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Title:
CIRCUITAL DEVICE WITH REED FUNCTIONALITY
Document Type and Number:
WIPO Patent Application WO/2018/025218
Kind Code:
A1
Abstract:
The present invention refers to the field of magnetic switches, universally known as reed contacts. Specifically, the present invention describes a circuit device that is adapted to replace a reed sensor having only two signal cables (/a, 7b) and a Hall effect or magnetoresistive sensor (3). Power supply is provided to the device through the two signal cables with aid of at least one capacitor (6) and at least one diode (5) comprised in said circuit device.

Inventors:
LAZZAROTTO, Roberto (Via belvedere 15, Castronno, Varese, 21040, IT)
Application Number:
IB2017/054759
Publication Date:
February 08, 2018
Filing Date:
August 03, 2017
Export Citation:
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Assignee:
LAZZAROTTO, Roberto (Via belvedere 15, Castronno, Varese, 21040, IT)
International Classes:
H03K17/95
Attorney, Agent or Firm:
BALDI, Raffaella Erminia et al. (Corso di porta Romana 132, milan, 20122, IT)
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Claims:
CLAIMS

A circuital device (1 ), comprising at least one solid state integrated circuit, that is an integrated element (2) comprising at least one Hall effect or magnetoresistive sensor (3) and means such as pins for electrical connections (9) said device being connected to at least a power source (4) characterized in that said integrated element (2) further comprising at least one diode (5) and said device comprising at least one capacitor (6) adapted to act as supplementary power source for that for said circuital device (1 ), being connected to said element (2) by means of pins (9), said diode (5) decoupling the capacitor (6) from said power source (4), said device comprising also at least another pin (9) of output (10), said output pin (10) and said al least one pin connected to one end at least to said capacitor (6) forming the two signal cables (7a, 7b), being adapted to be connected to other circuit components by means of said only two signal cables (7a, 7b) of the circuital device (1 ) for being connected to other circuit parts by means of said tow signal cables, being adapted to replace a sensor with reed functionality.

The circuital device (1 ) with reed functionality according to the preceding claims ,wherein said integrated element (2) in presence of magnetic field and connected in pull-up is feed by the capacitor, decoupled by means of the diode (5) and being feed on the same signal return cable (10, 7b, 7a).

The circuital device (1 ) with reed functionality according to the preceding claims, wherein said capacitor is comprised in said integrated element (2). The circuital device (1 ) with reed functionality according to the preceding claims, wherein said device (1 ) can be used in pull-up (8) or pull-down (12) circuits depending on the embodiment and on the arrangement of pins (9). The circuital device (1 ) with reed functionality according to the preceding claims wherein said integrated element (2) further comprises at least one further diode (D2,5) for using said device indifferently in pull-up (8) and/or Pull-down (12) circuits. The circuital device (1 ) with reed functionality according to the preceding claims, wherein said device (1 ) is adapted to be used in pull-up type circuits (8) and / or pull-down (12) type circuits.

The circuital device (1 ) with reed functionality according to the preceding claims, wherein said device (1 ) is suitable to be positioned in a circuit so as to detect the magnetic field in each spatial direction.

Description:
TITLE OF THE INVENTION:

"CIRCUITAL DEVICE WITH REED FUNCTIONALITY"

Text of the description

The present invention refers to the field of electronic devices for circuits, in particular the present invention refers to the field of magnetic switches, also known universally as reed contacts. Reed contacts have found use in the production of various types of sensors. There are two main modes of use of these contacts: realization of pure contacts, intended for the detection of a magnetic field, or realizations and applications for complex equipment, in which the reed contact is used as a transduction element.

To the first type of contacts belong for example the typical and known magnetic contacts for anti-theft alarms, wherein a permanent magnet is for example fixed on the edge of a door or of a window and on the adjacent doorpost the reed contact is mounted; until the door remains closed, the contact (under the influence of the magnet) remains closed. If the door is opened, the magnet by moving away, allows the opening of the contact.

Based on the same principle, the reed contact can be used for example as a proximity sensor namely a sensor adapted to detect the presence or absence of an object within the nominal range of said sensor.

To the second type of implementation or use of said reed contacts belong the reed transducers; for example the reed contacts may constitute the transduction element of a sensor designed for measuring physical quantities. For example it can be used for the creation of a low resolution data encoder (or encoder), useful for reading of angles or rotational speeds. The encoder, coupled to a wheel of known diameter, allows to perform linear velocity, space or acceleration measurements. The second case is not of interest for the purpose of the present invention, while it will be the described reed sensors.

l Said reed sensors therefore advantageously operate with only two wires to detect the presence of a magnetic field are therefore are of simple insertion within a complex electronic circuit.

Furthermore, the reed contact or sensor shows no dissipation of current and therefore of energy during the opening phase, since the foils that compose it remain separate, and therefore they physically interrupt the current flow through the sensor.

Said contacts by their nature, given their simplicity of realization have high reliability.

However, in a disadvantageous manner, the switching speed due to the mechanical construction of the sensor as known is not high. Moreover the life of the reed sensor has a duration dependent on its use, namely on the number of openings and closures that are performed, although being it a high number if it is also high the use, duration of the sensor is limited.

Also due to these last mentioned disadvantages in recent times it is common to replace when possible the reed sensors with Hall effect sensors. Said sensors in fact present as known a very high switching speed and an average life limited only by the reliability of the electronic component which is usually of many years. Other well-known sensors which are used to replace the reed sensors are magneto-resistive sensors.

The solution to adopt said sensors would appear valid in many respects, however, such replacement it is not always possible from a technical point of view since the Hall effect or magneto-resistive sensors, namely solid state switches, require the presence of three wires in total for their operation: or require the presence of two wires to provide for the power supply of the integrated circuit, in addition to the presence of a wire for signal return.

The problem of the three wires for the operation of the circuit comprising Hall effect or magneto-resistive sensors, therefore requiring three wires for their operation instead of the two necessary for the operation of the reed sensor, have the effect that a substitution in this sense is inconvenient making it necessary to completely modify the circuit and therefore also expensive both for the wire addition and for the modifications to be performed. This would frustrate the economic advantage of using Hall effect or magnetoresistive sensors.

One object of the present invention is to solve the prior art problems described here above.

A further object of the present invention is to describe a device suitable to maintain the advantages of reed sensors.

Still an advantage of the present invention is to describe a device suitable to maintain also the advantages of Hall effect and magnetoresistive sensors.

A further object of the present invention is to describe a device easy to integrate in any circuit.

Another object of the present invention is to describe a device that has high performance and is economical.

A further object of the present invention is to describe a device that achieves the functionality of a reed sensor and that is robust, reliable and long-lasting.

Another object of the present invention is to describe a device suitable to replace the reed sensors.

Note that there are devices that use two interface wires in a beneficial way, but their purpose is far from what will be described by the present invention; an example of a device with similar components but quite different in purposes and functioning is described in WO2007/132389, this device has as main purpose to make a current interface applicable at high frequencies as well.

The prior art invention essentially describes a current interface with purpose to solve the problem of voltage fluctuations to propose current interfaces for very accurate measurements.

The current interface with a block capacitor is known, but it has the drawback of presenting a low pass filter that blocks high frequency signals, the novelty of this document is to describe the introduction of a diode or voltage regulator that disconnects the signal from the low pass filter, so allowing also the high frequency current signals to be transmitted. The main purpose of this device is to ensure the functioning also in high frequency of a current interface with block capacitor; it should be noted that, in view of the objects of the invention described above, that purpose has nothing to do with any purpose of the present invention.

The only common factor are the two wires, which however have a totally different scope; in fact one of the main purpose of the present invention is to obtain a digital voltage interface by using only two wires: a reference and a power supply through a decoupling resistance.

In particular, a major purpose of the present invention is to ensure that a digital voltage signal is transmitted through two wires only, but having the wit of separating the power supply with a pull-up resistor that allows to transmit the digital signals. During the high signal, the power to the sensor is guaranteed form power given through the pull-up resistance, during the low signal

the power to the sensor is guaranteed by the storage capacitor, as long as this does not discharge. This will be described below with reference to some particularly preferred embodiments of the device innovatively proposed by the present invention.

These and further objects will be realized by the innovative circuit device provided with reed functionality described by the present invention which comprises at least one solid state integrated element which comprises at least one Hall effect or magnetoresistive sensor, means for realizing electrical connections and being connected at least to an external power source, in a particularly advantageous way said integrated element further comprises at least one diode and said circuit device comprises at least one capacitor adapted to act as a power supply for the circuit device during the low signal phase, thereby allowing to obtain the power supply of the integrated element on the same signal return cable enabling the replacement of reed sensors with the innovative device described here. Please note that it is totally new to separate the output of a signal from the external power supply of the integrated element decoupling them.

In a particularly advantageous way, the circuit device includes two signal wires to be connected to further circuit parts, therefore, in a highly innovative and advantageous manner, the present circuit device is suitable to be connected to other circuit parts by means of only two signal wires so performing the functions of a reed sensor.

So in a very innovative and advantageous way, the present circuit device is suitable to perform the functions of a reed sensor while maintaining the advantageous features of a Hall effect or magnetoresistive sensor.

In a further particularly advantageous embodiment of the solid state circuit device with innovative reed functionality described herein, said at least one capacitor will be included in said integrated circuit.

Basically, therefore, said solid state integrated element of said innovative circuit device is to all effects a new component.

The variants that comprise the at least one capacitor inserted in the integrated element or external to it, are derived from considerations of space and of configuration.

In a particularly advantageous way, therefore, the innovative circuit device allows to obtain the power supply of the integrated element on the same signal return wire allowing the replacement of reed sensors with the innovative device described herein which maintains all the advantages of economy, reliability and longer life also characterizing the Halle effect or magnetoresistive sensors.

In further advantageous manner it will be possible to replace reed sensors with the circuit device described herein without the need to make any substantial changes to the basic circuit.

In addition, in a further advantageous way, said circuit device will enable further economic savings due to the saving of the third power wire usually used in all circuits that uses Hall effect and magnetoresistive sensors.

Still in an advantageous way said circuit device is suitable to enter the market of ultra-low power integrated circuit, in fact, also for this device it will be sufficient the use of a small capacity capacitor, for example (=<1 uF), which usually is also economic, to ensure power supply to the device during the off-phase.

Additionally, said circuit device can operate with relatively low supply voltages, which allow long ignition cycles of the integrated circuit. Moreover said innovative circuit device, in an advantageous way exploits the phases in which the output signal is high to charge the power capacitor in particular embodiments.

Referring again to WO2007 / 132389, it is immediately noted that the device described by the present invention does not need to work of a current point i.e. "current source" such as that which happens instead for the device described in the cited document; moreover, the reading of the signal in that document is in current and analog. It follows that for this device analogue reading means are needed, while in the case described by the present invention less expensive digital means are used.

The circuit device described by the present invention consequently could not be used instead of the device described in the known art document, since such device comprises analog and current interfaces, in the case described by the present invention digital and voltage interfaces are comprised.

Finally, the condenser described by the present invention plays a role in storage, and has capacity greater than 1 uF, in the case described in the known art the capacitor function is that of a filter and has capacities lower than 1 uF: consequently the two circuits have different functions and purposes that make them not comparable.

The two devices have some common elements (capacitor, diode, and sensor) but they differ in the type of interface used: voltage and digital that described by the present invention and instead in current and analogue the one described in the prior art document, this so not permitting to exchange the devices or compare them to each other for purposes or uses.

These and other advantages, as well as variants and embodiments obtained thanks to the innovative circuit device described by the present invention will be further developed and described with reference to the accompanying figures in which:

in fig.1 it is represented a particularly preferred embodiment of the circuit device described by the present invention;

in fig.2 it is represented a detail of operation of the described circuit device;

in fig.2a and 2b are represented graphic examples of the signal analysis; in fig.3a it is represented a reed sensor in a particular mode of operation;

in fig.3b it is represented a particularly preferred embodiment of the circuit device described by the present invention;

in fig. 4 it is represented a further particularly preferred embodiment of the circuit device described by the present invention;

in fig. 5 it is represented a further particularly preferred embodiment of the circuit device described by the present invention.

With reference to Figure 1 it is represented a particularly preferred form of representation of the circuit device 1 described by the present invention; said circuit device 1 , in particular, here comprises at least one solid state integrated element 2 which comprises at least components of a Hall effect or magnetoresistive sensor 3, in a particularly advantageous way said integrated element further comprises at least one diode 5; said circuit device 1 further comprises connector pins 9 and comprises at least a capacitor 6. In this embodiment, in a particularly advantageous way, the circuit device 1 comprises two signal wires 7a, 7b suitable to connect said device 1 to further circuit parts including at least one power source 4.

In particular the diode 5 serve for decouple the storage capacitor 6 for the power source 4 and from the output signal when it is piloted low, to permit the reading of the low signal (situation which would not happen if the condenser remained coupled).

It appears immediately evident from fig.1 how said innovative circuit device 1 fulfills the functions of a classic reed sensor, therefore it can be advantageously connected to other circuit parts requiring only two wires for operation.

Therefore, unlike the known solid state circuits, it is no longer required two wires for the power supply of the integrated element plus an additional wire for signal return. Thanks to the present invention it is possible to obtain the power supply of the innovative device on the same signal return wire. Thanks to said innovative solution is therefore possible to replace the reed sensors with cheaper innovative circuit devices 1 described herein. In the present embodiment there are five output pin 9 this as before said is only an example, alternative embodiments that will be described within the scope of the present invention with advantageously comprise only three pins 9 in fig. 4. The operation of the circuit device 1 is as follows: two known cases have to be distinguished. In a first case, in the absence of a magnetic field in the proximity of the circuit device 1 , the integrated circuit 2 is in the high stable state HIGH and said integrated element 2 at the same time is powered by means of the pull- up resistance 8; this condition is a stable condition, and can be maintained for all the necessary time.

In a second case in the presence of a magnetic field in the proximity of the circuit device 1 , the integrated element 2 drives the output 10 in the low state LOW, disconnecting the continuous powering given by from the power source 8, in this case, the pull-up resistance.

The integrated circuit 2 in this phase is powered by the condenser 6, named bulk/storage capacitor, that ensures a working voltage for the time Toff.

The capacitor maintaining the power supply to the circuit permit a reading of the signal on the two same wires 7a, 7b.

When the voltage of the capacitor 6 is no longer sufficient to ensure the operation of the integrated element 2, the output is driven on high by the pull-up resistor 8 located on the signal wire as long as the voltage of the capacitor 6 returns sufficient to ensure the operation of the integrated element 2. This time is defined Ton interval namely the time in which, by means of the pull-up resistance 8 the capacitor is recharged.

The present innovative integrated device 1 , in this phase advantageously also benefits from the fact that the integrated circuits generally need a certain time to "awaken" the devices and be operational. This time is defined time to awake. During this phase in an entirely advantageous way the capacitor 6 here suitably dimensioned, as said is recharged, without any disadvantageous effect on the circuit.

There occurs therefore - as represented in fig.2 - an alternating turning on and off of the integrated element 2 of the circuit device 1 which produces a wave similar to a square wave as shown. Said wave similar to a square wave has a period determined by the current dissipation of the integrated element 2 and by the size of the bulk/storage capacitor 6.

In the case therefore of particularly advantageous replacement of the circuit device 1 in place of a reed sensor, a high signal will be produced in case of absence of the magnetic field in the proximity of the device and a low signal with a wave similar to a square wave having programmable period, instead of the signal continuous low, as is the case of the reed sensor, in the presence of a magnetic field.

Therefore, as for the reed sensor, the high and low signal state are obtained, characterized in the case of the use of the circuit device 1 , by a high (constant) signal in the absence of the magnet and a low (oscillatory) signal characterized by a wave similar to a square wave of programmable period.

The oscillatory signal of the low state, in a particularly advantageous way, is compensated as described below.

In fact, in the case where the circuit device 1 has to switch between the high state HIGH and the low state LOW with a frequency higher than the frequency of the charging and discharging of the integrated element 2, the capacitor 6 has the opportunity to recharge before the time Toff has elapsed, namely before the capacitor 6 is completely discharged.

This allows, advantageously, to maintain a steady state low as in the case of the reed sensor thus obtaining the desired waveform, and the required operating characteristics. Note that the pull-up resistance 8 should preferably have a high ohmic value, to ensure that the output signal in the absence of the magnet is read at a logic level as high.

It is of course to be observed that if the switching of the circuit device 1 between the high state and the low state occurs as described here above, in such case the output signal varies from low and high following the requested commutation but in both cases, both of high signal and of low signal, a constant signal is obtained.

In the case where the circuit device 1 switched between the high state and the low state with a lower frequency with respect to the frequency of charge and discharge of the integrated element 2 namely of the capacitor 6, the low signal when the capacitor is discharged assumes a form of a wave similar to a square wave having square-like wave having duration Ton, where Ton is the time of charging of the capacitor 6.

It is to be noted that the duration of Ton is very small compared to the overall duration of the low signal LOW (Ton « Toff), as is represented in fig.2a and 2b where it is represented a signal analysis of an operative example which shows the low state of the circuit device 1 in case of pull-up. Note how, for example, the signal remains in the low stable state Toff for 5 seconds - fig 2a - presenting a Ton time of 75 ms -fig.2b- any expert in the field is aware of the fact that to obviate this occurrence, it is sufficient to apply a software filter in order to discriminate the signal shown in fig 2a and read the whole advantageously as a stable low signal.

In an extremely advantageous way the innovative circuit device 1 described herein in the pull-up preferred embodiment, allows to fulfill the functions of a reed sensor while maintaining the advantages and combining thanks to the new integrated element 2, the advantages of the Hall effect or magnetoresistive sensors.

It is to be noted that each element considered is already known and in use in any circuit, in such a way that the innovative circuit device 1 can be inserted/replaced to a reed sensor at almost zero cost, obtaining the mentioned advantages.

It is to be noted that with regard to the operation of the magnetic field, it is known that the reed sensors act as an antenna and can receive the magnetic field in all spatial directions, the Hall effect sensors instead require a North-South magnetic field perpendicular to the sensor and the magnetoresistive or MR sensors experience the magnetic field only in the longitudinal direction of the sensor, this factor does not constitute any problem for the purpose and the realization of the advantages described by the present invention, since during installation of the sensors it is always easily possible to know the orientation of the magnetic field which interacts in an operative phase with the sensor, so it would just be necessary to install the circuit device 1 according to the magnetic field direction useful for its operation.

In a further advantageous fashion said innovative circuit device 1 can replace a known reed sensor is known both in the case of a pull-up operation or a pull- down operation. With reference in this last case fig.3a and 3b are described, where in fig.3a it is represented for completeness a pull-down circuit with a reed sensor. In this case a low signal is obtained in the absence of the magnet and a high signal in the presence of the magnet.

With reference to Figure 3b the innovative circuit device 1 includes also in this case a particularly innovative circuit element 2 comprising at least components of a Hall effect or magnetoresistive sensor 3, in a particularly advantageous way said second integrated circuit 2 element further comprises at least one diode 5 and said circuit element 2 comprises connection pins 9. In this case at least two output pins 9 are connected to a bulk/storage capacitor 6. Furthermore on a pin 9 of output 10 a pull-down resistor 12 is connected.

In this case the operation of the innovative circuit device 1 with the pull-down resistor 12 is as follows: in the absence of a magnetic field in the proximity of the circuit device 1 , the integrated circuit element 2 comprising Hall effect or magnetoresistive elements and the capacitor 6 are powered by means of the pull-down resistor 12, obtaining a high and stable output signal. Note that by way of example at the output of circuit the voltage is (Vsupp-Valim) obviously Vsupp refers to the pull-down resistance 12 and Valim refers to the integrated circuit 2. It appears evident that it is relevant to have an integrated circuit element 2 which is powered in a low voltage in such a way that the output signal is read as a high signal from the logic that manages said circuit devices.

