JPS6220504B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for driving a crossed coil type meter, which drives the crossed coil type meter with a trapezoidal wave signal.

It has been known that crossed coil instruments can be driven with signals that have a phase difference of 90 degrees in electrical angle and that change AC with trapezoidal wave characteristics. This has the advantage that the structure of the drive signal generation circuit is simpler than the sine wave drive, but on the other hand, it has the disadvantage that the linearity of the finger index is inferior.

The present invention has been made to solve the above-mentioned drawbacks. In other words, we focused on the fact that the linearity of the finger index changes when we change the shape of the trapezoidal wave that is the drive signal for a crossed coil type instrument, and found the trapezoidal wave that can best improve the linearity of the finger index. It is an object of the present invention to provide a method for driving a crossed coil type meter for driving a coil type meter.

The present invention will be explained in detail below based on embodiments shown in the drawings.

In Figure 1, 1 and 2 have mechanical intersection angles of 90
A movable magnet 3 magnetized into two poles is located in the internal space of these coils 1 and 2.
A pointer shaft 4 extends from the center of the movable magnet 3, and a pointer 5 is attached to the tip of the pointer shaft 4. 6 and 7 are drive signal generation circuits, and these drive signal generation circuits 6 and 7
have a phase difference corresponding to 90° in electrical angle,
And as shown in Figure 2, the current or effective current or voltage or effective voltage, etc. that changes AC with isosceles trapezoidal wave characteristics such that the ratio of the lower base to the upper base A is B/A is approximately 2.29. Drive signals 6a, 7a are generated, and the two-phase drive signals 6a, 7a are configured to advance in phase in accordance with an increase in a measured quantity such as vehicle speed or engine rotational speed.

The structure of this embodiment has been described above. Next, the operation will be described. By supplying the signals 6a and 7a that change AC with the isosceles trapezoidal wave characteristic as shown in FIG. can do.

That is, as is clear from FIG. 3a, the signals 6a and 7a have a phase difference corresponding to 90 degrees in electrical angle, and both are isosceles trapezoidal waves, so the phase α is 0<α.
When ≦α ₄ (=B/2), α=α ₃ (=B/
4), and as a result, the index curve also becomes symmetrical with respect to α=α _3. Therefore, in order to simplify the explanation, the phase α will be considered in the range of 0≦α≦α ₃ .

The deflection angle of the pointer 4 in the range where the phase α is 0≦α≦α ₂ (=A/2), that is, the indicating angle Φ (unit: radian) is Φ ₁ (α), and the phase α is α ₂ ≦α≦α
If the indicated angle Φ in the range of ₃ is Φ ₂ (α), tanΦ = function with phase α of waveform 6a as a variable/waveform 7
From the relational expression of the function with the phase α of a as a variable, Φ ₁ (α) = tan ^-1 α/α ₄ - α ₂ = tan ^-1 α/B/2-A/2 Φ ₂ (α) = tan ^{- 1} α/α ₄ −α = tan ⁻¹ α/B/2−α. On the other hand, the indicated angle Φ due to sine wave driving is Φ ₃
(α), Φ ₃ (α)=π/2α ₄ α=π/Bα. By the way, Φ ₁ (α) and Φ ₂ (α) are α
=α ₂ (=A/2), but it is connected like a broken line, but Φ ₁
(α) has a different curve depending on the value of A, whereas Φ ₂ (α) does not depend on the value of A, and moreover, in the range of phase α 0 < α < α ₃ , Φ ₃ (α ), the value becomes smaller than Φ ₁ (α) and Φ
In order to maximize the linearity of the index curve consisting of ₂ (α), Φ ₁
A such that there are two locations where the difference (index error) of (α) with respect to Φ ₃ (α) is maximum, and the magnitudes of the maximum index errors δ ₁ and δ ₂ are equal.
It turns out that it is best to choose the value of .

Therefore, the maximum index error δ ₁ is the point _{α 1 (} = _√ (2-2) {−(2
-A/2)}) The value of Φ ₁ (α) at Φ ₁ (α
₁ ) minus the value Φ ₃ (α ₁ ) of Φ ₃ (α), and δ ₁ = tan ^-1 α ₁ /α ₄ −α ₂ −π/2α ₄ α ₁ = tan ^-1 [1 /(B/2-A/2) ・√(2-2){-(2-2)}]-π/B√(2-2){-(2-2)} The index error δ ₂ is the point α ₂ (=
It is the value obtained by subtracting the value Φ ₁ (α 2 ) of Φ 1 (α) from the value Φ ₃ (α ₂ ) of _{Φ 3 (} α) in A/ ₂ ), and δ ₂ = π/2α ₄ α ₂ −tan ^-1 α ₂ /α ₄ −α ₂ = π/B·A/2−tan ⁻¹ A/2/B/2−A/2. Therefore, since B/2 corresponds to an electrical angle of 90°, B/2 = 90, and δ ₁ = δ ₂ or δ ₁ −
If δ ₂ =0 is solved for A, a value of A/2≒39.26° is obtained. As a result, the upper base A of the lower base B
The value of the ratio B/A is: B/A=B/2/A/2≒90/39.26≒22
.9, and in this case, δ ₁ (= δ ₂ = δ ₃ = δ ₄ ) is
It becomes 0.0267 radian (1.53°).

Therefore, if a crossed coil type instrument is driven with a drive signal that changes AC with an isosceles trapezoidal wave characteristic in which the ratio of the lower base to the upper base is approximately 2.29, the linearity of the finger strength can be maximized. It has the effect of

As described above, the present invention includes a pair of coils 1 and 2 arranged so that the directions of magnetic field generation are orthogonal to each other, and a movable magnet arranged so as to be rotatable so as to follow the direction in which the magnetic fields are synthesized by the pair of coils. In the driving method for driving a crossed coil type instrument having 3 and 3, the isosceles trapezoidal wave characteristic has a phase difference corresponding to 90 degrees in electrical angle and the ratio of the lower base to the upper base is approximately 2.29. This method of driving a crossed coil type instrument is characterized in that two-phase drive signals 6a and 7a that change at This has the effect of improving the linearity of the finger index.

Furthermore, since the drive signal according to the present invention is a trapezoidal wave, there is an advantage that the circuit configuration of the signal generating circuit is simpler than that for a sine wave output signal.

[Brief explanation of the drawing]

The drawings all show embodiments of the present invention; FIG. 1 is a schematic configuration diagram of a cross-coil meter, FIG. 2 is a drive signal waveform diagram thereof, and FIGS. 3 a and b are driving diagrams for explaining the same. They are a signal waveform diagram and a finger index characteristic diagram. 1, 2... Coil, 3... Movable magnet, 4... Pointer shaft, 5... Pointer, 6, 7... Drive signal generation circuit.

Claims (1)

[Claims] 1. A cross coil having a pair of coils 1 and 2 arranged so that the magnetic field generation directions are orthogonal to each other, and a movable magnet 3 arranged so as to be rotatable so as to follow the direction in which the magnetic fields are combined by the pair of coils. In the driving method for driving type instruments, the two have a phase difference corresponding to 90 degrees in electrical angle, and the ratio of the lower base to the upper base changes with isosceles trapezoidal wave characteristics of approximately 2.29.
The phase drive signals 6a, 7a are transmitted to the pair of coils 1,
2. A method for driving a cross-coil type instrument, characterized in that: