FIELD OF THE INVENTION
The present disclosure relates to a contactless switch for a vehicle. More particularly, the present
invention relates to a contactless switch with low quiescent current consumption and high
switching point accuracy.
BACKGROUND OF THE INVENTION
There exists two types of switching methods i.e. contact type and contactless for various
switching functions of an automobile and like. These functions may include stop lamp switch,
clutch switch, power window switch, lever combination switch, hazard switch, heat ventilation
and air conditioning switch, fog lamp switch, wiper switch etc. Contactless switching has been
widely used and has replaced the contact type switching. The contactless switching has various
advantages over contact type switching, such as, longer life, no contact bounce, no arching, no
carbon deposition etc. There are various sensors to perform contactless switching such as reed
switches, magneto resistance sensors, and hall effect sensors, etc. Hall effect sensors are
primarily used for contactless switching technology because of their lower cost and higher
switching point accuracy over other sensors. Switching point accuracy refers to a property of a
hall effect sensor, which is defined as the difference in magnetic operating point and magnetic
release point, which is magnetic hysteresis. The switching point accuracy and magnetic
hysteresis are thus inversely proportional.
FIG. 10, shows the circuit diagram of a prior art hall effect sensor based switch having low
magnetic hysteresis, that is, high switching point accuracy. Said switch has a switching point
accuracy of less than or equal to 60 μm which is within the desired range. However, said switch
draws a quiescent current of about 2200 μA, which is approximately 100 times more than the
desired maximum quiescent current of 25 μA. Since, the hall effect sensor based switch draws
quiescent current from the battery, it is required to minimize quiescent current consumption such
that the battery does not drain out.
3
To minimize quiescent current consumption, the hall effect sensor in the circuit of FIG. 10 was
replaced with another hall effect sensor, which draws low quiescent current of about 19 μA. The
replacement of hall effect sensor met the requirements of desired quiescent current consumption,
however, it did not meet the requirements of the desired the switching point accuracy. The
switching point accuracy provided by this switch is 900 μm to 1100 μm which is not within the
desired range.
Thus, there existed a need in the art to provide a hall sensor based switch which provides high
switching point accuracy and at the same time provides low quiescent current consumption.
OBJECT OF THE INVENTION
An object of the present disclosure is to provide a hall effect sensor switch having a low
quiescent current consumption and high switching point accuracy.
SUMMARY OF THE INVENTION
One or more shortcomings of the prior art are overcome and additional advantages are provided
by the present disclosure. Additional features and advantages are realized through the techniques
of the present disclosure. Other embodiments and aspects of the disclosure are described in detail
herein and are considered a part of the disclosure.
It is to be understood that the aspects and embodiments of the disclosure described above may be
used in any combination with each other. Several of the aspects and embodiments may be
combined together to form a further embodiment of the disclosure.
4
In an aspect, the present disclosure provides a hall effect sensor switch, having a first hall effect
sensor, a second hall effect sensor which is energized or de-energized based on an output
received from the first hall effect sensor, where the first hall effect sensor provides the output
when a magnet reaches to a first position from an initial position and the second hall effect
sensor gets activated when the magnet reaches a secondary position from the first position. The
magnet is attached to an actuator for moving the magnet to the first position and the second
position. The first position in proximity to the first hall effect sensor and the secondary position
in proximity to the second hall effect sensor, where the first hall effect sensor is separated from
the second hall effect sensor by a predetermined distance, the first hall effect sensor and the
second hall effect sensor is aligned along a path of motion of the magnet attached to the first and
second hall effect sensors.
In another aspect the present disclosure provides a hall effect sensor switch where, the first hall
effect sensor has a first quiescent current. The second hall effect sensor has a second quiescent
current, where the first quiescent current is less than the second quiescent current. . The first hall
effect sensor is coupled to a battery via a voltage level conversion element and a first protection
circuit, the voltage level conversion element is used for converting a voltage from the battery to a
voltage required to operate the first hall effect sensor. The first hall effect sensor has a latched
output.
In yet another aspect of the disclosure, a method for reducing quiescent current consumption in a
hall effect sensor based circuit is provided. The method having the steps of:
a) energizing or de-energizing a second hall effect sensor based on an latched output
received from a first hall effect sensor, wherein the first hall effect sensor provides the
latched output when a magnet reaches to a first position from an initial position;
b) activating the second hall effect sensor when the magnet reaches a secondary position
from the first position;
c) transmitting a signal based on an activation of the second sensor;
5
d) thereby, reducing the total quiescent power drawn without compromising switching point
accuracy.
In yet another aspect of the disclosure, the second hall effect sensor draws a second quiescent
current. The first hall effect sensor draws a first quiescent current, where said first quiescent
current is less than said second quiescent current. The magnet is moved to the first position and
the second position, the first position is proximal to the first hall effect sensor and the secondary
position is proximal to the second hall effect sensor.
In yet another aspect of the disclosure, a hall effect sensor circuit, having a first hall effect
sensor, a first transistor, where an output of said first hall effect sensor is electrically coupled to
the base of the first transistor, a second hall effect sensor in series with the first transistor, where
an activation of the first hall effect sensor turns the first transistor ON which energizes the
second hall effect sensor. A second transistor, where an output of the second hall effect sensor is
electrically coupled to base of the second transistor, where an activation of the second hall effect
sensor turns said second transistor ON, thereby providing an output to a high side driver. A
voltage level conversion element to convert a voltage received from a first protection circuit to a
predefined voltage, where the voltage level conversion element is electrically coupled to the first
hall effect sensor and the voltage level conversion element is electrically coupled to the second
hall effect sensor in series with the first transistor, and where the protection circuit comprises a
diode and a transient voltage suppression diode. The output of the second transistor energizes
one or more of a hazard light, a tail light, stop lamp and horn of an automobile.
In yet another aspect of the disclosure, a hall effect sensor switching system having a hall
effect sensor circuit as described above having a second circuit. The second circuit having a
second protection circuit comprising a diode and a transient voltage suppression diode coupled to
a third hall effect sensor. A third transistor, where an output of said third hall effect sensor is
coupled to base of the third transistor, and where an activation of the third hall effect sensor turns
ON said third transistor. The output of the third transistor deactivates a cruise control mode of an
automobile via at least a fourth transistor and a high side driver.
6
BRIEF DESCRIPTION OF DRAWINGS
The novel features and characteristic of the disclosure are set forth in the appended description.
The embodiments of the disclosure itself, however, as well as a preferred mode of use, further
objectives and advantages thereof, will best be understood by reference to the following detailed
description of the illustrative embodiment when read in conjunction with the accompanying
drawings. One or more embodiments are now described, by way of example only, with reference
to the accompanying drawings:
FIG. 1 illustrates a block diagram of the hall effect sensor switch according to an embodiment of
the present disclosure;
FIG. 2 illustrates a flow chart representing the working of the hall effect sensor switch according
to an embodiment of the present disclosure;
FIG.3 illustrates a perspective view of the hall effect sensor switch according to an embodiment
of the present disclosure;
FIG. 4 illustrates a cut away view of the hall effect sensor switch according to an embodiment of
the present disclosure;
FIGS 5A-5E exemplifies sectional views representing internal arrangement of the hall effect
sensor switch at different positions of the magnet according to an embodiment of the present
disclosure;
FIG. 6 illustrates a schematic diagram of a circuit for the hall effect sensor switch according to
an embodiment of the present disclosure;
7
FIG. 7 illustrates a schematic diagram of a circuit for cruise control according to the present
disclosure;
FIG. 8 illustrates a schematic diagram of the circuit for the hall effect sensor switch according to
another embodiment of the present disclosure;
FIG. 9 illustrates a schematic diagram of a circuit for the hall effect sensor switch according to
another embodiment of the present disclosure;
FIG. 10 illustrates a circuit of a prior art switch.
It should be appreciated by those skilled in the art that any block diagrams herein represent
conceptual views of illustrative systems embodying the principles of the present subject matter.
The figures depict embodiments of the disclosure for purposes of illustration only.
One skilled in the art will readily recognize from the following description that alternative
embodiments of the system and method illustrated herein may be employed without departing
from the principles of the disclosure described herein.
