JPH06245594A - Stepping motor starting control method - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a stepping motor start control method, and an object of the present invention is to provide a stepping motor start control method capable of reliably correcting the position between a stator and a rotor at low cost and in a small space. To do. [Structure] A stator 1 arranged in a circle is provided with m-phase exciting coils L _{1 to} Lm, and when a stepping motor rotationally driven by applying a pulse signal with a predetermined phase shift to the exciting coils is started, Initial startup excitation by applying m pulses each in sequence in the rotational arrangement direction of each excitation coil, with a pulse signal having a pulse width equal to or less than a value obtained by dividing the period T of the self-starting frequency region of the stepping motor by m. The position of the specific magnetic pole of the rotor 2, which is the origin of rotation, is set with respect to the excitation coil for pulse application.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor synchronous control method used for sheet conveyance and the like, and more particularly to a stepping motor start control method capable of accurately positioning a stepping motor with an uncertain initial position. .

In recent years, there has been a demand for improvement in the processing speed of electrophotographic apparatuses and the like, and along with this, there has been a demand for high-speed sheet conveyance and precise control of the conveyance amount.

[0003]

2. Description of the Related Art FIG. 4 shows a starting characteristic diagram of a conventional stepping motor. This characteristic diagram shows pulse frequency on the horizontal axis, load torque on the vertical axis, pull-in torque characteristics when used within the self-starting frequency range that is less than the maximum self-starting frequency that can be started without misstep, and stepping motor. It shows the relationship of escape torque characteristics when used in the through region because it is used at high speed rotation.

When used within the maximum self-starting frequency f, the pull-in torque is always large regardless of the positional relationship between the stator of the stepping motor and the pole teeth of the rotor. , The stator and rotor pole teeth are automatically synchronized and the motor starts rotating.

However, in order to increase the rotation speed, first, the pulse control is performed by starting in the self-starting frequency region below the maximum self-starting frequency f, gradually increasing the frequency of the exciting pulse, and then driving in the through region ( (Through-up control) is required, but when the frequency is increased as shown in the figure, the pull-in torque also decreases.

When this pulse control is performed, the pull-in torque is generated when the stator excited by the excitation pulse and the rotor are attempting to synchronize with each other unless the relationship between the stator of the stepping motor and the pole teeth of the rotor before starting is known. Insufficient stepping motor causes step out, or the specified amount of paper cannot be fed due to a misstep.

Therefore, in order to recognize the relational position of the pole teeth of the stator and the rotor before starting the stepping motor, an encoder that outputs an output pulse corresponding to the step angle of the stepping motor coaxially with the rotor (not shown) is set to the step angle. They were mounted so as to be synchronized with each other, and the pulse signal output from the encoder was used to recognize the relative position of the stator and the pole teeth of the rotor before the start-up, and perform the start-up control in which an exciting pulse suitable for the position was applied.

Alternatively, a mechanical lock structure is provided, and when the position of the pole teeth of the stator and the rotor at the time of start-up is mechanically locked, the position of the pole teeth is fixed, or the rotor has stator pole teeth. When it is stopped at the neutral point between the adjacent stator pole teeth and the adjacent stator pole teeth, excitation is performed on the adjacent stator of the pole teeth of the stator as the origin of rotation as described in JP-A-58-36195. A method is known in which a call is made and a position is corrected.

[0009]

According to the above-mentioned conventional positional relationship recognizing means for a rotor, a mounting space is structurally required and the number of parts such as memory elements is increased, which hinders downsizing of the apparatus and increases the cost. However, if the rotor is far away from the pole teeth of the stator, which is the starting point, there is a problem that the position cannot be corrected.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is a low-cost, space-saving method and can reliably ensure a space between the stator and the rotor even when the rotor is largely separated from the pole teeth of the stator, which is the starting point. An object of the present invention is to provide a stepping motor start control method capable of position correction.

[0011]

In order to achieve the above object, as shown in FIG. 1, stators 1 arranged in a circumferential shape are arranged.
Is provided with m-phase exciting coils L _{1 to} Lm, and when a stepping motor that is rotationally driven by applying a pulse signal having a predetermined phase shift is applied to the exciting coil, the cycle T of the self-starting frequency region of the stepping motor is set. A pulse signal having a pulse width equal to or smaller than the value divided by m is sequentially applied to the exciting coils one by one in the rotational arrangement direction of each exciting coil, so that the starting point of rotation is set to the exciting coil for initial starting exciting pulse application. The rotor 2 is configured to set the position of the specific magnetic pole.

[0012]

FIG. 1A shows the case where the number of phases is m = 4, where the position where the magnetic pole S of the rotor 2 faces the exciting coil L ₁ is the origin position of rotation when the stepping motor is started,
The rotation direction of the rotor 2 is clockwise, and the magnetic teeth are magnetized to the N pole by applying a pulse to each exciting coil, and the maximum self-starting frequency is set to f. It is defined as 1 / f.

In the case of FIG. 7A in which the position of the magnetic pole S of the rotor 2 before starting is located between the exciting coil L ₂ and the exciting coil L ₃ , the pulse signal φ shown in FIG. by applying ₁ (pulse signal having one pulse of pulse width less period T / m) to the exciting coil L _1,
Pole N of the rotor 2 is opposite to the exciting coil L ₄ is repelled, then the pulse signal phi ₂ (pulse signal having one pulse of the pulse signal phi ₁ follows the period T / m or less of the pulse width of the pulse ) Is applied to the exciting coil L ₂ ,
The magnetic pole S of the rotor 2 is attracted and faces the exciting coil L ₂ .

Thereafter, similarly, the magnetic pole S of the rotor 2 is sequentially attracted to the exciting coils L ₃ and L ₄ corresponding to the application of the pulse signals φ ₃ and φ ₄ , and the origin position of rotation is set. When the application of m pulses is completed, the magnetic pole S is at a position where the first pulse of the conventional starting excitation pulse to be applied next attracts the magnetic pole S without fail (here, the position facing the exciting coil L ₄ ). Is set to. After that, the start-up rotation can be reliably performed by the conventional start-up drive method.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings. In addition, in order to make the description of the configuration and operation easy to understand, the same reference numerals are given to the same portions throughout the drawings, and the duplicated description thereof will be omitted.

FIG. 1 is a diagram for explaining the starting control process of the present invention, which is adapted to an example of driving a permanent magnet type four-phase stepping motor called PM type by a two-phase excitation method. FIG. 1 (a) is a diagram showing changes in relative positions of the pole teeth of the stator and rotor, FIG. 1 (b) is a drive voltage waveform diagram supplied to each exciting coil, and FIG. 1A will be described with reference to FIG.

In both figures, 1 is a stator of a stepping motor, 2 is a rotor, 3 is pole teeth facing each other between the stator and L _{1 to} L ₄ are formed on a stator 1 arranged in a circumferential shape. An exciting coil of m phase (an example when m = 4) is shown. Here, the position of the magnetic pole S of the rotor 2 facing the tooth pole 3 of the exciting coil L ₁ is defined as the origin of rotation when the stepping motor is started, and the rotor 2 defines the magnetic pole N and the magnetic pole S of a pair of permanent magnets. Be prepared for the direction.

The pulse signals φ _{1 to} φ shown in FIG.
₄ shows a waveform of the pulse signal applied to the exciting coil L ₁ ~L ₄ respectively. In addition, the drive voltage waveforms of the pulse signals φ _{1 to} φ ₄ applied to the respective excitation coils L _{1 to} L ₄ are
When it is ON, the pole tooth 3 corresponding to the drive voltage ON and the exciting coil facing the rotor is magnetized to the N pole.

The drive voltage waveforms of the pulse signals φ _{1 to} φ ₄ are within a cycle T in which a pulse having a pulse width equal to or smaller than a value obtained by dividing the cycle T used in the self-starting frequency region of the stepping motor by m is used. It is a pulse signal having one pulse each. The array of pulse width signals of T / m or less formed in each of the pulse signals φ _{1 to} φ ₄ shows a waveform without a pulse interval (space area), but it is not limited to this, and a slight space There may be areas.

The pulse signals φ _{1 to} φ formed in this way
Excitation coils L _{1 to} L ₄ for m pulses of ₄ pulses one by one
By applying in the rotational arrangement direction of, it is possible to set the position of the specific magnetic pole of the rotor 2 which is the origin of rotation with respect to the exciting coil for applying the initial starting exciting pulse.

Each exciting coil L _{1 to} L ₄ is four (1
Pulse signal of each e) each excitation coil L ₁ sequentially
~L the sequentially the m partial one pulse in the rotational direction of arrangement of the exciting coil ₄ only be applied separately. The pulse signals φ _{1 to} φ ₄ (at each timing of applied ro-ho) corresponding to the first movement of the motor are called a dummy pulse train.

Next, the relative positional relationship between each exciting coil on the stator 1 side and the N magnetic pole or the S magnetic pole on the rotor 2 side will be described in correspondence with the pulse waveforms of the motor movements shown in FIG. explain. The timing shown in FIG. 6B shows the timing before the pulse signal is applied to each exciting coil, that is, the timing in the non-application state. At this time, the position of the N magnetic pole of the rotor 2 is shown in FIG. As shown in the above case, it is assumed that they are positioned facing each other in the middle of the exciting coil L ₁ and the exciting coil L ₄ .

[0023] For figure (b) B pulse signal phi ₁ pulse shown in the timing of the pole teeth 3 of the exciting coil L ₁ by first applied to the exciting coil L ₁ is to be magnetized to the N pole, the rotor 2 The magnetic pole N is repulsed by the exciting coil L ₁ and the exciting coil L ₄
The magnetic pole S of the rotor 2 is attracted by the pole teeth of the exciting coil L ₂ to face each other by applying the pulse of the pulse signal φ ₂ shown in the timing c to the exciting coil L ₂ next.

Next, the pulse signal φ ₃ shown at the timing d
By applying the pulse to the exciting coil L ₃ , the magnetic pole S of the rotor 2 is attracted by the pole teeth of the exciting coil L ₃ and faces each other. Similarly, the pulse signal φ ₄ shown at the timing of e
By applying the pulse to the exciting coil L ₄ , the magnetic pole S of the rotor 2 is attracted by the pole teeth of the exciting coil L ₄ and faces each other. In this way, the position of the magnetic pole S of the rotor 2 approaches the pole tooth 3 of the exciting coil L _{1 serving as} the origin while rotating in a predetermined rotation direction during one rotation.

At the time when the excitation timing section of the dummy pulse train ends, the application of the starting excitation pulse is switched by the original two-phase excitation method, for example. That is, at the timing shown in FIG. 1B, by applying the first pulse of the pulse signal φ ₁ to the exciting coil L ₁ , the magnetic pole S of the rotor 2
Faces the pole tooth 3 of the exciting coil L ₁ which is the starting point as shown in the position in FIG.

Next, at the timing of FIG. 1 (b),
By applying the two-phase pulse signals of the pulse signal φ ₁ and the pulse signal φ _{2 to} the exciting coil L ₁ and the exciting coil L ₂ , respectively, the magnetic pole S of the rotor 2 is excited as shown in the position of FIG. Face the intermediate position between coil L ₁ and exciting coil L ₂ .

Next, at the timing shown in FIG.
By applying the two-phase pulse signals of the pulse signal φ ₂ and the pulse signal φ _{3 to} the exciting coil L ₂ and the exciting coil L ₃ , respectively, the magnetic pole S of the rotor 2 is excited as shown in the position of FIG. Face the intermediate position between the coil L ₂ and the exciting coil L ₃ .

Similarly, no matter what position of the magnetic pole S is stopped before the start-up, m pulse signals φ _{1 to} φ ₄ are sequentially applied to the exciting coils L _{1 to} L ₄ one pulse by one pulse. By applying the exciting coil L _{1 to} L _{4 in} the rotational arrangement direction by the amount, the specific magnetic pole of the rotor can be set at the origin of rotation, and thereafter, the conventional driving method can be reliably transferred.

FIG. 2 is a layout view of the exciting coils of the stepping motor of the present invention, which is one detailed view of FIG. 1 (a),
FIG. 3 shows a basic circuit diagram for driving the exciting coil of the present invention,
3 will be described below with reference to FIG. In FIG. 2 C shows the common connection terminals of the exciting coils L ₁ ~L _4.

In FIG. 3, 4 is a pulse distributor,
Input a pulse train signal with a constant period and
When the pulser has m excitation coils,
The required pulse signal is extracted from the force signal into m series, and m = 4
In case of, pulse signal φ₁~ Φ _FourWith the function of distributing to
The pulse width at which each pulse signal is turned on is shown in Fig. 1 (b).
It will be less than T / m as shown in the dummy pulse train.
Form and distribute.

Reference numeral 5 denotes a power source (for example, direct current power source), Q _{1 to} Q ₄ denote switching transformers, and each pulse signal φ ₁
When the pulse of ~ φ ₄ is turned on, it is energized, and the exciting current is applied to the exciting coils L _{1 to} L ₄ connected in series. The stepping motor starting control of the present invention can be performed by using the basic circuit configured as described above.

[0032]

As is apparent from the above description, according to the present invention, missteps are eliminated and parts (encoder or the like) for recognizing the positional relationship between the rotor and the stator are not required, resulting in downsizing of the apparatus and low cost. Is effective in

[Brief description of drawings]

FIG. 1 is a diagram for explaining a startup control process of the present invention.

FIG. 2 is a layout diagram of excitation coils of a stepping motor according to the present invention.

FIG. 3 is a basic circuit diagram for driving an exciting coil according to the present invention.

FIG. 4 is a starting characteristic diagram of a conventional stepping motor.

[Explanation of symbols]

L _{1 to} L ₄ Excitation coil φ _{1 to} φ ₄ Pulse signal 1 Stator 2 Rotor 3 Pole tooth 4 Pulse distributor 5 Power supply

Claims (1)

[Claims] 1. A stator (1) which is arranged in a circle, is provided with m.
Phase exciting coil (L _{1 to} Lm) is provided, and when a stepping motor that is rotationally driven by applying a pulse signal with a predetermined phase shifted to the exciting coil is started, the cycle T of the self-starting frequency range of the stepping motor is set. A pulse signal having a pulse width equal to or smaller than the value divided by m is sequentially applied to the exciting coils one by one in the rotational arrangement direction of each exciting coil, so that the starting point of rotation is set to the exciting coil for initial starting exciting pulse application. A stepping motor start-up control method characterized by setting the position of a specific magnetic pole of the rotor (2).