DE2409925A1 - DRIVE CIRCUIT FOR A STEPPER MOTOR - Google Patents

Description

DIPL.-PHYS. F. FINALLY sos * jnterpfaffenhofen 25.5 ¹ ebr.

PATENT Attorney mailbox Ki / Ktz

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TELEGRAM ADDRESS: DIPL.-PHYS. F. FINALLY. D-8O34 UNTERPFAFFENHOFEN. POST BOX CABLE ADDRESS: PATENOLICHMUIMOMtN TELEX 5 212 3Ο8 PATE

Lawyer file: D-

Applicant: Kabushiki Kaisha Daini Seikosha, 51-1- »6-chome, Kameiao, Koto-ku,! Tokyo / Japan

Drive circuit for a stepper motor

The invention relates to a drive circuit for a Stepping motor according to the preamble of claim 1. In particular, the invention relates to a drive and control circuit for a stepper motor that can be used as a drive motor for watches. As conventional drive devices for this type of stepper motor can be operated with a pulse current with a fixed pulse duration, Such devices require a longer pulse duration than the fixed pulse duration compared to the motor To keep overloads and disturbances stable. The disadvantage here is that the power consumption then increases and the Battery must be larger, so that the conventional drive devices are uneconomical. Furthermore, there are all transistors

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are switched off immediately after a pulse has been fed into the drive coil, the coil connections are electrically open and as a result the eotor tends to oscillate freely, which results in a disadvantageous, low efficiency has the consequence.

The present invention is therefore intended to avoid and eliminate the aforementioned disadvantages. At the Arrfcriebsschalt for a stepper motor according to the invention this is indicated by the features in the characterizing part of Claim 1 achieved.

Advantageously, the invention provides a drive circuit for a stepper motor that can be used in watches created, in which the duration of a drive pulse applied to the motor by detecting a by drive current flowing to the motor is controlled to make a drive output impedance low during a period to hold during which the motor is not driven, whereby the stability of the motor is improved. In particular the drive circuit has a maximum efficiency at low power consumption, the duration of the drive pulse for the motor is controlled to one Immediate suppression of unwanted and unusable vibrations that affect the eotor after the switching step is finished.

Further advantages and details of the invention are explained in detail below with reference to the drawings. It demonstrate:

Fig. 1 is a block diagram of an embodiment of the invention; and

FIG. 2 shows waveforms for explaining the operation of the circuit of FIG. 1.

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In Fig. 1 are at the clock pulse input terminals T-, T ₂ of flip-flop circuits F ^, F ₂ clock pulses (which are denoted by A and B in Fig. 2), which are in phase opposition to each other and from a conventional one Clock pulse generator CP are generated.

The control electrodes of two pairs of complementary field effect transistors (FETs) are connected to the output terminals Q. and Q _{2 of} the flip-flop circuits F ^ and F _2, respectively. The connections of the field effect transistors FETs are connected to energy sources + Vnn or -Vnn, and a stepping motor M is connected between the common connections a and b of the field effect transistors FETs. Furthermore, a resistor R is connected between the energy source + Vnn and the field effect transistors FETs. A change in potential at a connection. C between the energy source + VQn and the field effect transistors FET'en is processed by means of an amplifier A, a differentiating circuit I and an inverter circuit IN. That. The signal vjixö processed in this way is then applied to the reset input of the flip-flop circuits F 1 and F p.

If ⁿ in the above-saddle .tungsanordnung the clock pulses, which are designated in FIG. 2 A and B, respectively to the input terminals 1 'and T ₂ of the flip-flop scarf tungeii F. and applied Fp v / ground flows a current through a drive coil of the hotors M, whereupon this begins to rotate. Simultaneously, the potential at node C shown in Fig. 1 changes as indicated by waveform 0 shown in Fig. 2; from this it can be seen that the potential, when the rotor begins to rotate, decreases somewhat and then recovers and increases again somewhat when the rotor rotates, and that the potential decreases again after the end of a rotation step of the rotor and see then after a certain

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Time span recovers and rises to the original level. The waveform C, which by means of the differentiating circuit I is differentiated is then transformed as indicated by a waveform D in FIG.

An output pulse E from the inverter circuit IN generates a differential pulse as shown at E in Fig. 2 at a point P. of the waveform C, where it decreases after one step of rotation of the rotor is completed. When this pulse is applied to the reset terminals Re of the flip-flop circuits F- and Fp, respectively, a clock pulse is generated at the output terminals F and G, as shown at F and G- in FIG. As a result, positive and negative pulses, as shown at H in Fig. 2, are applied to a drive coil of the motor M, so that the pulse duration is fully controlled and useful energy is saved since the rotor would not receive any pulse immediately after the completion of a rotating step. The motor coil is shunted with its connections to the energy source V- ^ or the potential V _gs even in the steady state, so that with the drive circuit for the motor according to the invention the oscillation of the motor is rapid after the end of operation or its drive can be attenuated and the output torque becomes larger with high efficiency without increasing the power consumption.

In addition, the invention has the advantage that the rotor can be operated very effectively in a stable manner, since the rotor receives a large switching torque that is instantaneous, large even in the stationary state of the rotor Counteracts disturbances.

- patent claims -

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Claims (2)

Claims / 1 / Drive circuit for a stepper motor that can be used in clocks, wherein the stepping motor for a rotational step a drive pulse from a pulse generator to Drive the clock receives, characterized by a device (FET'en-, R) for determining the termination a step of rotation of the motor (M), by means (A, 1, IW) for ending the duration of the drive pulse, if the locking device the linde of a turning step of the Motor (H) and by means for shorting the motor to a drive output impedance during a period of time when there is no drive. 2. Drive circuit according to claim 1, characterized in that that the device for determining the completion of a rotational step of the motor has a resistance (H), which between an energy source (+ Vtjtj) and the motor (M) is switched, and a voltage drop is induced across the resistor (E) when the motor (M) has finished a turning step. 3. Drive circuit according to claim 1, characterized in that the device for terminating the duration of the drive pulse has a circuit (IN) for generating a reset pulse when the detection device (FET'enj R) detects the end of a rotational step of the motor (M) and that the reset pulse is applied to the generator (F., F ₂ ) in order to block the drive pulse generated by this. 409837/0986