FIELD OF INVENTION:
This invention relates to the provision of protection against short circuit of electrical/electronic circuits in an automotive vehicle, including but not limited to two wheel vehicles.
BACKGROUND OF INVENTION:
An automotive vehicle is provided with various electrical circuits that perform different functions like turn signal indication, sounding of horn, switching of pilot lamp & headlamp etc. to name a few. The vehicle operator / rider operate switches, provided for this purpose to operate these functions. These switches are electrically connected to respective parts such as head lamp, horn, turn signal indicators etc. through electrical or electronic circuits. The switches may be conveniently non contact type as disclosed in Applicant's co¬pending patent application number 1494/MUM/2005 dated December 2, 2005. When a switch is actuated to a first position by the rider, the corresponding electric circuit is closed and the function is performed. Correspondingly, the actuation of the switch, manually or otherwise to the original position opens the circuit thereby stopping the function. The circuits may be operated with an AC or DC supply. These circuits and the functions performed by these circuits are well known and do not need detailed explanation.
In such circuits, it is quite possible that a part of the circuit is shorted owing to causes like faulty wiring, broken filament, seepage of water, assembly error to name a few. Shorting of a circuit may cause damage to the concerned parts or pose a safety Issue to the rider, especially if such incident occurs on the road.
For example, shorting of the electric circuit of the headlamp may cause the lamp filament to fuse, which is dangerous especially in night riding. Or if the switches are of contact type, the shorting of the circuit may cause an electric shock to the rider. Such incidents are avoidable and this invention intends to provide a safety release in the event of an electric short circuit.

STATEMENT OF INVENTION:
In a vehicle having a plurality of electric circuits which control the operation of certain functions of the vehicle, the invention provides:
- A means of assessing the amount of electric current flowing in an electric circuit of the vehicle;
- A logic controller to
- determine whether the flow of electric current exceeds a
predetermined value (condition A);
- deactivate the said circuit when condition A is positive; and
- activate another circuit to perform the same or a closely related function of the vehicle.
Preferably, the means of assessing the amount of electric current comprises
of a sensing means.
Preferably, such sensing means comprises a shunt resistor.
Preferably, the logic controller is a micro controller.
Preferably, the electric circuits pertain to operation of a vehicle headlamp.
Preferably, the alternate circuits are high beam and low beam circuits of the
said headlamp.
Preferably, if condition A is positive, a warning indicator is given to the vehicle
operator.
Preferably, the controller operates so as to re-assess the original circuit some
time after determining that condition A was positive. In the event that
condition A is no longer positive, the original circuit is re-activated.
OBJECTS OF THE INVENTION:
It is an objective of the invention to protect the components from damage in the event of shorting of at least one circuit.
It is another objective of the invention to provide a visual alert to the vehicle operator in the event of shorting of at least one circuit.

It is another objective of the invention to provide an arrangement of alternate path of electric supply to at least one circuit in the event of main circuit becoming short.
It Is yet another objective of the invention to provide safety to the vehicle operator from electric shocks.
DETAILED DESCRIPTION OF INVENTION :
According to the invention there is provided short circuit protection system for automotive vehicle which comprises a short circuit sensing means, a micro controller, a power switching means of circuit; the said short circuit sensing means providing signal to controller; controller being capable of actuating (i.e. making it ON/OFF) said power switching means of the circuit.
According to an embodiment of the invention, the controller is capable of switching over supply from the first circuit to the second circuit and vice versa in case of any one circuit being sensed as short by appropriately actuating power switching means of the first and second circuit.
The following is detailed description of the invention with reference to the accompanying drawings, in which:
Figure 1 illustrates a symbolic diagram of short circuit sensing system and input to controller. .
Figure 1a illustrates a logic diagram of short circuit protection system.
Figure 2 illustrates a symbolic diagram of short circuit protection system and its application to the headlamp circuit in switching from the high beam to the low beam according to an embodiment of invention.
Figure 1 illustrates a short circuit sensing system for the high beam circuit 6 and the low beam circuit 7 of a head lamp supplied with an AC power input 1

and a short circuit sensing system for horn circuit 15 and turn signal indicator circuit 16 supplied with a DC power input 18. The AC input 1 supplies power to headlamp high beam circuit 6 and to low beam circuit 7 through driver power circuits 4 and 5 respectively. The AC short circuit sensing means 2 is connected to AC input 1 to sense the short circuit in the high beam and low beam circuit and communicate such an eventuality to the microcontroller 3. Similarly, the DC input 18 supplies power to the horn 15 and the turn signal indicator circuit 16 through driver power circuits 13 and 14 respectively. A shunt resistor 17 for sensing DC short circuit communicates with micro controller 3 on such an eventuality. Switches 8, 9, 11 and 12 for operating high beam, low beam, horn and the turn signal indicators respectively are connected to the microcontroller 3. The logic behind working of short circuit sensing in high beam and low beam circuits of headlamp is explained in Figure la.
According to Figure la, the microcontroller senses the output from the short circuit sensing means and checks whether the current drawn by the circuit (say for high beam of the head lamp or the low beam) is below a predetermined threshold value. If the output from the short circuit sensing means is less that predetermined value, the controller generates a signal to continue the supply to circuit.
In case of a short circuit, when the current drawn by the first circuit (say, the high beam) is more than a predetermined or threshold value, the sensing means sends a signal to the microcontroller which continues to check this value for predetermined number of cycles in a predetermined time span (for example 7 times in 10 seconds). This aspect enables the microcontroller to judge whether the short circuit is a temporary phenomenon. If the output from the sensing means indicates higher level of current drawn in specified number of cycles in a specified span of time, the microcontroller sends output signal to power switching means to stop the supply of power to the first circuit (in this case the high beam circuit). This avoids heating of electrical/electronic components in the circuit preventing further damage and possible electric shock to the rider.

