplified version that is further described below in the detailed description. This summary is not intended to identify key features or essential features of the present invention, nor is it intended as an aid in determining the scope of the present invention.
The present subject matter at-least provides a system for detecting actuation of a switch. The system comprises a microcontroller, a normally-closed (NC) switch adapted to switch state to open based on a user-actuation, an interfacing-circuit for electronically linking said switch with the microcontroller. The interfacing-circuit comprises a plurality of interconnected electrical-resistors for defining a pre-defined resistance within the interfacing circuit, wherein said resistance undergoes variation based on the change in state of said NC switch. Further, the interfacing circuit comprises a transistor connected to said switch via the resistors and adapted to cause a predetermined voltage at the output based on the resistance within the interfacing circuit and thereby alert the microcontroller.
At least by virtue of aforesaid features, the present subject matter at-least provides improved SOS switches in vehicles and in line with standard laid down by Intelligent Transportation Systems (ITS) - Requirements for Public Transport Vehicle Operation vehicles. The SOS switch in the present subject matter is adapted to ensure passenger-safety in case of emergency to a maximum possible extent.
More specifically, the present subject matter at least enables the detection of multiple SOS switches which are connected in parallel and are normally closed while in normal operation. Accordingly, not only it remains easier to detect and thereby alert a malfunctioning switch, the provision of plurality of switches also facilitates the user to operate upon other than the malfunctioning-switch.
The advantages and details of the present invention will be apparent from the following detailed description and accompanying drawings, which are explanatory only and is not restrictive of the present invention.
Brief Description of the Accompanying Drawings
To further clarify the advantages and features of the present invention, a more particular description of the present invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the present invention and are therefore not to be considered limiting of its scope. The present invention will be described and explained with additional specificity and detail with the accompanying drawings in which:
Figure 1 illustrates a schematic-view of an emergency or SOS switch in an actuated condition, in accordance with an embodiment of the present subject matter.
Figure 2 illustrates a circuit-diagram representation with respect to a single SOS switch, in accordance with an embodiment of the present invention.
Figure 3 illustrates a circuit-diagram representation with respect to multiple SOS switches, in accordance with an embodiment of the present invention.
It may be noted that to the extent possible like reference numerals have been used to represent like elements in the drawings. Further, those of ordinary skill in the art will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily drawn to scale. For example, the dimensions of some of the elements in the drawings may be exaggerated relative to other elements to help to improve understanding of aspects of the present invention. Furthermore, the one or more elements may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefits of the description herein.
Detailed Description
For the purpose of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present disclosure is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the present disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the present disclosure relates.
The foregoing general description and the following detailed description are explanatory of the present disclosure and are not intended to be restrictive thereof.
Reference throughout this specification to “an aspect”, “another aspect” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises . . . a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this present disclosure belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.
Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings:
Figure 1 illustrates a schematic-view of an emergency or SOS switch 100 in actuated condition, in accordance with an embodiment of the present subject matter. As may be seen from Fig. 1, the SOS switch 100 may be mounted anywhere in the vehicle, e.g. roof, dashboard, passenger-seat, etc so as to enable access to every passenger in the vehicle. In case of a mass transit system such as a bus or train, a plurality of SOS switches may be provided with respect to every passenger-seat to enable safety of every passenger. In an example, the SOS switch in accordance with present subject matter is normally closed (NC) single-pole single throw (SPST) switch that is actuated to alert emergency-scenarios.
Figure 2 illustrates a circuit-diagram representation 200 for the single SOS switch, in accordance with an embodiment of the present invention. Such circuit-diagram representation may be referred as a system 200 for detecting actuation of a switch. The system 200 comprises a microcontroller (not shown in figure) and a normally-closed (NC) switch 100. The NC switch 100 or SOS switch 100 is adapted to switch to ‘open state’ based on a user-actuation and may be understood as a single pole single throw switch (SPST). The controller forms a part of Telematics Control-Unit (TCU) of an automobile, e.g. Electronic control unit (ECU).

The system 100 comprises an interfacing-circuit for electronically-linking said NC switch with the microcontroller. The interfacing-circuit comprises a plurality of interconnected electrical-resistors (R1, R125, R126, R31, R30) for defining a pre-defined resistance within the interfacing circuit, wherein an overall resistance within the interfacing circuit undergoes variation based on the change in state of said NC switch, i.e. from closed to open-state and vice versa.

More specifically, the switch and a plurality of resistors (R125, R31) define a voltage-divider biasing configuration for a transistor (NPN configuration), which is represented by ‘QbreakN’ in the present-figure. Said NPN transistor, which may be bi-junction transistor (BJT) is configured to act as an automatic-switch within the interfacing circuit. The NPN transistor is connected in a common emitter (CE) configuration via the NC switch through the resistors R1, R126, R31, R30 and transistor-biasing voltage sources 4.2V and 3.0 V. The transistor is adapted to cause development of a first predetermined-voltage or a maximum voltage Vmax at the output of the interfacing circuit, based on the instantaneous or current value of resistance within the interfacing-circuit. The microcontroller may be configured to interpret the analogue voltage present at the output of the transistor as logic 1 (Vmax) or logic 0 (Vmin).

The output of the interfacing-circuit may be defined as the VCE or a collector-emitter voltage with respect to the transistor. Further, the collector and emitter terminals are connected to 4.2V and 3.0V rated voltage-sources for biasing, the base terminal is connected through a voltage-divider arrangement with the 4.2 V voltage source for achieving a biasing base-voltage between 4.2V and 3.0V.

A ‘close’ state of the NC switch maintains a pre-defined resistance within the interfacing circuit through the voltage-divider arrangement formed by resistances R126 and R31 to thereby cause at least one of active linear mode or saturation mode of operation of the transistor. The saturation mode of operation of the transistor causes development of a second pre-determined voltage or Vmin at the output, said another pre-determined output voltage being substantially lower than the first pre-determined voltage and acting as a logic NULL to the microcontroller.

Further, an ‘open’ state of the NC switch (caused due to manual-actuation of the SOS switch by the user) disconnects the voltage-divider arrangement constituted by R126 and R31 from the 4.2V voltage source, minimizes the voltage at the base-terminal and thereby leads to development of negative base-emitter (VBE) and base-collector voltage (VCE) and in turn drives the transistor into a ‘cut-off’ mode of operation. Accordingly, the output of the interfacing-circuit or the collector-emitter voltage (VCE) of the transistor attains the first determined pre-determined output voltage or the maximum Vmax to thereby signal a ‘logic HIGH’ to the microcontroller. Accordingly, the user actuating the NC switch is able to signal a prevailing danger or emergency scenario. Further, a prolonged communication of ‘logic HIGH’ from the NC switch indicates a malfunctioned NC switch.

Figure 3 illustrates a circuit-diagram representation with respect to connection of multiple SOS switches, in accordance with an embodiment of the present invention. More specifically, Figure 3 represents multiple NC switches (e.g. 24) and corresponding number of interfacing circuits connected in parallel to a common microcontroller Also, the 4.2V and 3.0 V rated voltage-sources serve as common voltage-sources for the collector and emitter terminals of the transistors.
Overall, Fig. 3 refers the system 300 for detecting actuation of a switch out of a plurality of switches. The system comprises a plurality of normally-closed (NC) switches and a plurality of interfacing-circuits, wherein each of said plurality of interfacing-circuits links a designated NC switch with the microcontroller. Each of NC switch and the corresponding interfacing-circuit corresponds to the NC switch and the interfacing circuit defined in Fig. 2. The exemplary representation in Fig. 3 illustrates three parallel rows of NC switches and the interfacing circuit, each row in turn comprising a parallel-connection of 8 NC switches and corresponding 8 interfacing circuits.

Further, each of the interfacing circuit may be configured to generate a unique value of analogue voltage as Vmax as shown below.

Each generated analogue-voltage at the output of every interfacing circuit corresponds to a ‘logic 1’ at the input of microcontroller and is also used to identify as to which NC switch has been actuated. Accordingly, location of the person actuating the switch as well as the faulty switch remains traceable based on the characteristic voltage from the NC switch.
At-least by virtue of aforesaid features, the present invention refers the the use of multiple SOS switches which are connected in parallel. When any of the SOS switches gets damaged by any means, the circuit developed as per the present subject matter is able to detect the corresponding voltage. A Telematics Control Unit (TCU) forming a part of electronic control unit is able to detect the position of a faulty SOS switch even at a remote location based on the characteristic voltage. Such detection is facilitated by usage of a normally closed (NC) SOS switch in a normal operation, such that the user-actuated ‘open state’ of the NC switch is termed as logic HIGH and triggers the microcontroller to sound alert and signal an Emergency Response Centre.
Moreover, the presence of ‘multiple NC switches’ also facilitate the user to actuate switch of an adjacent passenger-seat in the automobile, in case the NC switch associated with the user is indicated as faulty to the user. In other words. the malfunctioning of the NC switch does not deter the user from communicating the location through usage of neighborhood switches.
The drawings and the forgoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein.
Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims

,CLAIMS:We claim:
1. A system (200) for detecting actuation of a switch, said system comprising:
a microcontroller;
a normally-closed (NC) switch (100) adapted to switch state to open based on a user-actuation;
an interfacing-circuit for electronically linking said switch with the microcontroller, said interfacing-circuit comprising:
a plurality of interconnected electrical-resistors for defining a pre-defined resistance within the interfacing circuit, wherein said resistance undergoes variation based on the change in state of said NC switch; and
a transistor connected to said switch via said resistors and adapted to cause a predetermined voltage at the output based on the resistance within the interfacing circuit and thereby alert said microcontroller.

2. The system as claimed in claim 1, wherein said controller forms a part of Telematics Control-Unit (TCU) of an automobile.

3. The system as claimed in claim 1, wherein said normally closed switch is a single pole single throw (SPST) switch and said plurality of resistors define a voltage-divider biasing configuration for the transistor.

4. The system as claimed in claim 1, wherein the transistor is an NPN bi-junction transistor (BJT) configured to act as an automatic-switch within the interfacing circuit

5. The system as claimed in claim 1, wherein a closed state of said NC switch maintains the pre-defined resistance within the interfacing circuit to thereby cause at least one of active linear mode or saturation mode of operation of the BJT.
6. The system as claimed in claim 5, wherein said saturation mode of operation of the BJT causes development of another pre-determined voltage at the output, said another pre-determined output voltage being substantially lower than the pre-determined voltage and acting as a logic NULL to the microcontroller.

7. The system as claimed in claim 1, wherein the user-actuated change in state of said switch from close to open causes a cut-off mode of operation of the BJT.

8. The system as claimed in claim 7, wherein said cut-off mode of operation of the BJT causes development of said pre-determined output voltage to thereby signal logic HIGH to the microcontroller.

9. The system as claimed in claim 7, wherein said cut-off mode of operation of the BJT causes development of said pre-determined output voltage to thereby signal logic HIGH to the microcontroller and cause detection of at least one of:
the user actuating the NC switch being in danger; and
a fault in the NC switch

10. A system (300, 200) for detecting actuation of a switch out of a plurality of switches, said system comprising:
a microcontroller;
a plurality of normally-closed (NC) switches, each of said NC switches adapted to switch state to open based on a user-actuation;
a plurality of interfacing-circuits, wherein each of said plurality of interfacing-circuits links a designated NC switch with the microcontroller and comprises:
a plurality of interconnected electrical-resistors for defining a pre-defined resistance within the interfacing circuit, wherein said resistance undergoes variation based on the change in state of said NC switch; and
a transistor connected to said switch via said resistors and adapted to cause a predetermined-voltage at the output based on the resistance within the interfacing circuit and thereby alert said microcontroller.