JP2947039B2 - Cross-coil instrument - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a cross-coil instrument that rotates a pointer by the action of a rotating magnet by a synthetic magnetic field of a cross coil based on a drive signal that changes in wave characteristics and cos wave characteristics. It relates to error correction.

[0002]

2. Description of the Related Art Conventionally, this type of cross-coil type instrument has been
Since it has a simple structure and can be reduced in weight and size, it is used for various instruments, and is applied to, for example, a speedometer or the like that requires a wide-angle indicating characteristic for automobiles. In particular, as a drive signal for obtaining such a wide-angle indicating characteristic, it is common to use a voltage (current) signal of a sine wave characteristic and a cosine wave characteristic corresponding to an electrical angle in a cross coil, and the measurement is performed. The conversion by ROM data according to the input signal corresponding to the value, the analog signal corresponding to this and the P of the duty ratio
The energization of the coil is controlled by conversion into a WM signal.

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

For example, in a cross-coil meter described in Japanese Patent Application Laid-Open No. 2-90063, a characteristic is given in which an energizing signal to the cross coil is given a canceling magnetic field with a magnetic field generated by the resetting magnet in order to correct the influence of the resetting magnet. Has been proposed to provide a sin wave characteristic to the cross coil,
This has the effect of making the rotation instruction characteristic of the pointer by the cosine wave characteristic more linear.

[0005]

However, in the configuration using the zero-return magnet, the repulsive action of the zero-return magnet always acts on the magnetic pole of the rotary magnet fixed to the pointer shaft regardless of its rotational position. Since the combined magnetic field generated by the crossing coil has a complicated effect and a strong acting force, it is difficult to set the correction signal characteristic, and the amount of additional power for correction increases, resulting in wasted driving power.

Further, since the size and shape of the zero-magnet itself cannot be complicated, it is not easy to adjust the magnetic properties for obtaining the zero-magnet force, and it is difficult to form a weak magnetic magnet itself. In order to obtain the indication characteristics, a large drive that overcomes the influence torque of the
A large amount of electricity is required to provide a stopping torque, and power consumption is remarkable.

Further, since the influence of the magnetic field due to the zero-magnet is complicated, in order to correct the influence, a ROM system (for example, corresponding to the input value) which stores the instruction data and performs the PWM drive by the data output corresponding to the input value. Did sin,
In the case of storing cos data), it is necessary to correct the data in all designated areas, and the ROM capacity is required for storing the corresponding data in all areas. Conversion to (90
(Phase shift conversion of degree), it is impossible to reduce the memory capacity.

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

[0009]

According to the present invention, a driving signal having a sine wave characteristic and a cosine wave characteristic is supplied to a cross coil, and a center point of the cross angle of the cross coil is approached to an outer magnetic pole of a rotating magnet. A return-to-zero member made of a metallic magnetic material is disposed, and the energization signal characteristics to the crossing coil are changed by applying the voltage to each coil to V with respect to the error angle a by the return-to-zero member.
When sin and Vcos are set, Vsin = Asin (θ + a) and Vcos = Acos (θ−a) where A is a voltage constant θ which determines a peak voltage and is an electrical angle. It is characterized by the following.

[0010]

[Function] There is no magnetic field effect on the rotating magnet due to the metallic magnetic material, and the influence on the indicating characteristic only by the attraction action by the magnetic force of the rotating magnet is corrected by the energization signal by simple angle correction to the cross coil, and the sine wave Properties and co
Good indication of linearity by s-wave characteristics can be obtained.

[0011]

FIG. 1 shows an embodiment of a circuit configuration in a cross-coil instrument according to the present invention. In this embodiment, the energization signal characteristic to a cross coil is set in advance as ROM data. It will be described together with the instrument main body structure.

If it is adopted as a vehicular speedometer, a pulse signal output from a speed sensor and having a frequency proportional to the traveling speed is shaped into a rectangular wave by a waveform shaping circuit 1 and input to a 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 cycle or a periodic method of counting other clock signals by the input pulse cycle. Output from the counter 2 is given to the ROM 3.

The ROM 3 previously stores sine wave characteristic (cos wave characteristic) data at a resolution of angle units 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 used as the running speed data from the counter 2. Here, in order to generate the drive signal with the sine wave characteristic and the cosine wave characteristic, sine wave data for at least 90 degrees, which is necessary at least, is stored, and a signal of 90 degrees or more and a COS wave characteristic signal are stored. The generation of
The sine wave data for 90 degrees is inverted or phase-shifted, and the ROM 3 determines the designated angle range by the input signal from the counter 2 and determines the sine wave and cos corresponding to the designated designated angle. It has a function of developing and converting the data into wave instruction data. Such processing can be performed by data arithmetic processing by a microcomputer including the counter 2 and the ROM 3.

A drive signal having a sine wave characteristic and a cosine wave characteristic is supplied to the crossing coils 5 and 6 by the drive circuit 4 based on the instruction data output from the ROM 3, and the drive signal is output from the ROM 3. D / D
The analog signal may be an A-converted analog signal, but here, a duty ratio (effective value: si
It is configured to energize the crossing coils 5 and 6 as a PWM signal having n-wave and cosine-wave characteristics).

The rotating magnet 7 pivotally supported in the resin bobbin case 10 is rotated by a composite magnetic field corresponding to the signal characteristics supplied to the cross coils 5 and 6, and the scale is set by the pointer 8 fixed to the rotating shaft 9. It is possible to read and compare with the dial 11 provided. Note that a stop pin for defining the return stop position of the pointer 8 is provided at the designated reference point (zero position on the scale) of the dial 11.
A return member 13 made of a metallic magnetic material is disposed at the mating portion of the bobbin case 10 so as to be close to the outer magnetic pole of the rotating magnet 7.

The return-to-zero member 13 may be formed in a predetermined shape from a magnetic material such as iron, permalloy, or silicon steel plate.
The use of permalloy can prevent the hysteresis of the indication due to the remanence, but if the effect is not particularly considered, it is possible to provide the function sufficiently with an inexpensive iron piece. According to the results, it was found that good characteristics were obtained by the iron piece, and the balance between the zero-force and the error correction could be easily adjusted by adjusting the thickness of the iron pieces, and the characteristics could be easily obtained.

FIG. 3 is an explanatory view showing the positional relationship between the cross coils 5 and 6 and the zero-return member 13. In FIG. The resetting member 13 is disposed at the position. The position of the pointer 8 is
Stopper pin 12 at the zero point on the scale as the reference base point
, And in this state, the stopper magnet 12 is brought into contact with and restricted to the stopper pin 12 by the attractive force of the rotating magnet 7 to the return-to-zero member 13.

FIG. 4 shows the correction characteristics of the cross-coil type meter according to the present invention. The error angle and the principle of correction in relation to each element in FIG. 3 are explained. A correction effect was obtained. FIG. 5A shows the relationship between the pointing error angle exerted by the return-to-zero member 13 at the turning position of the rotating magnet 7, and corresponds to the original linear command in the case where the waveform correction is not applied in the present invention. The error angle variation is shown for each electrical angle of 45 degrees.

In FIG. 1A, the relationship between the attractive force of the rotating magnet 7 and the return-to-zero member 13 is shown in the positive and negative directions with respect to the indicator characteristic of the meter. The variation diagram of the indicated error angle when the drive signals Asin and Acos θ are energized is described as a characteristic diagram in which the maximum degree is a degree. That is, in the positional relationship between the outer magnetic poles N and S poles of the rotating magnet 7 with respect to the return-to-zero member 13, when the pointing base point position of the pointer 8 shown in FIG. Therefore, the rotating magnet 7
Is sucked in the negative direction, and this suction force affects the instruction as the magnitude of the error.

At the 90-degree position, the south pole is close to the resetting member 13 so that the rotating magnet 7 is attracted in the positive direction, and this attractive force causes a positive indication error to appear. 45 degrees
When the north pole and the south pole are in the same suction direction with respect to the resetting member 13 such as at 135 degrees, no rotational force is applied by the resetting member 13 of the rotating magnet 7 at that position. It becomes zero.

