Title of Invention

AN ELECTRONIC DEVICE USEFUL FOR MEASURING DISPLACEMENT.

Abstract

The present invention provides an Electronic Device useful for measuring displacement which comprises a Light Dependent Resistor (LDR) (a) and a light source (b) placed and connected in such a manner so as to provide a change in output signal from the LDR proportional to the displacement to be measured, the LDR output being connected to electronic signal processing circuitry and display device, the said light source, LDR, signal processing circuitry and display device being provided with suitable means of power supply. The device of the present invention is based on the principle of photoelectric effect and can measure the mechanical displacement in non-contact mode.

Full Text

The -present invention relates to an Electronic device for measuring displacement. The device of the present invention based on the principle of photoelectric effect can measure the mechanical displacement in noncontact mode. The main usages of the device of the present invention are for measurement of weight or load of mechanical nature and in the applications of sensing the physical displacement between the two adjacent surfaces.Many secondary usages are the derivatives from the primary device such as collection of dataset of the displacement or in terms of weight from multiple locations for the purpose of maintaining records. The prior art in this field has been searched thoroughly in the patent as well as in the literature data base. But no relevant information can be incorporated in this document, simply because nothing exists to compare the principle of physics applied in the present case. In the usual type mechanical weighing machine , the effective displacement in owing to the load on the weighing pan is calibrated against the spring stiffness of the machine and displayed either through analog or through digital mechanism based on mechanical , electrical or electronic subcomponents. The main drawbacks in such systems are that , the record of weights or displacement at various locations are to be recorded separetely and data transmission for the purpose of monitoring from a single computer location is hardly possible. Moreover, the use of LVDT ( Linear Variable Differential Transformer) for the purpose of the measurement of displacement through electronics is a much costly proposition and the maintenance of LVDT is also a complex duty. All the known mechanical weighing machines are having sluggish response time and resistive to data transmission to locations beyond eye-sight. In the usual case of mechanical displacement measurement system the error due to contact force between rubbing elements produces an error which cannot be computed easily hence the uncertainity in the measurement system cannot be eliminated easily. This also varies with time. The main object of the present invention is to provide an Electronic Device useful for measuring displacement which obviates the drawbacks as detailed above. Another object is to provide a low cost electronic device based on photoelectric principle which - can sense the displacement due to load at an application point , such as a weighing pan. Yet another object of the present invention is to provide an Electronic Device which is capable to transmit displacement data or say,load data from different weighing machines located at different locations to a point of desired location, say, to a computer, for keeping records. Still another object of the present invention is to provide an Electronic Device useful for measuring displacement which is a noncontact sensor for displacement measurement. Yet another object of the present invention is to provide an Electronic Device useful for measuring displacement which can improve a mechanical weighing machine and which can be easily fixed to a mechanical weighing machine as a sensing electronic mechanism for the readout of weights. In the drawing accompanying this specification the block diagram of an embodiment of the device of the present invention has been shown. Block 'A1 is the weighing machine segment consisting of the weighing machine having the movement member such as moving rod(c) whose displacement is to be measured, LDR(a), ( Light Dependent Resistor ) and the light source(b). Block 'B' consists of a Signal Amplifier for enhancing the signal amplitude, sufficient to drive the analogue to digital converter along with the micro¬controller. Block 'C' is a micro controller for processing the signal and (d) are electrical connectors. Accordingly, the present invention provides an electronic device useful for measuring displacement which comprises a Light Dependent Resistor (LDR) (a) and a light source (b) placed and connected to provide a change in output signal from the LDR proportional to the displacement to be measured, the LDR output being connected to electronic signal processing circuitry and display unit, the said light source, LDR, signal processing circuitry and display unit being provided with suitable means of power supply The light source used may be such as a photo diode or any constatnt illuminating device.The electronic signal processing circuitry used may consist of a signal amplifier(B),an analogue to digital converter and a microcontroller(C). The display device used may be a multi segment light emitting diode (LED),liquid crystal display (LCD) or any voltage sensitive light emitting device. The power supply used may be such as electric main based or battery In an embodiment the presen invention provides an Electronic Device useful for measuring displacement which comprises a Light Dependent Resistor (LDR), a light source, a Signal Amplifier, a Micro Controller a. " a location of mechanical displacement member like the moving rod of an weighing machine whose displacement is to be monitored or measured. The above components are connected throuch esser.tia.. electronic/electrical means. In another embodiment of the present invention , a novel arrangement of measurement of displacement of a mechanical , geographical or