JPH07151787A - Crossed coil instrument - Google Patents

Abstract

PURPOSE:To improve the indicating characteristic of the pointer of a cross coil type gauge by constituting the pointer so that it can make zero returning operations and correcting the indication error of the pointer due to the zero returning operations. CONSTITUTION:A zero returning member 13 made of a metallic magnetic material is provided at a location close to the outer peripheral magnetic pole of a rotary magnet 7 at the center of the crossing angle of the cross coils 5 and 6 of a cross coil type gauge and, at the same time, an error angle (a) caused by the member 13 is corrected by supplying driving signals to the coils 5 and 6 based on correcting formulae, sin(theta+a) and cos(theta-a).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses sin depending on measured values.
A cross-coil type instrument for rotating a pointer in response to a rotating magnet by a composite magnetic field of a cross-coil based on a drive signal that changes depending on the wave characteristics and cos wave characteristics, and particularly to zero return to the rotation base point of the pointer. This relates to error correction.

[0002]

2. Description of the Related Art Conventionally, a cross-coil type instrument of this type is
Since it has a simple structure and can be made lightweight and compact, it is used in various measuring instruments, for example, it is applied to a speedometer or the like for automobiles that requires wide-angle indicating characteristics. In particular, as a drive signal for obtaining such a wide angle indicating characteristic, it has become common to use a voltage (current) signal having sin wave characteristics and cos wave characteristics corresponding to an electrical angle in the crossing coil. Conversion by the ROM data according to the input signal corresponding to the value and the corresponding analog signal or P of the duty ratio
Energization of the coil is controlled by conversion into a WM signal.

Further, in such an instrument, it is necessary to return the pointer to the zero position of the scale, which is the indication base point, when the power is turned off, and to maintain the zero position of the pointer. However, since a return torque to the movable body is always applied by such a return means, a method of energizing the correction signal in addition to the original instruction characteristic signal to the cross coil is adopted. ing.

For example, in the cross-coil type instrument disclosed in Japanese Patent Application Laid-Open No. 2-90063, in order to correct the influence of the zero-reset magnet, a characteristic is given to the energizing signal to the cross-coil to cancel the magnetic field of the zero-reset magnet. Has been proposed, the sin wave characteristic to the cross coil,
This has the effect of making the pointer rotation instruction characteristic based on the cosine wave characteristic more linear.

[0005]

However, in the structure using the zero-reset magnet, the magnetic attraction of the zero-reset magnet is always exerted on the magnetic pole of the rotating magnet fixed to the pointer shaft regardless of the rotational position thereof. Since the crossing coil has a complicated influence on the synthetic magnetic field and its acting force is strong, it is difficult to set the correction signal characteristic and the additional energization amount for correction becomes large, resulting in waste of driving power.

Further, since the size and shape of the zero-reset magnet itself cannot be complicated, it is not easy to adjust the magnetic characteristics for obtaining the zero-reset force, and it is also difficult to form a weaker magnetism magnet itself. In order to obtain the indicated characteristics, a large drive that overcomes the influence torque of the zero-reset magnet,
A large amount of electricity is required to give a stopping torque, resulting in significant power consumption.

Further, since the influence of the magnetic field by the zero-reset magnet is complicated, in order to correct this, a ROM system (for example, corresponding to the input value, which stores the instruction data and is PWM-driven by the data output corresponding to the input value) Did sin,
In the case of storing the cos data), the data in all the designated areas must be corrected, and the ROM capacity is required to store the corresponding data in all areas. Conversion to (90
It becomes impossible to reduce the memory capacity such as phase shift conversion).

According to the present invention, in the ROM data system, R
An object of the present invention is to perform zeroing of a cross-coil type instrument without increasing the OM capacity or setting complicated correction data, and without performing complicated waveform shaping even in an analog conversion method.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a drive signal having sin wave characteristics and cos wave characteristics is supplied to a crossing coil, and the crossing coil is set at a midpoint of the crossing angle to approach the outer magnetic poles of a rotating magnet. Then, a zeroing member made of a magnetic metal material is provided, and the energization signal characteristic to the crossing coil is determined by the voltage applied to each coil with respect to the error angle a by the zeroing member.
When sin and Vcos are used, Vsin = Asin (θ + a), Vcos = Acos (θ−a) where A is a voltage constant θ that determines the peak voltage is an electrical angle. It is characterized by

[0010]

[Function] The magnetic field of the rotating magnet is not influenced by the metallic magnetic material, and the influence of the magnetic attraction of the rotating magnet on the indicating characteristic is corrected by the energizing signal by the simple angle correction to the crossing coil, and the sin wave is generated. Characteristics and co
A good indication of linearity due to the s-wave characteristic can be obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a circuit configuration of a cross coil type instrument according to the present invention, in which the energization signal characteristic to the cross coil is preset as ROM data, as shown in FIG. It will be described together with the instrument main body structure.

