JPH0285764A - Meter drive device - Google Patents

Abstract

PURPOSE:To secure the excellent responsiveness of a meter and, at the same time, to cause the pointer of the meter to make natural oscillation by providing a switched state detecting means, elapsed time discriminating means, difference value calculating means, magnitude of difference value discriminating means, output value deciding means, etc. CONSTITUTION:When the period of input pulse signals is switched and the switched state is detected by means of a switched state detecting means, the difference value between the digital values calculated this time and last time is calculated by means of a difference value calculating means in response to either a switched state or elapse of prescribed time discriminated by an elapsed time discriminating means, whichever earlier. The difference value calculation is performed in response to the switched state at the time of high-speed operations and to a discriminated result of the elapsed time discriminated means at the time of low-speed operations. Then a magnitude of difference value discriminating means discriminates whether or not the absolute value of the difference value exceeds a prescribed value. When the absolute value exceeds the prescribed value, a prescribed value between the previous and current values is outputted. When the absolute value is smaller than the prescribed value, the current digital value is outputted as it is. Therefore, the pointer of a meter naturally oscillates without moving in the opposite direction.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a meter drive device used in tachometers, speedometers, etc. for automobiles.

(b) Conventional technology - II. As shown in Fig. 3, a speedometer for an automobile has a magnet for swinging the needle in a magnetic field formed by two orthogonal coils L, , Lc. A current is applied to the coils L, , Lc according to the input amount such as speed, and the magnet M is rotated to cause the needle to swing. The meter drive device in this type of speedometer inputs a pulse signal whose period changes depending on the input amount, that is, the speed, and also inputs a clock signal generated by a basic clock generator, Count the clock signal with a counter over the period, first find the period T of the pulse signal, and from this period T, calculate f = 1/T,
The frequency f was calculated. Since this digital data f is proportional to the input amount, a current corresponding to this digital value r is passed through the coils L, , LC, and the coils L, , L
The magnetic field generated by c causes a needle, which is a magnet, to swing to an angular direction determined by the digital value.

(c) Problems to be Solved by the Invention The conventional meter driving device described above calculates the period of a pulse signal that changes depending on the speed by counting clock signals, obtains the frequency, converts it into a digital signal, and converts it into a digital signal. sin , cos to specify the angular orientation according to
Since we are performing calculations, for example, if the human power suddenly changes from high speed to low speed, the frequency of the human power pulse signal will change from high frequency to low frequency and the period will become longer, so we will count one cycle of the clock signal. Previously, the problem was that the frequency after the change was not calculated, and the needle did not move until then, resulting in extremely poor response.

Also, according to the frequency, that is, digital data, sine and cosine calculations are performed, and a current corresponding to the input amount is passed through the orthogonal coils to cause the needle to swing. From /H, 25 KI
If you want to drastically change the instructions, move the needle to path A.
There was an inconvenience in that the vehicle did not try to head to 20 km/h, but instead tried to take Route B, heading in a direction that could not be followed by the instructions even though the speed was changing to a low speed.

This invention was made by focusing on the above-mentioned problems, and even if the amount of input decreases, the response speed does not slow down.
It is an object of the present invention to provide a meter drive device in which the movement of the instruction is natural.

(d) Means and operation for solving the problems The meter drive device of the present invention includes first and second coils that are orthogonal to each other, a means for inputting a pulse signal of a frequency corresponding to an input amount, and a lock. a signal generating means; a counting means for counting clock signals from the clock signal generating means;
calculation means for calculating a digital value proportional to the input amount based on the count value of the counting means;
a drive circuit that causes current to flow through the second coil; and a needle whose angular orientation is determined by a magnetic field generated by the current flowing through the first and second coils, and the value is proportional to the magnitude of the input amount. a switching detection means for detecting the switching of each period of the pulse signal; a time elapse determination means for determining whether a predetermined time has elapsed since the switching point; difference value calculation means for calculating the difference value between the current digital value and the previous digital value by the calculation means in response to the detection of the difference or the passage of time, whichever comes first; A difference value size determining means for determining whether the absolute value of the difference value is greater than or equal to a predetermined value, and a predetermined value between the current digital value and the previous digital value as the current output digital value. output value determining means for determining the currently calculated digital value as the output digital value when the absolute value of the difference value is smaller than a predetermined value; It is characteristically provided with a repetition control means for controlling each process of determining the output digital value to be repeated at predetermined time intervals.

In this meter drive device, the cycle of the input pulse signal switches, and when this switching is detected by the switching detection means, the switching is detected by the same switching detection means, or the period of time elapses. The difference value between the currently calculated digital value and the previously calculated digital value is calculated by the difference value calculation means in response to whether the predetermined time has elapsed by the determining means or whichever is earlier. If the input amount is relatively large, that is, if it is high speed, one cycle of the input pulse signal will arrive before a predetermined time elapses, so in this case, it will respond to the switching detection of the cycle switching detection means. Then, a difference value calculation is performed. On the other hand, if the input amount is smaller than the predetermined value, that is, if it is slow, the predetermined time will elapse before one cycle of the input pulse signal arrives, so in this case, the response will be responded to the determination output of the time elapse determination means. Then, a difference value calculation is performed. In this case, the current digital value is calculated based on the count value of the counting means that has not yet counted one cycle, so it is a digital value higher than the true frequency. In any case, once the difference value is calculated, the difference value size determining means then determines whether the absolute value of this difference value exceeds a predetermined value. If the absolute value of the difference value is smaller than the predetermined value, it is assumed that the change is small, and the current digital value is output as is. If the absolute value of the difference value exceeds the predetermined value, it is assumed that the change is large, and instead of suddenly outputting the current digital value and causing the needle to swing rapidly, the difference between the previous value and the current value is Output a predetermined value, for example, an intermediate value. Thereafter, at predetermined intervals, for example, each time, a digital value corresponding to the intermediate value between this time and the previous time is output, and the hand is made to swing one after another, and when the absolute value of the difference value becomes smaller than the predetermined value, the final Outputs the current digital value. This allows the needle to swing naturally without trying to move in the opposite direction.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 2 is a block diagram of a meter driving device showing one embodiment of the present invention. In the figure, the input signal circuit 1 is
A pulse signal generated in synchronization with the rotation of the wheels is input to the data calculation section 2. On the other hand, the reference clock signal generator 3
A clock signal from the data processing unit 2 is also input to the data calculation unit 2.

As shown in FIG. 1, the data calculation unit 2 includes a counter 20 that counts clock signals, and a rising detection circuit 21 that detects the rising edge (cycle switching) of an input pulse signal and generates a transfer signal and a reset signal. , a 10IIsec timer 22 that starts upon receiving a reset signal, this one
The flip-flop 23, which is set by the time-up output of the 0m5ec timer 22 and reset by the reset signal, receives the count value T from the counter 20 by the transfer signal from the rise detection circuit 21 or the 10m5ec timer 22, and calculates 1/T. The frequency calculation unit 24 performs calculation, that is, the frequency calculation, and the output of the frequency calculation unit 24 is “8, that is, the frequency f calculated this time to the frequency f calculated last time, −1
, a subtraction unit 25 that calculates the difference value f6, a memory 26 that stores the calculated difference value f4, a determination unit 27 that determines the set/reset state of the flip-flop 23 at the time when the difference value f4 is stored. When the determining unit 27 determines the set state of the flip-flop 23, the difference value f
.

is provided with a determining unit 28 that determines whether or not is greater than or equal to 0. When the determination unit 27 determines the reset state of the flip-flop 23, the determination process by the determination unit 28 is skipped.

In addition, when the determining unit 28 determines that fd>0, the data calculation unit 2 determines that there is definitely r i < r 4-t, and the determining unit 27 determines that Q=O (reset condition B).
), the absolute value of the difference value r4 is determined to be a predetermined (
A determining unit 29 determines whether or not it is greater than or equal to IK. If the determining unit 29 determines that K>lf and not 1, the difference value f,
is updated to 1/2 f, and when the determining unit 29 determines that K>lf, I, the difference value updating unit 3 skips the updating process.
o, an adder 31 that adds the difference value r4 and the previous frequency rt-+, a memory 32 that stores this added value f and outputs it as the current frequency f, in response to the output pulse of this memory 32, Equipped with 10m5ec Kuima 33 to start. When the 10m5ec timer 33 times up, the output of the memory 26 is re-derived.

Frequency data f! output from the memory 32 of the data calculation section 2! is 10-bit digital data, of which the upper two bits determine which quadrant one revolution is divided into four, and by these two bits, the quadrant determination unit 10 determines which of the four quadrants the needle to swing belongs to. A quadrant is determined, and the quadrant determination unit 1o outputs a direction signal determined by the determined quadrant.

The lower 8 bits are 01 to 90 in each quadrant.

These are the data corresponding to sine calculation unit 4 and c
are input to the os calculation unit 5, and are subjected to sine calculation and cos calculation, respectively.
The signals are calculated and input to a driver (drive circuit) 8.9 via a pulse width modulation circuit 6.7. The driver 8 sends a current having a value corresponding to the signal from the sine calculation section 4 and a polarity according to the direction signal to the coil L9, and the driver 9 sends a current having a value corresponding to the signal from the cos calculation section 5 and a current having a polarity according to the direction signal. A polar current is made to flow through the coil Le. Coil it.

When current flows through and Lc, a composite magnetic field is generated,
This composite magnetic field causes the needle to swing, indicating the angular direction according to the amount of input.

Next, the operation of the meter driving device of the above embodiment will be explained.

When a pulse signal corresponding to the rotation of the wheel is input from the input signal circuit 1, the rise detection section 21 detects the rise of the pulse signal, and first supplies a transfer signal to the counter 20, and then sends a reset signal. counter 20 and lom
It is input to the sec timer 22 and flip-flop 23. The counter 20 transfers the count value it had been counting to the frequency calculation unit 24 by the transfer signal, and is reset by the reset signal, and thereafter receives the clock signal from the reference clock generator 3 until the reset signal arrives. Count.

Also, by the reset signal by rising edge detection, lQms
The ec timer 22 is reset and started, and the flip-flop 23 is also reset. , lO...s
When the ec timer 22 times up, the flip-flop 23 is set by the time-up output, and a transfer signal is supplied to the counter 20. The counter 20 also outputs the contents counted up to that point to the frequency calculation section 24 in response to this transfer signal.

When the frequency of the human pulse signal is very high, that is, when one cycle is small, the rising edge is detected by the rising edge detection section 21, the counter 20 is reset, and the period from the transferred state until the next reset signal is input is is shorter than the time to time amplify the 10m5ec timer 22, so the output from the counter 20 is always based on the transfer command before resetting the counter 20, and therefore the output from the clock signal corresponding to one period of the pulse signal is The count value, that is, data T for one cycle is input to the frequency calculation section 24.

The frequency calculation unit 24 performs a calculation of 1/T to calculate the current frequency r, and inputs it to the subtraction unit 25. Subtraction section 25
is the previous frequency f! stored in the memory 32. -1
is received as the other input, the previous frequency f, -1 is subtracted from the current frequency ft, and the difference value f, is calculated. This difference value f4 is then stored in the memory 26.

Next, the determination unit 27 determines that the Q output of the flip-flop 23 is O.
Determine whether or not. Normally, when the frequency of the input pulse is high, the flip-flop 23 is in a reset state. Therefore, in this case, due to the output of Q=O, the discriminator 28 is skipped and the discriminator 29 determines the absolute value of the difference value f4. It is determined whether the value is smaller than a predetermined value.

Now, for example, if the needle deflection is relatively small, that is, the input signal frequency is low, but the needle deflects greatly, that is, the needle moves toward a higher frequency, and the deflection width suddenly increases. , the determination by the determination unit 29 is No. Subsequently, the difference value updating unit 30 calculates 1/2 of the difference value r, and the addition unit 31 adds a difference value of 1/2 to the previous frequency f, -1. The current frequency f is obtained by adding f4 corresponding to .

That is, the calculated frequency f, which corresponds to the intermediate value between the previous frequency and the current frequency, is stored in the memory 32, and this frequency rt is output to the sine calculation section 4, the cosine calculation section 5, and the quadrant determination section 10, respectively. do.

Then, according to the outputs of the sine calculation section 4, the cosine calculation section 5, and the quadrant determination section 10, a current flows through the driver 8 and the driver 9, and the current flows through the coil, and a magnetic field in a predetermined direction is generated. This allows the needle to swing to a point corresponding to the intermediate value between the previous deflection and the next target deflection.

On the other hand, in response to the output pulse outputted from the memory 32, the lQmsec timer 33 starts, and this time-up signal causes the difference value fd in the memory 26 to be derived again, and similarly, the discriminator 27 determines whether Q=O. The determining unit 29 determines whether the absolute value of the difference value fa is less than or equal to the absolute value of the difference value fa. In addition, the difference value ".

In the case of more than 50%, that is, the intermediate value and the target current value f,
If there is a large difference, in addition, 1/2 of the difference value
Find f and t, and add the difference value fa to the previous value of r2-5, that is, the intermediate value, to form a new f, and store this in the memory 32. It is output to the calculation section 4, cos calculation section 5, and quadrant determination section 10, respectively.

The above process is repeated every 10 m5ec, the intermediate value is set as the indicated target by 1/2, and the needle is smoothly brought closer to the target change value. Eventually, when the difference value r4 becomes smaller than K, the judgment of the discriminator 29 becomes YES, and in this case,
The process of the discriminator 30 that processes the difference value f4 by 1/2 is skipped, and the current value f1 is obtained by adding -1 to the difference value f, the previous value f, and this value is stored in the memory 32, and is directly stored in the final instruction memory. It will be output as

Next, when the cycle of the pulse signal input this time becomes very large, that is, the frequency becomes low, the time-up of the lQmsec timer 22 after reset is faster than the rise detection by the rise detection section 21, that is, the detection of one cycle. When the speed increases and the 10m5ec timer 22 times up, the flip-flop 23 is set and Q=1. on the other hand,
Since the transfer signal is output by the output of the LOmsec timer 22, even if the counter 20 has not yet counted one cycle of the clock signal, it assumes that the count value up to that point is the count value of one cycle, and calculates the frequency. The input is input to the calculation unit 24, frequency calculation is performed, the current frequency r positive of the virtual is calculated, and the subtraction unit 25 calculates the difference value f between the previous frequency and the current frequency.
4 is calculated and stored in the memory 26. After storing, the determining unit 27 determines whether or not the Q output of the flip-flop 23 is O. However, since the flip-flop 23 is set this time, an output of Q=1 is output, and the determining unit 28 determines whether the Q output is O or not. It is determined whether or not is greater than or equal to 0. If the difference value "4" is greater than or equal to 0, this means that the current frequency is greater than the previous frequency, and in this case, the needle is moving from 0 in the direction of large deflection. When performing frequency calculations using a count value that has not yet counted one cycle of the Nirunt value 20, a wave number that is apparently larger than the target frequency is calculated, so in this case, , the processing at frequency f4 is ignored, the process returns to the storage section of the memory 26, and the current processing is ignored.

However, for example, because the previous frequency was high and the input signal frequency became low, the flip-flop 23
is set, the current frequency f! The difference value f6 between and the previous frequency fi-1 is -. Therefore, the determination made by the determination unit 2 is NO, and then the determination unit 29 determines whether or not the absolute value of the difference value r4 is less than or equal to the absolute value. If the absolute value of the difference value f is very large, that is, if the frequency changes from a high frequency to a very low frequency, and if the runout of the needle is to be extremely small, then 1/2 of the difference value f4 is set as the new [d]. , this f4 is added to the previous frequency r, -1 and stored in the memory 32 as a new current frequency r. Note that in this case, since [4 is -, the new frequency r, is the previous frequency 1. If the frequency is lower than -1 (the frequency that is the intermediate value between the target frequency and the previous frequency is stored in the memory 32, and is also output to the sine calculation section 4, the cosage calculation section 5, and the quadrant determination section 10). Then, the current corresponding to the intermediate value is applied to the coil Li%Lc by the driver 8 and 9.
, and a magnetic field is generated so that the needle indicates an intermediate value between the deflection corresponding to the previous high frequency and the target low frequency indication.

At the same time as the output of this memory 32 is made, 10
The difference value fa in the memory 26 is derived at 10 m5ec intervals through the m5ec timer 33, and processed by the discriminator 27, the discriminator 28, and the discriminator 29, and the absolute value f is obtained.

is not smaller than the predetermined value, the difference value "4 is subjected to 1/2 arithmetic processing, and the deflection angle is gradually brought closer to the target deflection angle by 1/2.

(f) Effects of the Invention According to this invention, switching of each period of an input pulse signal is detected. It is equipped with an A detection means and a time elapse determination means for determining whether or not a predetermined time has elapsed since the switching point, and in response to the detection or determination output, whichever is earlier, the count value of the counter is changed. The system derives the frequency, calculates the frequency accordingly, and sends a current corresponding to the frequency to each driver to cause the needle to swing. Therefore, even if the frequency changes from a high frequency to an extremely low frequency, the counter will be 1.
Even if it is not possible to respond to the count value for the period, a temporary output is derived from the value counted up to that point, so responsiveness can be ensured, and even if the frequency changes extremely significantly. In this method, the output value does not immediately correspond to the target frequency, but is outputted sequentially so that the deviation is a predetermined value between the previous value and the current value, so a smooth and natural needle movement is achieved. It has the advantage of being able to obtain swing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the functional configuration of a data calculation section of a meter driving device according to an embodiment of the present invention, FIG. 2 is a schematic block diagram of a meter driving device according to an embodiment of the present invention, and FIG. , a diagram showing the relationship between the two coils and the needle of this meter device, and FIG. 4 are explanatory diagrams for explaining the problems of the conventional meter drive device. 1: Input signal circuit, 2: Data calculation unit, 3: Reference clock generator, 8/9: Driver, 20: Counter,
21: Rise detection section, 22/33: Timer,
25: Subtraction section, 29: Difference value absolute value size determination section, 31: Addition section, L, -Lc: Coil. Patent Applicant ROHM Co., Ltd. Agent Patent Attorney Shigeru Nakamura Figure 1 Figure 2

Claims (1)

[Claims] (1) First and second coils orthogonal to each other, means for inputting a pulse signal with a frequency corresponding to the input amount, a clock signal generating means, and a counting means for counting clock signals from the clock signal generating means. and a calculation means for calculating a digital value proportional to the input amount based on the count value of the counting means, and a current flowing through the first and second coils according to the digital value output from the calculation means. A meter having a drive circuit and a needle whose angular direction is determined by a magnetic field generated by a current flowing through the first and second coils, and for indicating a value proportional to the magnitude of the input amount. In the drive device, a switching detection means for detecting the switching of each period of the pulse signal, a time elapse determination means for determining whether a predetermined time has elapsed from the time of the switching, and a switching detection means for detecting the switching of each period of the pulse signal, difference value calculation means for calculating a difference value between the current digital value and the previous digital value by the calculation means in response to detection or the passage of time, whichever comes first; A difference value size determining means for determining whether the absolute value of the difference value is greater than or equal to a predetermined value, and a predetermined value between the current digital value and the previous digital value as the current output digital value. output value determining means for determining the currently calculated digital value as the output digital value when the absolute value of the difference value is smaller than a predetermined value; 1. A meter driving device comprising: a repetition control means for controlling each process of determining a value to be repeated at predetermined time intervals.