JPS62100196A - Drive circuit for stepping motor - Google Patents

Abstract

PURPOSE:To set the time when a stepping motor can work as a drive source sufficiently long, and to inhibit energy loss by changing frequency so as to acquire predetermined driving torque in response to the variation of supply voltage. CONSTITUTION:When the voltage of a battery 3 is detected by a voltage detecting circuit 4, the detecting value is memorized temporarily to a register 7 for a CPU5. When a drive command signal for a stepping motor 1 is outputted to the register 7 and a pulse generator 10 from a controller 6, the pulse generator 10 is brought to the state of the standby of the starting of operation, and the detecting value memorized to the register 7 is outputted to a frequency generator 8. The frequency generator 8 selects frequency corresponding to the detecting value, supply voltage, from a ROM9, and outputs a signal corresponding to frequency of interest to the pulse generator 10. The pulse generator 10 outputs a signal corresponding to said frequency to a driver 2 by the signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stepping motor drive circuit that is installed in devices and equipment that do not cause functional problems even if the stepping motor does not rotate at a constant speed.

[Conventional technology]

Stepping motors are used in a variety of devices and devices. For example, in printers, stepping motors are used to drive moving objects such as racks that operate a head up-down mechanism that rotates the print head toward and away from the platen. It is used as a driving source. The stepping motor is driven by a stepping motor driver that operates using a battery as a power source, for example.

[Problem that the invention seeks to solve]

By the way, as mentioned above, for example, in a stepping motor drive circuit whose power source is a battery whose voltage changes over time, the drive voltage (Va*v) shown in FIG.
- As shown in the explanatory diagram illustrating the drive torque (T) characteristics, at the initial high drive voltage ■1, the stepping motor was able to obtain a large drive torque T; voltage v2, and correspondingly a small driving torque T2. Therefore, in the case of a printer, for example, if the moving load of the moving object mentioned above becomes larger than this small driving torque T2, the moving object does not move, that is, the printer This resulted in a situation where the printer did not function properly and the battery had to be replaced, resulting in a relatively short operating time for the printer with one battery.

Generally, in order to obtain as long an operating time as possible in consideration of the relationship shown in FIG.
, is set larger than necessary to obtain a larger drive torque TI than necessary, but this causes a large amount of energy loss.

For this reason, conventional stepping motor drive circuits have had problems in terms of economy.

The present invention has been made in view of the actual situation in the prior art, and its purpose is to sufficiently extend the time during which a stepping motor can function as a drive source.
An object of the present invention is to provide a stepping motor drive circuit that can suppress energy loss.

[Means for solving problems]

In order to achieve this object, the present invention uses a detection means for detecting the voltage of a power source such as a battery, and selects a frequency at which a substantially constant driving torque of the stepping motor can be obtained in accordance with the detected value detected by this detection means. A selection/output means is provided, and the stepping motor driver is driven in accordance with the output of the selection/output means.

[Effect]

With the above configuration, in the present invention, when the detected value of the voltage of the power supply detected by the detection means is large, a high frequency is selected and output, and when the detected value changes small, a low frequency is selected and output. is selected and output so that a nearly constant stepping motor driving torque can be obtained at all times. Changes in driving torque due to changes in power supply voltage can be suppressed, and the desired driving torque can be achieved by changing the frequency. can be obtained, so the initial detected value, that is, the voltage of the power supply, does not need to be made larger than necessary.

〔Example〕

Hereinafter, a stepping motor drive circuit of the present invention will be explained based on the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram illustrating functional relationships set in the embodiment shown in FIG.

In FIG. 1, ▪ is a stepping motor, 2 is a stepping motor driver that drives this stepping motor 1, and 3 is a driving power source for this stepping motor driver 2, for example, a battery whose voltage value changes over time. 4 is a detection means that detects the voltage of the battery 3 and outputs it as a signal, that is, a voltage detection circuit; 5 is a central processing unit (
CPU).

The CPU 5 includes a controller 6 that outputs a drive command signal for driving the stepping motor 1, and a voltage detection circuit 4.
a register 7 that temporarily stores the detected value output from the register 7; a frequency generator 8 connected to this register 7;
It includes an OM 9 and a pulse generator 10 that is connected to the controller 6 and the frequency generator 8 and outputs a signal to the stepping motor driver 2.

The above-mentioned ROM 9 stores, for example, as illustrated in the explanatory diagram of FIG. 2, a drive torque T that allows the stepping motor 1 to sufficiently function as a drive source, and a necessary minimum drive torque T. The functional relationship between the detected value (voltage) and frequency that can be obtained is set in advance. For example, as illustrated in FIG. 2, when the voltage is V, the high frequency f1 corresponds, and when the voltage is V2, the low frequency f2 corresponds to the magnitude of the voltage and frequency. It is set in advance with corresponding settings.

The above register 7, frequency generator 8. The ROM 9 and the pulse generator 10 constitute a selection/output means that selects and outputs a frequency at which a substantially constant drive torque T0 of the stepping motor l is obtained in accordance with the detected value output from the voltage detection circuit 4. ing.

In this embodiment, the voltage of the battery 3 is detected by the voltage detection circuit 4.
When detected, the detected value is temporarily stored in the register 7 of the CPU 5. When a drive command signal for the stepping motor 1 is output from the controller 6 to the register 7 and the pulse generator 10, the pulse generator 10 enters a standby state for starting operation, and the detected value stored in the register 7 is output to the frequency generator 10. 8 is output. The frequency generator 8 selects a frequency corresponding to the detected value, that is, the voltage of the power supply, from the ROM 9, and outputs a signal corresponding to the corresponding frequency to the pulse generator 0. The pulse generator 10 thereby outputs a signal corresponding to the above frequency to the stepping motor driver 2, thereby driving the stepping motor 1.

In the stepping motor drive circuit configured in this way, even if the voltage of the battery 3 decreases over time, R
Based on the relationship between the detected value (voltage) set in OM9 and the frequency, the stepping motor driver 2 is driven according to a low frequency that provides a substantially constant driving torque T0 of the stepping motor 1 that can function as a driving source. Therefore, fluctuations in the driving torque of the stepping motor 1 can be suppressed over a long period of time. Therefore, it is possible to set a sufficiently long time during which the stepping motor l can function as a drive source, that is, it is possible to lengthen the operating time of devices such as printers and equipment using one battery 3, and it is also possible to The functional relationship between voltage and frequency is set so as to obtain torque T0, and since the frequency is variable, the initial voltage does not have to be too thick (unnecessary), and energy loss can be suppressed. It is economical because of this.

In the above embodiment, the battery 3 is used as an example of a power source for the stepping motor 1, but the present invention is not limited to this, and the battery 3 can be used instead as long as the voltage can be changed.

Further, the stepping motor drive circuit including the above-mentioned stepping motor 1 is applicable not only to printers but also to various devices,
It goes without saying that the scales apply to equipment.

〔Effect of the invention〕

As described above, the stepping motor drive circuit of the present invention is configured to change the frequency in response to changes in the power supply voltage so as to obtain the minimum required almost constant drive torque, thereby driving the stepping motor driver. Therefore, the time during which the stepping motor can function as a drive source can be set to be sufficiently long, energy loss can be suppressed, and there is an economical effect compared to the conventional method.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the stepping motor drive circuit of the present invention, FIG. 2 is an explanatory diagram illustrating the functional relationships set in the embodiment shown in FIG. 1, and FIG. FIG. 2 is an explanatory diagram illustrating drive voltage-drive torque characteristics. 1...Stepping motor, 2...Stepping motor driver, 3...Battery, 4...
... Voltage detection circuit, 5 ... Central processing unit (CPU), 6 ... Controller, 7 ...
...Register, 8...Frequency generation Figure 1

Claims (1)

[Claims] In a stepping motor drive circuit that includes a power supply whose voltage changes, a stepping motor driver that operates according to the output of this power supply, and a stepping motor driven by this stepping motor driver, the voltage of the power supply is changed. A detection means for detecting and a selection/output means for selecting and outputting a frequency at which a substantially constant driving torque of the stepping motor is obtained corresponding to the detected value detected by the detection means are provided, and this selection/output is performed. A stepping motor drive circuit, characterized in that said stepping motor driver is driven in accordance with an output of said means.