Magnetic sensor

Abstract

The present invention proposes a magnetic sensor in which, in order to compensate for the temperature dependence of a Hall electromotive force, a Hall element that is not used for detection in a detection Hall element included in the Hall sensor can be used for the generation of a reference voltage for temperature compensation. The magnetic sensor includes a Hall drive unit, an amplifier, an AD converter, and a reference voltage generation circuit, and generates a detection voltage by sequentially activating a plurality of built-in Hall elements.

Description

Technical Field

[0001] The present invention relates to a magnetic sensor, and more particularly to a magnetic sensor in which a temperature compensation reference voltage is generated using a separate Hall element from a Hall element involved in magnetic sensing among a plurality of Hall elements, and the temperature compensation reference voltage can be used to minimize errors caused by the temperature of the Hall element involved in magnetic sensing. Background Art

[0002] Magnetic sensors utilize Hall effect elements or magnetoresistive elements to convert electrical quantities corresponding to magnetic field strength. Hall effect elements can be implemented as elongated conductive plates with a predetermined current flowing in one direction, such as the x-axis. If a magnetic field is applied perpendicular to the plate, i.e., along the z-axis, the electromotive force generated along the y-axis, perpendicular to the magnetic field and current, is a Hall effect element.

[0003] Figure 1 An equivalent circuit of a conventional Hall element is shown.

[0004] Reference Figure 1 Conventional Hall effect elements have the shape of a bridge (Wheatstone bridge) composed of a combination of resistors. Resistors have the characteristic that their resistance value changes with temperature. In particular, in the semiconductor process used to manufacture Hall effect elements, errors in alignment and etching processes cause pattern inconsistencies, resulting in a predetermined difference between the resistance value of each resistor and the designed target value.

[0005] Because Hall elements have inherent pattern inconsistencies from the time of manufacturing, even when no external magnetic field is applied, the output voltage varies due to differences in the current flowing through each resistor. In particular, temperature fluctuations cause changes in the resistance value, which in turn causes changes in the output voltage. This voltage fluctuation is included in the output voltage as an offset voltage, ultimately preventing accurate magnetic field measurement. Summary of the Invention

[0006] (Problems to be solved by the invention)

[0007] The technical problem to be solved by the present invention is to provide a magnetic sensor in which, in order to compensate for the temperature dependency of the Hall electromotive force, the Hall elements not used for detection in the Hall sensor can be used to generate a reference voltage for temperature compensation.

[0008] (Measures taken to resolve the problem)

[0009] The magnetic sensor of the present invention for achieving the above-mentioned technical problem includes a Hall drive unit, an amplifier, an AD converter, and a reference voltage generation circuit.

[0010] The Hall effect driver includes: a first-type Hall effect element module, which generates two detection voltages corresponding to the measured magnetic direction and magnitude (hereinafter referred to as magnetic intensity) in response to a magnetic detection control signal and a temperature compensation control signal, and generates a temperature compensation auxiliary voltage in response to the temperature compensation control signal; and a second-type Hall effect element module, which generates two detection voltages corresponding to the measured magnetic intensity. The amplifier amplifies the difference between the two detection voltages. The AD converter converts the analog differential amplified detection voltage amplified by the amplifier into a digital signal using a temperature compensation reference voltage. The reference voltage generation circuit generates the temperature compensation reference voltage using the temperature compensation auxiliary voltage.

[0011] (Effects of the Invention)

[0012] According to the magnetic sensor of the present invention as described above, a plurality of Hall elements are activated sequentially while detecting magnetic intensity, while the other inactivated Hall elements are used as replica Hall elements. This has the advantage of minimizing the area of ​​the magnetic sensor while minimizing the temperature dependence of the Hall electromotive force. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 An equivalent circuit of a conventional Hall element is shown.

[0014] Figure 2 is an embodiment of the magnetic sensor according to the present invention.

[0015] Figure 3 This is an embodiment of the Hall effect driving unit according to the present invention.

[0016] Figure 4 This is an embodiment of the first type (TYPEI) of the Hall element module.

[0017] Figure 5 This is an embodiment of the second type (TYPE II) of the Hall element module.

[0018] Figure 6 yes Figure 4 and Figure 5 An embodiment of a selection tool.

[0019] Figure 7 This is an embodiment of a reference voltage generating circuit.

[0020] Figure 8 FIG. 1 is a timing diagram of control signals applicable to the magnetic sensor according to the present invention.

[0021] Figure 9 The structure of the magnetic sensor of the present invention including the Hall element module each including two Hall elements and the magnetic induction process are described.

[0022] Figure 10 This is an example of a Hall element module used in the magnetic sensor sensing process and temperature compensation voltage generation process. DETAILED DESCRIPTION

[0023] To fully understand the present invention, its operational advantages, and the objectives achieved by its implementation, reference should be made to the accompanying drawings that illustrate exemplary embodiments of the present invention and the contents depicted therein.

[0024] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings, and the present invention will be described in detail. The same reference numerals shown in the various drawings refer to the same components.

[0025] Figure 2 is an embodiment of the magnetic sensor according to the present invention.

[0026] Reference Figure 2 The magnetic sensor 200 according to the present invention includes: a Hall drive unit 210 , an amplifier 220 , an AD converter 230 , a reference voltage generating circuit 240 and a control signal generating circuit 250 .

[0027] The Hall drive unit 210 generates detection voltages (VP1 to VP4, VN1 to VN4) corresponding to the magnetic direction and magnitude (hereinafter referred to as magnetic intensity) around the Hall drive unit 210 in response to the magnetic detection control signal SD and the temperature compensation control signal SR, while also generating auxiliary voltages VEN1 to VEN4 for temperature compensation.

[0028] The amplifier 220 amplifies the difference between the detection voltages ( VP1 to VP4 , VN1 to VN4 ) output from the Hall driver 210 .

[0029] The AD converter 230 converts the differential amplified detection voltage VIN in analog form amplified by the amplifier 220 into a digital signal Data using a temperature compensation reference voltage ADVR.

[0030] The reference voltage generating circuit 240 generates a temperature compensation reference voltage ADVR using the temperature compensation auxiliary voltages VEN1 to VEN4 received from the Hall driver 210 .

[0031] The control signal generating circuit 250 generates a magnetic detection control signal SD and a temperature compensation control signal SR to control the operation of the Hall driver 210 .

[0032] Figure 3 This is an embodiment of the Hall effect driving unit according to the present invention.

[0033] Reference Figure 3The Hall driver 210 includes four Hall element modules (①②③④). The four Hall element modules (①②③④) can be divided into two types (TYPEI and TYPEII).

[0034] The Hall driver according to the present invention proposes that: instead of activating the four Hall element modules simultaneously, the detectable magnetic field is activated in sequence from the first Hall element module ① to the fourth Hall element module ④.

[0035] Therefore, when one Hall element module is activated to detect the magnetic intensity, the remaining three Hall element modules remain in an inactivated state. The present invention proposes that when one Hall element module is used to detect the magnetic intensity, one of the remaining three Hall element modules in an inactivated state is used to generate temperature compensation auxiliary voltages VEN1 to VEN4 for generating a temperature compensation reference voltage ADVR.

[0036] For example, when the first Hall element module ① and the second Hall element module ② are activated to detect the magnetic intensity, the inactivated third Hall element module ③ is used to generate an auxiliary voltage for temperature compensation. When the third Hall element module ③ and the fourth Hall element module ④ are activated to detect the magnetic intensity, the inactivated second Hall element module ② is used to generate an auxiliary voltage for temperature compensation.

[0037] According to the present invention, among the four Hall element modules constituting the Hall driver 210, two randomly selected element modules are configured to perform both magnetic field detection and temperature compensation auxiliary voltage generation, while the remaining two element modules are configured to perform only magnetic field detection.

[0038] The following description assumes that the Hall element module that performs both external magnetic field detection and temperature compensation auxiliary voltage generation is of the first type (TYPEI), and the Hall element module that performs only magnetic field detection is of the second type (TYPEII).

[0039] exist Figure 3 The arrangement positions of the two types of Hall element modules shown are only one embodiment, and the arrangement positions of the two types of Hall element modules can be selected in various ways according to the application field.

[0040] Figure 4 This is an embodiment of the first type (TYPEI) of the Hall element module.

[0041] Figure 5 This is an embodiment of the second type (TYPE II) of the Hall element module.

[0042] Figure 6 yes Figure 4 and Figure 5 An embodiment of a selection tool.

[0043] exist Figure 5 The second type (TYPEII) shown is that there is no Figure 4 In addition to the two selection tools R for generating the temperature compensation auxiliary voltage VEN in the first type shown, Figure 4 The same as shown, so the following Figure 4 The structure of the first type (TYPEI) shown is described and the description is applicable to Figure 5 The second type (TYPEII) is shown.

[0044] Reference Figure 4 The first type (TYPEI) is to generate detection voltages VP, VN and temperature compensation auxiliary voltage VEN in response to the magnetic detection control signal SD and the temperature compensation control signal SR. Figure 4 a), including a Hall element 410 and a plurality of selection tools D, R ( Figure 4 b), among the plurality of selection tools, the magnetic detection selection tool D performs a switching action in response to the magnetic detection control signal SD, and the temperature compensation selection tool R performs a switching action in response to the temperature compensation control signal SR ( Figure 4 c).

[0045] The selection tools D and R can be implemented using switches that electrically connect or disconnect the two terminals in response to the corresponding control signals in the magnetic detection control signal SD and the temperature compensation control signal SR. Hereinafter, it is assumed that the two terminals are electrically connected when the selection tool is activated or connected, and electrically disconnected when the selection tool is inactivated or disconnected.

[0046] Reference Figure 1 In the equivalent circuit shown, when the magnetic detection control signal SD is activated, the four magnetic detection selectors D are turned on, connecting the two terminals. At this point, a predetermined current flows through the Hall element module via two voltage sources, VREF and GND, connected to the two terminals 1 and 3 of the Hall element module. The difference in the magnitude of the current flowing along the two paths causes a difference in the voltage drops at the two nodes 2 and 4. The voltage dropped at the second node 2 is the VN detection voltage, and the voltage dropped at the fourth node 4 is the VP detection voltage.

[0047] Here, one of the two paths (the first path) includes node 1 (1), node 2 (2), and node 3 (3). The remaining path (the second path) includes node 1 (1), node 4 (4), and node 3 (3).

[0048] In the absence of an external magnetic field, the magnitudes of the currents flowing in the first path and the second path are the same, so the voltage level of the voltage VN dropped at the node 2 is the same as the voltage level of the voltage VP dropped at the node 4 .

[0049] In the presence of an external magnetic field, the magnitude of the current flowing in the first path and the second path along the direction of the magnetic field changes. Therefore, the voltage level of the voltage VN dropped at node 2 is different from the voltage level of the voltage VP dropped at node 4 according to the magnitude and direction of the magnetic field. This difference can be used to predict the direction change of the magnetic field and the magnitude of the magnetic field.

[0050] The first type (TYPEI) of Hall element modules proposed in the present invention generates a temperature compensation auxiliary voltage VEN to compensate for temperature-induced errors when the Hall element module in the active state detects magnetic intensity when inactive. Specifically, when one Hall element module measures magnetic intensity, it performs the same function, but generates a voltage corresponding to the magnitude of the current flowing through the other Hall element modules in the inactive state, namely, the temperature compensation auxiliary voltage VEN. This temperature compensation auxiliary voltage VEN is used to generate a voltage that compensates for the detection voltage of the activated Hall element module detecting the magnetic field, namely, the temperature compensation reference voltage ADVR.

[0051] exist Figure 5 The second type (TYPE II) shown is that as long as the Figure 4 The two selection tools R in the structure shown are Figure 4 The structures shown are the same and therefore will not be described in detail here.

[0052] Figure 7 This is an embodiment of a reference voltage generating circuit.

[0053] Reference Figure 7 The reference voltage generating circuit 240 includes a plurality of differential amplifiers 710, 720, 730, 740, a plurality of transistors M1, M2, NM3, M4 and a resistor RES, and generates a temperature compensation reference voltage ADVR using the temperature compensation auxiliary voltage VEN output from the driving unit 210.

[0054] exist Figure 7 The operation of the circuit shown can be easily understood by those skilled in the art, and therefore will not be described in detail here. However, to facilitate understanding of the operation of the circuit, a brief description is given below.

[0055] The first differential amplifier 710 amplifies the voltage difference between the reference voltage REF and the temperature compensation auxiliary voltage VEN to generate a bias voltage (Vbias).

[0056] The bias voltage (Vbias) is applied to the gate terminal of the first MOS transistor M1 and determines the magnitude of the current flowing from the power supply voltage VDD to the temperature compensation auxiliary voltage VEN in the first MOS transistor M1. This performs a negative feedback function to change the voltage level of the temperature compensation auxiliary voltage VEN.

[0057] The first differential amplifier 710 and the first MOS transistor M1 are used to amplify the voltage difference between the comparison reference voltage REF and the temperature compensation auxiliary voltage VEN to generate a stabilized bias voltage (Vbias).

[0058] The bias voltage (Vbias) determines the magnitude of the current flowing through the second MOS transistor M2. The current flowing through the second MOS transistor M2 determines the magnitude of the current flowing through the third and fourth MOS transistors M3 and M4, which form a current mirror. The current flowing through the fourth MOS transistor M4 determines the voltage level at one terminal of the fourth MOS transistor, i.e., the voltage level of the first output voltage V1.

[0059] The second differential amplifier 720 is a buffer having a negative input terminal connected to an output terminal and a temperature compensation reference voltage (ADC_REFH_REF) applied to a positive input terminal, thereby generating a first output voltage V1.

[0060] The temperature compensation reference resistor RES is provided between the first output voltage V1 and the second output voltage V2 , and changes the voltage difference between the first output voltage V1 and the second output voltage V2 as the temperature changes.

[0061] The third differential amplifier 730 and the fourth differential amplifier 740 buffer the first output voltage V1 and the second output voltage V2 respectively. The output voltage difference between the third differential amplifier 730 and the fourth differential amplifier 740 is a temperature compensation reference voltage ADVR.

[0062] Reference Figure 2 The temperature compensation reference voltage ADVR is used to minimize the deviation of the detection electric field amount caused by temperature when the AD converter 230 converts the analog differential amplified detection voltage VIN into the digital signal Data.

[0063] Figure 8 FIG. 1 is a timing diagram of control signals applicable to the magnetic sensor according to the present invention.

[0064] Reference Figure 8 The magnetic sensor 200 can use six control signals SD1, SD2, SR2, SD3, SR3, and SD4. SD and SR in the control signal refer to the magnetic detection control signal and the temperature compensation control signal, respectively. The Arabic numerals correspond to the numbers of the Hall element modules.

[0065] Reference Figure 8 , we can know that: when the first Hall element module ① detects external magnetism, the first magnetic detection control signal SD1 and the third temperature compensation control signal SR3 are activated respectively, while the remaining four control signals SD2, SR2, SD3, and SD4 are in an inactivated state.

[0066] Similarly, it can be seen that when the second Hall element module ② detects external magnetism, the second magnetic detection control signal SD2 and the third temperature compensation control signal SR3 are activated, while the remaining four control signals SD1, SR2, SD3, and SD4 are in an inactive state.

[0067] The descriptions of the third and fourth Hall element modules ③④ when detecting external magnetism can be replaced by the above descriptions.

[0068] Preferably, when the magnetic detection control signal SD and the temperature compensation control signal SR are applied to different Hall element modules, their activation intervals do not overlap.

[0069] Reference Figure 8 It can be seen that, for example, when the magnetic detection control signal SD1 drives the first Hall element module ① and when the magnetic detection control signal SD2 drives the second Hall element module ②, their activation intervals do not overlap with each other.

[0070] Preferably, the continuously operating temperature compensation control signal SR and the magnetic detection control signal SD1 are also the same, and their active intervals do not overlap with each other.

[0071] exist Figure 3 It is shown that each Hall element module includes one Hall element 410 , but as described below, an embodiment including two or more Hall elements 410 may also be implemented.

[0072] Figure 9 The structure of the magnetic sensor of the present invention including the Hall element module each including two Hall elements and the magnetic induction process are described.

[0073] Figure 10 This is an example of a Hall element module used in the magnetic sensor sensing process and temperature compensation voltage generation process.

[0074] Reference Figure 9 and Figure 10 , the magnetic sensor magnetic detection sequence including two Hall elements can also be the same as in Figure 3 Furthermore, when one Hall element module detects external magnetism, one of the remaining three Hall element modules generates temperature compensation auxiliary voltages VEN1 to VEN4 for generating a temperature compensation reference voltage ADVR.

[0075] (Industrial Applicability)

[0076] The present invention relates to a magnetic sensor which can be used in various industries, such as terrain training for visually impaired people, detecting defects in hollow inner walls, detecting the position of cranes, etc.

Claims

1. A magnetic sensor comprising: The Hall drive unit includes a first-type Hall element module and a second-type Hall element module. The first-type Hall element module generates two detection voltages corresponding to the measured magnetic direction and magnitude (hereinafter referred to as magnetic intensity) in response to a magnetic detection control signal and a temperature compensation control signal, and generates an auxiliary voltage for temperature compensation in response to the temperature compensation control signal. The second-type Hall element module generates two detection voltages corresponding to the measured magnetic intensity. an amplifier for amplifying the difference between the two detection voltages; An AD converter converts the analog differential amplified detection voltage amplified by the amplifier into a digital signal using a reference voltage for temperature compensation; and The reference voltage generating circuit generates the temperature compensation reference voltage using the temperature compensation auxiliary voltage.

2. The magnetic sensor according to claim 1, wherein The Hall driving unit includes two first-type Hall element modules and two second-type Hall element modules.

3. The magnetic sensor according to claim 2, wherein The Hall drive unit is: The two first-type Hall element modules and the two second-type Hall element modules are respectively arranged at vertex positions in a virtual positive direction.

4. The magnetic sensor according to claim 3, wherein The Hall drive unit is: When one of the two first-type Hall element modules and the two second-type Hall element modules generates the two detection voltages, one of the two first-type Hall element modules generates the reference voltage for temperature compensation, while the remaining Hall element modules do not perform any function.

5. The magnetic sensor according to claim 1, wherein The first type Hall element module includes: The Hall element includes a second node and a fourth node generating a voltage corresponding to a magnetic field intensity, and a first node and a third node supplying a voltage; a first detection process selection means for switching a power supply voltage to the first node in response to the magnetic detection control signal; a second detection process selection means, in response to the magnetic detection control signal, switching the voltage of the second node to one of the two detection voltages; a third-a detection process selection means for switching the third node to a ground power source in response to the magnetic detection control signal; a fourth-first detection process selection means, in response to the magnetic detection control signal, switching the voltage of the fourth node to the remaining one of the two detection voltages; a first temperature compensation process selection means for switching the second node to the temperature compensation auxiliary voltage in response to the temperature compensation control signal; and The second temperature compensation process selection means switches the fourth node to a ground power source in response to the temperature compensation control signal.

6. The magnetic sensor according to claim 5, wherein The second type Hall element module includes: The Hall element includes a second node and a fourth node generating a voltage corresponding to a magnetic field intensity, and a first node and a third node supplying a voltage; a first-second detection process selection means for switching a power supply voltage to the first node in response to the magnetic detection control signal; a second-second detection process selection means, responsive to the magnetic detection control signal, switching the voltage of the second node to one of the two detection voltages; a third-second detection process selection means for switching the third node to a ground power source in response to the magnetic detection control signal; and A fourth-second detection process selection means switches the voltage of the fourth node to the remaining one of the two detection voltages in response to the magnetic detection control signal.

7. The magnetic sensor according to claim 4, wherein: Also includes: The control signal generating circuit generates a magnetic detection control signal and a temperature compensation control signal.

8. The magnetic sensor according to claim 7, wherein The magnetic detection control signal specifically drives two of the first-type Hall element modules and two of the second-type Hall element modules; The temperature compensation control signal specifically drives two of the first-type Hall element modules.

9. The magnetic sensor according to claim 8, wherein The magnetic detection control signals applied to different Hall element modules have activation intervals that do not overlap with each other; The temperature compensation control signals applied to different Hall element modules have activation intervals that do not overlap with each other.

10. The magnetic sensor according to claim 1, wherein The Hall drive unit includes: The two first-type Hall element module pairs comprising two first-type Hall element module pairs connected in series include: There are two pairs of second-type Hall element modules, each of which is connected in series.

11. The magnetic sensor according to claim 10, wherein The Hall drive unit is: The two first-type Hall element module pairs and the two second-type Hall element module pairs are respectively arranged at vertex positions in a virtual positive direction.

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