The error angle characteristic in such a positional relationship is shown as a characteristic line shown in FIG. 3A, so that the sine wave characteristic and Even if a drive signal having the cosine wave characteristic is given, this error 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 return-to-zero member 13 made of a metallic magnetic material shown in FIG. 4A is extremely simple compared to the case where a magnet is used as the return-to-zero member, so that the correction thereof is also complicated. It is possible without the need.
In the present invention, while using a metallic magnetic material as the resetting member to perform the resetting function with a simple error as described above, the error is corrected by the drive signal, and basically Is the sin wave characteristic or c
In signal processing for generating a drive signal having the os-wave characteristic, the characteristic is changed only in phase, and as a result, a linear instruction characteristic is obtained.

As one implementation method, the ROM 3 shown in FIG.
, And generates wide-angle sine wave data and cos wave data based on data obtained by adding the error angle a degrees in advance to the 90-degree sine wave data stored in the sine wave data.
That is, in the circuit of FIG. 1, the digital output of the counter 2 is made to correspond to the electrical angle θ, and the electrical angle θ is made to correspond to the memory address of the ROM 3, and the sin data for 90 degrees is stored in the corresponding address of the ROM 3. By doing so, an output signal having a sine characteristic corresponding to the input can be obtained. As for the resolution, by giving characteristic data obtained by dividing 90 degrees into 256 equal parts, it is possible to give a smooth instruction without needle deflection. In addition, the data expansion to the entire designated angle range by the data of 90 degrees determines the input quadrant to which quadrant based on the data of the first quadrant, and stores the data in the ROM 3 based on the angle of the corresponding quadrant. By configuring the input stage circuit to specify a data address corresponding to sin or cos of the quadrant angle, 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 fluctuation in a 90-degree cycle, it is possible to expand to other angles and cos waves by correcting the error of this 90-degree. Of course, a method may be used in which all the correction data corresponding to the input values are stored in the ROM 3 in advance.
It is also possible to adopt a method of storing the data in the OM 3 and applying correction (fluctuation due to a phase shift) to the data by arithmetic processing.

In generating such a sine wave signal and a cosine wave signal, an instruction deflection angle is determined by setting a minimum value and a maximum value of an electrical angle with respect to an input value. The formula is described below.
The energization signal voltages to the crossing coils 5 and 6 are Vsin and Vco, respectively.
s, and the voltage constant for determining the signal peak voltage is A,
When the corrected instruction angle characteristic θa based on the electrical angle θ is obtained, θa = arctan (A sin (θ + a) / Acos (θ-a)), and the error angle Δθ with respect to the electrical angle θ at which the original instruction characteristic is obtained. Is Δθ = θa−θ.

As a result, this Δθ becomes an error in the output angle of the circuit, and this is the error of the instrument body having the resetting member 13 as shown in FIG.
The characteristic becomes substantially opposite to the error angle characteristic shown in (A), and the rotational angle is canceled by each other, and the rotation instruction is performed with the original linear characteristic.

Since the correction in the present invention is achieved based on the above-mentioned very simple formula, the specific correction can be simply performed without complicating the processing circuit and without, for example, complicating the program as arithmetic correction. It is only necessary to add the angle to the data, and the correction waveform is also sin wave and co
Since it is only necessary to simply phase shift the s-wave by the correction angle, the waveform can be expanded as ROM data.
Only the sine wave data of the degree need be stored, and even if the capacity is limited by using the ROM, it is not necessary to increase the memory capacity.

That is, the fingering error characteristic of the return-to-zero member 13 in the present invention is determined by the simple attractive force by using the metallic magnetic material and the setting of the positional relationship between the cross coils 5 and 6.
In addition to simplifying the circuit, by giving the circuit error of the inverse characteristic to cancel the error characteristic by the correction equation, it is possible to obtain a correction characteristic approximated by a very simple correction processing. The function 13 allows the pointer 8 to perform a zero-return operation, thereby reducing the finger error.

