JP2742270B2 - Meter drive - Google Patents

Description

The present invention relates to a meter driving device used for a tachometer, a speedometer, and the like for an automobile or the like.

(B) the prior art generally, the speedometer for an automobile, as shown in FIG. 3, two orthogonal coils L _s, the magnet M for swinging the needle into the magnetic field formed by L _c And place the coil L _s ,
The L _c, a current according to the input quantity of the speed or the like, and a magnet M is rotated, swung the needle. A meter driving device of this type of speedometer inputs a pulse signal whose period changes according to an input amount, that is, a speed, and also inputs a clock signal generated by a basic clock generator, and outputs one of the pulse signals. The clock signal is counted by the counter over the period, first, the period T of the pulse signal is obtained, and from this period T, the calculation of f = 1 / T is performed to calculate the frequency f. Since the digital data f is proportional to the input amount, a current corresponding to the digital value f is supplied to the coils L _s and L _c , and the magnetic field generated by the coils L _s and L _c causes the needle as a magnet. Is swung up to an angular orientation determined by the digital value.

(C) Problems to be Solved by the Invention The above-described conventional meter driving device calculates the frequency of a pulse signal that changes according to speed by counting clock signals, obtains a frequency, converts the frequency into a digital signal, and responds to the value. Since the sin and cos calculations are performed to specify the angle and direction, for example, if the input suddenly changes from high speed to low speed, the frequency of the input pulse signal changes from high frequency to low frequency, and the cycle becomes longer Therefore, the frequency after the change is not calculated until the clock signal for one cycle is counted.
Until then, there was a problem that the needle did not move and the response was extremely poor.

In addition, sin operation and cos operation are performed in accordance with the frequency, that is, digital data, and a current corresponding to the input amount is supplied to the orthogonal coils to swing the needle.
When the speed is rapidly changed from 145 Km / H to 25 Km / H as illustrated in the figure, the needle passes through the route A, does not try to go to 25 km / H, tries to pass through the route B, and changes to a low speed. Despite that, there was the inconvenience of heading in the direction where the instructions could be shaken off.

The present invention has been made in view of the above problems, and provides a meter driving device in which a response speed does not decrease even when an input amount decreases, and a movement of an instruction becomes a natural movement. It is intended to be.

(D) Means and Action for Solving the Problems The meter driving device according to the present invention has a first
A second coil (L _s , L _c ), a means (1) for inputting a pulse signal having a frequency corresponding to the input amount, a clock signal generating means (3), and counts the clock signal to obtain a count value. Calculating means (2) for calculating a digital value proportional to the input amount based on the input value; and a driving circuit (6, 7) for flowing a current corresponding to the digital value output from the calculating means to the first and second coils. ), And a needle (M) whose angle and orientation are determined by a magnetic field generated by a current flowing through the first and second coils, for indicating a value proportional to the magnitude of the input amount. In the above meter driving device, the calculating means includes: a counting means (20) for counting the clock signal; a switching detecting means (21) for detecting a switching of each cycle of the pulse signal; Predetermined time has elapsed A time elapse determining means (22) for determining whether or not the frequency has been switched, and a frequency for digitally calculating the frequency from the output of the counting means (20) in response to the detection of the period switching or the elapse of time, whichever is earlier. Calculating means (24) and difference value calculating means (25) for calculating a difference value between the digitally calculated value of the present time and the digitally calculated value of the previous time
And when the time elapsed by the time elapsed determination means is earlier than the detection of cycle switching by the switch detection means, determines whether the calculated difference value is greater than 0,
Discriminating means (28) for ignoring the difference value when the calculated difference value is larger than 0; and when the discriminating means determines that the calculated difference value is smaller than 0, the absolute value A difference value magnitude determining means (29) for determining whether or not the value is equal to or greater than a predetermined value; and a difference value between the present digital value and the previous digital value when the absolute value of the difference value is equal to or greater than the predetermined value. Is determined as a current output digital value, and when the absolute value of the difference value is smaller than a predetermined value, output value determination means (30, 31), a difference value calculation by the difference value calculation means, a difference value determination by the difference value determination means,
It is configured to perform repetitive control for controlling each process of determining the output digital value by the output value determining means so as to be repeated at predetermined time intervals.

In this meter driving device, the cycle of the input pulse signal is switched, and when this switching is detected by the switching detecting means, the switching is detected by the switching detecting means, or the time elapses thereafter. The difference value between the digital value calculated this time and the digital value calculated last time is calculated by the difference value calculating means in response to whether the elapse of the predetermined time is determined by the determining means or whichever is earlier. If the input amount is relatively large, that is, if the speed is high, one cycle of the input pulse signal arrives before the predetermined time elapses. Then, a difference value calculation is performed. on the other hand,
When the input amount is smaller than the predetermined value, that is, when the input speed is low, a predetermined time elapses before one cycle of the input pulse signal arrives. A difference value operation 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 that the digital value is higher than the true frequency. In this case, it is determined whether or not the difference value is larger than 0. If the difference value is larger than 0, the hand is moving in a direction in which the hand swings greatly from 0, and the count value is true. Since the digital value of the eye is higher than the frequency, the difference value processing is ignored. On the other hand, when the difference value is smaller than 0, it means that the hand is moving from the large swing to 0, and then it is determined whether the absolute value of the difference value exceeds a predetermined value. Is determined. Even when the input amount is relatively large and switching is detected before the predetermined time has elapsed, similarly, whether the absolute value of the difference value exceeds the predetermined value is determined by the difference value size determination means. I do.
If the absolute value of the difference value is smaller than the predetermined value, it is determined that the change is small, and the current digital value is output as it is. If the absolute value of the difference value exceeds the predetermined value, it is assumed that the change is large, and the digital value of the present time is output immediately and the hand is not suddenly moved. A digital value proportional to the difference value, for example, an intermediate value is output.
Thereafter, at predetermined time intervals, for example, each time, a digital value corresponding to the intermediate value between the current time and the previous time is output, and the hand is sequentially swung. When the absolute value of the difference value becomes smaller than the predetermined value, the final value is obtained. To output the current digital value. This allows the needle to swing naturally without trying to move in the opposite direction.

(E) Examples Hereinafter, the present invention will be described in more detail with reference to examples.

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

As shown in FIG. 1, the data arithmetic unit 2 includes a counter 20 for counting a clock signal, a rising edge detecting circuit 21 for detecting a rising edge (cycle switching) of an input pulse signal, and generating a transfer signal and a reset signal. A 10 msec timer 22 which starts upon receiving a reset signal, a flip-flop 23 which is set by a time-up output of the 10 msec timer 22 and is reset by the reset signal,
21 or 10msec Transfer signal from timer 22
Receiving the count value T from 20, the calculation of 1 / T, that is, the frequency calculation unit 24 that performs the frequency calculation, the output of the frequency calculation unit 24
f _i , that is, from the currently calculated frequency f _i to the previously calculated frequency f
The _i-1 is subtracted, the subtraction unit 25 for calculating the difference value f _d, a memory 26 for storing the calculated difference value f _d, the set / reset state of the flip-flop 23 at the time of storing the difference value f _d A determining unit 27 for determining, and a determining unit 28 for determining whether the difference value _fd is 0 or more when the set state of the flip-flop 23 is determined by the determining unit 27. When the determination unit 27 determines the reset state of the flip-flop 23, the determination process by the determination unit 28 is skipped.

When the determination unit 28 determines that f _d > 0 is not satisfied, that is, the data calculation unit 2 determines that f _i <f _i−1 , and the determination unit 27 determines that Q = 0 (reset state). when it is determined that there is the absolute value of the difference value f _d is, the determination unit 29 that determines whether more than a predetermined value K, K> in this discriminator 29 | f _d | not equal if it is determined, update the difference value f _d to 1 / 2f _d, in the determination unit 29 K> | f _d
| And if it is determined, a difference value updating unit 30 update processing is skipped, the difference value f _d an adder 31 for adding the previous frequency f _i-1,
Storing the added value f _i, the memory 32 to be output as a current frequency f _i, in response to the output pulse of the memory 32, and a 10msec timer 33 to start. 10msec timer 33
With the time-up, the output of the memory 26 is derived again.

Frequency data f _i output from the memory 32 of the data calculating unit 2 is a 10-bit digital data, of which upper 2 bits is to determine whether any were divided into four one revolution quadrant, The quadrant determining unit 10 determines the quadrant to which the needle to be moved belongs by these two bits, and the quadrant determining unit 10
Outputs a direction signal determined by the determined quadrant.
The lower 8 bits are data corresponding to 0 ° to 90 ° in each quadrant, which are input to a sin operation unit 4 and a cos operation unit 5, where a sin operation and a cos operation are performed, respectively, and a pulse width modulation circuit is used. The signals are input to drivers (driving circuits) 8 and 9 via 6 and 7. Driver 8 flows and a value corresponding to a signal from sin arithmetic unit 4, the polarity of current corresponding to the direction signal to the coil L _s, the driver 9 according to the value and direction signals corresponding to the signal from the cos arithmetic unit 5 Current with different polarity
L _{c is} to flow. A current flows through the coil L _s and L _c, the synthetic magnetic field is generated, the needle deflection by the composite magnetic field, showing the indication of angular orientation in accordance with the input amount.

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

When a pulse signal corresponding to the rotation of the wheel is input from the input signal circuit 1, the rising of the pulse signal is detected by the rising detecting unit 21. First, the transfer signal is supplied to the counter 20, and then the reset signal is output. The counter 20, the 10 msec timer 22 and the flip-flop 23 are input. Counter 20
Transfers the count value that has been counted by the transfer signal to the frequency calculation unit 24, and is reset by the reset signal. Thereafter, the clock signal from the reference clock generator 3 is counted until the next reset signal comes. .

Also, 10msec by reset signal by rising detection
The timer 22 is reset and started, and the flip-flop 23 is reset. When the 10 msec timer 22 times out, the time-up output sets the flip-flop 23 and supplies a transfer signal to the counter 20. The counter 20 also counts the contents counted up to that point by the transfer signal,
Output to

When the frequency of the input pulse signal is very high, that is, 1
In the state where the cycle is small, the rising detector 21 detects the rising, the counter 20 is reset, and the period from the transfer state to the next reset signal is shorter than the time to time up the 10 msec timer 22. Therefore, the output from the counter 20 is always based on the transfer command before the reset of the counter 20. Therefore, the count value of the clock signal corresponding to one cycle of the pulse signal, that is, the data T for one cycle is calculated by the frequency calculation. Input to the unit 24.

The frequency calculation unit 24 performs calculation of 1 / T, and calculates the current frequency f _i, and inputs to the subtracting section 25. Subtracting unit 25 receives the previous frequency f _i-1 stored in the memory 32 to the other input, subtracts the previous frequency f _i-1 from the current frequency f _i,
And calculates the difference value f _d. Then, the difference value f _d is the memory 26
Is stored.

Next, the determination unit 27 determines whether the Q output of the flip-flop 23 is 0 or not. Normally, when the frequency of the input pulse is high, the flip-flop 23 is in the reset state. Therefore, in this case, the output of Q = 0 skips the determination unit 28 and the determination unit 29 skips the difference value _Fd . It is determined whether or not the absolute value is smaller than a predetermined value K.

Now, for example, when the needle swing is relatively small, that is, the needle swings greatly from the state where the frequency of the input signal is small, that is, when the needle moves to the higher frequency, and the swing width suddenly increases. , The determination by the determination unit 29 is NO,
Following this calculates the half of the difference value f _d with a difference value updating unit 30 adds the f _d corresponding to the difference value of 1/2 the previous frequency f _i-1 by an adder 31, This frequency is assumed to be f _i . That is, the frequency f _i that is calculated corresponding to an intermediate value between the previous frequency and the current frequency is stored in the memory 32, respectively the frequency f _i to sin arithmetic unit 4, cos arithmetic unit 5 and the quadrant determining unit 10 Output. Then, the sin operation unit 4, the cos operation unit 5, and the quadrant determination unit
According to the output of 10, current flows through the driver 8 and the driver 9, the current flowing through the coil L _s and L _c, the magnetic field in a predetermined direction is generated, and the needle deflection previous Thereby, then shake the target Swings to a point corresponding to the intermediate value of.

On the other hand, in response to an output pulse which is output from the memory 32, and starts the 10msec timer 33, this time-up signal is derived again difference value f _d of the memory 26, also in the determination unit 27 Q = 0 Kano determination is made, the absolute value of the difference value f _d in the determination unit 29 is determined whether or less K. Note that the difference value f _d
For but above K, that is, when the current value f _i of the intermediate value and the target has a difference larger becomes further obtains a 1 / 2f _d of the difference value, the last time adding section 31 f _i-1 , That is, for the intermediate value,
Further, the difference value f _d is added to obtain a new f _i , which is stored in the memory 32.
And outputs the same to the sin operation unit 4, the cos operation unit 5, and the quadrant determination unit 10 as before.

The above process is repeated every 10 msec, and the intermediate value is set as the indicated target by 1/2, and the hand smoothly approaches the target change value. Then, when the difference value f _d is smaller than K, YES next determination of the determination unit 29, in this case, skipping determination unit 30 for 1/2 handle difference value f _d, the difference value f _d To the previous f
obtains the current value f _i obtained by adding _i-1, which was stored in the memory 32, will be output as a final instruction memory.

Next, if the cycle of the pulse signal input this time becomes very large, that is, if the frequency becomes low, the rise detection of the 10 msec timer 22 after reset is more effective than the rise detection by the rise detection unit 21, that is, the detection of one cycle. Faster, 10ms
When the ec timer 22 times out, the flip-flop 23 is set and Q = 1. On the other hand, since the transfer signal is output at the output of the 10 msec timer 22, even if the counter 20 has not yet counted the clock signal for one cycle, the counter value up to that time is assumed to be a count value for one cycle. Is input to the frequency calculation unit 24 to perform a frequency calculation to calculate a fictitious current frequency f _i , and a subtraction unit 25 calculates a difference value f _d between the previous frequency and the current frequency, and stores the difference value f _d in the memory 26. After the storage, whether the Q output of the flip-flop 23 is 0 or not is determined by the determination unit 27. This time, since the flip-flop 23 is set, an output of Q = 1 is output.
It is determined whether or not f _d is 0 or more. If the difference value f _d is greater than zero, the case is greater than the previous frequency towards this frequency, at this time, which needle is moved to the large consisting shake direction from zero, in this case When a frequency calculation is performed using a count value in which the count value 20 has not yet counted one cycle, f _i having an apparently larger frequency than the target frequency is obtained. In this case, the frequency f _d
Is ignored, the process returns to the storage unit of the memory 26, and the current process is ignored.

However, for example, because the frequency up to that point was high and the frequency of the input signal was low, the flip-flop 23
There when it is set, this time the frequency f _i and the previous frequency f _i-1 of the difference values f _d - become. Therefore, the determination is NO in determination section 28, then the absolute value of the difference value f _d is determined by the discrimination unit 29 to or less than K. When the absolute value of the difference value f _d is very large, that is, when the frequency changes from a high frequency to a very low frequency and the needle deflection is extremely small, the difference value f _d
1/2 of the new f _d, adds this f _d to the previous frequency f _i-1, as a new current frequency f _i, is stored in the memory 32. In this case, since f _d is −, a new frequency
f _i is the last frequency f _i-1 lower frequency than the frequency of the intermediate value between the frequency and the last frequency to be targeted is stored in the memory 32, again, sin arithmetic unit 4, cos arithmetic unit 5 and the quadrant It is output to the decision unit 10. Then, currents corresponding to intermediate values respectively flow through the coils L _s and L _c by the trivers 8 and 9, and the needle indicates an intermediate value between the previous swing corresponding to the high frequency and the target low frequency instruction. Magnetic field is generated.

The output of this memory 32 is made and also 10ms
Through the ec timer 33, the difference value f _d of the memory 26 is derived at 10 msec intervals, and the processing of the determination unit 27, the determination unit 28, and the determination unit 29 is performed. As long as the absolute value f _d is not smaller than the predetermined value K, , 1/2 to the difference value f _d
The calculation process is performed to sequentially approach the target swing angle by 1/2.

(F) Effects of the Invention According to the present invention, switching detection means for detecting switching of each cycle of an input pulse signal, and time lapse determination for determining whether a predetermined time has elapsed from the time of the switching. Means for deriving the count value of the counter in response to the earlier detection or discrimination output, performing a frequency calculation in accordance with this, flowing a current corresponding to the frequency to each driver, and waving the needle. Therefore, even if the frequency changes from a high frequency to an extremely low frequency,
Even if it is not possible to respond to the count value for the period, the provisional output is derived using the value counted up to that point, so that responsiveness can be ensured and the frequency greatly changes significantly The output value does not immediately correspond to the target frequency, but is sequentially output so as to be a predetermined value swinging between the previous value and the current value. There is an advantage that a swing can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a functional configuration of a data calculation unit 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 showing an embodiment of the present invention, and FIG. FIG. 4 is a diagram showing a relationship between two coils and a needle of the meter device, and FIG. 4 is an explanatory diagram for explaining a problem of a conventional meter driving device. 1: Input signal circuit, 2: Data operation section, 3: Reference clock generator, 8.9: Driver, 20: Counter, 21: Rise detection section, 22/33: Timer, 25: Subtraction section, 29: Difference value Absolute value magnitude discriminator, 31: adder, L _s · L _c : coil.

Claims (1)

(57) [Claims] A first and a second coil (L _s ,
L _c ), a means (1) for inputting a pulse signal having a frequency corresponding to the input amount, a clock signal generating means (3), and counts the clock signal, and is proportional to the input amount based on the count value. Calculation means for calculating a digital value (2)
And a drive circuit (6, 7) for flowing a current corresponding to a digital value output from the arithmetic means to the first and second coils.
And a stylus (M) whose angle and azimuth are determined by a magnetic field generated when a current flows through the first and second coils, for indicating a value proportional to the magnitude of the input amount. In the meter driving device, the calculating means includes: a counting means (20) for counting the clock signal; a switching detecting means (21) for detecting switching of each cycle of the pulse signal; Time elapse determining means (22) for determining whether or not the time has elapsed, and counting means (2) in response to the detection of the period switching or the elapse of time, whichever is earlier.
Frequency calculation means (24) for digitally calculating the frequency based on the output of (0), and difference value calculation means (25) for calculating a difference value between the current digitally calculated value and the previous digitally calculated value
And when the time elapsed by the time elapsed determination means is earlier than the detection of the cycle switching by the switch detection means, determines whether the calculated difference value is greater than 0,
Discriminating means (28) for ignoring the difference value when the calculated difference value is larger than 0; and when the discriminating means determines that the calculated difference value is smaller than 0, the absolute value A difference value magnitude determining means (29) for determining whether or not the value is equal to or greater than a predetermined value; and a difference value between the present digital value and the previous digital value when the absolute value of the difference value is equal to or greater than the predetermined value. Is determined as a current output digital value, and when the absolute value of the difference value is smaller than a predetermined value, output value determination means (30, 31), a difference value calculation by the difference value calculation means, a difference value determination by the difference value determination means,
A meter driving device, wherein repetitive control for controlling each process of determining an output digital value by said output value determining means to be repeated at predetermined time intervals is performed.