JPH01116471A - Magnetoresistance element assembly - Google Patents

Abstract

PURPOSE:To improve accuracy of correcting a magnetoresistance element assembly by performing a temperature characteristic correction of an offset voltage in a range of a sensor portion before an amplification circuit. CONSTITUTION:A magnetoresistance element 1 has a magnet 8 for biasing bonded on the underside thereof and electrically connected to a substrate 4 with a wiring pattern printed. A thick film resistance element 5 is printed on the substrate 4. A fine pattern portion of the magnetoresistance element 1 has magnetoresistance element components 101-104 mutually bridge connected to compose respective bridge circuits. Yokes 105 and 106 are located on both sides of the magnetoresistance element components 102 and 103 to ensure efficient action of an applied magnetic field. The thick film resistance element is so electrically arranged to contain at least magnetoresistance elements separated from each other in a pattern of the magnetoresistance element in a parallel circuit and a resistance value can be adjusted by trimming from outside.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is mainly used in facsimiles, telephone line input current detection elements such as telephones, current detection elements in various electronic circuits, or position detection elements. The present invention relates to a magnetoresistive element assembly using ferromagnetic thin film elements.

[Conventional technology]

FIG. 9 is an external perspective view of a conventional magnetoresistive element.
Figure 0 is a configuration diagram of the fine pattern.

FIG. 11 is an equivalent circuit diagram thereof. Reference numeral 11 indicates the entire magnetoresistive element, and its structure is such that a fine pattern portion 112 is formed on a substrate 71 (silicon or alumina substrate) by vapor deposition or swiping, and the substrate 71 is formed by molding resin 21. It is molded, and external terminals 31, 32, 33, and 34 are exposed, and the output voltage is output from terminals 34 and 32. On the other hand, a bias magnet 81 is bonded to the back side of the magnetoresistive element opening.

As shown in FIG. 10, the fine pattern 112 has a structure in which folded magnetoresistive elements 102 and 103 are arranged close to each other, and a thin film yoke 105 is placed on the outside thereof.
．． 106 are arranged, and the negative elements 101 and 104 are mutually arranged.

Moreover, it is arranged with a step difference from 102 and 103. Elements 102, 103 and 101° 104 are the first
As shown in the equivalent circuit of FIG. 1, this corresponds to the combination of mutually opposing sides in a bridge circuit configuration.

FIG. 12 shows a conventional application example for current detection. 9
is the head (Malloy wood), and its air gap f
The parts are arranged so as to sandwich fine pattern elmmen) 102 and 103.

In Figure 13, the full power supply voltage is applied between the ■ and ■ terminals.

This is an example of the characteristics of the output voltage V (E) versus the secondary current I when the output voltage V (■) between 0.0 (the terminal (■) is set as 10) is measured. Focusing on the characteristics at room temperature 25°C, bias Mg
The magnetic field 81 is applied perpendicularly to the longitudinal direction of the elements 102 and 103, and therefore, due to the effect of the bias magnetic field, nearly linear characteristics are obtained across the negative and positive directions of the current.

Here, for example, threshold voltages vA and VB are set corresponding to the current to be detected (set by a subsequent processing circuit).
Correspondingly, a negative current of -11° and a positive current of 111° can be detected.

[Problem that the invention seeks to solve]

Here, the first problem with the conventional method is the offset voltage V in FIG. ff itself may vary within a lot.Secondly, the offset voltage V. Since the ff itself has temperature characteristics, in the example shown in FIG. 13, the temperature increases from 0° C. to 25° C. and 1606° C., but the overall characteristics tend to shift upward.

Therefore, there is a problem in that the detected current value fluctuates widely due to temperature fluctuations within the loft with respect to a preset threshold voltage.

The causes of the above offset voltage variations and temperature fluctuations are:
Illustration 10 Element 101, 102゜103.104
It is thought that the main cause is the breakdown of the resistance balance of the bridge circuit due to variations in the bridge circuit itself and non-uniformity of thermal strain, and as shown in Figure 14, the offset voltage tends to increase with increasing temperature. In some cases, it shows a downward trend as shown by the dotted line.

