JP2000018975A - Device for stepping motor type instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for a stepping motor type instrument, where unnatural motions are eliminated in a usual use as an instrument by constituting so that the user can initialize at least in a failure due to step out, without having to initialize in normal use without step out. SOLUTION: A processing means 3 is provided for driving a stepping motor type instrument 5, based on a signal corresponding to a measured quantity, a pointer 8 fixed to a rotary end of a stepping motor body indicates a scale 7 on a dial 6, corresponding to the measured quantity, thereby indicating the measured quantity, a stopper is provided for limiting the rotation of the pointer 8 at specified min. indication position MIN, the indication start point on the dial 6, and the processing means 3 is constituted so as to output a reset signal by specified operation mode of an artificially operable switch 4 separately from a drive signal, corresponding to the quantity measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as an instrument movement that can be easily controlled digitally in place of an ammeter of a moving coil type or a cross coil type rotating magnet type. The present invention relates to a driving device for a stepping motor type instrument for instructing measurement of a measured amount such as a rotation speed based on a frequency signal input proportional thereto.

[0002]

2. Description of the Related Art In general, in this type of instrument device, a pointer fixed to a drive shaft end of an instrument movement is rotated in response to an input signal, and a numeral or a scaled character representing a measured amount to be measured is provided. It is configured to instruct the measurement by reading the contrast with the board.

[0003] In particular, in a stepping motor, the step operation of a magnet rotor is determined by the number of teeth of a comb yoke and the pitch of formation thereof, and in order to obtain a smooth rotation operation, the number of teeth is increased and the pitch of the comb teeth is increased. It is necessary to miniaturize or to perform so-called micro-step driving by a drive signal, and these forms are selected according to the allowable size of the stepping motor main body and the cost including the drive circuit according to the use conditions.

Further, it is desired that such a stepping motor be small regardless of the intended use. Since a so-called PM type stepping motor has a simple structure, it is easy to use by improving a rotor magnet and a comb-shaped yoke. Has become.

Further, with respect to digitization of a processing circuit (control by a microcomputer), such a stepping motor in which a pulse signal is controlled has attracted attention as a movement of an indicating instrument which performs reading by comparison with a dial graduation by a pointer. For example, the present invention can be applied to a fuel gauge and a thermometer by A / D processing of a traveling speed meter and an engine tachometer for a car, and also a detection signal.
Various proposals have been made toward practical use as disclosed in Japanese Patent Application Laid-Open No. 129575/1990 and Japanese Patent Laid-Open No. 1-223312 / 1990.

[0006]

However, when a stepping motor is used as a movement of an instrument as described above, unlike a vector follow-up type in which a rotating magnet follows a combined vector direction of a coil magnetic field as in a cross-coil type instrument. In many cases, the amount of change in the input signal at predetermined intervals is determined and step drive is performed by the amount of change, and the magnetic poles of the rotating magnet are driven at every pitch of the comb yoke or by microstep processing between the pitches. The position of the rotating magnet when the power switch is turned on is set to an initial value (for the indicating instrument, the starting point is initialized by, for example, forcibly returning to the zero position of the dial). A driving configuration is common.

Accordingly, the mechanical position on the rotating magnet due to the external vibration of the instrument device deviates from the angular position originally controlled by the step driving from the starting point, that is, the correct positional relationship between the comb yoke and the magnetic pole of the rotating magnet. There is a possibility that an angle shift of one pitch may occur, and once such an angle shift, so-called step-out, does not indicate the original correct angular position unless the start point initialization is performed by turning on the power again, and always includes a step-out error. Instruct at an angle.

Such a step-out phenomenon also occurs when the rotating magnet does not follow a change in an input signal, in addition to the above-described mechanical fluctuation due to external vibration or the like. That is, when the step driving torque of the stepping motor with respect to the rotating magnet cannot be obtained large due to structural or drive current limitation, or when the input signal changes, that is, the angular velocity is large with respect to such a limit of the driving torque, the rotating magnet cannot completely follow. There is a problem that step-out is repeated and a large angle error occurs as a result.

In particular, the stepping motor is based on a step operation corresponding to the pitch of the teeth of the comb yoke.
Smoothness is obtained by correcting the drive signal waveform, but such smoothness processing is merely a smoothing between the pole teeth pitches of the tooth yoke, and the step-out due to pitch over occurs as it is. Therefore, when the change of the measured amount is fast and the change of the input signal accompanying the change is faster than the following limit of the rotating magnet, the rotating magnet of the stepping motor cannot follow completely, and accurate indicating characteristics as an indicating instrument cannot be obtained.

In any case, in such a stepping motor type instrument device, it is general to initialize the starting point when the power is turned on again so as to minimize the indication error due to such a step-out. It is the easiest method to be performed, for example, as proposed in Japanese Patent Application Laid-Open No. Hei 6-38593, by turning an angle equivalent to or more than the maximum graduation angle of the instrument at the time of turning on the power in the direction of the starting point (zero point). There is a configuration that stops with a stopper.

However, in the method of positioning the starting point by such pointer control, the stop position of the stopper can be reliably detected as the starting point irrespective of the staying position of the pointer. Under the condition, the return to zero operation exceeding the maximum graduation angle is performed. Therefore, in most cases, the accurate position for the rare occurrence of step-out (the pointer position without turning on the power is the starting position. There is)
Despite the above, forced rotation is performed in the direction of the starting point by an angle larger than this maximum scale angle, and the pointer whose movement is restricted by the stopper collides with the stopper with the stepping operation of the stepping motor, Furthermore, a phenomenon that the pointer jumps many times from the stopper occurs as a result of the driving force on the ascending side due to the return AC wave signal while the movement in the decreasing direction is restrained by the stopper, resulting in a very uncomfortable movement with a strange feeling. turn into.

Even if a process or a movement of the pointer that enables such a return operation without jumping is performed, such an unnatural initialization operation unrelated to the instruction operation performed every time the power is turned on. Is driven each time the power is turned on, the user may feel uncomfortable as an unnecessary movement even if it is recognized that the stepping motor is necessary for initializing the stepping motor.

According to the present invention, the normal operation without the step-out is performed without performing such an initializing operation. The aim is to eliminate unnatural movements in.

[0014]

According to the present invention, there is provided a driving circuit for driving a stepping motor based on a digital signal corresponding to a measured quantity, and the measuring quantity is determined by a pointer fixed to a driving shaft end of the stepping motor. A stepping motor type instrument device for indicating a scale on a dial plate corresponding to the above and displaying the measured amount, wherein a pointer fixed to an end of the stepping motor drive shaft is turned at a predetermined designated starting point on the dial plate. The drive circuit outputs a return signal for returning the pointer to the designated starting position separately from the drive signal corresponding to the measured amount, and outputs the return signal to any artificial An operation switch for outputting by operation is provided, and a return signal output operation by the operation switch is enabled only in a predetermined operation mode. That.

Further, the present invention is characterized in that the operation switch is provided as a dedicated switch at a predetermined portion of the instrument device.

Further, according to the present invention, the operation switch is used also as an operation switch of another function provided in the meter device, and the return signal is output in an operation mode different from the original operation mode of the other function. Features.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A processing means 3 for forming a drive circuit for driving a stepping motor type instrument 5 based on a digital signal corresponding to a measured amount, and a pointer 8 fixed to a rotating end 16 of a stepping motor main body 14. Is used to indicate the scale 7 on the dial 6 corresponding to the measured quantity and to display the measured quantity.
A stopper 30 is provided so that the pointer 8 fixed to the end is limited in rotation at a minimum designated position MIN which is a predetermined designated starting point on the dial 6, and the processing means 3 is provided with a drive signal corresponding to the measured amount. Separately from the above, a return signal for lowering the pointer 8 to the predetermined minimum designated position MIN under a predetermined condition is output.

The output of the return signal from the processing means 3 is based on the push operation mode in which the distance reset switch 41 of the electronic mileage display device 40, which is digitally displayed by counting the number of travel signals by the electronic counter, is normally reset. A separate rotation operation mode is provided so as to be generated by this rotation operation mode.

As a result, during the normal instruction operation, no return signal is output including the power-on operation, and the pointer 8 only performs a normal operation without performing an abnormal initialization movement. When a step-out occurs due to a large impact due to a fall of the vehicle body or the like when the device is mounted as an instrument, a driver as a user rotates the reset switch 41 to output a return signal of the pointer 8 to initialize. Is made.

[0020]

FIG. 1 shows the basic configuration of the present invention.
Taking a speedometer for a vehicle as an example, when a frequency signal proportional to a traveling speed, which is a measured amount, is input from an input terminal 1, a rising or falling edge of the input signal is detected by a counting means 2 and detected. (Gate time method) or another high frequency clock signal is counted by an input signal (cycle measurement method), and the ever-changing running speed is calculated as digital data D.

The measured quantity obtained by the counting means 2 is:
The data is converted into the designated angle data A at a predetermined conversion cycle T by the processing means 3, and the previous designated angle data An is used every conversion cycle T.
The absolute value .DELTA.A of the difference between this and the latest designated angle data An + 1 and its increase / decrease state are obtained.

This output data An + 1 is adopted as the previous time data An in the next update, and the comparison and update with the latest designated angle data An + 1 are repeated by the same calculation.

The instruction angle data A updated in this way is subjected to appropriate waveform processing (microstep waveform or phase conversion) by the output means 4 to the two-phase excitation coil of the stepping motor.
Then, the instrument 5 is driven and the stepping motor type instrument 5 is driven, and the pointer 8 fixed to the end of the drive shaft is rotated by an angle instruction corresponding to the scale 7 of the dial 6.

Here, power supply to the processing means 3 as a drive circuit is performed from a power supply 10 via a power switch 9. In the case of an instrument for a vehicle, the power is supplied from a vehicle-mounted battery via an ignition key switch. Supply of
The processing means 3 does not initialize the starting point of the stepping motor type instrument 5 upon detecting the power-on via the power switch 9 (when the power is reconnected by replacing the vehicle-mounted battery, the output of such an initialization return signal is An initialization switch is connected to the processing means 3 so that the instrument device can be initialized by a manual operation if necessary.

As an instrument device for a vehicle, an electronic mileage display device 40 is provided in addition to a stepping motor type instrument 5 as a cruising speed meter, and the mileage display device 40 includes a liquid crystal display element or the like. The running signal is counted and displayed digitally by the electronic display of
Reset switch 4 for resetting the count value to zero
The reset switch 41 has a function as an initialization switch.

That is, the normal reset operation of the reset switch 41 is performed in the push operation mode, and the reset switch 41 has a rotation operation mode different from the push operation mode. The means 3 is configured to output a return signal for initialization.

Each of the above-mentioned means serves as a drive circuit for appropriately processing an input signal to drive the stepping motor type instrument 5, and the processing means 3 sets a meter indicating characteristic arbitrarily to indicate a traveling speed. And a memory (ROM) 31 storing the indicated angle data A corresponding to the counted digital data D, and fetching the digital data D at a predetermined conversion cycle. The designated angle data A of the memory address corresponding to this is read out and output.

The storage of the indicated angle data A in the memory 31 of the processing means 3 is performed by using digital data D corresponding to the measured amount.
The number of data for obtaining a desired resolution is provided in correspondence with the previous designated area from MIN to MAX, for example, 0.5 for the designated angle of 0 degree (MIN) to 360 degree (MAX).
The designated angle data A in degrees is stored, and the stored designated angle data An is read out at a predetermined conversion period T corresponding to the digital data D.

As the signal waveform for driving the stepping motor, an arbitrary two-phase signal can be set according to the number of teeth and the pitch of the comb yoke, and data of all the driving waveforms corresponding to all the designated angles of 360 degrees are stored in the voltage memory 32. However, in this case, the stepping motor drive signal of the stepping motor type instrument 5 is obtained by dividing 360 degrees by 1/6.
Voltage data for 0 degrees is prepared in the voltage memory 32, and this data is developed and used in each angle region to reduce the memory capacity.

That is, the voltage waveform of the drive signal applied to the two-phase excitation coils A and B with respect to the rotation angle of 360 degrees of the pointer 8 (connected magnet rotor) of the stepping motor type instrument 5 is as shown in FIG. , Approximately SI within an angle of 60 degrees
N, COS waveform changes, 60
It is developed in all angle ranges a to f in degrees. This expansion processing may be determined based on the pointing angle data A corresponding to the pointing area of the digital data D.
Driving voltage data V having resolution of 8 (A with respect to 0 degree)
The data is stored at an angle difference of 60/128 degrees from 0 to A60 with respect to 60 degrees.
In response to this, the voltage data V is read out, and the digital data D in the designated angle areas b to f are determined in each designated area, and the voltage data V in the determined area is determined.
Is read from the voltage memory 32, and the indicated position as the indicating instrument can be obtained in combination with the determination area.

In this regard, the stepping motor moves the magnetic pole position of the magnet rotor to the excitation position within that region if at least one set of teeth of the comb yoke is arranged in each designated region of FIG. Just because
It does not mean that the drive signal is different in each indication area,
The determination of the designated area based on the digital data D means that the voltage data V to be read from the voltage memory 32 may be read. For example, if the digital data D corresponds to a designated angle of 150 degrees, the designated area is determined to be c. And
By reading data corresponding to 30 degrees in this area from the voltage memory 32, the drive signal becomes as shown in FIG.

Here, the drive waveform shown in FIG. 2 is a typical approximate waveform for obtaining a smooth operation by a so-called micro-step drive for a mechanical step operation determined by a comb pitch of a comb yoke of a stepping motor. Actually, the SIN and COS waveforms are digital fine staircase waveforms, and the pitch of the microsteps depends on the change rate of the measured amount indicated by the indicating instrument, that is, the angular velocity of the pointer and the processing capacity of the processing circuit. Is set.

The stepping motor main body as the instrument movement of the traveling speedometer used for the stepping motor type instrument 5 in such a basic configuration has a laminated 2
An excitation coil for energizing a two-phase drive waveform is wound around two resin bobbins, and a comb-shaped yoke is placed above and below each bobbin, and a magnet rotor is rotatably supported in the hollow portion of the bobbin laminate. A PM type structure is used.

In FIG. 3, a stopper pin 30 is erected on the dial 6 such that the pointer 8 is indicated at the minimum designated position MIN which is the starting point of the pointer 8 on the dial 6, and the pointer is set. 8 is configured to use this position as the designated starting point.

In the above configuration, as shown in the figure, the MIN position on the dial 6 is set at the stopper pin 30 (the stopper for determining the designated starting point of the pointer 8 is particularly required to be provided at such designated starting position of the dial 6). The movable body can be stopped by the internal stopper so that the pointer 8 is restrained at the designated starting point of the dial 6). In a normal state, the pointer 8 accurately gives an instruction corresponding to the measurement signal,
When the power is turned off, the motor stops at the starting position with a predetermined instruction characteristic.

When the switch 9 is turned off during the measurement instruction,
Since the indicator signal stops at the indicated position when the pointer 8 is turned off, the pointer 8 stays at the indicated position. However, in terms of circuit processing, the processing means 3 detects the release of the power supply (for a certain period of time). If a pseudo step return signal from the designated position at that time to the starting position is generated, the instruction can be made at the starting position without step-out.

If the step-out occurs due to some reason, for example, a large vibration during a measurement instruction or a vibration that may occur in a motorcycle when the vehicle falls, the pointer 8 moves from the original indicated position to the next position. A position deviated by the step by the stepping motor structure of the present embodiment is indicated.

Therefore, if the continuous use is performed in this step-out state, the instruction will be given while including the step-out error.
In the case of the present invention, when the user determines that the step-out has clearly occurred, the reset signal is output from the processing means 3 by rotating the reset switch 41, the stepping motor type instrument 5 is driven, and the pointer 8 is driven. Return to the starting point.

Therefore, the pointer 8 which has been out of step is returned to the starting position of the stopper 30 by the return signal, and the starting point whose step out is corrected is initialized.

As described above, an operation switch which can be operated artificially is provided, and a return signal is output from the processing means 3 by this operation switch, and is effective only when the return signal output is in a predetermined operation mode. With this configuration, a return signal is output by a user's operation in a specific operation mode when a step-out occurs for some reason without any unnatural movement even when the power is turned on and off in the normal instruction state. By performing the initialization, the user can be securely initialized by operating a predetermined switch without giving a feeling of strangeness due to an unnatural movement different from the normal operation at the time of normal use, and at the time of step-out.

In the above-described embodiment, the reset switch 41 of the electronic mileage display device 40 is used as an initialization switch to return by an operation in a rotation operation mode different from a push operation mode in which a normal mileage zero reset is performed. Although a signal is output, a dedicated switch is provided as an initialization switch, for example, a special operation mode different from a normal push or rotation operation (a push or rotation operation at a fixed timing three times or a fixed operation mode is performed). It is also possible to configure to output a return signal in an operation mode in which push or rotation operation is performed continuously for more than a time.

The return signal is generated by an operation mode different from the original function operation mode of the other function switches.
In addition to the reset switch 41 of 0, for example, a correction switch of a clock provided therewith, an instrument illumination changeover switch, a rotation resistance switch of a brightness adjustment volume, and the like may be used.

[0043]

As described above, according to the stepping motor type instrument of the present invention, the return signal to the designated starting point is output by the operation switch which can be operated artificially.
In addition, by configuring the return signal output to be valid only in the predetermined switch operation mode, when a step-out occurs for any reason, a return signal is output by a user's operation in a specific operation mode to easily initialize. By doing so, the user does not feel uncomfortable with an unnatural movement different from the normal operation during normal use, and the initialization can be reliably performed at the time of step-out.

[Brief description of the drawings]

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

FIG. 2 is a drive waveform diagram showing an example of a stepping motor drive signal waveform of the present invention.

FIG. 3 is an operation explanatory diagram illustrating a principle of initializing a step-out starting point in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input terminal 2 Counting means 3 Processing means 4 Output means 5 Stepping motor type instrument 6 Dial 7 Scale 8 Pointer 30 Stopper pin 40 Electronic travel distance display device 41 Reset switch

Continuation of the front page (72) Inventor Motohiko Ogawa 2-34 Higashi-Zao, Nagaoka-shi, Niigata Nihon Seiki Co., Ltd. F-term (reference) 5H580 AA08 BB06 CA02 CA12 CB03 DD03 FA03 FA13 FA14 FA22 FA24 FB01 FC06 FD12 FD16 GG04 HH01 HH39 JJ02 JJ09 JJ13

Claims (3)

[Claims] 1. A driving circuit for driving a stepping motor based on a digital signal corresponding to a measured amount, and a pointer fixed to a driving shaft end of the stepping motor,
A meter device for indicating a scale on a dial corresponding to the measured amount and displaying the measured amount, wherein a pointer fixed to an end of a driving shaft of the stepping motor rotates at a predetermined start point on the dial. The drive circuit outputs a return signal for returning the pointer to the designated starting position separately from the drive signal corresponding to the measured amount, and outputs the return signal to any artificial A stepping motor-type instrument device comprising an operation switch for outputting an operation, and a return signal output operation by the operation switch is enabled only in a predetermined operation mode. 2. The stepping motor type instrument device according to claim 1, wherein the operation switch is provided as a dedicated switch at a predetermined portion of the instrument device. 3. The operation switch is also used as an operation switch of another function provided in the meter device, and performs a return signal output operation in an operation mode different from an original operation mode of another function. The stepping motor-type instrument device according to claim 1, wherein: