JPH0664088B2 - Drive device for cross coil type instrument - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention has a pair of cross coils intersecting with each other and a magnet rotor, and by rotating the magnet rotor by a magnetic field generated by the cross coil, The present invention relates to a drive device for a cross coil type meter that displays a predetermined measurement amount from a rotation angle.

[Conventional technology]

Cross-coil type instruments are generally shown in Figs. 1 (a), (b),
It is configured as shown in (c). In the figure, a cross coil L is constituted by _first and second coils L ₁ and L ₂ which are arranged so as to intersect with each other, and a magnet rotor Mg is rotatably arranged in a magnetic field generated by the cross coil L. .
A pointer A is attached to the central portion of the magnet rotor Mg. In addition, B is a scale plate that displays the measured amount in cooperation with the pointer A, and is provided with a vehicle speed display scale as shown in the figure, for example.

In the above-mentioned structure, when a current is passed through the first and second coils L ₁ and L ₂ , magnetic fields are generated by the coils. Make sure that the combined magnetic field direction of these magnetic fields matches the magnetic pole direction of the magnet rotor Mg.
Rotates. The direction of the composite magnetic field is the first and second coils L
Each of the magnetic fields generated by ₁ and L ₂ is vector-synthesized, and the magnitude of each magnetic field is proportional to the value of the current flowing through each coil L ₁ and L ₂ . Therefore, when a combined vector (combined magnetic field) is formed by passing a current corresponding to a predetermined measured amount through the coils L ₁ and L ₂ , the magnet rotor Mg rotates in that direction and the pointer A rotates to a predetermined rotation angle. Then, the pointer A displays the predetermined measured amount.

Conventionally, as the currents I ₁ and I ₂ passed through the coils L ₁ and L ₂ , for example, the currents shown in FIG. 5 have been used. That is, the current I ₁ is a trapezoidal wave having a 360 ° cycle which changes according to a predetermined measurement amount, and the current I ₂ is a trapezoidal wave having a phase difference of 90 ° with respect to the current I ₂ . FIG. 6 shows a driving device for driving the cross coil L by such trapezoidal wave current. In the figure, one ends of the first and second coils L ₁ and L ₂ are commonly connected, and a reference voltage is applied from the output terminal C ₁ of the drive circuit 9. The trapezoidal wave currents I ₁ and I ₂ are supplied from the output terminals C ₂ and C ₃ of the drive circuit 9 to the other ends of the coils L ₁ and L ₂ , respectively.

In this configuration, trapezoidal wave currents I ₁ and I ₂ corresponding to a predetermined measurement amount are set from FIG. 5, and the currents are supplied from the drive circuit 9 to the first and second coils L ₁ and L _2. By
The combined vector direction of the magnetic fields generated by the coils L ₁ and L ₂ corresponds to the measurement amount. Therefore, the magnet rotor Mg rotates in the direction of the combined vector, and the pointer A rotates accordingly, so that the measured amount can be displayed.

Further, a drive device using a current based on the tangent tan θ of the angle θ according to the measurement amount as the current supplied to the cross coil L has also been proposed. This drive is a magnet rotor
The Mg rotation range is set to 1 rotation (0 to 360 degrees) and the memory (RO
The tangent tan θ of the rotation angle θ of the magnet rotor Mg corresponding to the value of the predetermined measurement amount is stored in M). Further, one rotation of the magnet rotor Mg is divided into eight quadrants shown in FIG. 8, and which quadrant of the eight quadrants the pointer A is located is set according to the measured amount. Next, the current supplied to the cross coil L is set as follows with tan θ having an angle θ according to the measurement amount obtained from the memory. That is, in FIG.
Ta corresponding to the measured quantity in one quadrant of the selected octet
From nθ, the respective currents I ₁ and I ₂ are set to I ₁ = I ₀ tanθ I ₂ = I ₀ (I ₀ : constant). The respective currents I ₁ and I ₂ are applied to the first and second coils L.
By supplying ₁ and L ₂ , the combined vector becomes the direction of the angle θ, and since this angle θ corresponds to the predetermined measurement amount, the measurement amount can be displayed by the pointer A.