DETAILED DESCRIPTION OF THE INVENTION
While the embodiments in the disclosure are subject to various modifications and alternative
forms, specific embodiment thereof has been shown by way of example in the figures and will be
described below. It should be understood, however that it is not intended to limit the disclosure
to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications,
equivalents, and alternatives falling within the scope of the disclosure.
It is to be noted that a person skilled in the art would be motivated from the present disclosure
and modify the hall effect sensor switch. However, such modification should be construed within
the scope and spirit of the disclosure. Accordingly, the drawings show only those specific details
8
that are pertinent to understand the embodiments of the present disclosure so as not to obscure
the disclosure with details that will be readily apparent to those of ordinary skill in the art having
benefit of the description herein.
The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are
intended to cover a non-exclusive inclusion, such that a method, system that comprises a list of
components does not include only those components but may include other components not
expressly listed or inherent to such system. In other words, one or more elements in a system
proceeded by “comprises… a” does not, without more constraints, preclude the existence of
other elements or additional elements in the system.
The following paragraphs describe the present disclosure with reference to Figures 1-9. In the
figures the same element or elements which have same functions are indicated by the same
reference numerals.
The present disclosure relates to a hall effect sensor switch, method for reducing quiescent
current consumption in a hall effect sensor switch, and a hall effect sensor switching system for
achieving low quiescent current consumption and high switching point accuracy.
FIG. 1 exemplarily illustrates the switch according to the present disclosure. The switch
comprises a first protection circuit 108 connected to a battery of the vehicle, a second protection
circuit 109 connected to an ignition switch of the vehicle, a voltage level converter 116 or
voltage level conversion element 116 connected to the first protection circuit 108, a first hall
effect sensor 101 connected to the voltage level conversion element 116, a second hall effect
sensor 102 connected to first hall effect sensor 101 via a transistor circuitry 104, a third hall
effect sensor 103 coupled to the second protection circuit 109, a first driving circuit 105 coupled
to the second hall effect sensor 102, a second driving circuit 106 coupled to the third hall effect
sensor 103, a high side driver 107 for driving one or more loads based on the signals from the
first and second driving circuits 105,106.
9
The first hall effect sensor 101 is characterized by low quiescent current and low switching point
accuracy. The second and third hall effect sensors 102, 103 are characterized by high quiescent
current and high switching point accuracy. That is, the first hall effect sensor 101 draws low
quiescent current and provides low switching point accuracy in operation. On the other hand,
second and third hall effect sensors 102, 103 draws high quiescent current and provides high
switching point accuracy in operation.
Further, the first hall effect sensor 101 is characterized by a latched output. The voltage level
conversion element 116 converts the voltage from the battery to a voltage compatible to the first
hall effect sensor 101 and the second hall effect sensor 102. The output from the first hall effect
sensor 101 is fed to the transistor circuitry 104. The output of the transistor circuitry 104 is fed to
the second hall effect sensor 102 and the output of the second hall effect sensor 102 is fed to a
first driving circuit 105. The output of the first driving circuit 105 is fed to the high side driver
107 for driving one or more loads.
The voltage from the ignition switch is received through the interface “IG” 110 and is fed to the
third hall effect sensor 103 via the second protection circuit 109. The output of the third hall
effect sensor 103 is fed to the second driving circuit 106. The output from the second driving
circuit 106 is fed to the high side driver 107 for driving one or more loads. As used herein the
first driving circuit 105, the second driving circuit 106, the first protection circuit 109, the second
protection circuit 108, the high side driver 107 and the transistor circuitry 104 are sub-circuits of
the circuit implementing the switch as shown in the schematics of FIGs. 6-9 .
The first, second and third hall effect sensors are activated by a magnet 115. As shown in FIG. 1,
the switch comprises of a magnet 115 attached to an actuator (not shown) for generating
magnetic field required by the first, second and third hall effect sensors. The magnetic field is
received on the hall effect sensors when the magnet is in proximity of the respective hall effect
sensors.
As stated above, the high side driver 107 receives signals from the second hall effect sensor 102
and based on the signals turns “ON” or turns “OFF” a load for example a hazard light, a tail
10
light, stop lamp, clutch indicator, power window, lever combination, heat ventilation and air
conditioning unit, fog lamp, wiper of an automobile. The high side driver 107 further receives
signals from the third hall effect sensor 103 and based on the signals enables or disables a cruise
control function of the vehicle.
FIG. 2 exemplarily illustrates a flow chart explaining the working of the switch of FIG. 1. On
actuation of the actuator (not shown), the magnet 115 attached to the actuator comes in proximity
to the first hall effect sensor 101, thereby applying 201 a magnetic field/flux to the first hall
effect sensor 101. Providing 202 an output to the transistor logic circuitry 104, by the first hall
effect sensor 101 based on the application of the magnetic field/flux. Energizing 203 the second
hall effect sensor by the transistor logic circuitry in response to the output received at the
transistor logic circuitry 104. The actuator is further actuated, thereby applying 204 a magnetic
field/flux on the second hall effect sensor 102. Providing 205 an output to the high side driver
107 via the first driving circuit 105, by the second hall effect sensor 102, based on the
application 204 of magnetic field/flux. Turning 206 on a load connected to the high side driver
based on the output from the first driving circuit. If 207 a third hall effect sensor is energized by
a current received from an ignition switch through “IG” 110, then applying 208 a magnetic field
on the third hall effect sensor 103 by further actuation of the actuator. Providing 209 an output to
the high side driver 107 via the second driving circuit 106, by the third hall effect sensor 103,
based on the application 208 of magnetic field/flux on the third hall effect sensor 103. Turning
210 off a cruise control mode, based on the output from the second driving circuit to the high
side driver 107.
It is to be noted that the first hall effect sensor 101 keeps on providing an output as the first hall
effect sensor 101 has a latched output. Further, the first hall effect sensor 101 provides an output
when a magnetic field is applied by the south pole of the magnet 115 and the output of the first
hall effect sensor 101 can only be turned off by application of magnetic field applied by the north
pole of the magnet 115. The magnet 115 is fixed in a manner such that the first hall effect sensor
101 comes in proximity to the north pole followed by the south pole, when the actuator is
actuated thus turning the output of the first hall effect sensor 101 ON. Accordingly, when the
actuator is returned to the initial position by spring action once the actuation force is released, the
11
first hall effect sensor 101 comes in proximity to the south pole followed by the north pole thus
turning OFF the output of the first hall effect sensor 101.
It would be thus readily apparent to a person skilled in the art that the second hall effect sensor
102 having a high switching point accuracy and a high quiescent current consumption is
energized only when the first hall effect sensor provides an output and remains de-energized
when there is no output from the first hall effect sensor. The quiescent current consumption of
the first hall effect sensor 101 is low thus effectively a hall effect sensor based contactless switch
is realized with high switching point accuracy and a low quiescent current.
FIG. 3 shows a perspective view of the switch 100 with an actuator 301 according to an
embodiment of the present disclosure. The actuator drives the magnet for activation of the hall
effect sensors wherein the actuator is operatively coupled to the brake pedal of the vehicle and is
driven by an actuation force transmitted from the brake pedal.
FIG. 4 shows a cut away view of the switch 100 according to an embodiment of the present
disclosure. As shown in FIG. 4, the first hall effect sensor 101, the second hall effect sensor 102,
the third hall effect sensor 103 and the magnet 115 are disposed within a cavity. The third hall
effect sensor 103 is located adjacent to the second hall effect sensor 102. Also, FIG. 5A shows a
sectional view of the switch 100 with the magnet 115 in an initial position. In this position, no
actuation force is received on the actuator 301. The force applied to the brake pedal of the
vehicle is transmitted to the actuator 301, where the brake pedal transmits an actuation force to
the actuator 301, thereby moving the magnet 115 attached to the actuator to a first position,
second position, third position and fourth position, as illustrated in FIGS. 5A-5E. The magnet
115 moves to the above positions based on the amount of actuation force applied to the brake
pedal.
FIG. 5B shows a sectional view of the switch 100 with the magnet in a first position. In this
position, a first actuation force is received on the actuator 301 causing the magnet 115 to move.
At the first position, the first hall effect sensor 101 is exposed to the magnetic field from the
south pole of the magnet 115. The first hall effect sensor 101 which is energized by the voltage
12
from the voltage level conversion element, and the first hall effect sensor 101 gets activated as
soon as it is exposed to the magnetic field from the south pole of the magnet. Upon activation,
the first hall effect sensor 101 generates an output which is fed to the input of the second hall
effect sensor 102 thereby energizing the second hall effect sensor 102.
FIG. 5C shows a sectional view of the switch 100 with the magnet 115 in a secondary position.
In this position, a second actuation force is received on the actuator 301. The second actuation
force is greater than the first actuation force. At the secondary position, the first hall effect sensor
101 remains activated as it has a latched output. In this way, the first hall effect sensor 101
continuously keeps the second hall effect sensor energized. Further, in the secondary position,
the second hall effect sensor 102 which is energized from the output of the first hall effect sensor
101 gets activated as soon as it gets exposed to the magnetic field from the south pole of the
magnet 115 and provides an output in response to the said exposure.
Upon activation, the second hall effect sensor 102 generates an output which is fed to the high
side driver 107 through the first driving circuit 105. In this position, the third hall effect sensor
103 (not shown) is not activated as it does not get the required magnetic flux density from the
south pole of the magnet.
FIG. 5D shows a sectional view of the switch 100 with the magnet115 in a tertiary/third position.
In this position, a third actuation force is received on the actuator 301. The third actuation force
is greater than the first and second actuation force. At the tertiary position, the first hall effect
sensor 101 remains activated as it has a latched output. The second hall effect sensor 102 stays
energized and activated for providing an output to the high side driver 107. Also, in this position,
the third hall effect sensor 103 (not shown) gets sufficient (required) magnetic field from the
magnet 115. That is, the third hall effect sensor 103 which is energized by the voltage from the
ignition switch gets activated as soon as it is exposed to the required magnetic field from the
south pole of the magnet. Upon activation, the third hall effect sensor103 provides an output to
the high side driver 107 via the second driving circuit 106.
13
FIG. 5E shows a sectional view of the switch 100 with the magnet115 in a final position. In this
position, a fourth actuation force is received on the actuator 301. The fourth actuation force is
greater than the first, second and third actuation forces. This position signifies full actuation of
the actuator. In this position, the first hall effect sensor 101, the second hall effect sensor 102 and
the third hall effect sensor 103 all remain activated.
FIG. 6 shows a schematic diagram showing the electrical circuit of the switch according to
embodiment of the present disclosure. The circuit shows different active and passive electronic
elements and electrical paths which connect the electronic elements as per the present disclosure.
The circuit of the switch is based on hall effect sensors which reduces the quiescent current
drained by the circuit from a vehicle battery, without compromising the switching point
accuracy.
The circuit comprises of the first protection circuit 108, the voltage level conversion element
116, the first hall effect sensor 101, the transistor circuitry 104, the second hall effect sensor 102,
the first driving circuit 105 and the high side driver 107. The quiescent current drawn by the first
hall effect sensor 101 is less than the quiescent current drawn by the second hall effect sensor
102. The switching point accuracy of the second hall effect sensor 102 is greater than that of the
first hall effect sensor 101.
FIG. 6 will now be described in detail. A voltage from a battery (not shown) is received by the
first protection circuit 108. The first protection circuit 108 comprises a capacitor 619 to eliminate
noise and fluctuations of voltage received from the battery, a transient voltage suppression diode
(TVS diode) 617 to ground any transient voltages spikes and a diode 618 connected in series
with the voltage level conversion element 116. The input of the voltage level conversion element
is grounded using capacitors 614, 615 to eliminate noise and fluctuations in the voltage received
through the diode 618. The purpose of the diode 618 is to prevent damage to the circuit due to an
accidental connection of reverse polarity from the battery. The voltage level conversion element
comprises of a low dropout voltage regulator (LDO) 613 for reducing the voltage supplied by the
battery to an operable voltage for the first and second hall effect sensors.
14
A capacitor 616 is used to eliminate noise and fluctuations from the output voltage provided by
the LDO 613. A resistor 602 is in series with the output of the LDO 613 to limit a current surge
and the first hall effect sensor 101 is fed through the resistor 602. A capacitor 603 is coupled to
the input of the first hall effect sensor 101 to eliminate noise and fluctuations in the voltage
received from the LDO 613. The output of the first hall effect sensor 101 is coupled to the
transistor circuitry 104. The transistor circuitry comprises a first transistor 601, a base input
resistor 604, a pull up resistor 605 and an output resistor 606. The first transistor 601 has its base
coupled to the output of the first hall effect sensor 101 via the base input resistor 604. The base
of the transistor 601 is pulled up by the resistor 605 to the supply voltage received from the LDO
613. The collector of the first transistor 601 is coupled to the second hall effect sensor 102 via
the output resistor 606. The emitter of the first transistor 601 is coupled to the supply voltage
received from the LDO 613. The input of the second hall effect sensor 102 is coupled to the
ground via a capacitor 607 to eliminate noise and fluctuations in the voltage received from the
collector of the first transistor 601. The output of the second hall effect sensor 102 is coupled to
the first driving circuit 105. The first driving circuit 105 comprises a second transistor 610, a
base input resistor 608, a pull up resistor 609 and a voltage divider formed by resistors 611, 612.
The second transistor 610 has its base coupled to the output of the second hall effect sensor 102
via the base input resistor 608. The emitter of the second transistor 610 is coupled to the supply
voltage received from the first protection circuit 108. The base of the second transistor 610 is
pulled up via the pull up resistor 609. The collector of the second transistor 610 is coupled to the
ground via resistors 611, 612 which forms the voltage divider. An output is drawn from the
voltage divider and is fed to the high side driver 107.
FIG. 7 shows a schematic of the circuit of the contactless switch 100 for cruise control. A
voltage from the ignition switch (IGN) is received by the second protection circuit 109. The
second protection circuit 109 comprises a capacitor 711 to eliminate noise and fluctuations of
voltage received from the ignition switch, a transient voltage suppression diode (TVS diode) 710
to ground any transient voltages spikes, and a diode 709 connected in series with the third hall
effect sensor 103 via a resistor 708. The resistor 708 limits the current supplied to the third hall
effect sensor 103. The purpose of the diode 709 is to prevent damage to the third hall effect
sensor 103 due to an accidental connection of reverse polarity from the ignition. The output of
15
the third hall effect sensor 103 is coupled to the second driving circuit 106. The second driving
circuit 106 comprises a third transistor 701, a base input resistor 707, a pull up resistor 706, a
voltage divider formed by 704, 705, a fourth transistor and a resistor 703 connected to the
collector of the fourth transistor. The third transistor has its base coupled to the output of the
third hall effect sensor via the base input resistor. The emitter of the third transistor 103 is
coupled to the supply voltage received from the second protection circuit 109. The base of the
third transistor 701 is pulled up via the pull up resistor 706. The collector of the third transistor
701 is coupled to the ground via resistors 704, 705 which forms the voltage divider. An output is
drawn from the voltage divider and is fed to the base of a fourth transistor 702, where the output
from the collector of the fourth transistor 702 is used to turn off or turn on the cruise control
function of the vehicle.
The working of the circuits of figures 6 and 7 is explained with reference to different positions of
the magnet as discussed in figures 5A-5E. In the initial position as defined in figure 5A, the first
hall effect sensor 101 is not exposed to the magnetic field of the magnet 115. The first hall effect
sensor 101 is thus not activated. The first transistor 601 thus remains in an OFF condition, and
therefore the second hall effect sensor 102 does not get the supply voltage received from the
LDO 613. Further, there is no output from the second hall effect sensor 102 since it is not
activated and accordingly there is no output from the high side driver 107.
In the first position as defined in figure 5B, the first hall effect sensor 101 gets exposed to the
magnetic field of the magnet 115. The first hall effect sensor 101 gets activated and produces an
output. The output of the first hall effect sensor 101 on exposure to the magnetic field is 0Vor
ground. Since, the output of the first hall effect sensor 101 is coupled to the base of the first
transistor 601, it provides the necessary bias to the first transistor 601 to turn ON. This couples
the supply voltage provided by the LDO 613 to the second hall effect sensor 102 via the first
transistor 601 and energizes the second hall effect sensor 102. Since, the second hall effect
sensor 102 is not exposed to a magnetic field from the magnet 115, the second hall effect sensor
102 does not gets activated and does not provides any output. Thus, the second transistor 610
does not have the required bias to turn ON and accordingly there is no output from the second
transistor 610.
16
In the secondary position as defined in figure 5C, the first hall effect sensor 101 still remains
activated because of its latched output. Since, the output of the first hall effect sensor 101 is
coupled to the base of the first transistor 601 , it provides necessary bias to the first transistor 601
to stay ON. This continues providing the supply voltage provided by the LDO 613 to the second
hall effect sensor 102. Now, since the magnet 115 is in proximity to the second hall effect sensor
102, this position of the magnet provides sufficient magnetic flux to activate the second hall
effect sensor 102. When activated the second hall effect sensor provides 0V or ground as the
output. Since, the output of the second hall effect sensor 102 is coupled to the base of the second
transistor 610, the base of the second transistor 610 receives the sufficient bias to turn ON . The
high side driver 107 receives the output from the second transistor 610 and drives the load for e.g
stop lamp of a vehicle.
Further, in the tertiary position as defined in figure 5E, the magnet 115 comes in proximity to the
third hall effect sensor 103. As shown in figure 7, the third hall effect sensor 103 is energized by
the voltage from the ignition switch. Considering that the third hall effect sensor 103 is energized
the proximity of the magnet to the third hall effect sensor provides sufficient magnetic flux to
activate it. On activation the third hall effect sensor outputs 0V or ground, which provides the
necessary bias to the third transistor 701 via the base input resistor 707 and thus the third
transistor 701 turns ON. The output from the voltage divider arrangement by the resistors 704,
705 biases the base of the fourth transistor 702 to turn the fourth transistor ON. Thus, the output
of the fourth transistor 702 is fed to the high side driver which controls the cruise control
function of the vehicle.
FIG. 8 shows a schematic diagram showing the electrical circuit of the switch according to
another embodiment of the present disclosure. The circuit of FIG. 8 is same as the circuit of FIG.
6, except the first driving circuit driving the hazard lamp 801 directly. In this embodiment, the
output of the second transistor 610 is connected to the high side driver and also to the hazard
lamp.
17
FIG. 9 shows a schematic diagram showing the electrical circuit of the switch according to yet
another embodiment of the present disclosure. The circuit of FIG. 9 is same as the circuit of FIG.
6, except the base of the second transistor 601 is coupled to ground via a capacitor 901. This
capacitor filters out noise due to electromagnetic interference.
The hall effect sensor switch of the present disclosure provided a switching point accuracy of
less than equal to 60 μm which is within the acceptable range. At the same time it draws a
quiescent current of 17 μA which is also within the acceptable range.
However, it is apparent to a person skilled in the art that the switch and method of the present
invention are not restricted to a stop lamp switch only but can be used in other contactless
switches also. Further the transistors 610, 601 can be replaced by another semiconductor device
such as field effect semiconductor devices such as FET, MOSFET or the like which can function
as a switch in response to the output received by the hall effect sensors 101, 102.
Advantages of the present disclosure:
- Providing a circuit and method for a contactless switching in a vehicle with ultra-low
quiescent current consumption.
- Providing a circuit and method for a contactless switching in a vehicle with high
switching point accuracy.
- The switch of the present disclosure solves the problem of high standby current
consumption in switches for vehicles when these switches have been operated directly on
vehicle’s battery. Function of these kind of switches is to switch ON and switch OFF the
required load like stop lamp switching system, hazard warning switching system, horn
switching system or the like whichever is battery operated.
18
- The switch of the present disclosure solves the problem of high standby current
consumption in switches for vehicles when these switches have been operated directly on
vehicle’s battery by achieving maximum allowable standby current consumption below
to 25μA.
The switch of the present disclosure solves the poor switching point accuracy problem by
providing a high switching point accuracy of less than or equal to 60 μm.
The disclosed invention is thus attained in an economical, practical, and facile manner. It is to be
understood that various further modifications and additional configurations will be apparent to
those skilled in the art. It is intended that the specific embodiments, configurations and
calculations herein disclosed are illustrative and should not be interpreted as limitations on the scope of the invention.

We Claim:
1. A hall effect sensor switch, comprising:
a first hall effect sensor;
a second hall effect sensor being energized or de-energized based on an output
received from the first hall effect sensor, wherein the first hall effect sensor provides
the output when a magnet reaches to a first position from an initial position and the
second hall effect sensor gets activated when the magnet reaches a second position
from the first position.
2. The hall effect sensor switch of claim 1, wherein said first hall effect sensor draws a
first quiescent current and said second hall effect sensor draws a second quiescent current,
and wherein the first quiescent current is less than the second quiescent current.
3. The hall effect sensor switch of claim 1, wherein the magnet is attached to an actuator
for moving the magnet to the first position and the second position;
wherein, in the first position, the magnet is positioned in proximity to the first hall
effect sensor and in the second position, the magnet is positioned in proximity to the
second hall effect sensor; and
wherein, the first hall effect sensor is separated from the second hall effect sensor by a
predetermined distance, the first hall effect sensor and the second hall effect sensor
aligned along a path of motion of the magnet.
4. The hall effect sensor switch of claim 1, wherein the first hall effect sensor is coupled
to a battery via a voltage level conversion element and a first protection circuit, said voltage
level conversion element being providedfor converting a voltage from the battery to a voltage
required to operate the first hall effect sensor.
5. The hall effect sensor switch of claim 1, wherein the first hall effect sensor has a
latched output.
6. A method for reducing quiescent current consumption in a hall effect sensor switch,
said method comprising:
energizing or de-energizing a second hall effect sensor based on an output of a first
hall effect sensor, wherein the first hall effect sensor provides the output to the
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second hall effect sensor when a magnet reaches to a first position from an initial
position; and
activating the second hall effect sensor when the magnet reaches a second position
from the first position.
7. The method of claim 6, wherein the first hall effect sensor draws a first quiescent
current and the second hall effect sensor draws a second quiescent current, and wherein said
first quiescent current is less than said second quiescent current.
8. The method of claim 6, wherein, in the first position, the magnet is positioned in
proximity to the first hall effect sensor and in the second position, the magnet is positioned
in proximity to the second hall effect sensor.
9. The method of claim 6, wherein the first hall effect sensor has a latched output.
10. A hall effect sensor switch, comprising:
a first hall effect sensor;
a first transistor having its base electrically coupled to an output of the first hall effect
sensor ; and
a second hall effect sensor coupled in series with said first transistor, wherein
activation of said first hall effect sensor turns first transistor ON which energizes said
second hall effect sensor.
11. The hall effect sensor switch of claim 10, further comprising:
a second transistor having its base electrically coupled to an output of the second hall
effect sensor, wherein activation of said second hall effect sensor turns said second
transistor ON, thereby providing an output to at least a high side driver;
12. The hall effect sensor switch of claim 10, further comprising a voltage level
conversion element to convert a voltage received from a battery via a first protection circuit
to a predefined voltage, wherein said voltage level conversion element is electrically coupled
to said first hall effect sensor and to said first transistor for providing said predefined voltage,
and wherein said first protection circuit comprises a diode and a transient voltage suppression
diode.
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13. The hall effect sensor switch of claim 11, wherein said output of said second transistor
energizes one or more of a hazard light, a tail light, stop lamp and horn of an automobile.
14. A hall effect sensor switching system, comprising:
a first section comprising a hall effect sensor switch as claimed in claim 10; and
a second section comprising:
a third hall effect sensor;
a second protection circuit coupled to the third hall effect sensor, said second
protection circuit comprising a diode and a transient voltage suppression diode; and
a third transistor having its base electrically coupled to an output of the third hall
effect sensor, wherein an activation of said third hall effect sensor turns ON said third
transistor.
15. The hall effect sensor switching system of claim 14, wherein said output of said third
transistor deactivates a cruise control mode of an automobile via a fourth transistor .