JPH0549299A - Multimode step motor - Google Patents

Abstract

PURPOSE:To provide a multi-mode step motor which can optimally be driven with a plurality of power supply voltages or a plurality of rotational speeds. CONSTITUTION:Each phase driving coil of a step motor 1 is split into sections L1, L3, L5, L7 having high number of turns and sections L2, L4, L6, L8 having low number of turns, and respective driving coils are connected with driving transistors TR1-TR8. Under low speed mode or high voltage mode, the transistors TR1, TR3, TR5, TR7 drive the coils L1, L3, L5, L7 while under high speed mode or low voltage mode, the transistors TR2, TR4, TR6, TR8 drive the coils L2, L4, L6, L8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multimode stepping motor which can be optimally driven at a plurality of power supply voltages or a plurality of rotation speeds.

[0002]

2. Description of the Related Art FIG. 5 shows a connection diagram of a conventional four-phase stepping motor 3 and a drive circuit 4. L1, L3, L
5, L7 are drive coils for each phase, and the drive coils for each phase are drive transistors TR1, TR3, TR5, TR7.
Driven by. When it is necessary to drive this stepping motor with two kinds of voltages, for example, DC6V of battery voltage or DC12V of AC power supply, the stepping motor is made as 6V specification. However, when a 12V power source is used, an unnecessarily large amount of current flows, which causes problems such as heat generation and vibration. When this stepping motor is used for lateral feeding of a carriage of a printer such as a word processor and the printing speed is driven at two speeds, for example, a pulse rate of 1000 pps or 500 pps, the torque is "current" and "coil winding". Since it is proportional to the product of "numbers", driving a motor aligned at 1000 pps at 500 pps will result in extremely low efficiency.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a novel stepping motor which is capable of suppressing heat generation and vibration with respect to a plurality of driving power supplies, and which does not deteriorate in efficiency even if the pulse rate is changed. Is.

[0004]

According to the present invention, a drive coil of a stepping motor is divided into a portion having a large number of turns and a portion having a small number of turns in each phase, and a coil having a large number of turns and a coil having a small number of turns are respectively driven. It is characterized in that a transistor is connected and optimally driven according to a multimode power supply voltage or a rotation speed.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an internal wiring diagram of a coil of a stepping motor according to the present invention and a drive circuit. Hereinafter, an example of unipolar drive as a drive system will be described. In the figure, L1, L3, L5, and L7 are coils with a large number of turns, and L2, L4, L6, and L8 are coils with a small number of turns. Each coil has drive transistors TR1 to T1.
R8 are respectively connected. That is, the coil L1
And a drive transistor TR1, a coil L3 and a drive transistor TR2, a coil L5 and a drive transistor TR5, a four-circuit configuration including a coil L7 and a drive transistor TR7, and a coil L2 and a drive transistor TR2, a coil L4 and a drive transistor TR4, and a coil L6. And drive transistor TR6, coil L8 and drive transistor TR
It has an eight-circuit configuration of eight.

The present invention will be described below with reference to an example of driving at two rotation speeds or two power supply voltages (two-mode driving). By the way, the torque of the motor is proportional to the product of the current flowing through the drive coil and the number of turns of the drive coil (ampere turn). When the stepping motor of the present invention is driven at high speed (1000 pps), the ON time of the drive transistor of each phase becomes short. Therefore, if the number of turns of the coil is too large, the inductance becomes large and the coils L1 and L
When 3, L5, and L7 are driven by a drive circuit (hereinafter, referred to as a first drive circuit) including a drive transistor TR1, a drive transistor TR3, a drive transistor TR5, and a drive transistor TR7, as shown by a curve A in FIG. The current flowing through each drive coil does not rise sufficiently within the on-time T2.

Therefore, in order to reduce the number of turns of the coil and improve the rising characteristics, the coil L having a small number of turns is used.
2, L4, L6, and L8 are drive transistors TR, respectively.
2, drive transistor TR4, drive transistor TR
6, a drive circuit including a drive transistor TR8 (hereinafter,
When driven by a second drive circuit), the rising characteristics of the current flowing through the drive coil are improved as shown by the B curve in FIG. 2, and the drive transistors TR2, TR4, TR6, T
It is possible to drive by increasing the current flowing through the drive coil within the time T2 when R8 is turned on.

However, when the motor is driven at a low speed by the second drive circuit (500 pps), the on time of the drive transistor becomes T1, which is twice T2, so that the current flowing through the drive coil increases and the current consumption increases. To do. Therefore, when the second drive circuit is switched to the first drive circuit to increase the number of windings of the coil to reduce the current flowing in the drive coil, the same torque can be obtained and power saving drive can be performed. Become.

In the present invention, the driving with respect to the rotational speed of the two modes has been described as the driving condition. Next, the mode of driving with the first driving circuit and the second driving circuit at the power supply voltage of the two modes as the driving condition will be described. ..
As described above, the torque of the stepping motor is proportional to the product of the current flowing through the drive coil and the number of turns of the drive coil. When the power source is in the low voltage mode, the current rising characteristic is prioritized, so that the rising characteristic of the current flowing through the driving coil is made steep by using the driving circuit 2, and when the power source is in the high voltage mode, the first driving is performed. By using a circuit, the same torque can be obtained even if the current flowing through the drive coil is reduced, and optimal drive is possible.

FIG. 4 shows an example of a pulse pattern for two-phase excitation. In FIG. 4, A of FIG. 4 is a pulse pattern of two-phase excitation applied to the drive transistors TR1, TR3, TR5 and TR7 of the drive circuit 1 in the low speed mode or the high voltage mode, and the pulse width is the ON time. Matches T1. At this time, the driving transistors TR2 and T
Since R4, TR6 and TR8 are not turned on, there is no pulse. In addition, FIG. 4B shows the driving transistors TR2, TR4, TR in the high speed mode or the low voltage mode.
6 、 Two-phase excitation pulse pattern applied to TR8,
The pulse width matches the ON time T2. At this time, the driving transistors TR1, TR3, TR5, and TR7 are not turned on, so that there is no pulse. Although the present invention has been described as a unipolar drive system as an embodiment, it can be implemented by a bipolar drive system, and the number of windings of the drive coil is not limited to two, and the drive transistor can be further divided. It is also possible to connect and implement.

Next, when the number of windings of the drive coil is divided and used, as shown in FIG. 3, in order to obtain the required number of windings and increase the space factor to increase the number of windings. The drive coil L7 of FIG. 1 will be described as an example.
Among them, the portion L8 is made thicker and the portion L9 is made thinner to change the wire diameter, thereby increasing the space factor and increasing the torque. The wire diameter may be reversed.

[0012]

According to the present invention, in each mode, heat generation, vibration, and power loss can be minimized for optimum driving, and the space factor can be increased, so that torque can be increased. ..

[Brief description of drawings]

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

FIG. 2 is a characteristic diagram illustrating an operation of the present invention.

FIG. 3 is a sectional view of the wire diameter of the drive coil of the present invention.

FIG. 4 is a diagram showing a pulse pattern for two-phase excitation of the present invention.

FIG. 5 is a circuit diagram of a conventional example.

[Explanation of symbols]

1. Stepping motor 2. Drive circuit L1 to L
8 ... Drive coil TR1-TR8 ... Drive transistor

Claims (1)

[Claims] 1. A driving coil of a stepping motor is divided into a portion having a large number of turns and a portion having a small number of turns in each phase, and a driving transistor is connected to each of the coil having a large number of turns and the coil having a small number of turns to provide a multi-mode coil. A multi-mode compatible stepping motor which is optimally driven according to a power supply voltage or a rotation speed.