On the contrary in the presence of a magnetic field in the proximity of the circuit device 1 in this case a closed circuit is obtained and a low and stable output signal, here in fact the circuit device 1 and of course including the integrated circuit element 2 as well as the capacitor are powered by standard power. In this case the piloted low output will give a reading of 0 V.

It is to be noted that to obtain the advantageous effects described above the pulldown resistance of the has substantially preferably an appropriate value. Therefore in the case of realization of an innovative circuit device 2 of the pulldown type it will be sufficient to apply a filter to deny the logic of the outputs of the logic and thus obtain the logic of the reed sensor as used in a pull-down circuit.

Finally in fig.4 it is represented a further embodiment of the innovative circuit device 1 of the pull-up type in which the connection pins 9 of the circuit element 2 integrated 9 with the capacitor 6 are two instead of the three shown in Figure 1 where the pins of the circuit element 1 are connected externally with respect to the integrated element 2 to the condenser 6. In fig. 1 the input/output pins from the integrated 2 were two, in this embodiment only one, with considerable spatial advantages from the point of view of size and ease of installation.

Referring now to fig.5, there is represented a particular preferred and versatile embodiment of the innovative circuit device 1 described in the present invention; in particular in this embodiment said innovative circuit device 1 comprises said integrated element 2 advantageously realized to be work as well with a pull-up or pull-down circuit.

In particular, in the present embodiment, said integrated element 2 comprises at least components of a Hall or magnetoresistive 3 sensor, and at least one diode D1 ,5 and a diode D2,5. In particular, said circuit device 1 comprises three connection pin 9, of which two at least to one capacitor 6 and at least one in output 10 from said circuit element 2.

Note that in a particularly advantageous way as mentioned, in this embodiment said circuit device 1 , if used in a pull-up circuit will work with the diode D1 in operation and the diode D2 interrupted, i.e. it does not work.

In the case instead, where said circuit device 1 is used in a Pull-down circuit the diode D2 will operate in conduction and diode D1 in interdiction, that is, it does not work, of course, it depends on the circuit connections that will be made with simplicity ad hoc, by any industry expert.

Finally, reference is made to the above mentioned prior art document, as it has been pointed out from the description, the purposes are basically different, the main difference between the two devices is the type of interface (voltage digital for the present invention, i.e. discrete measurements of the voltage signal, against current analogue for the known art device, i.e. continuously measuring of the current variation) and further in a particularly evident way, from the fact that in the present device described by the present invention the capacitor acts as an additional power, while in the case of the prior art it acts as a filter. In the present invention, the device in the case of very low-frequency signals (<1 Hz) acts by switching on and off the sensor (this is why it is important to have sensors which work at low power consumption), while in the case of prior art, note the power supply must always be guaranteed.

Advantageously, in the present invention it is possible to use digital sensors can (easier to use) instead of analogs: substantial difference especially for the reading of the signal, as known easier with digital signals.

The present invention does not include current source points, with consequent saving of components in economic terms and space.

The present invention is further more versatile, as the innovative device can be used with low quality power supplies, which do not guarantee in continuous manner the power supply (in fact, in this case the capacitor plays the role of auxiliary power supply), while the known art device requires better power supplies that ensure a continuous feeding.

It appears obvious that each variant of the innovative device here described, therefore also for circuit devices of the pull-down type or further embodiments in which the pins are arranged differently are to be considered included in the object of the present invention.

It appears further evident that the described circuit arrangement 1 realizes all the innovative purposes described here; in a particularly advantageous way, therefore said circuit device 1 is and comprises, in effect, a new circuit element. In particular with reference to the integrated circuit element 2 newly developed. Dimensional variants of the integrated circuit element are also to be considered object of the present invention, connections with external components such as at least one capacitor 6, or insertion of the at least one capacitor 6 in the innovative integrated element 2, inputs and outputs pull-up resistors or pull-down resistors, sizing of the components with regard to configuration, voltages, resistances etc., type of logical filters applied, external control modes by means of microcontrollers etc .., orientation of the circuit device 1 with respect to the applied magnetic field, variations in performance etc .. are to be considered object of the present invention as described in the appended claims .