JPH08327665A - Meter driver - Google Patents

Abstract

PURPOSE: To enhance the convergence rate to final indication value by subjecting a quantity to be measured varying at high rate to digital delay processing and turning the pointer of meter smoothly with high response using a correction value. CONSTITUTION: In addition to a function for driving a meter 4 by processing an electric signal corresponding to a quantity to be measured received from an input terminal 1 through an operating means, the operating means 2 has digital delay function for sampling the electric signal at a predetermined period to obtain a target data D, determining the difference between the target data D and a current indication data Xn-1, adding a correction value to the difference and dividing the sum by a predetermined constant, and adding the quotient to the current indication data Xn-1 to produce an updated indication data Xn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pointer-type meter driving device for instructing a measured quantity such as a running speed of a vehicle or an engine tachometer, which changes rapidly.

[0002]

2. Description of the Related Art In a pointer-type meter that indicates this kind of measured quantity in an analog manner, for example, a pulse signal of a frequency proportional to a running speed from a vehicle speed sensor is smoothed and converted into a characteristic, and an ammeter or the like is used. From the analog drive system that drives the meter to direct current, it becomes a digital control system that drives the meter by counting the pulse signal as it is or measuring the cycle by the clock signal and processing the digital signal to improve the calculation accuracy and response. Moreover, miniaturization is progressing by making circuits ICs.

However, in such a digital control method, the smoothness of rotation of the meter pointer is influenced by the sampling cycle for digitizing the measured quantity and the calculation cycle for calculating the indicated value, and particularly such resolution depends on high-speed processing of the circuit. Therefore, in order to absorb the step operation of the final instruction data due to the low resolution in the low-cost circuit and drive the pointer smoothly, the drive stage that supplies the operation output to the meter is D /
The A conversion means is interposed and the smoothing means is used to delay the step operation to obtain a smooth turning instruction.

[0004]

However, the analog smoothing means for obtaining smoothing of the rotation instruction is as follows.
It greatly impairs the responsiveness of the instruction and hinders the miniaturization by digital processing circuits and the integration of circuit parts. In particular, smoothing processing requires many capacitors with different capacitances to absorb ripples in a wide frequency band. Then, at least a capacitor with a large capacity had to be used, and large parts were connected around the chip processing circuit for digital processing, and as a result, the volume of the circuit section had to be increased.

According to the present invention, such delay processing is performed by digital processing to eliminate analog smoothing means or to suppress a sufficient jumping operation with a small-capacity component and to have a good responsiveness to changes in the quantity to be measured. It is an object of the present invention to provide a drive device that can obtain the above.

[0006]

SOLUTION: To solve the problem, a calculating means for inputting an electric signal corresponding to the measured quantity and calculating and outputting as an instruction signal, and a rotating position of a pointer for the measured quantity based on the instruction signal of the calculating means. At this time, the calculation means samples the electric signal at a predetermined cycle and obtains the difference between the target data obtained by this sampling and the current instruction data. It is characterized in that it has a digital delay function of dividing a value obtained by adding a predetermined correction value to the difference by a predetermined constant and adding the divided value to the current instruction data to obtain update instruction data.

It is characterized in that the correction value is a sum of a value surplus in the previous division processing and a predetermined coefficient value.

It is characterized in that the constant for performing the division is the number of times the instruction data is updated a plurality of times during the sampling period or an integer close to this.

[0009]

By adding a correction value to the difference between the target data obtained by sampling and the current instruction data, a value obtained by adding a correction value to the difference in addition to the step division processing of simply dividing the difference by a predetermined constant. By performing the division with respect to, the convergence step operation near the convergence to the target data by the operation becomes faster, and the convergence is achieved in a short time.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a basic circuit block diagram of the present invention. An embodiment in which the traveling speed of a vehicle is indicated by a cross coil type meter will be described.

In the figure, an input terminal 1 is for inputting digital data (electrical signal) obtained by counting or periodically measuring pulse signals having a frequency proportional to the traveling speed of the vehicle. Applied to the configuration in which the process of measuring and outputting the output pulse signal as digital data is executed by the vehicle controller (the vehicle speed is also obtained by the processing unit such as engine control and transferred to the meter side by time division communication). ing.

The measurement digital data input to the input terminal 1 is supplied to the calculation means 2 (microcomputer) on the meter side, which is synchronized with the transmission cycle of the measurement digital data or has its own predetermined sampling cycle. Then, this is taken in and the digital delay processing described later is executed as target data.

The operation output data (instruction signal) which has been digitally delayed by the operation means 2 is supplied to the cross coil meter 4 through the driver 3 to indicate the sampled measured quantity by the rotating position of the pointer.

The cross-coil type meter 4 has a rotating magnet arranged in a magnetic field generated by a pair of intersecting coils, and a pointer at the tip of a pointer shaft fixed to the meter is rotated on the dial by the magnetic field control response of the rotating magnet. It can be composed of a meter known per se that enables contrast reading with an index, and the indicator signal to each crossing coil is, for example, SIN, COS for obtaining the indicator characteristic.
This is a signal, and generation of such a signal can be easily achieved by reading out memory data such as a ROM based on the operation output data in the operation means 2.

The operation of the above configuration will be described with reference to the flowchart of FIG. 2. The digital delay function in the arithmetic means 3 immediately uses the difference between the input sampling digital data and the current instruction data as the instruction data. Rather, it performs digital fine step change processing of digitally performing a finer step operation between the differences, and as a result, performs digital delay processing so as to converge to the final designated value.

First, an electric signal (digital data) corresponding to the quantity to be measured is sequentially input to the input terminal 1. The arithmetic means 2 samples this digital data at a cycle of several hundred milliseconds (from the vehicle controller side). (Depending on the time-division communication cycle of 1), and based on this, the target data D to be instructed by the meter 4 is determined.

The calculation means 2 executes a calculation for subjecting the target data D to a digital delay process for converging the instruction of the meter 4, but as shown in the figure, the current instruction data Xn- for the target data D is obtained. The difference of 1 is calculated, the correction value a + b is added to this, and a predetermined constant C (instruction update cycle is set to 10
300 if the sampling cycle is 300 milliseconds with millisecond
/ 10 = 30 or a value close to this value is set as C), and the division value is added to the current instruction data Xn-1.

That is, by such an arithmetic process, the jumping operation (step operation) is prevented when the sampling target data D having a difference from the current instruction data Xn-1 is immediately instructed and controlled as an instruction signal, and the difference of the difference is calculated. A so-called delay function that causes a convergent change as a fine step operation for each of the above 1 works.

Here, a of the correction values a + b is a value left over by the same division as the previous time, and the correction value is changed depending on the size of this value. This is corrected by adding it to D as an unprocessed portion and increasing the convergence rate. Further, b is a predetermined coefficient value, and in particular, by increasing the difference of the calculation objects near the convergence to the target data D, the convergence speed is increased and the step operation is made less noticeable. That is, when the convergence is approaching, the difference between the target data D and the update instruction data Xn-1 becomes small, and as a result, the remainder due to the division becomes a small value. Therefore, by supplementing this with b, the convergence rate is improved.

The update instruction data Xn thus obtained is output to the driver 3 as the operation output of the operation means 2 and drives the meter 4. The update instruction data Xn is immediately the present instruction data Xn-. It is replaced as 1 and used for the next similar delay processing operation.

Therefore, by repeating the calculation steps shown in the flow chart of FIG. 2, a convergence instruction operation to the current target data D is performed until the next new sampling target data D is determined, and as a result, here. For example, the update calculation is repeated 30 times during the sampling period, and a quadratic curve-like 30 step as the drive output instruction signal of the meter 4 from the current instruction value (current instruction data Xn-1) to the target value (target data D). Converge in small steps.

Since the convergence speed at this time is processed by the same number of updates including minute steps until the data is completely coincident with the target data D equivalent position which is the target value, the convergence speed is strict. Is the new sampling target data D
Until the value is updated, the correction value a + b
By the addition of, the convergence near the position corresponding to the target data D becomes faster, and visually it seems that the convergence to the target value is almost stable.

The complete convergence to the final target value is repeatedly calculated to be executed to the end because of the calculation process.
When the difference between the target data D and the update instruction data Xn-1 becomes extremely small immediately after the convergence, the calculation process may be stopped and the target data D may be immediately replaced with Xn.

[0024]

As described above, according to the present invention, the electric signal corresponding to the quantity to be measured is sampled at a predetermined cycle, and the difference between the target data and the current instruction data obtained by this sampling is calculated.
When the correction target value is added to this difference and division is performed by a predetermined constant, and this division value is added to the current instruction data to be the update instruction data, the sampling target data greatly changes from the current instruction data. However, without giving a large jump (step motion) instruction, an extremely smooth command characteristic can be visually obtained by the convergence motion to the target data in the fine step motion, and even if the correction value is close to the convergence to the target data, It is possible to obtain a stable instruction by improving the convergence rate and suppressing the needle-like movement of the pointer.
Further, since the delay operation is performed by digital processing, it is possible to obtain a pointer rotation instruction with a fast convergence speed to a target value and good response, and it is also possible to downsize the circuit unit by a digital processing circuit. Is.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a representative embodiment of the present invention.

FIG. 2 is a flowchart showing digital delay steps of the calculating means in FIG.

[Explanation of symbols]

 1 input terminal 2 computing means 3 driver 4 crossing coil type meter

Claims (3)

[Claims] 1. An electric signal corresponding to a measured quantity is input,
Computation means for computing and outputting as an instruction signal, and a meter for instructing the measured quantity to be compared with the index on the dial at the rotating position of the pointer based on the instruction signal of the computing means, the computing means comprising: The electric signal is sampled at a predetermined cycle, the difference between the target data obtained by this sampling and the current instruction data is obtained, the value obtained by adding a predetermined correction value to this difference is divided by a predetermined constant, and this division is performed. A meter driving device having a digital delay function of adding a value to the current instruction data to obtain update instruction data. 2. The meter driving device according to claim 1, wherein the correction value is a sum of a value surplus in a previous division process and a predetermined coefficient value. 3. The meter driving device according to claim 1, wherein the constant for performing the division is the number of times of updating the instruction data that is updated a plurality of times during the sampling period or an integer close to this. .