If it is adopted as a vehicle speedometer, a pulse signal having a frequency proportional to the traveling speed output from the speed sensor is shaped into a rectangular wave by the waveform shaping circuit 1 and input to the counter 2. The digitization of the traveling speed information by the counter 2 may be performed by an input pulse counting method for each gate period or a periodic method for counting other clock signals by the input pulse period. It is output from the counter 2 and given to the ROM 3.

Sine wave characteristic (cos wave characteristic) data is stored in advance in the ROM 3 at a resolution in units of angles obtained by dividing 360 degrees into 256, and a data read signal according to an address command of a storage area of each angle data is stored. Is used as the traveling speed data from the counter 2 at that time. Here, in order to generate a drive signal with sin wave characteristics and cos wave characteristics, sine wave data for 90 degrees, which is the minimum required, is stored, and signals of 90 degrees or more and COS wave characteristic signals are stored. Is generated by
It is assumed that the sine wave data for 90 degrees is inverted or phase-shifted, and the ROM 3 determines the indicated angle range by the input signal from the counter 2 and determines the sine wave and cos corresponding to the corresponding indicated angle. It shall have a function of expanding and converting data into wave instruction data. Such processing can be performed by data calculation processing by a microcomputer including the counter 2 and the ROM 3.

A drive signal having sin wave characteristics and cos wave characteristics is applied to the crossing coils 5 and 6 by the drive circuit 4 based on the instruction data output from the ROM 3. The drive signal is output from the ROM 3. Digital instruction data is D /
Although it may be an A-converted analog signal, here, a duty ratio corresponding to the size of the data (si as an effective value is
The crossing coils 5 and 6 are energized as a PWM signal having n-wave and cos-wave characteristics.

The rotary magnet 7 pivotally supported in the resin bobbin case 10 is rotated by a synthetic magnetic field corresponding to the signal characteristics of the crossing coils 5 and 6, and the scale is fixed by the pointer 8 fixed to the rotary shaft 9. It is possible to read in contrast with the dial 11. In addition, a stopper pin that defines the return stop position of the pointer 8 is provided at the indication base point (zero position on the scale) of the dial 11.
A bobbin case 10 is provided with a zeroing member 13 which is made of a metallic magnetic material and is arranged close to the outer peripheral magnetic poles of the rotating magnet 7.

The zero-reset member 13 may be formed of a magnetic material such as iron, permalloy, or a silicon steel plate in a predetermined shape.
By using permalloy, it is possible to prevent the hysteresis of the indication due to the residual magnetism, but if you do not think about the effect in particular, it is possible to give the function sufficiently with an inexpensive iron piece, According to this, it was found that good characteristics were obtained by the iron piece, and the balance between the zero-return force and the error correction could be easily adjusted by adjusting the thickness, and the characteristics could be easily obtained.

FIG. 3 is an explanatory view showing the positional relationship between the crossing coils 5 and 6 and the zero-return member 13. The crossing coils 5 and 6 are close to the outer magnetic poles of the rotating magnet 7 at the midpoint of the crossing angle. The zeroing member 13 is arranged at the position. The position of the pointer 8 is
Stopper pin 12 at the zero point position on the scale as the indication base point
It is stopped by this, and in this state, the stopper pin 12 is contacted and restrained by the attraction force of the rotary magnet 7 against the zero-reset member 13.

FIG. 4 shows the correction characteristic of the cross-coil type instrument according to the present invention. The error angle and the correction principle in relation to each element of FIG. 3 are explained, and experimentally almost the same. The correction effect was obtained. FIG. 7A shows the relationship of the instruction error angle exerted by the zeroing member 13 at the rotational position of the rotary magnet 7, which corresponds to the original linear instruction when the waveform correction of the present invention is not applied. The error angle variation is shown for each 45 degree electrical angle.

In FIG. 1A, the relationship between the attraction force between the rotary magnet 7 and the zero-return member 13 is shown in the positive and negative directions with respect to the indicator characteristic of the instrument. It is described as a characteristic diagram in which the variation state of the instruction error angle when the drive signals of Asin and Acos θ are energized is set to the maximum degree a. That is, in the positional relationship of the outer magnetic poles N and S of the rotating magnet 7 with respect to the zeroing member 13, when the pointing reference point position of the pointer 8 shown in FIG. 3 is 0 degree, the N pole is close to the zeroing member 13. Therefore, the rotating magnet 7
Is sucked in the negative direction, and this suction force affects the indication as the magnitude of the error.

