Claims:We claim:
1. A sensing system (100) for sensing an operating condition of a vehicle component in a vehicle, said sensing system (100) comprising:
a first switching unit (SU1); and
a second switching unit (SU2),
the second switching unit (SU2) configured to detect a voltage across said vehicle component, said vehicle component provided in one or more topologies driven by one or more voltage signal; and
at least one indication unit (111) capable of being controlled by said first switching unit (SU1) at least based on the voltage detected by said second switching unit (SU2).
2. The sensing system (100) as claimed in claim 1, wherein the sensing system (100) comprising:
a positive sensing terminal (102);
a negative sensing terminal (101);
a source terminal (BT); and
an output terminal (OT),
wherein
said positive sensing terminal (102) connected to a higher potential node of said vehicle component and said negative sensing terminal (101) connected to a lower potential of said vehicle component,
the source terminal (BT) is connected to a power source (B) of the vehicle, and
the output terminal (OT) is connected to the at least one indication unit (111) of the vehicle.
3. The sensing system (100) as claimed in claim 1, wherein the first switching unit (SU1) comprises:
a first switch element (Q1), said first switch element (Q1) comprising:
a first emitter terminal (E1) forming said source terminal (BT) connected to the power source (B); and
a first collector terminal (C1) forming said output terminal (OT); and
a first base terminal (B1) functionally connected to the second switching unit (SU2).
4. The sensing system (100) as claimed in claim 1, wherein the second switching unit (SU2) comprises:
a second switch element (Q2), said second switch element (Q2) comprising:
a second emitter terminal (E2) forming said negative sensing terminal (101);
a second collector terminal (C2) functionally connected to said first switching unit (SU1); and
a second base terminal (B2) forming said positive sensing terminal (102).
5. The sensing system (100) as claimed in claim 1, wherein the vehicle component is selected from a group consisting of a headlamp, a tail lamp, a daytime running lamp, and a position lamp, said vehicle component being capable of switching between a low voltage condition and a high voltage condition.
6. The sensing system (100) as claimed in claim 2, wherein said negative sensing terminal (101) is electrically configured to a voltage regulator circuit (103), said voltage regulator circuit (103) comprising a regulating zener diode (D2) provided in a parallel configuration with a regulating resistor (R1) and a filtering capacitor (C1).
7. The sensing system (100) as claimed in claim 3, wherein the sensing system (100) includes a spike protection diode (D1) electrically configured across said second emitter terminal (E2) of said first switch element (Q1).
8. The sensing system (100) as claimed in claim 2, wherein said first switch element (Q1) is electrically connected to a second switch element (Q2) through a second collector resistor (R3).
9. The sensing system (100) as claimed in claim 8, wherein said first switch element is (Q1) actuated by said second switch element (Q2) if a voltage across said positive sensing terminal (102) and said negative sensing terminal (101) is greater than a threshold voltage set by a base zener diode (D3), and said base zener diode (D3) to set a threshold voltage for said sensing system (100) coupled to a sense diode (D4)
10. The sensing system (100) as claimed in claim 1, wherein said positive sensing terminal (102) is electrically configured to said sense diode (D4) in a forward biased condition.
11. The sensing system (100) as claimed in claim 1, wherein said indication unit (111) includes a tell-tale LED in an instrument cluster or a beeper.
12. The sensing system (100) as claimed in claim 1, wherein said one or more voltage signal is an AC signal and a DC signal.
13. The sensing system (100) as claimed in claim 1, wherein a rectifier circuit (200) is configured to receive one or more voltage signal from said positive sensing terminal (102) and said negative sensing terminal (101), wherein said rectifier is a bridge rectifier.
14. The sensing system (100) as claimed in claim 13, wherein said rectifier circuit (200) is coupled to a voltage regulator circuit (103) and a sense diode (D4).
15. A method to sense a high beam condition of a headlamp in a vehicle through a sensing system (100) comprising:
checking ON condition of said headlamp;
sensing a voltage across said headlamp;
rectifying said voltage sensed across said headlamp;
filtering and regulating said voltage by a voltage regulator circuit (103);
comparing said voltage with a threshold voltage by a base zener diode (D3);
activating a first switch element (Q1) by a second switch element (Q2) when said voltage is greater than said threshold voltage; and
actuating an indicator unit (111) by said first switching unit (SU1).
, Description:TECHNICAL FIELD
[0001] The present subject matter relates generally to a vehicle. More particularly but not exclusively the present subject matter relates to a high beam sensing system in said vehicle.
BACKGROUND
[0002] Most of the vehicles are installed with halogen lamps in the headlight assembly. Halogen lamps are relatively inexpensive compared to other options like light emitting diodes (LEDs) bulbs. However, every vehicle is restricted by the availability of power sources. Hence, it becomes crucial that the head lamp should not take up the entire power as the vehicle may require more energy from the energy source during starting the vehicle. Even after refining the design of halogen lamps to make it power efficient, still compared to LED, halogen lamps consume more power.
[0003] Light Emitting Diodes (LEDs) are durable and efficient source of light. In order to achieve the light intensity produced by a halogen lamp multiple LEDs are coupled in form of array in parallel combination, series combination or mix of both series and parallel. Depending of the requirement, the headlamp may have combination of LEDs along with halogen lamp arranged in one or more architecture.
[0004] Different vehicles have different electrical architecture based on cost, feature requirements and other requirements of that vehicle. The architecture may consist of Alternating current (AC) component supplying to some loads and Direct current (DC) component supplying to other loads. The architecture may comprise AC component alone or DC component alone or combination of both. Headlamp is an important part in this architecture having two modes of operation namely, high beam (driving beam) and low beam (passing beam). When the high beam is in active mode a tell-tale indication need to be provided in the vehicle to enable the driver to know whether the high beam is in ON condition or in OFF condition.
[0005] General methods for high beam indication for AC filament headlamp are connecting indication bulb or LEDs in series with a resistor across high beam filament. For DC filament headlamp, same method can be used. High beam indication can also be driven by host controller of an instrument cluster. The sensing can be done through suitable voltage conversion circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Figure 1 illustrates a block diagram of a sensing system.
[0007] Figure 2 illustrates an architecture of the sensing system to sense high beam condition of the headlamp.
[0008] Figure 3 illustrates another embodiment of the present subject matter where the sensing system is connected to an indication device.
[0009] Figure 4 illustrates another embodiment of the preset subject matter where the sensing system is electrically configured to a rectifier.
[00010] Figure 5 illustrates a high side driver circuit in which the LED lamp is connected to a RR (regulator-rectifier) unit.
[00011] Figure 6 illustrates embodiment for a low side LED driver implementation with the sensing system.
[00012] Figure 7 illustrates another embodiment for a low side LED driver implementation with the voltage sensing circuit.
[00013] Figure 8 illustrates another embodiment where headlamp circuit employs AC regulator rectifier supplying negative AC (Alternating current).
[00014] Figure 9 illustrates a flow chart to depict a method of sensing the high beam condition in a head lamps such as a headlamp which is capable of switching between a low beam condition or a high beam condition.
DETAILED DESCRIPTION
[00015] LED headlamp has plurality of LEDs driven by an LED driver. LED driver can be of various topology of headlamp circuit such as high side driving, low side driving or mixed topology. The supply to LED can be positive or negative. During high beam condition, a specific set of LEDs are operated. And during low beam condition, different set of LEDs might be operated.
[00016] Such variations in the architecture and feature requires several different types of sensing circuit for indicating high beam condition in instrument cluster. This results in manufacturing multiple variants of speedometer. The speedometer can be standardised across product models or variants by adding external sensing circuit, but again there is need for variants of sensing circuit for sensing high beam condition.
[00017] Hence, it is the object of the present subject matter is to provide a improved sensing system for a vehicle which can sense the high beam condition in different topologies irrespective of the type of vehicle component used and to indicate the same through an output such as an LED of tell–tale in instrument cluster eliminating the need of manufacturing different instrument clusters for each type of topology. The vehicle component is selected from a group consisting of a headlamp, a tail lamp, a daytime running lamp, and a position lamp. Also, the vehicle component is capable of switching between a low voltage condition and a high voltage condition
[00018] Another aspect of the present subject matter is to provide a sensing system comprising a first switching unit and a second switching unit such that the second switching unit is configured to detect a voltage across a vehicle component of the vehicle causing the first switching unit to control one or more indication source such as LED of tell-tale in instrument cluster of the vehicle or a beeper to indicate the user of the vehicle about the high beam condition.
[00019] Yet another aspect of the present subject matter provides a sensing system comprising a positive sensing terminal and a negative sensing terminal functionally connected across two points of the vehicle component such as a headlamp in order to sense the voltage. The positive sensing terminal connected to a higher potential node of said vehicle component and said negative sensing terminal connected to a lower potential of said vehicle component.
[00020] Still another aspect of the present subject matter provides a source terminal configured to the sensing system to provide power from a power source such as a battery provided in the vehicle and an output terminal which connects the indication source to provide indication.
[00021] Yet another aspect of the present subject matter provides a rectifier circuit which is configured to receive one or more voltage signal from the positive sensing terminal and the negative sensing terminal of the sensing system which allows the sensing system to get connected to a vehicle component thereby eliminating the requirement of connecting the positive sensing terminal to a higher potential node an the negative sensing terminal to a lower potential node which makes the sensing system easy to assemble and eliminates any risk of circuit failure.
[00022] Another aspect of the present subject matter is to provide a voltage regulator circuit comprising a regulating zener diode provided in a parallel configuration with a regulating resistor and a filtering capacitor to filter out the AC signal.
[00023] Yet another aspect of the present subject matter is to provide a zener diode to set a threshold voltage for the sensing system.
[00024] Fig. 1 illustrates a block diagram of a sensing system (100) which comprises a first switching unit (SU1), a second switching unit (SU2) and an indication unit (111). The second switching unit (SU2) is configured to detect the voltage across the headlight of the vehicle. The headlight may have one or more topologies like high side driving topology, low side driving topology that may be driven by one or more voltage signal such as an AC signal or a DC signal. The indication unit (111) is controlled by the first switching unit (SU1) depending on the voltage detected by the second switching unit (SU2).
[00025] Fig. 2 illustrates an architecture of the sensing system (100) to sense high beam condition of the headlamp. The sensing system (100) comprises two sensing terminal, namely, a positive sensing terminal (102) and a negative sensing terminal (101). The sensing system (100) senses a high beam condition for high side driving topology or low side driving topology. The sensing system (100) comprises a first switching unit (SU1) and a second switching unit (SU2).
[00026] The first switching unit (SU1) comprises a first switch element (Q1) comprising a first emitter terminal (E1) forming source terminal (BT) connected to power source (B) such as a battery. Then, a first collector terminal (C1) forming the output terminal (OT) and then a base terminal (B1) functionally connected to the second switching unit (SU2).
[00027] The second switch element (Q2) comprises a second emitter terminal (E2) forming negative sensing terminal (101), a second collector terminal (C2) is functionally connected to the first switching unit (SU1) and then a second base terminal (B2) forms the positive sensing terminal (102).
[00028] Further, the positive sensing terminal (102) is electrically configured to a sense diode (D4) which is a uni-junction p-n diode connected in a forward biased condition, such that the p-type semiconductor of the sense diode (D4) is connected to the positive sensing terminal (102). The negative sensing terminal (101) is electrically configured to a voltage regulator circuit (103) comprising a regulating zener diode (D2) arranged in a parallel configuration with regulating resistor (R1) and a filtering capacitor (C1).
[00029] P-type semiconductor of the zener diode (D2) is configured to an second emitter terminal (E2) of a second switch element (Q2). The second base terminal (B2) of the second switch element (Q2) is connected to a second base resistor (R2) and anode of a base zener diode (D3). The cathode or the n-type semiconductor of the sense diode (D4) is connected to the cathode of the base zener diode (D3). The base zener diode (D3) sets a threshold voltage for the sensing system (100) and a biasing voltage for the second switch element.
[00030] Further, the collector terminal of the second switch element (Q2) is connected to a base terminal of the first switch element (Q1) through a second collector resistor (R3). The first emitter terminal (E1) of the first switch element (Q1) receives current supply from a power supply (B) by electrically connecting the first emitter terminal (E1) of the first switch element (Q1) to the positive terminal of the battery (B). A spike protection diode (D1) has been connected across the first emitter terminal (E1) and the first collector terminal (C1) of the first switch element (Q1) in order to protect the first switch element (Q1) from any power spike that may be generated by the power source (B) connected to the first emitter terminal (E1) of the first switch element (Q1). The first base terminal (B1) of the first switch element (Q1) is connected to the battery (B) through a second base resistor (R5). The first collector terminal (C1) of the first switch element (Q1) is connected to an output terminal (OT) which is configured to an indication unit (111) that is a high beam indicator such as an LED of the tell-tale in the instrument cluster or a beeper.
[00031] The sensing system (100) is used for sensing a high beam condition when connected to one or more type of LED topology. The second switch element (Q2) is responsible for switching the first switch element (Q1). The second switch element (Q2) gets actuated if the voltage across positive sensing terminal (102) and negative sensing terminal (101) is greater than a threshold voltage set by the base zener diode (D3) and the biasing voltage for the second switching element. The positive sensing terminal (102) and the negative sensing terminal (101) are connected to a driver circuit of the headlamp circuit such that the voltage at positive sensing terminal (102) is higher compared to the voltage at the negative sensing terminal (101). With this configuration the sensing system (100) is capable of sensing even for low side driving topology of the headlamp. The regulating resistor (R2), second base resistor (R1) and filtering capacitor (C1) attenuates and smoothens the AC (alternating current) voltage.
[00032] Fig. 3 illustrates another embodiment of the present subject matter where the sensing system (100) is connected to an indication device in a speedometer. Whenever a high beam condition is detected by the sensing system (100) then the high beam indicator (111) starts glowing. The high beam indicator (111) can be located in a speedometer in order to indicate the vehicle user that the high beam condition is in active mode. Therefore, the collector terminal of the first switch element (Q1) is connected to the high beam indicator (111) which is mainly a head lamp like an LED (Light emitting diode).
[00033] Fig. 4 illustrates yet another embodiment of the preset subject matter where the sensing system (100) is electrically configured to a rectifier (200). With the inclusion of the rectifier circuit (200), the need for changing the sense terminals for different topologies of the headlamp and also for different types of power supply (AC or DC) gets eliminated. The sense terminals of the rectifier circuit (200) can be connected to any topology of the headlamp circuit irrespective of the polarity of the terminals or the type of the signal whether an AC (Alternating current) signal or a DC (Direct signal) signal. The rectifier circuit (200) is bridge type rectifier which is connected to the sensing system (100) comprises of two bridges with two p-n junction diodes in each bridge and one bridge in forward biased condition and another in reverse biased condition. The rectifier circuit (200) is configured to receive one or more voltage signal from the positive sense terminal (102) and negative sense terminal (101) of the sensing system (100) in which the voltage signal can be either AC signal or a DC signal. The rectifier circuit (200) is coupled to a voltage regulator circuit (103) and the sense diode (D4) of the sensing system (100).
[00034] Fig. 5 illustrates a high side driver circuit in which the LED lamp is connected to a RR (regulator-rectifier) unit (406). The circuit is a constant current driven circuit. There are two conditions, one is a low beam condition and another is the high beam condition for the LED lamp. At the time of low beam condition, the high beam LED diode (402) remains in OFF condition and a high beam switch (401) remains in closed condition therefore the voltage drop across the switch remains zero. Then the current flows from the low beam LED diodes (404,405). During the high beam condition, the high beam LED diode (402) gets energized. During the high beam condition, the voltage drop across the entire LED string is higher than that of low beam condition. This leads to sensing of the high beam condition. The RR unit (406) supplies negative rectified voltage to a first node (403) which is a lower potential node of the LED string, therefore, potential at first node (403) is negative and second node (404) is at positive potential which is a higher potential node when the high beam switch (401) gets open.
[00035] The sensing system (100) is connected to the first node (403) and the second node (404). The sense terminals with the positive sensing terminal (102) connected to the second node (404) and the negative sensing terminal (101) to detect the potential difference and a high beam condition gets indicated in the instrument cluster when the potential difference between the first node (403) and the second node (404) gets more than the threshold voltage set by the base zener diode (D3) and the biasing voltage of the second switching element. With the presence of rectifier circuit (200), any of the sense terminal can be connected to the first node (403) and the second node (404).
[00036] Fig. 6 illustrates another embodiment of the high side driving topology for driving LED headlamp where the RR unit (406) provides positive voltage to the LED string. The sensing can be accomplished by connecting the positive sensing terminal (102) to a string connecting point (201) and connecting negative sensing terminal (101) to a ground terminal (503). A high beam switch (504) has been provided. When the high beam switch (504) is opened then the high beam diode (504) gets illuminated and the potential at string connecting point (201) increases compared to the ground terminal (503). The sensing system (100) senses this difference in the voltage and an indication for high beam condition is provided.
[00037] Fig. 7 illustrates another embodiment for a low side LED driver (603) implementation with the voltage sensing circuit (100). The driver supplies positive voltage to the LED string. The sensing of the voltage is being done by connecting positive sensing terminal (102) to positive terminal of the battery and the negative sensing terminal (101) connected to connecting point (604).
[00038] Fig. 8 illustrates another embodiment where headlamp circuit employs AC regulator rectifier (702) supplying negative AC (Alternating current) to a lamp (701). The lamp (701) comprises of a low beam bulb (701a) and high beam bulb (701b). the negative voltage appears at node (703) during the high beam condition. Sensing of the high beam can be performed by connecting the positive sensing terminal to the ground terminal and the negative sensing terminal to the node (703). Similarly, the AC regulator rectifier (702) can be substituted by a DC regulator rectifier circuit to supply DC voltage.
[00039] Fig. 9 illustrates a method of sensing the high beam condition in a headlamp which is capable of switching between a low beam condition or a high beam condition. The headlamp of the vehicle can have one or more topologies. In step S301, it is checked whether headlamp is in ON condition or not. If the head lamp is not working, then the voltage is not sensed. If the light is in ON condition then in step S302, the voltage across the headlamp is sensed by the sensing system (100). Then in step S303, sensed voltage gets rectified by a rectifier circuit (200), in case the voltage is AC signal. Further, in step 204 the voltage gets filtered and regulated by the voltage regulator circuit (103). Then in step S305, it is checked whether the voltage across the headlamp sensed by the sensing system (100) is greater than the threshold voltage or not. If the voltage sensed by the sense system (100) is greater than the threshold voltage then in step S306, the first switch element (Q1) gets activated by a second switch element (Q2) in order to actuate an indication unit (111) in step S307. The sensing process continues as long as the vehicle is in ON condition.