WO2006035350A1

WO2006035350A1 - Sensor

Info

Publication number: WO2006035350A1
Application number: PCT/IB2005/053072
Authority: WO
Inventors: Hans Van Zon
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2004-09-27
Filing date: 2005-09-19
Publication date: 2006-04-06
Also published as: JP2008514913A; TW200628806A; EP1797438A1; KR20070057259A

Abstract

Devices (1) with sensor arrangements (10) comprising movable objects (13) for, in response to movements, changing magnetic fields, are provided with a field detector (12) comprising a bridge with two or more elements (21-24,31-34) and a further bridge with two or more elements (35-38) for detecting components of magnetic fields in planes of the bridges. The bridge comprises first properties depending on the movements in Z-directions and second properties depending on the movements in X-directions. The further bridge comprises third properties depending on the movements in Z-directions and fourth properties depending on the movements in Y-directions. The first and third properties indicate that the resistance values of all elements have increased or decreased with substantially the same value. The second and fourth properties indicate that the resistance values of two elements have increased with substantially the same value and that the resistance values of two other elements have decreased with substantially the same value.

Description

SENSOR

The invention relates to a device with a sensor arrangement, and also relates to a sensor arrangement, and to a sensing method.

Examples of such a device are portable pc's and small handheld electronic devices such as mobile phones, personal digital assistants, digital cameras and global positioning system devices.

A prior art device is known from US 6,738,043 B2, which discloses a coordinates input apparatus comprising magnets for generating magnetic fields and electromagnetic transducers for generating output voltages. These output voltages have values that vary according to changes in gaps between the electromagnetic transducers and the magnets. This way, movements of one of the magnets in a three-dimensional space are converted into three-dimensional coordinates.

The known device is disadvantageous, inter alia, owing to the fact that it needs a personal computer to evaluate the output voltages. In other words, the known device generates output voltages which define movements in a relatively indirect way. This is relatively complex and relatively expensive.

It is an object of the invention, inter alia, to provide a device comprising a sensor arrangement which defines movements in a relatively direct way.

Further objects of the invention arc, inter alia, to provide a sensor arrangement which defines movements in a relatively direct way and a sensing method which defines movements in a relatively direct way. The device according to the invention comprises a sensor arrangement comprising: a movable object for, in response to a movement, changing at least a part of a magnetic field, and a field detector comprising a bridge with elements for detecting per element a component of the magnetic field in a plane of the bridge, which bridge comprises a first property depending on the movement in a first direction and a different second property depending on the movement in a different second direction. By introducing a field detector in the form of a bridge comprising at least two magnetic field dependent elements, such as magneto-resistive elements, which arc elements of which a resistance value depends on a strength and on a direction of a magnetic field in which the elements are located, the different properties of the bridge can be used for indicating different movements in a relatively direct way. As a result, the complex and expensive personal computer for evaluating the prior art output voltages of the electromagnetic transducers is no longer required. A first property of the bridge depends on a movement of the movable object in a first direction and indicates a first coordinate in a first direction, and a different second property of the bridge depends on a movement of the movable object in a different second direction and indicates a second coordinate. Other magnetic field dependent elements than magneto-resistive elements are not to be excluded. The device according to the invention is further advantageous, inter alia, in that, compared to using a personal computer for evaluating the prior art output voltages of the electromagnetic transducers, the total power consumption is reduced.

An embodiment of the device according to the invention is defined by a length axis of an clement and a direction of a magnetization of this element making an angle of 25- 65 degrees for a rest position of the movable object and for a given strength of the magnetic field. This embodiment is advantageous in that barberpole strips can be avoided. Such barberpole strips when located on an element decrease the total resistance value of this element and increase the power consumption. An embodiment of the device according to the invention is defined by the angle being substantially 45 degrees. This embodiment is advantageous in that the sensor arrangement has a maximum linearity and a maximum sensitivity.

An embodiment of the device according to the invention is defined by the sensor arrangement further comprising - a fixed object, the field detector being located between both objects and one of the objects comprising a field generator for generating the magnetic field and the other object comprising a field conductor for conducting the magnetic field. Compared to using two or more magnets as disclosed in US 6,738,043 B2, the use of a field generator such as for example a magnet and of a field conductor reduces the costs of the device.

An embodiment of the device according to the invention is defined by the first property being an external property and the second property being an internal property and the first direction being a direction substantially perpendicular to the plane of the bridge and the second direction being a direction substantially in the plane of the bridge. In case the plane of the bridge corresponds with the X-axis and the Y-axis, the first direction corresponds with the Z-axis and the second direction for example corresponds with the X- axis.

An embodiment of the device according to the invention is defined by the bridge comprising first and second external terminals for supplying the external property and first and second internal terminals for supplying the internal property and first and second serial branches located in parallel between the external terminals, which first serial branch comprises first and second elements coupled to each other via the first internal terminal and which second serial branch comprises third and fourth elements coupled to each other via the second internal terminal. The external property for example indicates that the resistance values of all elements have increased with substantially the same value or have decreased with substantially the same value. The internal property for example indicates that the resistance values of two elements have increased with substantially the same value and that the resistance values of two other elements have decreased with substantially the same value. This internal property is relatively independent from temperature changes, the external property is relatively dependent from temperature changes.

An embodiment of the device according to the invention is defined by the sensor arrangement further comprising a temperature compensator for compensating a temperature dependency of the bridge.

The temperature compensator compensates the temperature dependency of the bridge and therefore compensates the temperature dependency of the external property and allows the sensor arrangement to be used under changing temperature conditions. An embodiment of the device according to the invention is defined by the field detector comprising a further bridge with further elements for detecting per further element a component of the magnetic field in a further plane of the further bridge, which further bridge comprises a third property depending on the movement in the first direction and a fourth property depending on the movement in a different third direction. This sensor arrangement is sensitive to movements in three different directions. Usually, the plane of the bridge and the further plane of the further bridge will be substantially coinciding planes.

An embodiment of the device according to the invention is defined by the third property being an external property and the fourth property being an internal property and the first direction being a direction substantially perpendicular to the further plane of the further bridge and the third direction being a direction substantially in the further plane of the further bridge, the second and third directions being substantially perpendicular directions. In case the further plane of the further bridge corresponds with the X-axis and the Y-axis, the first direction corresponds with the Z-axis and the third direction for example corresponds with the Y-axis.

An embodiment of the device according to the invention is defined by the further bridge comprising third and fourth external terminals for supplying the external property and third and fourth internal terminals for supplying the internal property and third and fourth serial branches located in parallel between the external terminals, which third serial branch comprises fifth and sixth elements coupled to each other via the third internal terminal and which fourth serial branch comprises seventh and eighth elements coupled to each other via the fourth internal terminal. The external property for example indicates that the resistance values of all elements have increased with substantially the same value or have decreased with substantially the same value. The internal property for example indicates that the resistance values of two elements have increased with substantially the same value and that the resistance values of two other elements have decreased with substantially the same value. This internal property is relatively independent from temperature changes, the external property is relatively dependent from temperature changes.

An embodiment of the device according to the invention is defined by the sensor arrangement further comprising a temperature compensator for compensating a temperature dependency of the bridges.

The temperature compensator compensates the temperature dependency of the bridges and therefore compensates the temperature dependency of the external properties and allows the sensor arrangement to be used under changing temperature conditions. An embodiment of the device according to the invention is defined by the temperature compensator comprising two temperature dependent elements forming part of a yet further bridge further comprising the bridge and the further bridge. By locating the bridge and the further bridge into the yet further bridge and by locating the two temperature dependent elements into the yet further bridge, which temperature dependent elements for example have a temperature dependency similar to the temperature dependency of the bridge and the further bridge, the temperature dependent external properties of the bridge and the further bridge have been converted into an internal property of the yet further bridge, which is relatively temperature independent. An embodiment of the device according to the invention is defined by the temperature dependent elements and the elements being made of the same magnetic material, and the temperature dependent elements each comprising a pair of resistors constructed in such a way that the temperature dependent elements do not respond to changes in the magnetic field. For example in case of an anisotropic magneto-resistive material being used, the pair of resistors for example comprises two substantially perpendicular resistors.

Embodiments of the sensor arrangement according to the invention and of the method according to the invention correspond with the embodiments of the device according to the invention.

The invention is based upon an insight, inter alia, that a sensor arrangement should define a movement in a relatively direct way, and is based upon a basic idea, inter alia, that the field detector should comprise at least one bridge comprising different properties that replace the prior art evaluations of output voltages.