[Problems to be Solved by the Invention]

In the above-described conventional drive device, first, the former trapezoidal wave current causes an error of about 1.7 ° in the rotation angle of the magnet rotor Mg with respect to the measured amount. Also cross coil L
The magnitude of the combined vector of the magnetic fields generated by the magnet rotor Mg corresponds to the rotation torque of the magnet rotor Mg. However, in the former drive device, the torque is not uniform during one rotation of the magnet rotor Mg, so the magnet rotor Mg with respect to the measured amount is The rotation angle relationship of is non-linear.

Further, even in the latter case of tangent tan θ, as shown in FIG. 7, the magnitude I ₀ ′ (= I ₀ (1 + tan ² θ) of the composite vector of the magnetic field during one rotation of the magnet rotor Mg.
^1/2 ) is not uniform, and the magnitude of the magnetic field acting on the magnet rotor Mg changes depending on the direction of the combined magnetic field of the angle θ. That is, even if the positional relationship of the magnet rotor with respect to the direction of the combined magnetic field is constant, the rotational torque characteristic of the magnet rotor with respect to the combined magnetic field, that is, the responsiveness, is not constant due to the change of the combined magnetic field direction.
There is a problem in that the pointer does not move smoothly because the pointer moves faster or slower depending on the pointer position, resulting in unnatural movement.

Therefore, an object of the present invention is to provide a drive device for a cross-coil type instrument in which the rotational torque characteristic of the magnet rotor, that is, the response characteristic with respect to the combined magnetic field is made constant to enable smooth and natural movement of the pointer. There is.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, a driving device for a cross-coil type instrument according to the present invention is a first device which is arranged so as to cross each other.
A cross coil including a second coil and a magnet rotor provided in a magnetic field generated in the cross coil, a current according to a predetermined measurement amount is applied to the cross coil, and the magnet rotor is rotated by the magnetic field generated by the current. In the driving device of the cross-coil type instrument that displays the measured amount based on the rotation angle, the sine of a predetermined 90 ° angle with respect to the digital data corresponding to the predetermined measured amount. The sine data read from the storage means by the digital data and the cosine data formed by the sine data read out from the storage means by the digital data shifted by 90 ° are provided. The sine data output means and cosine data output means for outputting, and the sine data output means and cosine data output means Sine duty pulse generating means and cosine duty pulse generating means for respectively generating a sine duty pulse and a cosine duty pulse each having a duty corresponding to the output sine data and cosine data, and said sine duty pulse generating means and cosine duty pulse generating means Driven by the sine duty pulse and the cosine duty pulse respectively generated by the driving means for flowing the first and second rectangular wave currents in the first and second coils, respectively, and the driving means for driving the first and second rectangular wave currents based on the digital data. Direction determining means for determining the directions of the first and second rectangular wave currents flowing through the second coil.

[Action]

In the above configuration, when a predetermined measurement amount is input, the sine data and cosine data output means stores the sine (sin) data for a predetermined 90 ° angle with respect to the digital data corresponding to the measurement amount. The sine data is read from the storage means, and the read sine data and the cosine data composed of the sine data read from the storage means by the 90 ° phase-shifted digital data are output. The sine duty pulse generating means and the cosine duty pulse generating means respectively generate a sine duty pulse and a cosine duty pulse having a duty corresponding to the sine data and the cosine data output from the sine data output means and the cosine data output means, respectively. The sine duty pulse and the cosine duty pulse cause the driving means to cause the first and second coils to flow the first and second rectangular wave currents, respectively.
The direction of the first and second rectangular wave currents flowing through the first and second coils is determined by the direction setting means based on the digital data.

As described above, the combined vector direction of the magnetic field generated by the flow of the first and second rectangular wave currents in the predetermined method determined for the first and second coils rotates 360 °, and Since the direction of the vector corresponds to the predetermined measurement amount, the predetermined measurement amount can be recognized from the rotation angle of the magnet rotor. Further, since the duty of the first and second rectangular wave currents are changed by the sine data and the cosine data, respectively, the magnitude of the combined vector during one rotation of the magnet rotor is always constant, and the magnet in the direction of the combined magnetic field is always constant. When the positional relationship of the rotor is constant, the rotational torque characteristic of the magnet rotor with respect to the combined magnetic field, that is, the responsiveness is constant even if the combined magnetic field direction changes.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. According to the present invention, the first and second coils L ₁ and L ₂ shown in FIGS.
The second rectangular wave current is used, and the duty of each rectangular wave current is changed in accordance with the sine data and cosine data of the angle corresponding to the predetermined measurement amount.

That is, in the combined vector diagram of the first and second coils L ₁ and L ₂ shown in FIG. 3, the deflection angle θ of the pointer A is the current flowing in the first and second coils L ₁ and L ₂ , respectively. _{If 1} and I ₂ , θ =
tan ^- determined by ^{_{1 (I 1 / I 2)}} . On the other hand, the currents I ₁ and I ₂ are I ₁ = I ₀ sin θ I ₂ = I ₀ cos θ (I ₀ : constant), respectively. Therefore, by setting the angle θ to a value corresponding to the predetermined measurement amount, the deflection angle θ of the pointer A displays the predetermined measurement amount. Moreover, in the range where the pointer A makes one rotation (0 ° to 360 °), Thus, a constant torque is applied to the magnet rotor Mg in the entire rotation range, and the resultant vector direction corresponds to the angle θ, that is, the predetermined measurement amount. Therefore, the magnet rotor Mg rotates in this composite vector direction, and the pointer A points in the vector direction. This allows the measured amount to be displayed.

FIG. 2 shows an embodiment of the driving device according to the present invention.
In the figure, the counter circuit 1 has a rectangular wave signal whose cycle changes according to a predetermined measurement amount (for example, vehicle speed) and a basic clock for counting the cycle of the rectangular wave signal output from the clock circuit 8. Is entered. The digital data output from the counter circuit 1 according to the cycle is si
It is input to the n-function generating circuit 2. The circuit 2 is composed of a ROM, and as shown in Table 1, sine data of the angle θ corresponding to the digital data is stored.

That is, as shown in FIG. 4, the rotation range of the pointer A is 0 ° to 360 °.
If the position of 0 ° is set to the position shown in the figure, the angle θ corresponding to the digital data “0” (when the information value is “0”) is set to 0 °, and the rate of change of the digital data (first
In the table, “1”) is associated with an angle of 1 °, and its sin θ is stored. This sin θ is stored in the range of 0 ° ≦ θ ≦ 90 °, 90 ° ≦ θ ≦ 180 °, 180 ° ≦ θ ≦ 270 °,
And within the range of 270 ° ≦ θ ≦ 360 °, the above-mentioned sin θ of 0 ° ≦ θ ≦ 90 ° is corresponded as shown in Table 1. The output (sin θ) data of the sin function generating circuit 2 is input to the sin duty pulse generating circuit 3. The sin duty pulse generation circuit 3 generates a rectangular signal having a duty corresponding to the output data from the sin function generation circuit 2.

Furthermore, from the sin function generation circuit 2, sin (90 ° ± θ) = cos
Based on the relationship of θ, an angle obtained by shifting the angle θ corresponding to the digital data by 90 °, (90 ° + θ) sin, that is, cos θ data is output, and the output data is input to the cos duty pulse generation circuit 4. The cos duty pulse generation circuit 4 generates a rectangular wave signal having a duty corresponding to this output. The rectangular wave signals from the generation circuits 3 and 4 are input to the drive circuits 5 and 6, respectively, and the drive circuits 5 and 6 supply the terminals a ₁ and a _{2 of} the _first and _second coils L ₁ and L ₂ , respectively. The first and second rectangular wave currents I ₁ and I ₂ are supplied to b ₁ and b ₂ , respectively.

On the other hand, the output of the counter circuit 1 is input to the direction setting circuit 7, which sets which quadrant the pointer A is located in the quadrant of FIG. ,
The directions of the first and second rectangular wave currents output from the drive circuits 5 and 6 for the second coils L ₁ and L ₂ are set as shown in Table 2.

In the above configuration, the period of the rectangular wave signal input to the counter circuit 1 is counted based on the basic clock, converted into digital data according to the period, and output. The sin function generation circuit 2 accesses the sine sin θ data of the angle θ corresponding to this digital data. Also, sin data at (θ + 90) °, which is 90 ° phase shift from the angle θ,
That is, access the cos θ data and calculate the sine sin for the angle θ
The θ data and the cosine cos θ data are output. This sin θ data and cos θ data are input to the sin and cos duty pulse generation circuits 3 and 4, respectively, and sin θ data and cos θ data are input.
A rectangular wave signal having a duty corresponding to the data is output and input to the drive circuits 5 and 6.

On the other hand, the digital data from the counter circuit 1 is input to the direction setting circuit 7, and the output terminals a ₁ , a ₂ , b ₁ , b ₂ of the drive circuits 5, 6 shown in Table ₂ are selected according to the digital data. . The current directions of the first and second rectangular wave currents with respect to the first and second coils L ₁ and L ₂ are set from the selected output terminal, and the pointer A is set in the quadrant of FIG. The quadrant in which it is located is set.

From the above operation, the first and second rectangular wave currents supplied to the first and _second coils L ₁ and L ₂ become values corresponding to the sine data and cosine data of the angle according to the predetermined measurement amount, The combined vector direction of the magnetic field generated in the coil L corresponds to the measurement amount. Therefore, the magnet rotor Mg rotates in the combined vector direction, and the pointer A indicates the combined vector direction to display the measured amount.

〔effect〕

As described above, according to the present invention, in the range of one rotation (0 ° to 360 °) of the magnet rotor, the combined vector direction generated in the cross coil accurately corresponds to the predetermined measurement amount, and the magnitude of the vector is large. Is constant with respect to an arbitrary rotation angle of the magnet rotor, the response of the magnet rotor to the combined magnetic field is constant when the relationship between the direction of the combined magnetic field and the current position of the magnet rotor is constant, and Will move smoothly and naturally.

Further, the magnet rotor is rotated 360 ° by the sine duty pulse and the cosine duty pulse generated based on the data from the storage means storing the 90 ° angle sine data and the direction in which the current is determined by the direction setting means. Therefore, the sine data for 90 ° can be prepared, and the capacity of the storage means can be reduced accordingly, and the structure is economical.

[Brief description of drawings]

1 (a), (b), and (c) are a top view, a perspective view, and a configuration diagram of a cross coil unit, respectively, showing a cross coil type instrument, and FIG. 2 is an embodiment of a drive device according to the present invention. Block diagrams shown in FIGS. 3, 3 and 4 are combined vector diagrams of magnetic fields for explaining the operation of the present invention, and diagrams showing the rotation range of the magnet rotor, and FIG. 5 is a current waveform supplied to a conventional cross coil. FIG. 6, FIG. 6 is a diagram showing an apparatus for driving a cross coil by the electric current of FIG. 5, and FIGS. 7 and 8 are magnetic field synthesis for explaining another conventional means for driving a cross coil. It is a vector diagram and a figure which shows the rotation range of a magnet rotor. L ...... cross coil, _{L 1} ...... first coil, _{L 2} ......
Second coil, Mg ... Magnet rotor, A ... Pointer,
1 ... Counter circuit, 2 ... sin function generating circuit, 3 ... s
in duty generation circuit, 4 …… cos duty generation circuit, 5,6 …… drive circuit, 7 …… direction setting circuit.

Claims (1)

[Claims] 1. A cross coil comprising first and second coils arranged so as to intersect with each other, and a magnet rotor provided in a magnetic field generated in the cross coil, wherein the cross coil responds to a predetermined measurement amount. In a drive device of a cross-coil type instrument in which an electric current is passed, a magnet rotor is rotated by a magnetic field generated by the electric current, and the measured amount is displayed from the rotation angle, digital data corresponding to the predetermined measured amount is previously stored. It has a storage means for storing sine data for a predetermined 90 ° angle, and stores the sine data read from the storage means by the digital data and the digital data phase-shifted by 90 °. Sine data output means and cosine data output means for outputting cosine data composed of the sine data read from the means; A sine duty pulse generating means and a cosine duty pulse generating means for respectively generating a sine duty pulse and a cosine duty pulse having a duty corresponding to the sine data and the cosine data output from the data output means and the cosine data output means, respectively; Drive means for causing first and second rectangular wave currents to flow through the first and second coils respectively by a sine duty pulse and a cosine duty pulse generated by a pulse generation means and a cosine duty pulse generation means, respectively; and the digital data. Drive means for determining the direction of the first and second rectangular wave currents to flow through the first and second coils by the drive means.