Therefore, when a drive signal of Vsin = Asinθ and Vcos = Acosθ is supplied without correcting the crossing coils 5 and 6, the error angle a at each indicated angle by the resetting member 13 when the drive signal is supplied.
If an error characteristic including (a is the maximum error angle) is measured and a correction process based on the above-described correction formula is performed based on the determination of the error angle a, the error can be suppressed to a small value. If the magnitude of the error angle a is reduced so that a sufficient indicating torque as an instrument can be obtained by selection and setting of the voltage constant A, the effect of the correction based on the correction formula is greatly effective and the indicating characteristic with a smaller error is obtained. Can be obtained.

The principle of correction of the correction formula of the present invention can be explained with reference to the characteristic diagram of FIG. That is, the return-to-zero member at the time of driving the sine wave and the cosine wave with the voltage constant A
13, the normal sin wave S and co
As the correction of the error angle characteristic by the s-wave C, the error of -a degree at 0 degree can be corrected by electrically giving an opposite error of + a degree. The phase of the waveform is shifted so as to be generated at 0 degrees. That is, in order to correct the error of -a degree at 0 degree, the value of the sine wave S having a large rate of change with respect to the electrical angle θ is shifted by 0 degree at minus 0 degree to generate an equivalent error. And to correct the + a degree error at 90 degrees,
By shifting the value of the s-wave C by a degree plus at 90 degrees, an equivalent error can be generated.
Since the error angle characteristic in the generated magnetic field due to the phase shift of the a-degree of the cos wave can be represented by the characteristic line C in FIG. 4C, an ideal characteristic line for canceling the error due to the effect of the resetting member 13. It can be seen that the correction approximates to b, and good correction can be performed.

FIG. 4 shows that such an approximate correction is possible.
In the characteristic explanatory diagram of (B), a sine wave S and a cosine wave C
The change rate of each electrical angle due to the phase shift is almost negligible near the waveform peak value, and is close to the shift angle due to the electrical angle shift because the tilt angle is close to 45 degrees near the 0 value. In the present invention, the error characteristics can be simplified by using a metal magnetic material for the resetting member 13 and selecting the installation position with respect to the cross coils 5 and 6. By performing the correction process based on the obtained correction formula,
It is possible to provide a highly practical correction method.

[0031]

As described above, the present invention uses a metallic magnetic material as a return-to-zero member for a rotating magnet, arranges this return-to-zero member at the midpoint of the crossing angle of the crossing coil, and drives the crossing coil. As signals, sin (θ + a) and cos
By performing the correction process based on the correction formula of (θ-a), the error characteristics due to the zero-reset member can be simplified, and good error correction can be performed by an extremely simple correction process. It is possible to improve the indicator characteristics together with the zero return operation of the indicator without inducing the increase in the data memory capacity and without complicating the arithmetic processing.

[Brief description of the drawings]

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

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

FIG. 3 is a diagram showing a positional relationship between a cross coil and a resetting member in a cross coil meter according to the present invention.

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

[Explanation of symbols]

 2 Counter 3 ROM 4 Drive circuit 5, 6 Cross coil 7 Rotating magnet 8 Pointer 10 Bobbin case 11 Dial 13 Returning member made of metallic magnetic material

Claims (1)

(57) [Claims] 1. A rotary magnet rotatably supported in a bobbin case, a coil crossed outside the bobbin case, a pointer fixed to a rotary output shaft of the rotary magnet, and a lower part of the pointer. And a dial provided with an indication scale and a sine wave characteristic and c
a drive circuit that supplies a drive signal having an os-wave characteristic, and a return-zero member made of a metallic magnetic material disposed close to the outer periphery having the magnetic pole of the rotating magnet at the midpoint of the intersection angle of the coil. In addition to the configuration, when the voltage applied to each coil is Vsin, Vcos with respect to the error angle a due to the zero-return member, the characteristics of the energization signal from the drive circuit to the coil are given by: = A cos (θ-a) where A is a voltage constant θ that determines a peak voltage and an electrical angle. A cross-coil meter.