In a further aspect of the invention, the microcontroller activates a second circuit (say, the low beam circuit) to perform the same or a closely related function of the vehicle.
The short circuit sensing means illustrated here works on the principle of voltage level sensing, other methods or principles also can be suitably used.
The microcontroller continues to assess the current flowing through the first circuit that has been deactivated as detailed above. If the current flowing through the first circuit is returned to the normal, the short circuit sensing means generates an appropriate signal to the microcontroller to re-activate the first circuit and de-activates the second.
According to an embodiment of the invention applied to the head lamp comprising a high beam circuit 6 and a low beam circuit 7 as illustrated in Figure 2, wherein the high beam circuit is the first operating circuit. The AC input 1 supplies power to the high beam circuit 6 of the head lamp and the low beam circuit 7 through driver power circuits 4 and 5 respectively. The switches 8 and 9 of the high beam circuit 6 and the low beam circuit 7 are respectively connected to microcontroller 3. An AC short circuit sensing means 2 connected to the AC input 1 senses the occurrence of the short circuit in the high beam and low beam circuits and communicates to the microcontroller 3. The micro controller 3 assesses the value of current flowing through the first circuit for a predetermined number of cycles in a predetermined span of time. If the value of current is lower than predetermined value, the controller continues power supply to the first circuit, which is the high beam in this example (as illustrated in Condition 1 in figure 2). If the value of current is higher than the predetermined value measured over a predetermined number of cycles in a predetermined span of time, the microcontroller 3 deactivates this first circuit and automatically activates the second circuit (as illustrated in Condition 2 of figure 2), which in this instance is the low beam circuit. The microcontroller 3 continues to actively check the value of the current in the deactivated high beam circuit 6, through the short

circuit sensing means 2, even after tliis circuit lias been deactivated. In tlie event of normalcy being restored in the first circuit, which is the high beam circuit 6, the second circuit (which is the low beam circuit 7 in this example) is deactivated by the microcontroller and the first circuit 6 is activated. A similar logic applies when the head lamp is operating in low beam circuit 7 (as the main circuit) and a short circuit occurs in this circuit. In this event, the microcontroller 3 stops power supply to the low beam circuit 7 and activates power supply to the high beam circuit 8, as illustrated in the condition 3 in figure 2.
In a further aspect of the invention, a visual alert lamp may be provided to the vehicle operator on a convenient location such as the instrument console to warn the operator of deactivation of at least one circuit in the vehicle.
In a further aspect of the invention and as matter of abundant caution and rider safety, a visual warning indication may be provided in the event of both the high beam and the low beam circuits of the headlamp getting deactivated owing to higher value of current flowing in them. Such a visual warning may conveniently be simultaneous blinking of all side indicators with or without an audio buzzer, implying a crisis like situation for the vehicle operator.
According to another embodiment of this invention, if the power supply is of DC nature, the short circuit sensing means can be an inbuilt device with a high side driver module, wherein shunt resister circuit may be used for short circuit protection, in which the value of current flowing through any DC circuit is sensed and its milli volt drop is measured. The measured milli volt drop is communicated to the micro controller, which in turn deactivates the circuit if the measured value is higher than the predetermined threshold value.
Modifications of the invention may be evident to the skilled readers of the art. The invention may be modified to apply to other electrical circuits in a vehicle. The visual alert to the operator may be in different forms. All such modifications are considered to be included in this application.

WE CLAIM:
1. A system comprising a means of sensing the amount of electric current flowing in an electric circuit of a vehicle, a logic controller to determine whether the flow of said electric current exceeds a predetermined value (condition A) and, when condition A is positive, to deactivate the said circuit and activate an alternate circuit to perform the same or a closely related function of the vehicle.
2. The system as claimed in Claim 1 which operates to re-assess the said electric circuit after a predetermined time after determining that condition A was positive.
3. The system as claimed in Claim 2 where in the event that condition A is no longer positive, the original circuit is re-activated and the alternate circuit deactivated.
4. The system as claimed in Claim 1 where an audio alert is sounded when the condition A is positive.
5. The system as claimed in Claim 1 where a visual alert is displayed when the condition A is positive.
6. The system as claimed in Claim 1 where the means for sensing the electric current is a shunt resistor.
7. The system as claimed in Claim 1 where the logic controller is a micro controller.
8. The system as claimed in any of the preceding Claims where the said electric circuits pertain to operation of a headlamp of the vehicle.

9, The system as claimed in Claim 8 where the original circuit is a high
beam circuit of the said headlamp, and where the alternate circuit is a
low beam circuit of the said head lamp.
10. The system as claimed in Claim 8 where the original circuit is a low
beam circuit of the said headlamp, and where the alternate circuit is a
high beam circuit of the said head lamp.