the similcy: object, electronically, by means of LDR ( Light Dependent Resistor) and the associated processing electronic components as in the above paragraph, when the sensor, that is, the LDR is placed on the object of measusement and not in physical contact with the adjacent measurement component, that is to say , it is a noncontact method of measurement of displacement. The description of the device of the present invention, in an embodiment Electronic device useful for measuring displacement is given as follows: When weight is placed on the weighing machine the pointer on the scale indicates the load. The weight is transmitted to the dial gauge or to the indicator gauge through a rod; the displacement of which is proportional to the weight to be measured. That means, the displacement is proportional to the weight.Below the LDR a source of light is placed.Due to the displacement of the rod connected to the LDR the distance between LDR and the light source changes. As a result the intensity .of light falling on the LDR changes. The resistance of the LDR changes according to changed intensity of light. Thus a photoelectric current flows in the LDR which is proportional to the intensity of light. With the help of the LDR and the amplifier, a photocell amplifier circuit is designed. The analog voltage output of this circuit is the input to a microcontroller. The microcontroller gives a digital output which after proper conditioning may be fed to a computer. First the weighing machine is calibrated. This is done by applying different loads and noting the corresponding digital output of the microcontroller.Linearity of the output can be increased with the help of • the microcontroller comprising the resident software. As weight is proportional to digital output, it is given by the expression: W = D/K , where W is the weight .to be evaluated, D is the digital output and K is the constant of proportionality. If the value of the constant of proportionality and the digital output for different loads are known , the computer can calculate the load. Thus an electronic display of weight is achieved. The construction of the device is as follows; on a printed circuit board the different components are soldered. Wires are soldered onto it for connection to the power supply and for measuring the output. The LDR and light source are enclosed in a hollow black tube so that external light does not affect the readings. The following examples are given by way of illustration of the device of the present invention and should not be construed to limit the scope of the present invention. Example I A weighing machine manufactured by M/s Avery India having the weighing capacity upto 20 Kg. was taken for the validation of the present invention.The light source (Photodiode) was placed on the movement rod which transmits the mechanical displacement for the weighing pan to the dial gauge.Calibration of the dial reading with the electronic output was carried out by placing calibrated weights on the weighing pan & noting down the electronic reading from the electronic display device & plotting a graph to examine the linearity.By using this graph the actual weight to be measured was found out and displayed through the microcontroller associated with the display hardware. Further possible uses of the device of the present invention are: (i) The device can measure weight as a noncontact sensor and can feed a computer for data recording from different weighing machines which are fitted with such devices through CAN ( controller area network) when the weighing machines are located at different places. (ii) The device can sense the displacement of two adjacent surfaces when they move with slow speed. (iii) The device can measure the shift of bulk objects from a point of reference. (iv) The device can measure the contraction or expansion of an object of interest for the purpose of study or research. The main advantages of the device of the present invention are : 1. It is a noncontact device hence data is not modified due to changed frictional forces. 2'. Transmission of readings , electronically , to different locations are possible. 3. Study shows, it is one of the cheapest solution of measuring the weight electronically. LVDT is much costlier. We Claim: 1. An electronic device useful for measuring displacement which comprises a Light Dependent Resistor (LDR) (a) and a light source (b) placed and connected to provide a change in output signal from the LDR proportional to the displacement to be measured, the LDR output being connected to electronic signal processing circuitry and display unit, the said light source, LDR, signal processing circuitry and display unit being provided with suitable means of power supply. 2. An electronic device as claimed in claim 1, wherein the light source used is selected from a group comprising a photodiode or any constant illuminating device. 3. An electronic device as claimed in claim 1, wherein the electronic signal processing circuitry used consists of a signal amplifier (B), an analogue to digital converter and a micro controller (C). 4. An electronic device as claimed in claim 1, wherein the display unit used is selected from a group comprising a multi segment light emitting diode (LED), liquid crystal display (LCD) or any voltage sensitive light emitting unit. 5. An electronic device as claimed in claim 1, wherein the power supply used is selected from a group comprising electric main or battery based. 6. An electronic device useful for measuring displacement substantially as herein described with reference to the examples.

Documents:

1108-del-1998-abstract.pdf

1108-del-1998-claims.pdf

1108-del-1998-correspondence-others.pdf

1108-del-1998-correspondence-po.pdf

1108-del-1998-description (complete).pdf

1108-del-1998-drawings.pdf

1108-del-1998-form-1.pdf

1108-del-1998-form-19.pdf

1108-del-1998-form-2.pdf

1108-del-1998-form-5.pdf

1109-DEL-1998-Abstract.pdf

1109-DEL-1998-Claims.pdf

1109-DEL-1998-Description (Complete).pdf

1109-DEL-1998-Drawings.pdf

1109-DEL-1998-Form-1.pdf