At the 90-degree position, since the S pole is close to the zero-return member 13, the rotary magnet 7 is attracted in the positive direction, and this attraction force causes a positive indication error. 45 degrees
When the N pole and the S pole are in the same attraction direction with respect to the zero-return member 13 like 135 degrees, the rotational force by the zero-return member 13 of the rotary magnet 7 at that position is not applied. It becomes zero.

Since the error angle characteristic in such a positional relationship is shown by the characteristic line shown in FIG. 9A, the sin wave characteristic and the sin wave characteristic are obtained for the crossing coils 5 and 6 of the instrument having such an error factor. Even if a drive signal having a cosine wave characteristic is given, this error component is added to the original linear instruction characteristic, and as a result, a similar error angle occurs at each instruction angle.

However, the effect of the zero-reduction member 13 made of a magnetic metal material shown in FIG. 4A is extremely simple as compared with the case where a magnet is used as the zero-reduction member, and the correction is complicated. It is possible without cost.
In the present invention, by using a metal magnetic material as the zero-reduction member, the error component is corrected by the drive signal while performing the zero-reduction function with the above-mentioned simple error. Is the sin wave characteristic or c
In the signal processing for generating the drive signal having the os wave characteristic, only the phase of the characteristic is changed, and as a result, a linear indicating characteristic is obtained.

One implementation method is the ROM 3 of FIG.
Can be performed by generating wide-angle sine wave data and cos wave data based on data obtained by adding an error angle a degree to the sine wave data for 90 degrees stored in FIG.
That is, in the circuit of FIG. 1, the digital output of the counter 2 is made to correspond to the electrical angle θ, this electrical angle θ is made to correspond to the memory address of the ROM 3, and the sin data of 90 degrees is stored at the corresponding address of the ROM 3. By doing so, an output signal having sin characteristics corresponding to the input can be obtained. As for the resolution, it is possible to give a smooth instruction without needle shake by having the characteristic data obtained by dividing 90 degrees into 256 equal parts. Further, the data expansion for the entire designated angle by the data for 90 degrees is performed by determining which quadrant the input value corresponds to based on the data of the first quadrant, and based on the angle of the corresponding quadrant of the ROM3. By configuring the input stage circuit to specify the data address corresponding to sin or cos of the quadrant angle, the data of the entire designated angle can be output from the ROM 3. Therefore, the error angle characteristic of FIG.
Since it is a simple one having the same positive / negative characteristic variation in the 90 degree cycle, it is possible to expand to other angles and cos waves by correcting the error of 90 degrees. Of course, it is possible to store all the correction data corresponding to the input values in the ROM 3 in advance, and only the basic data R
It is also possible to employ a method in which the data is stored in the OM3 and correction (variation due to phase shift) is added to the data by arithmetic processing.

In order to generate such sin wave and cos wave signals, the command deflection angle is determined by setting the minimum value and the maximum value of the electrical angle with respect to the input value. For example, a correction to obtain the signal characteristic as the maximum angle of 360 degrees. The formula is described below.
Energization signal voltages to the crossing coils 5 and 6 are set to Vsin and Vco, respectively.
s, and the voltage constant that determines the signal peak voltage is A,
When the corrected pointing angle characteristic θa based on the electrical angle θ is obtained, θa = arctan (Asin (θ + a) / Acos (θ−a)), and the error angle Δθ with respect to the electrical angle θ at which the original pointing characteristic is obtained. Is Δθ = θa−θ.

As a result, this Δθ becomes an output angle error of the circuit, which is shown in FIG.
The error angle characteristics shown in (A) are almost opposite to each other, and these characteristics are canceled each other to give a rotation instruction with the original linear characteristics.

Since the correction in the present invention is achieved based on the above-mentioned extremely simple formula, the specific correction can be simply performed without complicating the processing circuit and without complicating the program as the arithmetic correction. All you have to do is add the corners to the data, and the correction waveforms will be sin and co
Basically 90 waveforms can be developed as ROM data because it is necessary to simply phase-shift only the correction angle for both s waves.
Since only the sin wave data for the frequency need be stored, it is not necessary to increase the memory capacity even when the ROM is used and the capacity is limited.

That is, the finger pointing error characteristic by the zeroing member 13 in the present invention is determined by the simple attraction force due to the use of the metallic magnetic material and the setting of the positional relationship between the crossing coils 5 and 6.
In addition to being simple, by giving a circuit error of an inverse characteristic that cancels out this error characteristic by the correction equation, it is possible to obtain a correction characteristic approximated by a very simple correction process, and as a result, a zero-reset member. 13 makes it possible to perform the zero-removing operation of the pointer 8 and reduce the finger pointing error due to this.