The invention solves the problem, inter alia, to provide a device comprising a sensor arrangement which defines movements in a relatively direct way, and is further advantageous, inter alia, in that, compared to using a personal computer for evaluating the prior art output voltages of the electromagnetic transducers, the total power consumption is • reduced.

These and other aspects of the invention will be apparent from and elucidated with reference to the cmbodiments(s) described hereinafter.

In the drawings:

Fig. 1 shows diagrammatically a device according to the invention comprising a sensor arrangement according to the invention shown in cross section; Fig. 2 shows diagrammatically a performance of the sensor arrangement according to the invention;

Fig. 3 shows diagrammatically a field detector comprising elements and discloses per element a component of the magnetic field, a magnetization and a current; Fig. 4 shows diagrammatically the movable object and the field detector separated by the distance Dl and the fixed object separated from the field detector by a distance D2 in cross section;

Fig. 5 shows a strength of the component of the magnetic field as a function of a position in a plane of the field detector for different distances Dl between the movable object and the field detector;

Fig. 6 shows diagrammatically a field detector comprising a bridge with elements coupled to a further element for detecting an external property of the bridge in a non-differential and non-temperature-compensated way; Fig. 7 shows diagrammatically a field detector comprising a bridge and a further bridge forming part of a yet further bridge further comprising two temperature dependent elements for detecting external properties of the bridge and the further bridge in a differential and temperature-compensated way; and

Fig. 8 shows a temperature dependent element made from anisotropic magneto-resistive material and which is insensitive to changes in the magnetic field.

The device 1 according to the invention shown in Fig. 1 comprises a sensor arrangement 10 according to the invention. The sensor arrangement 10 comprises a fixed object 1 1, such as for example a field generator for generating a magnetic field, such as for example a magnet. The sensor arrangement 10 further comprises a field detector 12 for detecting a component (as shown in Fig. 3) of the magnetic field, and a movable object 13, such as for example a movable field conductor, such as for example a joy stick, for, in response to a movement, changing at least a part of the magnetic field. The projection of the magnetic field on the plane of the field detector is a substantially radial field. The component of the magnetic field to be detected is a magnetic field vector situated in the plane of the field detector. In other words, this component is a radial field vector. The changing for example comprises the shifting of a radial field center 19 (as shown in Fig. 2).

The fixed object 1 1 such as for example a permanent magnet and the movable object 13 such as for example a magnetically conductive stick are for example integrated in a package together with a chip. The package is modified in such a way that the movable object 13 can be mounted in a blind hole in the package with for example a flexible glue 14, an O- ring or any other mechanical spring. The field detector 12 is mounted on a substrate 16, which is coupled via wirebonds to a leadframc 15. The performance of the sensor arrangement 10 shown in Fig. 2 discloses that the movable object 13 comprises a pivoting point located between a point of the movable object 13 and an end of the movable object 13 located closest to the field detector 12. Preferably, this pivoting point substantially coincides with this end of the movable object 13 located closest to the field detector 12. By pivoting the movable object 13, the radial field center 19 of the component of the magnetic field (as shown in Fig. 3) is shifted, which is detected by the field detector 12. Such a field detector 12 for example comprises elements as shown in Fig. 3.

The field detector 12 shown in Fig. 3 comprises elements 21-24. Per element 21-24, a radial field H, a magnetization M and a current I are disclosed. The radial field arises when the magnetic field emanating from the field generator is projected onto the plane of the field detector. Point C is the center of the radial field H in the rest position of the movable object 13. The magnetic field lines of this radial field arc indicated by the arrows H. Four magneto-resistive elements 21-24, which are elements of which a resistance value depends on a strength and on a direction of a magnetic field in which the elements are located, i.e. four strips of magneto-resistive material for example without barberpolc stripes, are placed such that the magnetization M in the element and the length direction of the magneto- resistive elements 21-24 make a certain angle, such as for example an angle of 25-65 degrees, preferably an angle of 45 degrees. A current 1 flows through the magneto-resistive elements 21-24. The magnetization M within the elements 21-24 wants to align with the length direction of the elements 21-24 on the one hand, on the other hand it wants to align with the direction of the radial field H. As a result, the magnetization M will take a position between the length direction of the elements 21-24 and the component of the magnetic field H. For low magnetic fields H it will be closer to the length direction of the elements 21-24, for higher magnetic fields H it will be closer to the direction of the component of the magnetic field H. At an infinite high magnetic field H, the magnetization M will be aligned with the magnetic field H.

The angle θ between the magnetization M and the current I in the element 21- 24 determines the resistance value of the clement 21-24, whereby in case of anisotropic magneto-resistors the resistance R = Ro + ΔR cos²θ in which R is the total resistance value of the element 21-24, R₀ is the base resistance and ΔR/Ro is the magneto-resistance effect. If the angle θ is chosen in the neighborhood of 45 degrees, the response characteristic of the element 21-24 will be more or less linear. Best linearity is obtained for θ = 45 degrees. By setting the magnetic field under an angle with the length direction of an element 21-24, no barberpole stripes are required which gives a number of advantages (easier processing, higher resistance, better resistance reproducibility). Normally this configuration would increase hysteretic switching of the magnetization when the magnetic field is cycled from positive to negative and back. However, in this configuration with the permanent magnetic field, firstly the magnetic field is not cycled between positive and negative (only modulated around a specific value) and secondly the magnetic field is larger than the anisotropy field which brings the magnetization outside the hysteretic region.

The radial field H is for example a radial field vector situated in a plane of the field detector 12, in other words situated in a plane of the elements 21-24. This plane for example comprises the X-axis and the Y-axis. When the center 19 of the radial field is moved from position C to position D in this X-Y plane, mainly the directions of the radial field H are altered. In the elements 21 and 23, the radial field vector moves towards the direction of the current I, reducing the angle between the magnetization M and the current 1 and thus increasing the resistance value of the elements 21 and 23. For the elements 22 and 24, the opposite occurs. The radial field vector moves away from the direction of the current I, increasing the angle θ between the magnetization M and the current I and thus decreasing the resistance value. By properly connecting the elements 21-24 into a bridge configuration, such as a Wheatstonc bridge, an output signal can be created which varies approximately linearly with the radial field center position 19 in the X-direction. For the Y-direction a similar configuration can be made by rotating the complete configuration over 90 degrees. Typically the distance between the elements 21-24 and the radial field center 19 of the radial component will be much larger (e.g. 300 μm) than typical displacements of that center (e.g. 20 μm). Therefore, when the radial field center 19 is displaced mainly the direction of the radial field H will be changed and only to a lesser extent the strength of the radial field H will be changed.

The movable object 13 and the field detector 12 separated by a distance Dl and the fixed object 11 separated from the field detector 12 by a distance D2 are shown in Fig. 4 in cross section. To allow the distance Dl to be variable, in Fig. 1 the glue 14 may be a flexible glue, without excluding other embodiments that allow 3-dimensional movements. The strength of the radial field H as a function of a position in a plane of the field detector 12 is shown in Fig. 5 for different distances Dl between the movable object 13 and the field detector 12. This strength clearly depends on this distance Dl.

The field detector 12 comprising a Wheatstone bridge with elements 31-34 is shown in Fig. 6. A first external terminal of the Wheatstone bridge is coupled to a voltage supply 50, and a second external terminal is coupled to a resistor 30, which is further coupled to ground. Via the internal terminals of the Whcatstone bridge a movement in the X-dircction will be indicated. Via the external terminals a movement in the Z-direction will be indicated. Owing to the fact that the resistor 30 and the Wheatstone bridge together form a serial circuit, the movement in the Z-direction will also be indicated across the resistor 30. This can be derived as follows.

In the rest position the radial field center 19 will be at the position C. The strength of the radial field at the position of the elements will have a certain value. This value is e.g. determined by the axial distance between the fixed object 11 and the field detector 12, D2, and/or by the distance between the field detector 12 and the movable object 13, Dl . In Fig. 5 the calculated strength of the radial field as a function of the distance Dl is shown. With changing distance the strength of the radial field changes.

When the distance between the movable object 13 and the field detector 12 is changed, e.g. by pressing the movable object in the axial direction, the position of the radial field center 19 of the radial component in the X-Y plane remains at position C. The direction of the radial field remains unchanged. However, owing to the fact that the distance changes the magnitude of the magnetic field, the magnitude of the radial field is altered. In Fig. 3, in case the strength of the magnetic field is altered, the direction of the magnetization M is changed for all elements. And for all elements, this change in the direction of the magnetization M will be the same. Because the magneto-resistive elements 21-24,31-34 are part of a Wheatstone bridge configuration, the output at the internal terminals of the bridge is not altered by this change in the strength of the magnetic field H. In other words, the bridge output is not sensitive to a motion of the movable object 13 in vertical direction.

