FUSE BULB INDICATOR

Field of the invention
The present invention generally relates to a device for detecting working of a lamp mounted on an automotive vehicle. More particularly, the present invention relates to a lamp failure indicating device used in vehicular applications.

Background of the invention
A fault indicating systems for vehicles constructed by combination of large number of devices such as d.c. power source, fault indicating units, monitoring units are known in the prior art .Each fault indicating units are operable by a predetermined address signal which on being operable after a delay produces an output representative, indicating the operational condition of the device. However, these devices are downright complex and expensive and use a large number of materials.

Warning means for vehicles are known wherein the malfunction in the device is first indicated by a visual indication followed by a voice generation, when it is determined that a predetermined time has expired from the time of beginning of the visual indication.

Single series test circuits for indicating the failure of the lamps are known. However, these circuits are not very reliable as they detect all the failure through series circuit and thus decoding the actual failing device and type of fault will be difficult and error prone.

Thus, there is a strong need to provide a simple and cost-effective device which is effective and at the same time, simple to implement.

Object of the invention
The object of the present invention is to provide a lamp failure indicating device for vehicular application.

Summary of the invention
Accordingly, the present invention relates to a lamp failure indicating device for vehicular application, said device comprises a lamp; a D.C. power source connected to the said lamp; a shunt resistor being connected between the lamp and the DC power source to enable drop of a measurable shunt voltage across its terminals; a sensing circuit for sensing the shunt voltage drop across the shunt resistor and determining as to whether a value of the shunt voltage drop (VSH) is within a predetermined threshold limit (VTH) and in response generating an alarm signal; and an alarm indicating device connected to the sensing circuit for outputting the alarm signal.

The present invention also provides a lamp failure indicating device for vehicular application where said device comprising a plurality of lamps (L1, L2, L3,…Ln); a D.C. power source connected to each of the plurality of lamps via a separate electrical path; a plurality of shunt resistors (R1, R2, R3, …Rn) being connected to the D.C. power supply such that each electrical path between the D.C. power source and the plurality of lamps has at least one shunt resistor connected thereto, thereby enabling drop of measurable shunt voltages across the terminals of each of the plurality of shunt resistors (VSH1, VSH2, VSH3, …, VSHn); a sensing circuit for sensing each of the shunt voltage drop and determining as to whether a value of each of the shunt voltage drop is within a predetermined threshold limit allocated to it (VTH1, VTH2, VTH3, …VTHn) and in response generating a corresponding alarm signal (S1, S2, S3, … , Sn); and one or more alarm indicating devices connected to the sensing circuit for outputting the alarm signal.

The following paragraphs are provided in order to describe the best mode of working the invention and nothing in this section should be taken as a limitation of the claims.

Brief description of the Accompanying Drawings
In order that the invention may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying drawings, where like reference numerals refer to identical or functionally similar elements throughout the separate views. The figures together with a detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present invention where:

Figure 1 illustrates a block diagram of the lamp failure indicating device for vehicular application that detects failure of plurality of lamps mounted on the automotive vehicle.

Figure 2 illustrates the block diagram of the circuit which is connected to terminal identified as C6 in Figure 1.

Figure 3 illustrates the block diagram of the circuit which is connected to terminal identified as C7 in Figure 1.

Figure 4 illustrates the block diagram of the circuit which is connected to terminal identified as C8 in Figure 1.

Figure 5 illustrates the block diagram of the circuit which is connected to terminal identified as C9 in Figure 1.

Figure 6 illustrates the block diagram of the circuit which is connected to terminal identified as C10 in Figure 1.

Skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the drawings may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.

Detailed description of the preferred embodiments
Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the device has been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention 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, are intended to cover a non-exclusive inclusion, such that a process, method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process, method. Similarly, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.

As can be observed from Figure 1, it can be noticed that a microcontroller is provided to act as a sensing circuit for sensing the shunt voltage across a shunt resistor (not shown in Figure 1, but shown in figures 2 to 6) and for determining as to whether the value of the shunt voltage (VSH) thus measured is within a predetermined threshold value (VTH). In figure 1, port numbers 6, 7, 8, 9 and 10 are shown to be configured to receive the shunt voltage. If the microcontroller determines that the shunt voltage (VSH) thus measured is within a predetermined threshold value (VTH), then no alarm signal is generated. On the other hand, if the shunt voltage (VSH) thus measured is not within a predetermined threshold value (VTH), the microcontroller generates an alarm signal and sends the same to an alarm indicating device. In figure 1, the alarm indicating device has been shown as an LED which glows in presence of the alarm signal. However, it can be understood by a person skilled in the art that other types of alarm indicating devices could be used in place of LED, for example, any other device capable of producing visual effect or any other device capable of producing an audible effect such as a speaker etc.

Furthermore, figure 1 shows the microcontroller as having provision for connecting plurality of alarm indicating device. More particularly, figure 1 depicts the alarm indicating devices to be connected to port numbers 2, 3, 5, 11 and 15. However, it may be noted that if the microcontroller is configured to detect failure of only one lamp mounted on the automotive vehicle, then the number of alarm indicating device thus connected to the microcontroller could be restricted to one. Thus, in general, it may be preferred to have a 1-1 correspondence between the number of alarm indicating devices connected to the microcontroller and the number of lamps failure of which are to be detected by the microcontroller.

The microcontroller may be additionally supplied a reference voltage (which can act as the threshold value) with which the shunt voltage can be compared. In figure 1, a reference voltage is being supplied to the microcontroller via port number 12.

A person skilled in the art would observe that the remaining ports of the microcontroller may be utilized for other conventional purposes (such as but not limited to supply of VCC to the microcontroller, connecting the microcontroller to ground terminal, connecting the microcontroller to BERG stick, etc.).

Now coming to the Figure 2, it can be observed that Coupler 1 can be used for connection to the lamp and Coupler 2 can be used to connection to the D.C. power supply. It can be observed that shunt resistor S1 is located in the electrical path formed between the D.C. power source and the lamp. Port number 6 (C6) of the microcontroller may be coupled in the electrical path between the shunt resistor S1 and the lamp via a protection circuit (which for example, may be constituted by a resistor, a capacitor and a diode) for receiving the shunt voltage.

Similar arrangement (as shown in figures 3 to 6) can be adopted in respect of the remaining ports of the microcontroller which are configured to receive shunt voltage as the input.

When a particular lamp experiences failure, value of the shunt voltage across the shunt resistor will fall outside the predetermined limit and which can be sensed by the microcontroller. It can be observed that the protection circuit ensures that the voltages in excess of a predetermined value does not get applied to the microcontroller under both the normal operating status of the lamp as well as the failure status of the lamp.

The foregoing detailed description has described only a few of the many possible implementations of the present invention. Thus, the detailed description is given only by way of illustration and nothing contained in this section should be construed to limit the scope of the invention. The claims are limited only by the following claims, including the equivalents thereof.

WE CLAIM

1. A lamp failure indicating device for vehicular application, said device comprising:
a) a lamp;
b) a D.C. power source connected to the said lamp;
c) a shunt resistor being connected between the lamp and the DC power source to enable drop of a measurable shunt voltage across its terminals;
d) a sensing circuit for sensing the shunt voltage drop across the shunt resistor and determining as to whether a value of the shunt voltage drop (VSH) is within a predetermined threshold limit (VTH) and in response generating an alarm signal; and
e) an alarm indicating device connected to the sensing circuit for outputting the alarm signal.

2. A lamp failure indicating device for vehicular application, said device comprising:
a) a plurality of lamps (L1, L2, L3,…Ln);
b) a D.C. power source connected to each of the plurality of lamps via a separate electrical path;
c) a plurality of shunt resistors (R1, R2, R3, …Rn) being connected to the D.C. power supply such that each electrical path between the D.C. power source and the plurality of lamps has at least one shunt resistor connected thereto, thereby enabling drop of measurable shunt voltages across the terminals of each of the plurality of shunt resistors (VSH1, VSH2, VSH3, …, VSHn);
d) a sensing circuit for sensing each of the shunt voltage drop and determining as to whether a value of each of the shunt voltage drop is within a predetermined threshold limit allocated to it (VTH1, VTH2, VTH3, …VTHn) and in response generating a corresponding alarm signal (S1, S2, S3, … , Sn); and
e) one or more alarm indicating devices connected to the sensing circuit for outputting the alarm signal.

3. A lamp failure indicating device for vehicular application substantially as herein described with reference to the foregoing description and the accompanying drawings.