CN211236203U - Magnetic field sensing device - Google Patents

Abstract

The utility model provides a magnetic field sensing device, comprising a plurality of magnetoresistive sensor groups with different average resistances, and first and second magnetization direction setting elements. The number of these magnetoresistive sensor groups is four. A portion of the first and second magnetoresistive sensor groups are coupled to form a first bridge arm. Another portion of the first and second magnetoresistive sensor groups are coupled to form a second bridge arm. A portion of the third and fourth magnetoresistive sensor groups are coupled to form a third bridge arm. Another portion of the third and fourth magnetoresistive sensor groups are coupled to form a fourth bridge arm. The first to fourth bridge arms are coupled together to form a Wheatstone bridge. The first and second magnetization direction setting elements are respectively arranged to overlap with two magnetoresistive sensor groups in the first to fourth magnetoresistive sensor groups. The magnetic field sensing device can effectively eliminate the zero field output offset and have an accurate measurement result.

Description

Magnetic field sensing device

technical field

The utility model relates to a magnetic field sensing device.

Background technique

With the development of science and technology, electronic products with navigation and positioning functions are becoming more and more diverse. Electronic compasses provide functions equivalent to traditional compasses in the application fields of car navigation, aviation, and personal handheld devices. In order to realize the function of the electronic compass, the magnetic field sensing device becomes a necessary electronic component.

In a general magnetic field sensing device, the magnetoresistive sensing element is used to form a Wheatstone bridge, and the external magnetic field is measured by the output signal of the circuit. However, during the manufacturing process of the magnetoresistive sensing element, due to process factors (etching process, lift-off process, etc.), the magnetoresistive sensing element in different regions has different resistances, and the difference in resistance is quite obvious, that is, the resistance is different. matching phenomenon. As a result, the existing magnetic field sensing device has an obvious zero-field output offset (zero-field output offset) before measuring the external magnetic field, thereby causing inaccurate measurement results.

Utility model content

The utility model provides a magnetic field sensing device, which can effectively eliminate the zero-field output offset and have accurate measurement results.

An embodiment of the present invention provides a magnetic field sensing device, which includes a plurality of magnetoresistive sensor groups, a first magnetization direction setting element and a second magnetization direction setting element. The average resistances of these magnetoresistive sensor groups are different from each other, and each magnetoresistive sensor group includes a plurality of magnetoresistive sensors. These magnetoresistive sensor groups include first to fourth magnetoresistive sensor groups. A part of the first magnetoresistive sensor group is coupled with a part of the second magnetoresistive sensor group to form a first bridge arm. Another part of the first magnetoresistive sensor group is coupled with another part of the second magnetoresistive sensor group to form a second bridge arm. A part of the third magnetoresistive sensor group is coupled with a part of the fourth magnetoresistive sensor group to form a third bridge arm. Another part of the third magnetoresistive sensor group is coupled with another part of the fourth magnetoresistive sensor group to form a fourth bridge arm. The first to fourth bridge arms are commonly coupled to form a Wheat bridge. The first magnetization direction setting element is arranged to overlap with the two magnetoresistive sensor groups in the first to fourth magnetoresistive sensor groups. The second magnetization direction setting element is arranged to overlap with the other two magnetoresistive sensor groups in the first to fourth magnetoresistive sensor groups.

In an embodiment of the present invention, in the first to fourth bridge arms, the circuit connection method is an S-type loop connection method.

In an embodiment of the present invention, in the first to fourth bridge arms, the circuit connection methods in them are S-type circuit connection method and straight circuit connection method.

In an embodiment of the present invention, the above-mentioned magnetic field sensing device further includes a current generator. The current generator is used for generating current to the first magnetization direction setting element and the second magnetization direction setting element, wherein the current flowing in the first magnetization direction setting element is opposite to the current flowing in the second magnetization direction setting element .

In an embodiment of the present invention, the above-mentioned first magnetization direction setting element, the first magnetoresistive sensor group and the second magnetoresistive sensor group are arranged overlappingly, and the second magnetization direction setting element and the third magnetoresistive sensor The group overlaps with the fourth magnetoresistive sensor group.

In an embodiment of the present invention, the above-mentioned first magnetization direction setting element, the first magnetoresistive sensor group and the second magnetoresistive sensor group are arranged overlappingly, and the second magnetization direction setting element and the third magnetoresistive sensor The group overlaps with the fourth magnetoresistive sensor group.

In an embodiment of the present invention, the above-mentioned first bridge arm and second bridge arm are coupled to the first terminal. The second bridge arm and the fourth bridge arm are coupled to the second terminal. The third bridge arm and the fourth bridge arm are coupled to the third terminal. The fourth bridge arm is coupled to the first bridge arm and the fourth terminal. The first endpoint, the second endpoint, the third endpoint, and the fourth endpoint are different from each other.

In an embodiment of the present invention, the extending directions of the above-mentioned magnetoresistive sensors are perpendicular to the extending directions of the first magnetization direction setting element and the second magnetization direction setting element.

In an embodiment of the present invention, the type of the above-mentioned magnetoresistive sensor is an anisotropic magnetoresistive sensor.

Based on the above, in the magnetic field sensing device of the embodiment of the present invention, it has a plurality of first, second, third and fourth magnetoresistive sensors with different average resistances. The way of cross-coupling to form the first, second, third and fourth bridge arms of the Huistong bridge, so the related errors caused by the process factors can be dispersed in these bridge arms, which can effectively The zero-field output offset is effectively eliminated with accurate measurement results.

In order to make the above-mentioned features and advantages of the present utility model more obvious and easy to understand, the following examples are given and described in detail in conjunction with the accompanying drawings as follows.

Description of drawings

FIG. 1 is a schematic diagram of a magnetic field sensing device according to an embodiment of the present invention.

FIG. 2 is an active circuit diagram of the magnetic field sensing device of FIG. 1 .

3A and 3B illustrate different layout methods of the anisotropic magnetoresistive sensor in FIG. 1 .

FIG. 4 is a schematic diagram of a magnetic field sensing device according to another embodiment of the present invention.

Description of reference numbers:

100, 100a: magnetic field sensing device;

110: magnetoresistive sensor group;

112: the first magnetoresistive sensor group;

114: the second magnetoresistive sensor group;

116: the third magnetoresistive sensor group;

118: the fourth magnetoresistive sensor group;

120: the first magnetization direction setting element;

130: the second magnetization direction setting element;

140: current generator;

ARM1, ARM1a: the first bridge arm;

ARM2, ARM2a: the second bridge arm;

ARM3, ARM3a: the third bridge arm;

ARM4, ARM4a: the fourth bridge arm;

D: extension direction;

D1, D2: direction;

FF: ferromagnetic film;

GND: ground terminal;

H: external magnetic field;

I: current;

M: magnetization direction;

MR: magnetoresistive sensor;

SB: Shorting bar;

SD: sensing direction;

V _DD : voltage supply terminal;

WHB: Wheatstone bridge.

Detailed ways

FIG. 1 is a schematic diagram of a magnetic field sensing device according to an embodiment of the present invention. FIG. 2 is an active circuit diagram of the magnetic field sensing device of FIG. 1 . 3A and 3B illustrate different layout methods of the anisotropic magnetoresistive sensor in FIG. 1 .

Referring to FIG. 1 , in this embodiment, the magnetic field sensing device 100 includes a plurality of magnetoresistive sensor groups 110 , first and second magnetization direction setting elements 120 and 130 and a current generator 140 . Each of the above elements will be described in detail in the following paragraphs.

In this embodiment, each magnetoresistive sensor group 110 includes a plurality of magnetoresistive sensors MR, and the extending direction of each magnetoresistive sensor MR is, for example, the direction D2. The number of these magnetoresistive sensor groups 110 is, for example, four, which are referred to as first, second, third, and fourth magnetoresistive sensor groups 112 , 114 , 116 , and 118 , respectively. Due to process factors, the average resistances of the magnetoresistive sensor groups 110 in different regions are different from each other. In FIG. 1 , the magnetoresistive sensors MR belonging to the first to fourth magnetoresistive sensor groups 112 , 114 , 116 , 118 are marked with different cross sections.

As mentioned above, the magnetoresistive sensor MR refers to a sensor whose resistance can be changed correspondingly through the change of the external magnetic field. The magnetoresistive sensor MR may be an anisotropic magnetoresistive sensor (Anisotropic Magneto-Resistive resistor, AMRresistor). In this embodiment, the extending direction of the magnetoresistive sensor MR is the direction D2. Referring to FIGS. 3A and 3B , the anisotropic magnetoresistive sensor MR has, for example, a barber pole-like structure, that is, the surface of the anisotropic magnetoresistive sensor MR is provided with an extension extending at an angle of 45 degrees relative to the extending direction D of the anisotropic magnetoresistive sensor MR. a plurality of electrical shorting bars SB, these shorting bars SB are spaced apart from each other and arranged in parallel on a ferromagnetic film FF, and the ferromagnetic film FF is the main body of the anisotropic magnetoresistive sensor MR, Its extension direction is the extension direction of the anisotropic magnetoresistive sensor MR. The sensing direction SD of the anisotropic magnetoresistive sensor MR is perpendicular to the extending direction D. In addition, opposite ends of the ferromagnetic film FF may be tapered.

In this embodiment, the first and second magnetization direction setting elements 120 and 130 can be any one or a combination of coils, wires, metal sheets, and conductors that generate a magnetic field by energizing, and the first and second magnetization direction setting elements 120 and 130 The extension direction of the magnetization direction setting elements 120 and 130 is, for example, the direction D1, and the direction D1 is perpendicular to the direction D2.

In this embodiment, the current generator 140 refers to an electronic component for providing current.

In order to explain the configuration effect of the magnetic field sensing device 100 of the present embodiment, the following paragraphs will introduce the basic principle of the magnetic field sensing device 100 of the present embodiment for measuring the magnetic field in conjunction with FIG. 3A and FIG. 3B .

Referring to FIGS. 3A and 3B , before the anisotropic magnetoresistive sensor MR starts to measure the external magnetic field H, its magnetization direction can be set by the first and second magnetization direction setting elements 120 and 130 . In FIG. 3A , the first and second magnetization direction setting elements 120 and 130 can generate a magnetic field along the extension direction D (or the long axis direction) by energizing, so that the anisotropic magnetoresistive sensor MR has the magnetization direction M .

Next, the first and second magnetization direction setting elements 120 and 130 are not energized, so that the anisotropic magnetoresistive sensor MR starts to measure the external magnetic field H. When there is no external magnetic field H, the magnetization direction M of the anisotropic magnetoresistive sensor MR is maintained in the extending direction D. At this time, the current generator 140 can apply the current I, so that the current I flows from the left end of the anisotropic magnetoresistive sensor MR. If it flows to the right end, the flow direction of the current I near the shorting bar SB will be perpendicular to the extension direction of the shorting bar SB, so that the current I near the shorting bar SB will flow 45 degrees to the magnetization direction M. At this time, the anisotropic magnetoresistive sensor The resistance value of MR is R.

When the external magnetic field H faces the direction perpendicular to the extension direction D, the magnetization direction M of the anisotropic magnetoresistive sensor MR will be deflected in the direction of the external magnetic field H, so that the magnetization direction and the current I near the shorting bar are clamped. When the angle is greater than 45 degrees, the resistance value of the anisotropic magnetoresistive sensor MR has a change of -ΔR, that is, it becomes R-ΔR, that is, the resistance value becomes smaller, and ΔR is greater than 0.

However, as shown in FIG. 3B , when the extending direction of the shorting bar SB in FIG. 3B is set at a direction of 90 degrees from the extending direction of the shorting bar SB in FIG. 3A (at this time, the extending direction of the shorting bar SB in FIG. 3B is still 45 degrees with the extension direction D of the anisotropic magnetoresistive sensor MR), and when there is an external magnetic field H, in addition, the magnetic field H will still deflect the magnetization direction M to the direction of the external magnetic field H, at this time, the magnetization direction M and The angle between the current I near the shorting bar SB will be less than 45 degrees, so the resistance value of the anisotropic magnetoresistive sensor MR will become R+ΔR, that is, the resistance value of the anisotropic magnetoresistive sensor MR will increase.

In addition, when the magnetization direction M of the anisotropic magnetoresistive sensor MR is set to the opposite direction shown in FIG. The resistance value of the anisotropic magnetoresistive sensor MR becomes R+ΔR. Furthermore, when the magnetization direction M of the anisotropic magnetoresistive sensor MR is set to the opposite direction shown in FIG. 3B by the magnetization direction setting element 130, the anisotropic magnetoresistive sensor of FIG. 3B under the external magnetic field H after that The resistance value of MR becomes R-ΔR.

According to the above, in this embodiment, the resistance of the magnetoresistive sensor MR in the magnetoresistive sensor group 110 changes due to the external magnetic field, and the external magnetic field can be used to determine the external differential signal through the differential signal of the voltage output terminal of the Wheat bridge WHB The direction and magnitude of the magnetic field. However, if the resistance value R of the magnetoresistive sensor MR in different regions is too different due to process factors, the Wheat bridge WHB will have an obvious zero-field output offset before measuring the external magnetic field. Therefore, at least one purpose of the magnetic field sensing device 100 of the present embodiment is to solve the above-mentioned problem of zero-field output offset.

The configuration of each element in the magnetic field sensing device 100 of this embodiment will be described in detail in the following paragraphs.

Referring to FIG. 1 , generally speaking, in this embodiment, the first magnetization direction setting element 120 is disposed overlapping the first and second magnetoresistive sensor groups 112 and 114 , and is disposed on the first and second magnetoresistive sensors Below the clusters 112,114. The second magnetization direction setting element 130 is disposed overlapping the third and fourth magnetoresistive sensor groups 116 and 118 and is disposed below the third and fourth magnetoresistive sensor groups 116 and 118 . The current generator 140 is coupled to the first and second magnetization direction setting elements 120 and 130 through wires to form an S-shaped loop. After the current generator 140 generates the current I, the current I flows into the first and second magnetization direction setting elements 120 and 130 through the wires. The current direction in the first magnetization direction setting element 120 is the direction D1, and the The direction of the current in the second magnetization direction setting element 130 is the opposite direction of the direction D1, that is, the current flow directions in the first and second magnetization direction setting elements 120 and 130 are anti-parallel to each other. Therefore, the first magnetization direction setting element 120, for example, sets the magnetization direction M of the first and second magnetoresistive sensor groups 112 and 114 to the direction D2, and the second magnetization direction setting element 130, for example, sets the third and second magnetization direction setting elements to the direction D2. The magnetization directions of the four magnetoresistive sensor groups 116 and 118 are set to be opposite to the direction D2.

Referring to FIG. 1 again, in this embodiment, the magnetoresistive sensors MR of the first to fourth magnetoresistive sensor groups 112 ˜ 118 having different average resistances are coupled by interdigitate. The first to fourth bridge arms ARM1 to ARM4 of the Wheat bridge WHB are used to disperse the difference between the resistances into the bridge arms. The so-called average resistance in the magnetoresistive sensor group 110 refers to the arithmetic mean of the resistances of all the magnetoresistive sensors MR in the corresponding magnetoresistive sensor group 110 . For example, it can be seen in FIG. 1 that there are three magnetoresistive sensors MR in the first magnetoresistive sensor group 112, so the average resistance of the first magnetoresistive sensor group 112 is the three magnetoresistive sensors MR(112) After adding up, do the arithmetic average, and so on. The coupling method of each bridge arm will be described in detail in the following paragraphs.

In this embodiment, the first bridge arm ARM1 is, for example, formed by coupling a part (one) of the first magnetoresistive sensor group 112 and a part (two) of the second magnetoresistive sensor group 114 .

The second bridge arm ARM2 is, for example, formed by coupling another part (two) of the first magnetoresistive sensor group 112 and another part (one) of the second magnetoresistive sensor group 114 .

In this embodiment, the third bridge arm ARM3 is, for example, formed by coupling a part (two) of the third magnetoresistive sensor group 116 and a part (one) of the fourth magnetoresistive sensor group 118 .

The fourth bridge arm ARM4 is, for example, formed by coupling another part (one) of the third magnetoresistive sensor group 116 and a part (two) of the fourth magnetoresistive sensor group 118 .

Based on the above, that is to say, in this embodiment, each of the bridge arms ARM1 - ARM4 is formed by coupling the magnetoresistive sensors MR with the same magnetization direction. In this embodiment, the wire connection method in each bridge arm ARM1 - ARM4 is an S-type connection method. From another point of view, in each of the bridge arms ARM1 to ARM4, the wires between the two magnetoresistive sensors MR are bent wires.

Please refer to FIG. 1 and FIG. 2 simultaneously. In the magnetic field sensing device 100 of the present embodiment, the first and second bridge arms ARM1 and ARM2 are coupled to the first terminal P1. The second and fourth bridge arms ARM2 and ARM4 are coupled to the second terminal P2. The third and fourth bridge arms ARM3 and ARM4 are coupled to the third terminal P3. Fourth, the first bridge arms ARM4 and ARM1 are coupled to the fourth terminal P4. The first to fourth terminals P1-P4 are different from each other, wherein the first terminal P1 is for example a voltage supply terminal V _DD , the second and fourth terminals P2 and P4 are for example a voltage output terminal, and the third terminal P3 is for example a voltage output terminal. The ground terminal is GND, but the present invention is not limited to this.

As mentioned above, in the magnetic field sensing device 100 of the present embodiment, the first to fourth magnetoresistive sensor groups 112 , 114 , 116 , and 118 whose average resistances are different from each other are provided. The magnetic field sensing device 100 forms the first, the second, the third and the third of the Wheat bridge WHB by coupling the first to fourth magnetoresistive sensor groups 112 , 114 , 116 and 118 to each other in the above-mentioned manner. Four bridge arms ARM1-ARM4, so the related errors caused by process factors can be dispersed in these bridge arms ARM1-ARM4 through the above-mentioned coupling method, thereby effectively eliminating the zero-field output offset and having accurate measurement result.

It must be noted here that the following embodiments use parts of the previous embodiments, omitting the description of the same technical content, and the same component names can refer to part of the previous embodiments, which will not be repeated in the following embodiments.

FIG. 4 is a schematic diagram of a magnetic field sensing device according to another embodiment of the present invention.

Please refer to FIG. 4 , the magnetic field sensing device 100 a of FIG. 4 is substantially similar to the magnetic field sensing device 100 of FIG. 1 , and the main differences are: the first and second magnetization direction setting elements 120 , 130 and the first to fourth The arrangement relationship among the magnetoresistive sensor groups 112, 114, 116, and 118 is different, and the number, properties and wire connection methods of the magnetoresistive sensors in the first to fourth bridge arms ARM1a-ARM4a are all different. In the following paragraphs The reason for the above differences will be explained in detail.

In this embodiment, the first magnetization direction setting element 120 is disposed overlapping the first and fourth magnetoresistive sensor groups 112 and 118 and is disposed below the first and fourth magnetoresistive sensor groups 112 and 118 , and the second magnetization The direction setting element 130 overlaps with the second and third magnetoresistive sensor groups 114 and 116 and is disposed below the second and third magnetoresistive sensor groups 114 and 116 . Since the current directions of the current I generated by the current generator 140 in the first and second magnetization direction setting elements 120 and 130 are the direction D1 and the opposite direction of the direction D1, respectively, the first magnetization direction setting element 120 will 1. The magnetization direction M of the magnetoresistive sensors MR in the fourth magnetoresistive sensor groups 112 and 118 is set as the direction D2, and the second magnetization direction setting element 130 sets the magnetization direction M of the second and third magnetoresistive sensor groups 114 and 116 The magnetization direction M of the magnetoresistive sensor MR is set to be the reverse of the direction D2.

In this embodiment, the first bridge arm ARM1a is, for example, formed by coupling a part (three) of the first magnetoresistive sensor group 112 and a part (three) of the second magnetoresistive sensor group 114 .

In this embodiment, the second bridge arm ARM2a is, for example, formed by coupling another part (three) of the first magnetoresistive sensor group 112 and another part (three) of the second magnetoresistive sensor group 114 .

In this embodiment, the third bridge arm ARM3a is, for example, formed by coupling a part (three) of the third magnetoresistive sensor group 116 and a part (three) of the fourth magnetoresistive sensor group 118 .

In this embodiment, the fourth bridge arm ARM4a is, for example, formed by coupling another part (three) of the third magnetoresistive sensor group 116 and another part (three) of the fourth magnetoresistive sensor group 118 .

It should be noted that the equivalent circuit of the Wheat bridge formed by the bridge arms ARM1a-ARM4a can also refer to the equivalent circuit of FIG. 2, and the description thereof is similar to that of FIG.

Based on the above, that is to say, in this embodiment, each bridge arm ARM1a-ARM4a is formed by coupling the magnetoresistive sensors MR with different magnetization directions. In addition, the wiring connections in the bridge arms ARM1a to ARM4a are also slightly different. In detail, in each bridge arm ARM1a to ARM4a, the wire connection between some of the magnetoresistive sensors MR is, for example, the S-type connection, and the wire connection between the other part of the magnetoresistive sensors MR is, for example, the straight connection. .

To sum up, in the magnetic field sensing device of the embodiment of the present invention, there are a plurality of first, second, third and fourth magnetoresistive sensors with different average resistances. The resistance sensors are cross-coupled to each other to form the first, second, third and fourth bridge arms of the Huistong bridge. Therefore, the related errors caused by the process factors can be dispersed in the cross-coupling method. In these bridge arms, the zero-field output offset can be effectively eliminated to have accurate measurement results.

Although the present utility model has been disclosed above with examples, it is not intended to limit the present utility model. Any person skilled in the art can make some changes and modifications without departing from the spirit and scope of the present utility model. Therefore, the protection scope of the present utility model shall be determined by those defined by the appended claims.

Claims (9)

1. a magnetic field sensing device, is characterized in that, comprises: a plurality of magnetoresistive sensor groups, the average resistances of the plurality of magnetoresistive sensor groups are different from each other, and each of the magnetoresistive sensor groups includes a plurality of magnetoresistive sensors, wherein the plurality of magnetoresistive sensor groups include first to first Four magnetoresistive sensor groups; A part of the first magnetoresistive sensor group is coupled with a part of the second magnetoresistive sensor group to form a first bridge arm; Another part of the first magnetoresistive sensor group is coupled with another part of the second magnetoresistive sensor group to form a second bridge arm; A part of the third magnetoresistive sensor group is coupled with a part of the fourth magnetoresistive sensor group to form a third bridge arm; Another part of the third magnetoresistive sensor group is coupled with another part of the fourth magnetoresistive sensor group to form a fourth bridge arm; The first to the fourth bridge arms are commonly coupled to form a Wheat bridge; a first magnetization direction setting element, provided to overlap with two magnetoresistive sensor groups in the first to fourth magnetoresistive sensor groups; and The second magnetization direction setting element is arranged to overlap with the other two magnetoresistive sensor groups in the first to the fourth magnetoresistive sensor groups. 2 . The magnetic field sensing device according to claim 1 , wherein, in the first to the fourth bridge arms, the circuit connections therein are S-type loop connections. 3 . 3 . The magnetic field sensing device according to claim 1 , wherein, in the first to the fourth bridge arms, the circuit connections therein are S-loop connection and straight-line connection. 4 . Law. 4. The magnetic field sensing device according to claim 1, further comprising: a current generator for generating current to the first magnetization direction setting element and the second magnetization direction setting element, Wherein the flow of the current in the first magnetization direction setting element is opposite to the flow direction of the current in the second magnetization direction setting element. 5 . The magnetic field sensing device according to claim 4 , wherein the first magnetization direction setting element, the first magnetoresistive sensor group and the second magnetoresistive sensor group are arranged to overlap, And the second magnetization direction setting element, the third magnetoresistive sensor group and the fourth magnetoresistive sensor group are arranged to overlap. 6 . The magnetic field sensing device according to claim 4 , wherein the first magnetization direction setting element, the first magnetoresistive sensor group and the second magnetoresistive sensor group are arranged to overlap, And the second magnetization direction setting element, the third magnetoresistive sensor group and the fourth magnetoresistive sensor group are arranged to overlap. 7. The magnetic field sensing device according to claim 1, wherein, the first bridge arm and the second bridge arm are coupled to the first terminal; the second bridge arm and the fourth bridge arm are coupled to the second terminal; the third bridge arm and the fourth bridge arm are coupled to the third terminal; and the fourth bridge arm is coupled to the first bridge arm and the fourth terminal, wherein the first endpoint, the second endpoint, the third endpoint and the fourth endpoint are different from each other. 8 . The magnetic field sensing device according to claim 1 , wherein an extension direction of each of the magnetoresistive sensors is perpendicular to the extension directions of the first magnetization direction setting element and the second magnetization direction setting element. 9 . 9. The magnetic field sensing device according to claim 1, wherein the type of the magnetoresistive sensor is an anisotropic magnetoresistive sensor.

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