However, the total resistance value of the bridge is changed. This can be detected by another circuit such as for example the resistor 30 to provide the Z-functionality. E.g. when a constant voltage is applied to the bridge, the change in the resistance value will result in a current change. By sending this current through the resistor 30 in series with the Wheatstone bridge, the current change can be converted to a voltage change across that resistor 30 which can be measured. This way, the total resistance value of the bridge is detected in a non-differential and non-temperature-compcnsated way. To detect the total resistance value of the bridge in a temperature-compensated way, a temperature compensator can be introduced, for example by making the resistor 30 temperature dependent with for example the same temperature dependency as the bridge. In other words, the device 1 according to the invention comprises a sensor arrangement 10 according to the invention comprising a field detector 12 comprising a bridge with at least two and preferably four elements 31-34 for detecting per element a component of the magnetic field in a plane of the bridge, which bridge comprises a first property depending on the movement in a first direction and a different second property depending on the movement in a different second direction. The first property is an external property defining an outer value of the bridge in an overall view. The second property is an internal property defining an inner value of the bridge in a balanced/unbalanced view. In case the plane of the bridge corresponds with the X-axis and the Y-axis, the first direction corresponds with the Z-axis and the second direction for example corresponds with the X- axis.

Preferably, the field detector 12 further comprises a further bridge with further elements 35-38 for detecting per further element a component of the magnetic field in a further plane of the further bridge, which further bridge comprises a third property depending on the movement in the first direction and a fourth property depending on the movement in a different third direction. Usually, the plane of the bridge and the further plane of the further bridge will be coinciding planes. The third property is an external property and the fourth property is an internal property. In case the further plane of the further bridge corresponds with the X-axis and the Y-axis, the first direction corresponds with the Z-axis and the third direction for example corresponds with the Y-axis.

In case of a bridge comprising four elements, the external properties for example indicate that the resistance values of all elements have increased with substantially the same value or have decreased with substantially the same value. The internal properties for example indicate that the resistance values of two elements at crossed locations have increased with substantially the same value and that the resistance values of two other elements at other crossed locations have decreased with substantially the same value. In case of a bridge comprising two elements, the external properties for example indicate that the resistance values of all elements have increased with substantially the same value or have decreased with substantially the same value. The internal properties for example indicate that the resistance value of one of the elements has increased or decreased and that the resistance value of the other element has not changed.

The field detector 12 shown in Fig. 7 comprises a bridge and a further bridge forming part of a yet further bridge further comprising two temperature dependent resistors 39,40. The temperature dependent resistor shown in Fig. 8 is insensitive to changes in the magnetic field. This all is to be looked at as follows.

The internal properties are relatively independent from temperature changes, but the external properties are relatively dependent from temperature changes. The temperature coefficient of an element comprising for example NiFe is about 2.9 x 10^{~3 0}C^"1. A temperature change of 80⁰C (which is a likely temperature inside a laptop) will therefore cause a change of 23% in the resistance value. This change has to be compared with the 2% maximum change in resistance due to the anisotropic magneto-resistive effect. The change in the resistance value resulting from a movement of the movable object 13 in the Z-direction will be even much lower (0.1%).

To overcome this temperature problem, a temperature compensator might be introduced. The temperature compensator compensates the temperature dependency of the bridges and therefore compensates the temperature dependency of the external properties and allows the sensor arrangement 10 to be used under changing temperature conditions. Such a temperature compensator for example measures the temperature, calculates the effect of the measured temperature on the common mode resistance value (the external property) of the bridges, and compensates the common mode resistance value of the bridges.

Alternatively, the common mode resistances of the bridge and the further bridge arc put in a yet further bridge, such as a Wheatstone bridge again. The yet further bridge consists of the two Wheatstone bridges (one for the X- and one for the Y-detection) and two temperature dependent elements 39,40 which are for example also present on the die. These temperature dependent elements preferably have the same temperature dependency as the bridge and the further bridge. Therefore they might be made of the same (magnetic) material. However, they should not respond to changes in the magnetic field H. By means of a special configuration of these temperature dependent elements, they can be made (almost) insensitive to changes in magnetic field.

The idea is based on the fact that one half of the element responds to changes in the direction of the radial component according to Ro+ΔRo.sin²φ (φ being the angle between the magnetization and the current) while the other half of the element changes according to Ro+ΔRo.cos²φ. By summing these elements the total resistance becomes

2(Ro+ΔR₀) which is independent from the angle φ. On the die, four of these resistors can be present. Two can be used to make the new (nested) Wheatstone bridge while the other two can be used for a temperature measurement of the die itself. In this way, any resulting temperature dependence (a Wheatstone bridge is never able to completely eliminate the temperature dependency, there will always be slight variations in the temperature coefficients of the various resistors in the bridge) can be compensated by means of software, if necessary. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and its conjugations docs not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS:

1. A device (1) with a sensor arrangement (10) comprising: a movable object (13) for, in response to a movement, changing at least a part of a magnetic field, and a field detector (12) comprising a bridge with elements (21-24,31-34) for detecting per element a component of the magnetic field in a plane of the bridge, which bridge comprises a first property depending on the movement in a first direction and a different second property depending on the movement in a different second direction.

2. The device (1) according to claim 1 , a length axis of an element and a direction of a magnetization of this element making an angle of 25-65 degrees for a rest position of the movable object and for a given strength of the magnetic field.

3. The device (1) according to claim 2, the angle being substantially 45 degrees.

4. The device (1) according to claim 1, the sensor arrangement (10) further comprising a fixed object (1 1), the field detector (12) being located between both objects (1 1,13) and one of the objects (1 1) comprising a field generator for generating the magnetic field and the other object (13) comprising a field conductor for conducting the magnetic field.

5. The device (1) according to claim 1, the first property being an external property and the second property being an internal property and the first direction being a direction substantially perpendicular to the plane of the bridge and the second direction being a direction substantially in the plane of the bridge.

6. The device (1) according to claim 5, the bridge comprising first and second external terminals for supplying the external property and first and second internal terminals for supplying the internal property and first and second serial branches located in parallel between the external terminals, which first serial branch comprises first and second elements (31,33) coupled to each other via the first internal terminal and which second serial branch comprises third and fourth elements (32,34) coupled to each other via the second internal terminal.

7. The device (1) according to claim 1, the sensor arrangement (10) further comprising a temperature compensator for compensating a temperature dependency of the bridge.

8. The device (1) according to claim 1, the field detector (12) comprising a further bridge with further elements (35-38) for detecting per further element a component of the magnetic field in a further plane of the further bridge, which further bridge comprises a third property depending on the movement in the first direction and a fourth property depending on the movement in a different third direction.

9. The device (1) according to claim 8, the third property being an external property and the fourth property being an internal property and the first direction being a direction substantially perpendicular to the further plane of the further bridge and the third direction being a direction substantially in the further plane of the further bridge, the second and third directions being substantially perpendicular directions.

10. The device (1) according to claim 9, the further bridge comprising third and fourth external terminals for supplying the external property and third and fourth internal terminals for supplying the internal property and third and fourth serial branches located in parallel between the external terminals, which third serial branch comprises fifth and sixth elements (35,37) coupled to each other via the third internal terminal and which fourth serial branch comprises seventh and eighth elements (36,38) coupled to each other via the fourth internal terminal.

1 1. The device (1) according to claim 8, the sensor arrangement (10) further comprising a temperature compensator for compensating a temperature dependency of the bridges.

12. The device (1) according to claim 1 1, the temperature compensator comprising two temperature dependent elements (39,40) forming part of a yet further bridge further comprising the bridge and the further bridge.

13. The device (1) according to claim 12, the temperature dependent elements (39,40) and the elements (31-38) being made of the same magnetic material, and the temperature dependent elements (39,40) each comprising a pair of resistors constructed in such a way that the temperature dependent elements (39,40) do not respond to changes in the magnetic field substantially.

14. A sensor arrangement (10) comprising: a movable object (13) for, in response to a movement, changing at least a part of a magnetic field, and a field detector (12) comprising a bridge with elements (21-24) for detecting per element a component of the magnetic field in a plane of the bridge, which bridge comprises a first property depending on the movement in a first direction and a different second property depending on the movement in a different second direction.

15. A sensing method comprising the steps of: in response to a movement, changing at least a part of a magnetic field, and detecting per element of a bridge a component of the magnetic field in a plane of the bridge, which bridge comprises a first property depending on the movement in a first direction and a different second property depending on the movement in a different second direction.