Turn Signal Device with Auto Cancellation Feature FIELD OF THE INVENTION: The present invention belongs to the field of automobiles. More particularly the invention belongs to the class of vehicles having a steering mechanism that is controlled by a handle operatively connected to the wheel (through a steering column). Still more particularly the invention pertains to turn-signal devices or direction indicators for such kind of vehicles.

BACKGROUND OF THE INVENTION: These days in the automobile sector, the movement of the vehicles is communicated to other vehicles in the traffic (andlor surrounding people) using turn signals. These turn signals are lights on either side of the vehicle (usually on front as well as back side). These lights are switched on (as appropriate i. e. left side for left turn and vice versa) by the driver/rider of the vehicle using a switch and the bulb starts flashing (sometimes alongwith a beep sound). This visual (and sometimes audible) indication warns others that the vehicle is going to change its course of movement and they be careful in negotiating their movements around it. These turn signals are also known as indicators and blinkers. We use the term turn signal predominantly in the specification but wherever the term indicator or blinker is used it should be construed to read as turn signal.

The turn signal is usually initiated through a switch. This switch sends an indication to the relevant indicator bulb and it starts flashing. This flashing gives an indication of vehicle's movement and now it can be carefully steered towards the indicated direction. Once the vehicle has moved/turned in the indicted direction, it is desirable to switch off the turn signal. Failure to do so i. e. continued blinking even after taking the turn, would lead to confusion amongst the fellow motorists and pedestrians, which may also lead to accidents.

This switching off mechanism can be manual i. e. user switches off the turn signal after the desired movement or it can also be automatic wherein an inbuilt mechanism switches off the blinker on the basis of a certain logic.

Presently in the four-wheeler class vehicles i. e. vehicles driven using a steering wheel, the turn signals are automatically cancelled after the vehicle has taken a turn and has started moving straight. Such a mechanism relieves the user of the need to remember

switching off the signal once the turn has been taken. In existing motor vehicles (four wheelers), where self-cancellation blinker is used, switch is mounted on the steering- column (this rotates and turns the wheel). In four wheelers only the steering-column is rotated whereas the switch remains stationary. As a result the cancellation gets a stationary part with which it can engage and disengage. It is rack and pinion arrangement. The plane of rotation of the steering wheel (for turning the vehicle) and the actual wheel is different. The transmission of power from the steering wheel to the wheel of the vehicle is not direct, i. e. it is transmitted from the steering wheel to the steering- column, to the wheel-axle and finally to the front wheels through the rack and pinion arrangement and hence such an arrangement is possible.

In two wheelers and other handle driven vehicles (including three wheelers e. g. auto rickshaws popular in India) where the transmission of power is direct, i. e. from handlebar to the front-wheel, the plane of movement of the handle and the wheel is same.

In this class of vehicles, the switch is also rotated along with the handlebar and as a result it does not get any stationary part with which it can engage. The position of the switches on the handle is at a large distance from the centre of handlebar thus a mechanical arrangement linking the switch to the movement of the handlebar is not easily feasible.

Most of the present day vehicles belonging to handle driven category, therefore use manual switching off of the turn signal, which has the following disadvantages: - possibility of forgetting to switch off the indicator and thus creating confusion, - diversion of concentration of the driver/rider during switching off the indicator which may cause problems in high-traffic scenarios, - accidentally switching on the other indicator while switching off the first one, leading to confusion.

Various attempts have been made in the past to provide for an auto cancellation feature in turn signal devices for handle bar driven vehicles such as two wheelers and three wheelers (e. g. auto rickshaw kind of vehicles in India).

US Publication No. 20020024434A1 and US Patent No. 4,403, 211 disclose the system and method for generating a turn signal from direction indicator lamp based on

direction indicating signal from a switch, an angular speed sensor for detecting angular speed of vehicle & vehicle speed sensor for detecting speed of vehicle. The mechanism is quite complex and is therefore it is not possible to fit into existing vehicles (retro fitment). Also a manual override in case of a wrong signal is not mentioned. Furthermore these systems do not take active measure to compensate for the situation of zigzag driving.

US Patent No. 6, 020,813 for self-cancellation vehicle turn signal with safety reactivation, uses a timing circuit to electrically activate & deactivate the flashing turn signal. It also utilizes momentary spring loaded auxiliary switches for reactivation of the signal after the time elapses. The timing circuit is dependent on the signals received from the vehicle's speed sensor to indicate whether the vehicle is moving. It is not adaptable in a zig-zag style of driving. Also if the indication is given and the handle bar remains straight for a time more than the specified time then the blinking will stop.