Therefore, when the drive signals of Vsin = Asinθ and Vcos = Acosθ are supplied without correction to the crossing coils 5 and 6, the error angle a at each indicated angle by the zeroing member 13
By measuring the error characteristics including (a is the maximum error angle) and performing the correction processing based on the above-described correction formula based on the determination of the error angle a, the error can be suppressed to a small level, and especially the zeroing member 13 If the size of the error angle a is made small by selecting and setting the voltage constant A so that a sufficient indicating torque as an instrument can be obtained, the effect of the correction based on the correction formula becomes large and the indicating characteristic with a smaller error is obtained. Can be obtained.

Regarding the correction formula of the present invention, the correction principle can be explained with reference to the characteristic diagram of FIG. That is, the zero-return member at the time of driving the sin wave and the cos wave with the voltage constant A
With respect to the error angle characteristic B by 13, the normal sin wave S and co
In order to correct the error angle characteristic by the s-wave C, in order to correct the error of −a degree at 0 degree, it is sufficient to electrically give the opposite error of + a degree. The phase of the waveform is shifted so that it is generated at 0 degree. That is, in order to correct the error of −a degrees at 0 degrees, the value of the sin wave S having a large change rate with respect to the electrical angle θ may be shifted by a degrees at 0 degrees to generate an equivalent error amount. In addition, in order to correct the + a degree error at 90 degrees, co
By shifting the value of the s wave C by 90 degrees plus 90 degrees, an equivalent error can be generated.
Since the error angle characteristic in the magnetic field generated by the phase shift of the cos wave by a degree can be represented by the characteristic line C in FIG. 4C, the ideal characteristic line for canceling the error due to the influence of the zero-reset member 13 is shown. It can be seen that this is close to B and good correction can be performed.

FIG. 4 shows that such an approximate correction is possible.
In the characteristic diagram of (B), sin wave S and cos wave C
The change rate for each electrical angle due to the phase cyst is almost zero near the peak value of the waveform and can be neglected, and near 0 value, the inclination angle is close to 45 degrees and is close to the shift angle due to the electrical angle shift. This is because the value appears in the indicated angle, and the present invention simplifies the error characteristic by using the metallic magnetic material of the zeroing member 13 and selecting the installation position for the crossing coils 5 and 6, and also provides an approximate characteristic that cancels this error characteristic. By performing a correction process based on the obtained correction formula,
It is possible to provide a highly practical correction method.

[0031]

As described above, according to the present invention, a metallic magnetic material is used as a zeroing member for a rotating magnet, and the zeroing member is arranged at the midpoint of the crossing angle of the crossing coil and a drive for energizing the crossing coil. As a signal, sin (θ + a) and cos with respect to the error angle a due to the zeroing member
By performing the correction process based on the correction formula of (θ-a), the error characteristic due to the zero-reset member can be simplified, and the excellent error correction can be performed by the extremely simple correction process. It is possible to improve the indicating characteristic with the pointer zero-returning operation of the instrument without causing an increase in the size and the data memory capacity and without complicating the arithmetic processing.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of a drive circuit configuration of a cross coil type instrument of the present invention.

FIG. 2 is a cross-sectional view showing an embodiment of the cross-coil type instrument main body of the present invention.

FIG. 3 is a positional relationship diagram between a crossing coil and a zero-return member in the crossing coil type instrument of the present invention.

FIG. 4 is an explanatory diagram of an error characteristic and a correction characteristic in the cross coil type instrument of the present invention.

[Explanation of symbols]

 2 counter 3 ROM 4 drive circuit 5, 6 crossing coil 7 rotating magnet 8 pointer 10 bobbin case 11 dial plate 13 zero return member made of metallic magnetic material

Claims (1)

[Claims] 1. A rotating magnet rotatably supported in a bobbin case, a coil wound so as to cross the outside of the bobbin case, a pointer fixed to a rotation output shaft of the rotating magnet, and a lower portion of the pointer. And a dial with an indicator scale and the cross-wound coil with sin wave characteristics and c
A drive circuit for supplying a drive signal having an os wave characteristic, and a zero-reduction member made of a magnetic metal material which is disposed close to the outer periphery having the magnetic poles of the rotating magnet at the intersection midpoint of the coil. When the voltage applied to each coil is Vsin and Vcos with respect to the error angle a due to the zeroing member, Vsin = Asin (θ + a), Vcos = Acos (θ-a) where A is a voltage constant θ that determines the peak voltage and the electrical angle is an electrical angle. A cross-coil type instrument characterized by: