JP2007010333A - Meter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent drive amount of stepping motor per rotation from becoming excessive, and thus prevent the stepping motor from becoming out of synchronism (step out), in a meter device of analog needle type using the stepping motor. <P>SOLUTION: The meter device comprises a difference calculating means 12 for determining a difference between a target vehicle speed value (input value) and a present indication value, a division condition setting means 14 for setting a division number increasing with increase in determined difference, a variation amount calculating means 15 for calculating a variation amount of the stepping motor per rotation by dividing the determined difference by the division number N, a timer means 16 for producing an indication value calculation timing corresponding to output period T/N of the indication value, an indication value calculating means 17 for calculating a next indication value by adding the variation amount calculated by the variation amount calculating means 15 to the present indication value every output period T/N of the indication value, and a sin/cos conversion table 19 and PWM conversion section 20 for driving the stepping motor based on the indication value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an on-vehicle analog pointer type meter device using a stepping motor.

In an analog pointer type speedometer using a conventional stepping motor, the indication value of the speedometer pointer is determined by controlling the rotation of the rotor of the stepping motor in accordance with the input speed data. Specifically, the difference between the input value and the current instruction value is obtained, a value obtained by multiplying the obtained difference by 1 / n (n is an integer) is added to the current instruction value, and stepping is performed so as to indicate the added value. By repeating the process of driving the motor n times, the indicated position is moved by 1 / n of the difference between the input value and the current indicated value, and finally the input value is indicated (see Patent Document 1). .
JP 2001-91302 A

  When sudden acceleration or sudden deceleration is performed, the difference between the input value and the current instruction value becomes large, and the value obtained by setting the difference to 1 / n also becomes large. For this reason, the driving amount per step of the stepping motor becomes large, and the stepping motor may be out of synchronization (step out).

  The present invention has been made in view of the above circumstances, and by changing the value of the division number n stepwise in accordance with the difference between the input value and the current indication value, the driving amount per stepping motor can be increased. An object of the present invention is to provide a meter device that prevents the stepping motor from becoming out of synchronization (step-out).

  A meter device according to the present invention is an analog pointer type meter device using a stepping motor, and includes a difference calculating means for obtaining a difference between an input value and a current indicated value, and a division number and an instruction based on the obtained difference. A division condition setting means for setting the output cycle of the value, a change amount calculating means for obtaining the change amount of the indicated value by dividing the obtained difference by the set number of divisions, and for each set output cycle of the indicated value An instruction value calculating means for calculating the next instruction value by adding the change amount of the instruction value to the instruction value; a stepping motor driving means for driving the stepping motor to move the pointer each time the instruction value is calculated; Is provided.

  According to the above configuration, the larger the difference between the input value and the instruction value, the smaller the change amount of the instruction value by setting a larger number of divisions, thereby causing the stepping motor to lose synchronization (step out). ) Can be prevented.

  According to the present invention, since the change amount of the instruction value can be kept small, it is possible to prevent the stepping motor from being out of synchronization (step-out).

  Hereinafter, the best mode for carrying out the invention will be described based on examples.

  FIG. 1 is a block diagram of a meter device according to an embodiment of the present invention. This meter device displays a vehicle speed, and includes a target value register 11 for storing a target vehicle speed value (input value) supplied from the vehicle side at a predetermined cycle T (for example, 10 milliseconds), and a target vehicle speed value ( Each time an input value is supplied, a difference calculation means 12 for obtaining a difference between the target vehicle speed value (input value) and the current indicated value, a difference register 13 for storing the obtained difference, and division based on the obtained difference The division condition setting means 14 for setting the number N and the output cycle T / N of the indicated value, and the change per step of the stepping motor by dividing the obtained difference by the division number N set by the division condition setting means 14 Change amount calculating means 15 for calculating the amount, timer means 16 for generating an instruction value calculation timing corresponding to the output period T / N of the instruction value based on the division number N set by the division condition setting means 14, and an instruction Out of value The instruction value calculation means 17 for calculating the next instruction value by adding the change amount calculated by the change amount calculation means 15 to the current instruction value for each period T / N, and the instruction value calculation means 17 An instruction value register 18 for storing an instruction value, a sin / cos conversion table 19 and a PWM converter 20 constituting a stepping motor driving means, a stepping motor (not shown), and a pointer driving mechanism (not shown) ing.

  A target vehicle speed value (input value) supplied every predetermined cycle T (for example, 10 milliseconds) from the vehicle side is stored in the target value register 11. When the target vehicle speed value (input value) is stored in the target value register 11, the difference calculation means 12 calculates the difference between the target vehicle speed value (input value) and the current instruction value, and stores the calculated difference in the difference register 13. Store.

  The division condition setting unit 14 includes a division number setting table in which the difference value and the division number are associated with each other, and determines the division number based on the difference between the target vehicle speed value (input value) and the current instruction value. . Here, the number of divisions is set so as to increase stepwise as the difference value increases. For example, as shown in FIG. 2, five levels of division numbers 32, 16, 8, 4, and 1 are set. The

  The change amount calculation means 15 divides the difference value between the target vehicle speed value (input value) stored in the difference register 13 and the current instruction value by the division number N set corresponding to the difference, The divided value is output as the amount of change.

  The timer means 16 generates an instruction value calculation timing of a cycle T / N obtained by dividing the input cycle T of the target vehicle speed value (input value) by the division number N. The instruction value calculation means 17 adds the change amount supplied from the change amount calculation means 15 to the current instruction value at each instruction value calculation timing of the cycle T / N, and outputs the added value as the next instruction value. Repeat that. The instruction value calculated by the instruction value calculation means 17 is stored in the instruction value register 18.

  The sin / cos conversion table 19 includes a correspondence table between the instruction value and the electrical angle for driving the stepping motor, and outputs an electrical angle corresponding to the instruction value. The PWM converter 20 generates and outputs voltage signals S + and S− supplied to the S phase coil of the stepping motor and voltage signals C + and C− supplied to the C phase coil based on the electrical angle corresponding to the indicated value. To do.

  FIG. 2 is an explanatory diagram showing the correspondence between the difference between the target vehicle speed value (input value) and the current command value and the number of divisions, and FIG. 3 is an explanatory diagram showing the relationship between the number of divisions and the driving cycle of the stepping motor.

  When the difference between the target vehicle speed value (input value) and the current instruction value is extremely large, the division number N is set to 32. Therefore, a value obtained by dividing the difference between the target vehicle speed value (input value) and the current instruction value by 32 is set as the amount of change per time, and as shown in FIG. Each time the amount of change is added to the indicated value, the stepping motor is driven.

  When the difference between the target vehicle speed value (input value) and the current instruction value is large, the division number N is set to 16. Therefore, a value obtained by dividing the difference between the target vehicle speed value (input value) and the current instruction value by 16 is set as the amount of change per time, and as shown in FIG. 3B, every T / 16 period. Each time the amount of change is added to the indicated value, the stepping motor is driven.

  When the difference between the target vehicle speed value (input value) and the current instruction value is medium, the division number N is set to 8. Therefore, a value obtained by dividing the difference between the target vehicle speed value (input value) and the current instruction value by 8 is set as the amount of change per time, and changes every T / 8 cycle as shown in FIG. The stepping motor is driven each time the amount is added to the indicated value.

  When the difference between the target vehicle speed value (input value) and the current instruction value is small, the division number N is set to four. Therefore, a value obtained by dividing the difference between the target vehicle speed value (input value) and the current instruction value by 4 is set as the amount of change per time, and changes every T / 4 cycle as shown in FIG. The stepping motor is driven each time the amount is added to the indicated value.

  When the difference between the target vehicle speed value (input value) and the current instruction value is minimal, the division number N is set to 1. Therefore, the difference between the target vehicle speed value (input value) and the current instruction value is set as the amount of change, and the amount of change is added to the instruction value every period T as shown in FIG. Is done.

  In this way, by increasing the number of divisions stepwise as the difference between the target vehicle speed value (input value) and the current instruction value increases, the driving amount per stepping motor can be kept small. Thereby, it is possible to prevent the stepping motor from being out of synchronization (step-out).

  According to the present invention, since the change amount of the indicated value can be kept small, the stepping motor can be prevented from being out of synchronization (step-out), and a meter device such as a speedometer for a vehicle, a tachometer, etc. Useful for.

The block diagram of the meter apparatus based on the Example of this invention Explanatory diagram showing the correspondence between the difference between the target vehicle speed value and the current command value and the number of divisions Explanatory drawing which shows the relationship between the number of divisions and the drive cycle of a stepping motor

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Target value register 12 Difference calculation means 13 Difference register 14 Division condition setting means 15 Change amount calculation means 16 Timer means 17 Instruction value calculation means 18 Instruction value register 19 sin / cos conversion table 20 PWM converter

Claims (1)

An analog pointer type meter device using a stepping motor,
A difference calculating means for obtaining a difference between the input value and the current indicated value;
Division condition setting means for setting the number of divisions and the output period of the indicated value based on the obtained difference;
A change amount calculating means for determining a change amount of the indicated value by dividing the obtained difference by the set number of divisions;
An instruction value calculation means for calculating a next instruction value by adding a change amount of the instruction value to the instruction value for each set output period of the instruction value;
And a stepping motor driving means for driving the stepping motor to move the pointer each time the indicated value is calculated.

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