US Patent No. 5,790, 017 for vehicle turn signal control system and method includes a turn signal lever, a dipswitch with at least two dual position toggle switch & control circuitry. The circuitry controls the number of pulses flashed by left or right indicator lights when signal ins in intermediate position & automatically returns the lever to its off position after predetermined number of flashes. This is not a very intelligent and enhanced way to cancel the blinking as the driving habits and the traffic situation vary in different situations.

Objectives And Summary Of The Invention: It is an object of the present invention to overcome the aforementioned drawbacks and provide an auto cancellation turn signal device for handle bar driven vehicles (including two wheelers and three wheelers).

It is an objective of the present invention to provide an auto cancellation turn signal device that cancels the indicator signal once the vehicle starts moving in a straight path after the turn.

It is a further objective of the present invention to include timer logic in the device so that the blinker is not cancelled if the turning is for lesser time than the preset time in the circuit.

It is a further objective of the present invention to have a manual override to the automatic canceling turn signal.

To achieve the aforementioned objective and to overcome the drawbacks of the prior art, the present invention provides for a turn signal device with auto cancellation feature. This microprocessor driven device uses the microprocessor logic to switch on and off the indicator light bulb once a mechanically operated switch has given a turn signal. The microprocessor has a timer logic as well as it has an input, which informs it of the current position of the handle bar. Once the microprocessor has turned the indicator bulb on, it waits for i) a signal that conveys the handle bar is straight again and ii) the time period as specified by the timer logic to elapse (after the handle is turned for a time period more the preset time in the circuit). Only when both the conditions are true, the microprocessor would send a signal to switch off the indicator bulb.

The invention also provides for an override mechanism to bypass the microprocessor controller turn signal.

BRIEF DESCRIPTION OF THE FIGURES: Figure 1 is a block diagram of the arrangement of the device as per the invention alongwith switches and indicator light bulbs.

Figure 2 is a figure showing the arrangement of the reed switch on the vehicle's steering mechanism.

DETAILED DESCRIPTION OF THE DRAWINGS: The present invention discloses a setup, which can be incorporated in handle bar driven vehicles so as to achieve the functionality of auto cancellation of the turn signals.

This functionality has been introduced using a microprocessor driven logic circuit that controls the blinking of the indicator. This digital electronic circuit is coupled to switches to initiate the (left and right) turn signal as well as (left and right) turn signal indicator bulbs.

The logic followed by the inventive device is as follows: - on manual switching on of the turn signal, turn the appropriate indicator bulb on

- check if the handle bar is in straight or turned position, - start the timer logic with turning of the handle bar t2|if the handle is kept turned till the time the timer elapses and then straightened then switching off the turn signal.

The invention also provides for a manual override function in case of a wrong signal given.- Figure 1 is a block diagram illustrating the arrangements of various components of the device. For each direction there are two mechanically operated switches (S1, S2).

These switches are connected to the vehicle's electrical system (B). The electrical signal given by these switches is converted into a beam of modulated light and back into a lower voltage electrical signal by using optoisolators (01, 02). The resultant signal's voltage intensity is of a sufficiently low strength to be fed to the microprocessor (MP).

The microprocessor on receiving the signal commands the appropriate direction's indicator bulb (s) (LF, LR, RF, RR) to start blinking. This command is controlled through relays (not shown). At the same time timer logic within the microprocessor is also started if the handle bar is turned.

To detect handle bar's position it is also given another input by a reed switch (RS) that is connected to the vehicle handle bar (HB) in such a manner that its output determines whether the vehicle is going straight or is turning. The timer alongwith this signal determine when the indicator bulb is to be switched off.

The arrangement of this switch is shown in figure 2. The reed switch (4) is mounted on a bracket (2) that moves alongwith the handle bar (not shown) of the vehicle. A magnet (5) facing the reed switch is connected to the steering column (3) using a bracket (1), which remains stationary during turns and inclinations. The arrangement is such that when the vehicle is moving straight, the magnetic field between the switch and the magnet is maintained and the signal is'on'. When the vehicle takes a turn either way, the reed switch moves and the contact is broken thus dissipating the magnetic turning the signal'off'. Although we have described the methodology using a magnetic switch, alternatively a contact switch can also be used in situations where strong surrounding magnetic fields exist that can disturb the signal of the reed switch. In

this case an electrical field would be established that would be switched on and off on the movement of the handle.

The above arrangement can also be reversed i. e. having the switch on the steering column and the magnet on the moving portion of the vehicle. The only care that needs to be taken is that any substantial movement of the vehicle breaks the contact so as to result a change in the signal value.

In all cases the switches are connected in such a way that any minor turn of the vehicle (i. e. inclination by small angles) does not break the circuit. E. g. in the case of magnetic switch the strength of the magnet is chosen to be effective up to a certain inclination. This is an important consideration as sometimes the vehicle is inclined for other reasons than taking a turn hence indicator is not required. This setting is specific to each model of the vehicle.

Initially when the user switches on the indicator the signal from this switch is 'on'. Thereafter the vehicle takes a turn the handle bar moves and with it the reed switch and hence the connection breaks i. e. signal is now'off'. On the handle bar turning, the microprocessor initiated the inbuilt timer logic. While the vehicle is taking a turn this signal remains'off'. After the turn, the handle bar (and with it the steering column) is straightened and once again the reed switch contact is established generating signal'on' for the microprocessor and switching on the timer. When the handle is straight again, the microprocessor checks if the timer has elapsed, if it has then the indicator is switched off else it remains on. This logic is introduced to differentiate between the straightening of handle after a turn has been negotiated and in straightening of handle during zigzag driving conditions. In situations of heavy traffic where zigzagging is a common phenomena handle is typically straightened in 1.5-2. 5 seconds and an appropriate timer can be set. In zigzag driving even after indicator is switched on, the handle bar is turned straight one or more times to negotiate the traffic. Switching off the indicator only on the basis of handle direction would fail in this scenario. Hence a timer is built with logic for appropriate amount of time.

The invention also provides for a manual override switch that can be used by the driver/rider at any time to switch off the turn signal. This would help in cases where the driver/rider himself gave the wrong signal and wants to cancel it

We would now briefly describe the various components of the circuit : Optoisolator: It is an optical isolating device or optical isolator or optoisolator that bridges the gap between incompatible wire communication systems. It contains an input amplifier, a light emitting diode, a photodiode and an output amplifier. An optoisolator is implemented as a semiconductor device that allows signals to be transferred between circuits or systems, while keeping those circuits or systems electrically isolated from each other. In its simplest form, it consists of a photodiode such as LED (Light emitting diode), IRED (Infrared-emitting diode), for signal transmission and a photosensor for signal reception. The"transmitter"takes the electrical signal and converts it into a beam of modulated visible light. This beam travels across a transparent gap and is picked up by the"receiver"which converts the modulated light back into an electrical signal. The electrical output waveform is identical to the electrical input waveforms, although the input and the output amplitudes (signal strength) often differ. The optoisolator is enclosed in a single package, and has the appearance of an integrated circuit or a transistor with extra leads.

RC-circuit: The Resistor-Capacitor is used to supply a constant voltage to the microprocessor. The Resistor-Capacitor circuit is used to give a positive pulse whenever the microprocessor starts executing. The circuit's job is to protect the microprocessor from less-than-perfect power-ups, but it relies on supply voltage to rise quickly enough for that purpose. The RC circuit causes reset to be held low after the supply voltage starts to come up. If the voltage rises quickly enough, reset will be sufficiently low to hold the microprocessor in reset, allowing its circuiting to settle down before normal operation is resumed.

Relays: A relay is a device that functions as an electrically operated switch. In response to an electrical signal, the relay opens or closes its contacts in some prearranged and fixed continuations. The contacts may be in the same circuit as the operating signal or in another circuit. Varieties of relays are available in market such as electromagnetic relay,

solid-state relay. These relays are used as switches to switch on and off the indicator bulbs.

Microprocessor: It is a digital device on a chip which can fetch instructions from a memory, decode and execute them i. e. , it performs certain arithmetic and logical operations, accepts data from input devices, and sends results to output devices. Therefore, a microprocessor is interfaced with memory and input/output (I/O) devices. Basically a microprocessor performs the following operations: (a) FETCHES an instruction from memory, (b) EXECUTES the instruction The microprocessor has a inbuilt programmed timer logic. The microprocessor is clocked using a crystal oscillator.

The whole logic circuit can be enclosed in a small box and fixed to an immovable and less shaky portion near the handle bar of the vehicle without changing the design of the vehicle. This makes the device a retro fit ready device that is ready to be fitted in existing vehicles without incurring heavy expense of time and money.

The aforementioned is just an illustrative embodiment describing the basic logic and the circuit for implementing the concept behind the invention. Around the same concept various other features can be added on to the invention without taking away from the spirit of the invention.

In yet another embodiment there can be an arrangement of reed switch, which would not only tell the microprocessor that the handle bar as turned but also the direction of its turn. For example the reed switch in central position can normally be off and magnets placed on either side. Whenever a turn beyond a certain angel takes place, a contact is established and an'on'signal is transmitted. The additional information about the direction can be utilized for building in better logic such as detecting if the wrong indicator has been given and thereafter taking corrective actions such as switching off the indicator if the user gives wrong signal.

In another possible embodiment by changing logic of the microcontroller, the same setup can be used for setting up a hazard warning system (i. e. in case vehicle breaks down all four indicator lights can be activated) by a certain operation of the switch lever.

In yet another embodiment, the frequency of flashing can be changed if the switch lever operated in a certain position for some different indication like U-Turn blinker.