JPH0778508B2 - Meter drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a meter driving device, and more particularly to a meter for driving a cross coil meter which gives a desired angular direction by a magnetic field generated by energizing two coils orthogonal to each other. A drive device.

[Prior Art] Conventionally, two exciting coils orthogonal to each other are made to generate a magnetic field by lengthening a current according to an input amount, and a torque is applied to a magnet rotatably supported by the magnetic field to obtain a desired angular direction. A cross coil meter for instructing is known and is used for a speedometer, a tachometer, a fuel gauge, a hydraulic gauge, etc. of an automobile or the like.

[Related Art] FIGS. 2 and 3 show schematic configuration diagrams of a cross coil meter recognized by the inventors as related art. Two exciting coils L _{S and}
L _C generates a magnetic field in a desired angular orientation by being supplied with a pulse current according to an input amount such as speed. The rotatably supported permanent magnet M receives torque due to the magnetic fields generated by the two exciting coils L _S and L _C. Then, the indicator needle fixed to the permanent magnet M is at the reference position so as to indicate the predetermined position of the meter indicating plate on which the physical quantity (speed in FIG. 3) to be measured is displayed as shown in FIG. It rotates by θ and shows an instruction value according to the input amount.

A meter drive device for driving these cross-coil meters used for speedometers and fuel gauges of automobiles, etc. generally has the following configuration. That is,
A pulse signal whose frequency changes according to an input amount, for example, speed, is input, while a reference clock signal generated by a reference clock generating means is also input, and one cycle of the pulse signal is counted by the pulse of this reference clock signal. To calculate the frequency.

Then, a current corresponding to the calculated frequency is pulse-width modulated (PWM) and passed through the orthogonal coils L _S and L _C. A current corresponding to the frequency of the input pulse signal is applied to the coil L _S ,
In order to flow to L _C , the meter deflection angle θ for some input value values S is determined in advance, and these values (S, θ)
Is stored in an E ² PROM which is a ROM that can be electrically erased and written. For example, as shown in FIG. 4 (a), the meter deflection angles θ ₁ , θ ₂ , θ ₃ , θ ₄ corresponding to the _four input amount values S ₁ , S ₂ , S ₃ , S ₄ are stored in the E ² PROM. Remember. Then, when the meter deflection angle θ corresponding to the input amount value S to be metered is calculated, the above parameters are read from this E ² PROM and θ = θ _n + (θ _{n + 1} −θ _n ) / ( S _{n + 1} −S _n ) ・ (S−
S _n ) (1) However, N = 1, 2, 3, 4 is calculated according to the equation, and a predetermined calculation process is performed according to the calculated θ, and a current is passed.

In this way, the meter deflection angle θ for the predetermined input amount S is stored in the electrically erasable E ² PROM, and the meter deflection angle θ corresponding to the input amount to be metered is calculated according to the stored contents. With the configuration, it is possible to drive various meters with one meter driving device. That is, when driving a meter such as an automobile,
Different driving methods are required because the meter indicating method differs depending on the type of vehicle installed, but electrically erasable and writable
By appropriately rewriting the contents (S, θ) stored in the E ² PROM which is the ROM, it is possible to provide versatility that can be easily dealt with.

[Problems to be Solved by the Invention] However, in the conventional meter driving device, the calculation program is complicated because the meter deflection angle θ according to the input amount S is calculated according to the above-mentioned formula (1). There was a problem of becoming. That is, the meter deflection angle θ
The calculation includes a division operation (θ _{n + 1} −θ _n ) / (S _{n + 1} −S _n ), as shown in the equation (1). Since it has to be incorporated in the IC, the number of instruction ROMs has increased and the processing steps have been complicated.

The present invention has been made in view of the above-mentioned conventional problems, and its object is to have a versatility similar to the conventional one, while simplifying the processing steps, and capable of reliably performing a meter instruction according to an input amount. To provide a device.

[Means for Solving the Problems] In order to achieve the above object, the meter driving device of the present invention includes a clock signal generating means for generating a reference clock signal and a frequency of a pulse signal according to an input amount for generating the clock. Frequency calculation means for calculating by counting the reference clock signal from the means, a plurality of predetermined input amount values and a meter deflection angle for performing a meter instruction corresponding to the plurality of predetermined input amount values, and A non-volatile memory that stores, as a parameter, a coefficient that gives a change in a meter deflection angle corresponding to a change between two adjacent input amount values of a plurality of predetermined input amount values, a frequency calculated by the frequency calculating means, and the A deflection angle calculation means for outputting a meter deflection angle signal according to an input amount based on the parameters read from the memory, and the deflection angle calculation Drive means for energizing the first and second exciting coils which are orthogonal to each other based on a signal from the means, and a magnetic field generated by the first and second exciting coils excited by the driving means to receive torque and input amount It is characterized in that it has an instructing means for indicating a deflection angle according to.

[Operation] The meter driving device of the present invention has the above-mentioned configuration, and calculates the frequency of the input pulse signal by counting the number of reference clock pulses from the reference clock generating means. Then, when the meter deflection angle θ corresponding to the calculated frequency (denoted as S _IN ) is calculated, it is shown in FIG. 4 (b) instead of the conventional calculation processing including division. A plurality of input quantity values S _m (m = 1, 2, ...) Predetermined as described _above , the meter deflection angle θ _m corresponding to this S _m , and two adjacent input quantity values S _m , S of the input quantity values. _{m + 1}
Of the meter deflection angles θ _m and θ _{m + 1} , that is, three types of parameters, ie, the slope R _m of the meter deflection angle θ, are stored in advance in a non-volatile memory. And
In order to calculate the meter deflection angle θ according to the input amount, the parameters are read from this non-volatile memory and calculated according to the following equation: θ = θ _m + R _m · (S _IN −S _m ) ... (2)

Then, the drive unit causes the current corresponding to the meter deflection angle thus calculated to flow through the first and second exciting coils which are orthogonal to each other, and gives an angular azimuth according to the input amount.

In this way, by storing the inclination of the meter deflection angle θ obtained in advance in the non-volatile memory, it is possible to calculate the meter deflection angle θ according to the input amount without performing division. Becomes

[Embodiment] A preferred embodiment of a meter driving device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration block diagram of this embodiment. Generally, the speed sensor rotation speed sensor outputs a digital signal having a pulse number proportional to the speed or rotation speed, while the water temperature sensor or the fuel sensor outputs an analog signal according to the water temperature or the fuel amount. In this embodiment, in order to deal with the case where the signal sent from the sensor is digital and analog,
It has two signal processing systems. That is, when the input signal is an analog signal, it is input to the control CPU 12 that controls the system by converting the analog amount into an 8-bit binary by the A / D converter 10, while the input signal is a pulse. Is input to the cycle detection circuit 14.

The cycle detection circuit 14 is a circuit for detecting the cycle T of the pulse signal by inputting the reference clock signal from the reference clock generator 16, and within the time from the rise or fall of the input pulse signal to the next rise or fall. In other words, counting the number of pulses of the reference clock signal within one cycle
Latch to a 21-bit binary counter. Then, the value latched by the counter, that is, the cycle T is output to the arithmetic processing block 18 which performs various arithmetic processing. In this embodiment, the reference clock generator 16 and the surrounding detection circuit
A frequency divider 20 is provided between the reference clock signal generator 14 and the frequency divider 14 so that the frequency (2 MHz) of the reference clock signal from the reference clock generator 16 can be divided at an appropriate frequency division ratio according to the input signal by the command from the control CPU 12 Has become.

Now, the analog signal that has passed through the A / D converter 10 and the control CPU or the pulse signal that has passed through the cycle detection circuit 14 is input to the arithmetic processing block 18, and frequency calculation, sin calculation, cos calculation, deflection angle θ calculation, etc. Various kinds of arithmetic processing are performed. At this time, the control CPU 12 reads the parameters stored in advance in the electrically erasable and writable E ² PROM 22, and supplies the read parameters to the calculation processing block to perform the calculation processing.

Here, a characteristic of the present embodiment is that a plurality of predetermined input amount values S _m (m = 1, 2, ...) Predetermined in the E ² PROM 22 in which each parameter required for the arithmetic processing is stored. it is that two adjacent input quantity value S _m of the corresponding meter deflection angle theta _m and the input quantity value S _m, slope R _m meter deflection angle between S _{m + 1} is stored in. The inclination R _m depends on the jig etc. E ² PROM16
It can be calculated and stored when the parameters are stored in. As the input amount value S _m , if the meter to be driven is a meter that shows a linear change according to the input amount such as a speedometer or a tachometer, two points, that is, a start point and an end point may be selected. In the case of a meter whose meter deflection angle does not show a linear change with respect to the input amount, as shown in FIG. 4 (b), the required number of input amount values are set in addition to the start point and end point. It can be dealt with.

Since the parameters are stored in the E ² PROM 22 in such a format, when the arithmetic processing is performed in the arithmetic processing block 18, the input amount value S _m and the meter shake angle θ are input from the control CPU 12.
_{Since m and the} slope R _m are supplied, it is possible to calculate the meter deflection angle θ corresponding to the input signal S by the above equation (2) θ = θ _m + R _m · (S−S _m ).

Then, the calculated meter shake angle θ is calculated as sin and cos and output to the driving means 24.

The driving means 24 is two pulse width modulation circuits 24 for sin and cos for pulse width modulating the output signal from the arithmetic processing block 18.
a, a quadrant determiner 24b and an output driver 24c that directly drives the cross coils L _S , L _C , and the same number of cross coils as the number of cross coils to be driven are provided. It is excited by energizing to drive the meter. The quadrant determination unit 24b is a unit that determines the signs of sin and cos. For example, the first quadrant can be set as sin positive and cos positive, and the second quadrant can be set as sin positive and cos negative to determine the quadrant. .

Here, when the inclination R _m of the meter deflection angle, which is obtained in advance as in the present embodiment, is stored in the E ² PROM 22, this inclination is stored.
Since R _m is in a wide range, it is preferable to store it in a floating point system so as not to increase the storage capacity. For example, if the polarity S is 1 bit, the mantissa D is 10 bits, and the exponent m is 5 bits, and the total is 16 bits, then the gradient R is expressed as R = (− 1) ^S · D · 2 ^−m. As a result, a wide range of inclination R of −1023 ≦ R ≦ −102 × 2 ⁻³¹ 1023 × 2 ⁻³¹ ≦ R ≦ 1023 can be set with a small storage capacity.

[Effects of the Invention] As described above, the meter driving device of the present invention stores the inclination of the meter deflection angle calculated in advance in the non-volatile memory, and the input amount to be indicated by the meter based on the stored inclination. This is for calculating the deflection angle of the meter according to the above. It has the versatility to drive various meters and does not require a division program.
The number of parts such as ROM can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an embodiment of a meter driving device according to the present invention, FIGS. 2 and 3 are operation explanatory views for explaining the operation of a cross coil meter, and FIG. 4 is a conventional example and a book. It is a graph which shows the characteristic of the parameter in an Example. 10 …… A / D converter 12 …… Control CPU 16 …… Reference clock generator 18 …… Computation processing block 22 …… E ² PROM 24 …… Drive means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masakazu Kobayashi 2-1910 Nisshin-cho, Omiya-shi, Saitama Kanto Seiki Co., Ltd. (72) Masanori Narita 2-1910 Nisshin-cho, Omiya-shi, Saitama Kanto Seiki Co., Ltd. (56) References JP-A-1-149175 (JP, A)

Claims (1)

[Claims] 1. A clock signal generating means for generating a reference clock signal, and a frequency calculating means for calculating the frequency of a pulse signal according to an input amount by counting the reference clock signal from the clock generating means. Corresponding to a plurality of predetermined input amount values and a meter deflection angle for performing a meter instruction corresponding to the plurality of predetermined input amount values, and a change between two adjacent input amount values of the plurality of predetermined input amount values A non-volatile memory that stores, as a parameter, a coefficient that gives a change in the meter shake angle, and a meter shake angle signal according to the input amount based on the frequency calculated by the frequency calculation means and the parameter read from the memory. The deflection angle calculating means for outputting and the first and second exciting coils orthogonal to each other based on the signal from the deflection angle calculating means are passed. Drive means for energizing, and an instruction means for receiving a torque by a magnetic field generated by the first and second exciting coils excited by the drive means and for indicating a deflection angle according to an input amount. Meter drive device.