JPH0150320B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for driving a pulse motor used as a spacing motor in printers and the like.

In a pulse motor, its rotation is driven by pulses, so that it rotates by one step each time one electric pulse is applied, and it is necessary to always apply a normal pulse voltage.

(Conventional technology) A conventional example thereof will be explained below.

FIG. 1 is a drive circuit diagram of a pulse motor.

In the figure, 1 is a pulse motor drive circuit, 2 is a pulse motor, _R1 is a coil resistance formed on each pulse motor 2, E is a drive power source for the pulse motor 2, _S1 is a switch of an overdrive circuit, S ₂ ～
S ₅ is a switch for each phase of the pulse motor, T _r1 and T _r1 ′ are transistors for the overdrive circuit switch S ₁ ,
T _r2 to _{T r5} are switches for each phase of the pulse motor S ₂ to _{S 5}
transistor, i is the current flowing in the phase of the pulse motor.

The pulse motor with the circuit configuration above is
It is a two-phase excitation overdrive system, in which the current of the drive source E is converted into a pulse voltage by the pulse motor drive circuit 1, and the pulse application period is also changed, which is applied to each switch _S1 to _S5. The voltage is applied to the two-phase coil of the pulse motor 2 via the pulse motor 2 to rotate the pulse motor 2.

This change in the pulse application period in the pulse motor drive circuit 1 has the effect of changing the rotational speed of the pulse motor 2.

FIG. 2 is a time chart showing conventional pulse motor drive.

In the figure, S ₁ to S ₅ are the configuration switches in FIG. 1, T ₁ is the pulse application period, T ₂ is the overdrive time, and switches S ₁ to _{S 5} are the respective pulse application periods T ₁ This shows the application state of the pulse motor 2 to the pulse motor 2.

In this case, depending on the coil resistance r1 wound around the pulse motor ₂ shown in FIG. 1, the overdrive time _T2 becomes much shorter than the pulse application period _T1 . Therefore, torque ripple occurs in the rotation of the pulse motor 2, resulting in the disadvantage that the pulse motor 2 cannot rotate smoothly.

(Objective of the Invention) Therefore, the object of the present invention is to solve the conventional drawbacks by overdriving voltage or by chopping the energized two-phase coil.

(Structure of the invention) Its characteristics are as follows.

In order to obtain stable rotation during low-speed rotation of the pulse motor, chopping is performed on the switch side of each phase of the pulse motor corresponding to the overdrive time, and the two-phase coil of the pulse motor is not excited for only that time.

Alternatively, perform chopping in response to the overdrive time on the overdrive voltage side,
The purpose is to bring the two-phase coil of the pulse motor into a state in which it is not excited.

This is to prevent the generation of abnormal current by temporarily reducing the current in the two-phase coil of the pulse motor by momentarily interrupting the pulse voltage applied to the pulse motor.

Thereafter, the two-phase coil is excited again until the end of the predetermined overdrive control period.

(Example) Examples of the present invention will be specifically described below using time charts. Note that the explanation in Figure 1 applies mutatis mutandis to the drive circuit diagram of the pulse motor.
Its explanation is omitted here.

FIG. 3 shows a time chart when the pulse motor according to the first embodiment of the present invention rotates at high speed, and the same shows a time chart when it rotates at low speed.

S ₁ to S ₅ are each switch configured in Fig. 1, T ₁ is the pulse application period, T ₂ is the overdrive time, i is the current flowing through the two-phase coil of the pulse motor, and T ₃ is the overdrive time T ₂ T ₄ is the compensation time for switching.

As shown in Figure 3, when the pulse motor rotates at high speed, it is rotated using the same driving method as conventional ones.
The overdrive time T 2 is set so that only the compensation time T ₄ , which is used to prevent spike current from occurring in the two-phase coil of the pulse motor due to the time delay when switching each switch, is applied at the _next switch switching.
This method corresponds to

Therefore, in the case of low-speed rotation of the pulse motor, which is _the main focus of the present invention, as shown in _{FIG .} 2
Chopping T ₃ is performed on the phase coil for its overdrive time T ₂ .

By doing this, the tipping T ₃
The application of the pulse voltage is momentarily interrupted for a time of By supplying smooth current to the two-phase coil of the motor, smooth low-speed rotation of the pulse motor can be achieved.

Of course, the compensation time _T4 at high speed is also used in the same way.

Furthermore, the following second embodiment is available as a method for obtaining the same effects as the first embodiment.

FIG. 4 is a time chart during high-speed rotation of a pulse motor drive, showing a second embodiment of the present invention.
This is a time chart at low speed rotation.

As shown in FIG. 4, in this case as well, when the pulse motor rotates at high speed, the method is the same as in the conventional method, and the compensation time T ₄ performed in the first embodiment is performed in the same manner as in the first embodiment. Here, the method is to release the excitation of the two-phase coil of the pulse motor by turning off the switch _S1 on the overdrive side.

Next, in the case of low-speed rotation shown in Fig. 4, the method is to turn off the switch _S1 on the overdrive side in the same way as in the case of high-speed rotation described above, but the timing of the chopping is different from the low-speed rotation of the first embodiment. In the same way as time, the pulse application period
2 of a pulse motor that is excited within the range of T ₁
In order to prevent the phase coils from being excited, a chopping _T3 is performed on the overdrive _T2 , and the application of current to the two-phase coils of the pulse motor is cut off for that time, thereby canceling the excitation of the two-phase coils. Compensation time _T4 is also performed in the same manner as in the case of high-speed rotation.

Then, as in the first embodiment, the current i flowing through the two-phase coil of the pulse motor becomes lower due to the above-mentioned chopping _T3 , and no abnormal current is applied to the pulse motor, as shown in the figure. 1
As in the embodiment, a smooth current can be applied to the two-phase coil of the pulse motor, and the pulse motor can be smoothly rotated at low speed, thus achieving the same effects as in the first embodiment.

(Effects) As explained above in detail, when the pulse motor rotates at low speed, the switch side or overdrive circuit side of each phase of the pulse motor performs stepping in response to the overdrive time as in the first and second embodiments. By doing this, the excitation of the two-phase coil of the pulse motor is released and the current is reduced at the same time, so it is possible to prevent the generation of abnormal current and apply a smooth current, thereby reducing the torque ripple that occurs when the pulse motor rotates at low speed. It is also possible to solve this problem using an overdrive drive method. Therefore, even an overdrive type pulse motor that rotates at high speed can smoothly rotate at low speed.

In this way, it has become possible to operate at a wide range of rotational speeds from high to low speeds with the same pulse motor, which improves the performance of printers, etc. that adopt the method of this embodiment. .

[Brief explanation of drawings]

Figure 1 is a pulse motor drive circuit diagram, Figure 2 is a conventional pulse motor drive time chart, and Figure 3 is a pulse motor drive circuit diagram.
The figure shows a time chart for high-speed rotation driven by a pulse motor according to the first embodiment of the present invention, the same figure shows a time chart for low-speed rotation, and FIG. 4 shows a time chart for high-speed rotation driven by a pulse motor according to the second embodiment. The figure is a time chart showing the case of low speed rotation. 1...Pulse motor drive circuit, 2...Pulse motor.

Claims (1)

[Claims] 1. A method for driving a pulse motor in a device that rotates the pulse motor at both high and low speeds and performs overdrive control for a predetermined period of time during the excitation period of each phase of the motor, including: During the overdrive control period, the excitation phase continues to be excited by a constant amount, and during low speed rotation, the excitation phase is excited by a predetermined amount during the overdrive control period, and then the excitation is cut off for a predetermined period, and then until the end of the period. A method for driving a pulse motor characterized by re-excitation.