Conventionally, as a method for correcting temperature fluctuations in the offset voltage, methods such as adding an element such as an NTC thermistor to the subsequent stage amplifier circuit and performing correction by the latter stage amplifier circuit, as shown in Fig. 15, have been used. For example, even if the actual magnetoresistive element and amplifier circuit are housed in a one-piece case, there will be a slight temperature difference between them, and due to this effect, it is not possible to accurately correct the temperature characteristics of the offset voltage. When the magnetoresistive element and the amplifier circuit are installed apart from each other, the influence of a wide temperature difference occurs, and therefore, there is a problem that errors due to temperature characteristics in current value measurement cannot be completely corrected. .

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetoresistive element assembly that performs temperature characteristic correction of offset voltage in a portion of the sensor before the amplifier circuit, and that can improve the accuracy of correction more than conventional methods.

[Structure of the invention]

In the present invention, a resin-molded magnetoresistive element composed of a magnetoresistive element made of a ferromagnetic thin film element and a thin film yoke is electrically connected to an external substrate on which a thick film resistance element is printed, and the magnetic resistance element is electrically connected to an external substrate on which a thick film resistance element is printed. Resistance element NoJ? In the turn configuration, four magnetoresistive element elements are bridge-connected to each other, and two opposing elements are placed close to each other.

The magnetoresistive element assembly is characterized in that a thin film yoke is disposed on both sides thereof, and the two universally opposed elements are separated to both sides of the thin film.

Further, the thick film resistive element printed on the external substrate is included in a parallel magnetoresistive parallel circuit separated from each other at least in the A' turn of the magnetoresistive element, and the thick film resistive element has a resistance value. An NTC thermistor with a negative temperature coefficient or a PTC thermistor with a positive temperature coefficient of resistance can also be used.

〔Example〕

FIG. 1 shows an external view of a magnetoresistive element assembly according to the present invention. The magnetoresistive element 1 has a bias magnet 8 adhered to its lower side, and is electrically connected to a substrate 5 on which wiring and turns are printed.

The structure of the fine pattern part of the magnetoresistive element 1 is as follows.
Similar to the figure, magnetoresistive element elements 101, 102, 103 and 104 are bridge-connected to each other, and the opposite combinations 102 and 103 of the bridge sides are close to each other, - the universal combination 101, 104 is separated. Yoke 105° and 106 are magnetoresistive elements (Niremen) 10
Reeds on both sides of 2,103, the applied magnetic field is
It has the function of efficiently acting on ゜103.

Here, 102 and 103 have the role of receiving an external magnetic field,
On the other hand, resistors 101 and 104 act as fixed resistors opposed to each other in the bridge circuit without receiving any external magnetic field. FIG. 3 shows an equivalent circuit of the magnetoresistive element 10. A fine pattern is formed on the substrate 7.

The external terminal 3 is electrically connected via a hexending wire 311. The terminals ■ and ■ are power input terminals, and the terminals ■ and ■ are output terminals. In the equivalent circuit shown in Figure 3, when R2 and R3 change in the direction where the resistance value decreases, the output voltage (■ terminal (=+ side) indicates a tendency to change in the positive direction.

A wiring pattern and a thick film resistive element 5 (initial resistance value R5o) are printed on the substrate 4. In the example of FIG. As shown in the equivalent circuit of the magnetoresistive element assembly in FIG. 2, the magnetoresistive element is connected in parallel to the fixed resistor R4 on the pattern.

The board 4 is provided with external connection terminals 61, 62, 63° 64.

Figure 4 shows ■' and solid' when thick film resistor element 5 is added.
FIG. 4 is a diagram showing a tendency of change in voltage V(4)'III' between terminals 64 and 63.

If the resistance ratio Rso/R4 is less than 5, V4 / s t will drop rapidly in response to a change in R50, making it unsuitable for use as an offset adjustment.
V4 t 5 t fluctuation width Δ
V and on the other hand V215/ (voltage between terminals 61 and 62)
is fixed, so the offset voltage V. ff4'2
The fluctuation width ΔVof f is equal to the above fluctuation ΔV Δ■
The relationship is: off = ΔV.

Figure 5 shows the offset voltage ■ on the thick film resistor 5. ff4'2
' and then add a cut portion 51 by laser trimming or sandblasting to a predetermined offset voltage value V. An example is shown in which the resistance value is adjusted until .

The method shown in FIG. 5 allows the offset voltage to be adjusted to the standard value at room temperature, and is a measure to improve the conventional problem of variations in the offset voltage of the magnetoresistive element itself.

FIG. 6 shows another embodiment of the present invention in which an NTC thermistor 5'' (see FIG. 6(b)) having a negative temperature coefficient of resistance is used as a thick film resistor for adjustment.

In this case, when the offset voltage of the original magnetoresistive element 1 has a positive temperature coefficient, it is effective for temperature characteristic correction of the offset voltage.

As shown in FIG. 6(C), it is possible to keep the temperature characteristics of the offset voltage flat compared to the case of using the adjusting resistor 5' where the temperature coefficient is almost zero.

Furthermore, in the case where the offset voltage of the original magnetoresistive element 1 has a negative temperature coefficient, a thick film resistance element made of a PTC thermistor material with a positive resistance temperature gradient can be used as the correction resistor 5''. good.

FIG. 7 shows still another embodiment of the present invention, and FIGS. 7 and 8 show its equivalent circuit. Niremen of magnetoresistive element 1) 10
1. Adjustment thick film resistance element 5'' in parallel with (resistance value R1)
It contains

Almost the same effect as the embodiment shown in FIG. 1 can be obtained. However, the direction of change in the resistance value of the thick film resistor 5'' and the direction of change in the offset voltage V.ff4''2'' are shown in FIG.

Although the effect is exactly opposite to that shown in FIGS. 5 and 7, it poses no problem in practical use.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to improve the offset voltage variations of conventional magnetoresistive elements and the temperature characteristics of the offset voltage at the front stage of the processing amplifier circuit, and to provide a magnetoresistive element assembly with high detection accuracy. can.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention. FIG. 2 is an equivalent circuit thereof, FIG. 3 is an equivalent circuit diagram of a single magnetoresistive element, FIG. 4 is an operation explanatory diagram, and FIG. 5. 6 and 7 respectively show other embodiments of the present invention, FIG. 8 is an equivalent circuit of FIG. 7, FIG. 9 is an explanatory diagram of a conventional magnetoresistive element alone, and FIG. The pattern diagram and Figure 11 are its equivalent circuit. FIG. 12 shows a conventional application example, FIGS. 13 and 14 show conventional characteristic diagrams, and FIG. 15 shows a conventional countermeasure example. 1, and'' magnetoresistive element, 12, 112-...
Fine pattern part, 2.21...resin mold. 31.32, 33.34...Terminal, 311...Ponding clear, 4...Circuit board $5 #5'
l 5'j 5"...thick film resistor, 51.52.53
．． 54...Cut part for adjusting resistance value, 61, 62, 6
3.64...Lead terminal, 8,81...Bias-
, 7, 71... Magnetoresistive element internal substrate, 9... Head. Figure 1 - (Input voltage) Figure 4 Figure 5 (α) (b) Figure 6 Figure 7 Figure 15 Figure 14 Temperature ("C)

Claims (3)

[Claims] 1. A resin-molded magnetoresistive element consisting of a magnetoresistive element made of a ferromagnetic thin film element and a thin film yoke is electrically connected to an external substrate on which a thick film resistance element is printed. The pattern configuration consists of four magnetoresistive elements connected to each other in a bridge.
One of the opposing two elements is close to each other and a thin film yoke is arranged on both sides thereof, while the other two opposing elements are spaced apart to both sides of the thin film. magnetoresistive element assembly 2. The thick film resistive element printed on the external substrate is electrically arranged so as to include at least mutually separated magnetoresistive elements in a parallel circuit in the pattern of the magnetoresistive element, and is trimmed from the outside. Magnetoresistive element assembly according to claim 1, in which the resistance value can be adjusted. 3. The thick film resistance element is an NT having a negative temperature coefficient of resistance.
The magnetoresistive element assembly according to claim 1, which is a C thermistor or a PTC thermistor with a positive temperature coefficient of resistance value.