JPH0191698A - Pulse motor controlling circuit - Google Patents

Abstract

PURPOSE:To contrive the heat generation of an equipment with a mounted pulse motor, not to be too much excessive even at the time of a high temperature, by setting hold current according to an ambient temperature. CONSTITUTION:With a temperature detecting circuit 40, an ambient temperature is detected by using a temperature sensor. According to the ambient temperature detected with the temperature detecting circuit 40, hold current is set by a hold current setting means 50. By a hold current varying means 20 in a pulse motor driving circuit 10, hold current flowing to the exciting coil of a pulse motor is variably controlled according to a set value. Accordingly, also at the time of a high temperature, the heat generation of an equipment with the mounted pulse motor can be contrived not to be too much excessive, even at the time of a high temperature, and according to proper radiation designing, the equipment can be designed.

Description

[Detailed description of the invention] 〔overview〕 The present invention relates to a pulse motor control circuit.

The purpose is to prevent the hold current and drive current of the pulse motor from becoming larger than necessary at high temperatures.

The pulse motor drive circuit is equipped with a temperature detection circuit that detects the ambient temperature and a hold current setting means that sets a hold current according to the ambient temperature detected by the temperature detection circuit. The hold current variable means variably controls the flowing hold current, and the hold current variable means applies a voltage to the excitation coil of the pulse motor according to the setting of the hold current setting means when the pulse motor is in a stopped state. It is configured so that a small hold current flows as the temperature increases.

Furthermore, the present invention.

The present invention includes a temperature detection circuit that detects ambient temperature, and drive current setting means that sets a drive current according to the ambient temperature detected by the temperature detection circuit.

The pulse motor drive circuit includes drive current variable means for variably controlling the drive current flowing through the excitation coil of the pulse motor, and the drive current variable means adjusts the drive current setting means when the pulse motor is in the drive state. According to the setting, a small drive current is controlled to flow through the excitation coil of the pulse motor as the ambient temperature increases.

[Industrial application field]

The present invention provides a pulse motor control circuit that makes it possible to hold the pulse motor with a hold current that matches the load state of the surrounding environment, and a drive current that matches the load state of the pulse motor. The present invention relates to a pulse motor control circuit that makes it possible to drive a pulse motor.

Pulse motors, which are widely used to control the positioning of image scanners, printer carriers, etc., are driven by passing a drive current through an excitation coil according to a predetermined phase excitation sequence. Holding is performed by passing a hold current through the drive current or hold current, but if the current value of the drive current or hold current is set to a value larger than necessary, heat generation will increase accordingly, so a pulse motor is implemented. The problem arises that the main body of the device cannot be made smaller. From now on, the drive current for driving the pulse motor and the hold current for holding the pulse motor need to be set at appropriate current values.

[Conventional technology]

Pulse motor drive circuits are classified based on the method of passing drive current to the excitation coil, and are divided into two types: unipolar drive, in which drive current is passed through the excitation coil in only one direction, and bipolar drive, in which drive current is passed alternately in both directions through the excitation coil. There are two types of drive methods: the constant voltage drive method, which generates the drive current by connecting a constant voltage power supply to the excitation coil, and the constant voltage drive method, which generates the drive current by connecting a constant voltage power source to the excitation coil. There are two drive methods: a constant current chopper drive method that performs chopper control so that the current is constant. Furthermore, constant current chopper drive methods include a passive chopper method that creates a chopper by superimposing a triangular AC signal on a DC reference voltage, and an automatic chopper method that creates a chopper using positive feedback from a comparator. There are two methods.

Conventional pulse motor drive circuits are configured so that the drive current flowing through the excitation coil has a predetermined constant value no matter which combination of these drive methods is used. When holding the rotating shaft of the pulse motor, this holding is achieved by passing a hold current having a smaller value than the drive current through the excitation coil.

In this conventional pulse motor drive circuit.

This hold current was also configured to be executed with a predetermined constant value.

[Problem that the invention seeks to solve]

However, in the conventional technology that realizes hold of a pulse motor with a hold current showing a constant value, for example, when a pulse motor is equipped with a flat cable and is used for positioning control of a printer head, 2. To be able to hold the printer head against the return force or repulsion force based on a more hardened flat cable at low ambient temperatures.

It was necessary to set the hold current at a value greater than that required at high ambient temperatures. Therefore, even at high temperatures, which do not require much hold current, a hold current of the same magnitude as at low temperatures will flow, resulting in increased heat generation from the pulse motor and power supply, which will be necessary for equipment in which pulse motors will be mounted. There was a problem in that compactness was hindered by forcing a heat dissipation design with more leeway.

Furthermore, in conventional technology in which a pulse motor is driven with a drive current that exhibits a constant value, the load on the drive unit that uses the pulse motor generally decreases as the ambient temperature decreases. This is because it shows the property of increasing.

In order to be able to drive the drive unit against high loads at low temperatures, it was necessary to set the drive current at a value larger than that required at high ambient temperatures. . Therefore, even at high temperatures, which do not require much drive current, the same drive current flows as at low temperatures, which similarly forces a heat dissipation design with more leeway than necessary, making it more compact. There were problems in that the traffic was obstructed and the noise became loud.

The present invention has been made in view of such circumstances, and by preventing the hold current and drive current of the pulse motor from becoming larger than necessary at high temperatures, the present invention is designed to prevent the hold current and drive current of the pulse motor from becoming larger than necessary at high temperatures. The aim is to provide a pulse motor control circuit that does not require a generous heat dissipation design.

[Means for solving problems]

FIG. 1 is an explanatory diagram of the principle of the present invention.

In the figure, 10 is a pulse motor drive circuit, 20 is a hold current variable means, 40 is a temperature detection circuit, and 50 is a hold current setting means.

The pulse motor drive circuit 10 is a drive circuit that drives the pulse motor by passing a drive current through the excitation coil of the pulse motor according to a predetermined phase excitation sequence, and when holding the rotation axis of the pulse motor, the excitation coil This is done by applying a hold current to.

The hold current variable means 20 is a pulse motor drive circuit 1
This is a means for variably controlling the hold current flowing through the excitation coil of the pulse motor included in the motor. The temperature detection circuit 40 is a temperature detection circuit that detects ambient temperature using a temperature sensor. The hold current setting means 50 is a means for setting a hold current according to the ambient temperature detected by the temperature detection circuit 40, and the hold current variable means 20 is a means for setting a hold current according to the ambient temperature detected by the temperature detection circuit 40. Execute control to achieve it.

FIG. 2 is a detailed explanatory diagram of the present invention.

In the figure, 10 is a pulse motor drive circuit, 30 is a drive current variable means, 40 is a temperature detection circuit, and 60 is a drive current setting means.

The pulse motor drive circuit 10 is a drive circuit that drives a pulse motor by passing a drive current through an excitation coil of the pulse motor according to a predetermined phase excitation sequence. The drive current variable means 30 is.

This is means for variably controlling the drive current flowing through the excitation coil of the pulse motor included in the pulse motor drive circuit 10. The temperature detection circuit 40 is a temperature detection circuit that detects ambient temperature using a temperature sensor. The drive current setting means 60 is a means for setting a drive current according to the ambient temperature detected by the temperature detection circuit 40, and the drive current variable means 30 is a means for setting a drive current according to the ambient temperature detected by the temperature detection circuit 40.

Control is executed so that the drive current set by the drive current setting means 60 is realized.

[For production]

In the hold current control circuit for a pulse motor of the present invention, the hold current setting means 50 sets a hold current value that becomes smaller as the ambient temperature becomes higher, and the hold current variable means 20 sets a hold current value that becomes smaller as the ambient temperature becomes higher. When the motor is in a stopped state, a small hold current is controlled to flow through the excitation coil of the pulse motor according to the settings of the hold current setting means 50 as the ambient temperature becomes higher.

As described above, according to the hold current control circuit for a pulse motor of the present invention, the hold current does not become larger than necessary even when the ambient temperature is high.
It becomes possible to design equipment that mounts a pulse motor according to an appropriate heat dissipation design.

Further, in the pulse motor drive current control circuit of the present invention, the drive current setting means 60 sets a drive current value that becomes smaller as the ambient temperature becomes higher.

The drive current variable means 30 controls such that a small drive current flows through the excitation coil of the pulse motor as the ambient temperature increases, according to the settings of the drive current setting means 60 when the pulse motor is in the drive state. do.

In this way, according to the pulse motor drive current control circuit of the present invention, the drive current does not become larger than necessary even when the ambient temperature is high, so the pulse motor can be mounted according to an appropriate heat dissipation design. Not only will it be possible to design equipment, but it will also be possible to suppress noise.

〔Example〕

The present invention will be described in detail below with reference to one drawing.

FIG. 3 is a configuration diagram of an embodiment for realizing a hold current control circuit and a drive current control circuit according to the present invention. This embodiment shows an example in which the present invention is applied to a bipolar constant voltage drive system. First, a case where the circuit operates as a hold current control circuit will be described.

In FIG. 3, 10 is a pulse motor drive circuit.

20a is a transistor which is the hold current variable means 20, 40 is a temperature detection circuit, and 50 is a hold current setting means. The pulse motor drive circuit 10 is.

Basically, it corresponds to a conventional bipolar drive constant voltage drive type pulse motor drive circuit, and the excitation coil L1 of the pulse motor and the direction of flow of current for A-phase excitation and A-phase excitation are connected to this L1. Transistor Ql to realize
, Q2. Q3. With Q4.

Flyba 7 to eliminate energy remaining in Ll
diode DI, D2. D3. It is equipped with D4. The temperature detection circuit 40 includes a series connection of a thermistor indicated by 41 and a resistor indicated by 42, and a divided voltage generated when a DC voltage is applied to this series connection by an A/D converter.
It is composed of an A/D converter 43 that converts the temperature, and detects the ambient temperature at the location where the thermistor 41 is placed.

The hold current setting means 50 controls the A/
51 that reads the converted value of the D converter 43, calculates the detected temperature by calculation, and outputs a digital value for realizing a hold current corresponding to the detected temperature.
From a microprocessor indicated by , a D/A converter indicated by 52 which converts the digital output value of this microprocessor 51 into a D/A, and an operational amplifier indicated by 53 which amplifies the entire analog output of this D/A converter 52. configured.

The base of the transistor 20a is connected to the operational amplifier 53, so that the pulse motor drive circuit 1
0 is configured to control the level of the DC voltage supplied to the DC voltage.

Next, the operation of the embodiment of FIG. 3 constructed in this way will be explained. When the pulse motor is in a driving state, a phase excitation sequencer (not shown) is activated.

When Ql and Q4 are ON, Q2. By periodically and repeatedly selecting A-phase excitation where Q3 is OFF and human-phase excitation where Q1 and Q4 are OFF and 02°Q3 is ON, direct current is applied to the excitation coil L1 via the transistor 20a. A voltage (VH) is connected, a drive current flows, and the pulse motor is driven.

At this time, the microprocessor 51 operates the operational amplifier 53
D/A converter 5 so that the output of
A digital value is output to the transistor 20a, and this output increases the base current of the transistor 20a.
is set to be in the saturated 6M range, so a large DC voltage approximately close to VH is applied to the exciting coil L1, causing a large drive current to flow.

When it becomes necessary to stop the rotation of the pulse motor and hold the rotation axis of the pulse motor at a predetermined position, the microprocessor 51 sets D so that the output of the operational amplifier 53 becomes a voltage higher than the LO level. A digital value is output to the /A converter 52. Here, the output of this digital value is set so that when the ambient temperature detected by the temperature detection circuit 40 is high, the output of the operational amplifier 53 becomes a higher voltage, and when the ambient temperature is low, the output of the operational amplifier 53 is set to a higher voltage. is configured so that the voltage is set to a lower voltage. The output of operational amplifier 53 is L
When the voltage is set to be lower than O level.

The base current of the transistor 20a decreases, and the collector-emitter voltage VCE of the transistor 20a increases, so the DC voltage applied to the excitation coil L1 decreases and the pulse motor can be held with a hold current smaller than the drive current. It will be executed. At this time, the output of the operational amplifier 53 is set to be a higher voltage when the ambient temperature is high, so the hold current becomes smaller and the output of the operational amplifier 53 is set to a higher voltage when the ambient temperature is higher. If the temperature is low, the voltage is set to be lower, so the hold current becomes larger.

Therefore, by using the hold current control circuit of the present invention that operates in this manner, 1. For example, when a high load is applied at low temperatures due to hardening of a flat cable, a reliable hold can be achieved by increasing the hold current. At the same time, the hold current becomes smaller for low loads at high temperatures, thereby making it possible to prevent excess heat generation.

In the above explanation, the case where the configuration of FIG. 3 operates as a hold current control circuit of the present invention has been explained.
And, if the transistor 20a is replaced with the drive current variable means 30 of FIG.

This configuration operates as the drive current control circuit of the present invention. That is, when the pulse motor is driven, the microprocessor 51 controls the D/A converter 52 so that the output of the operational amplifier 53 becomes the LO level.
Rather than outputting a digital value to the temperature detection circuit 4
By adopting a configuration in which the output of the operational amplifier 53 is set to a voltage lower than the LO level level when the ambient temperature detected by the 0 is high, the drive current is not increased unnecessarily at high temperatures. You will be able to do this. Therefore, by using the drive current control circuit of the present invention that operates in this manner, 1. For example, when the drive unit is under high load at low temperatures due to the viscosity of the lubricating oil, the drive current increases, thereby ensuring reliable drive. In addition to this, the drive current is reduced for low loads at high temperatures, thereby preventing excess heat generation.

FIG. 4 is a block diagram of another embodiment for realizing a hold current control circuit and a drive current control circuit according to the present invention. This embodiment shows an example in which the present invention is applied to a unipolar constant voltage drive system. Since the pulse motor drive circuit 10 in FIG. 4 is the same as the conventional technology, a detailed explanation will be omitted, but in short, the transistor Q5
A-phase excitation of the pulse motor and human phase TiJJ magnetization are realized in the 0N10FF state of Q6, and the magnitude of the current value of the drive current at this time is determined by the ON of these transistors.
Since the state is effectively realized by 0N10FF pulses, it is determined by the duty ratio of the pulses. Also, when holding the pulse motor, the hold is executed with an effective hold current that is determined by the duty ratio of this pulse.

In the hold current control circuit of the present invention shown in FIG.
The setting of the hold current according to the ambient temperature is determined by the duty ratio of the pulse sent out by the microprocessor 51 of the hold current setting means 50. That is, when the temperature detection circuit 40 detects a high ambient temperature, the microprocessor 51 sends out a pulse with a small duty ratio to set the hold current to a small value. This is achieved by sending out large pulses and setting a large hold current. In addition.

In this configuration, transistors Q5 and Q6 correspond to the hold current variable means 2o shown in FIG.

AND gate 54 constituting hold current setting means 50
, 55 are transistors Q5. Provided for selecting Q6.

The configuration shown in FIG. 4 is also the same. If the hold current variable means 20 is replaced with the drive current variable means 30 and the hold current setting means 50 is replaced with the drive current setting means 60.

This configuration operates as the drive current control circuit of the present invention.

FIG. 5 is a block diagram of another embodiment for realizing the hold current control circuit and drive current control circuit of the present invention. This embodiment shows an example in which the present invention is applied to a bipolar drive automatic constant current chopper drive system. Since the pulse motor drive circuit 10 in FIG. 5 is the same as the conventional technology, a detailed explanation will be omitted, but in short, the drive current is converted into voltage by the current detection resistor R1, and this voltage is converted to a hysteresis characteristic by positive feedback. Comparator C
The transistor is set to 0 by comparing it with a constant reference voltage at MP 1.
N10FFL, the drive current is chopper-controlled so that the voltage drop across the current detection resistor R1 becomes this reference voltage. Therefore, the magnitude of the drive current is set by setting the voltage level of the reference voltage, and the hold current for holding the pulse motor is also set by setting the voltage level of this reference voltage. That will happen.

In the hold current control circuit of the present invention shown in FIG.
How to set the hold current according to the ambient temperature.

It is determined by the digital value of the reference voltage that the microprocessor 51 sends to the D/A converter 52. That is, when the temperature detection circuit 40 detects a high ambient temperature, the microprocessor 51 sets a lower reference voltage and a smaller hold current, and when it detects a lower ambient temperature, the microprocessor 51 sets a higher reference voltage. This is achieved by setting the hold current to a relatively large value. Note that in this configuration, transistor Q3 (transistor Q4 for human phase excitation)
) corresponds to the hold current variable means 20 shown in FIG.

The configuration shown in FIG. 5 is also the same. If the hold current variable means 20 is replaced with the drive current variable means 30 and the hold current setting means 50 is replaced with the drive current setting means 60.

This configuration operates as the drive current control circuit of the present invention.

In the embodiment described above, an example is shown in which the hold current setting means 50 and the drive current setting means 60 are configured by a microprocessor, but the present invention is not limited to this, and can be realized by a hardware circuit. It is also possible. The simplest example of implementation using this hardware circuit is to simply connect the divided voltage generated by the series connection of a thermistor and a resistor to the hold current variable means 20 or the drive current variable means 30 as it is.

It is also possible to realize the hold current control circuit and drive current control circuit of the present invention. In the present invention having such a configuration, the hold current setting means 50 is connected to the temperature detection circuit 40.
At the same time, the drive current setting means 60 is incorporated into the temperature detection circuit 40.

〔Effect of the invention〕

As explained above, according to the pulse motor hold current control circuit of the present invention, the hold current for holding the pulse motor is appropriately set according to the ambient temperature, so that the pulse motor can be mounted even at high temperatures. It is possible to prevent the heat generation of the equipment used to exceed the necessary level, and to design the equipment according to an appropriate heat dissipation design.

Furthermore, according to the pulse motor drive current control circuit of the present invention, the drive current for driving the pulse motor is appropriately set according to the ambient temperature, so that the equipment in which the pulse motor is mounted will not generate heat even at high temperatures. This means that the amount of heat is not more than necessary, the equipment can be designed according to an appropriate heat dissipation design, and noise can also be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the hold current control circuit of the present invention. FIG. 2 is a diagram explaining the principle of the drive current control circuit of the present invention. FIG. 3 is a configuration diagram of an embodiment of the present invention. FIG. 4 is a configuration diagram of another embodiment of the present invention. FIG. 5 is a block diagram of another embodiment of the present invention. In the figure, 10 is a pulse motor drive circuit, 20 is a hold current variable means, 30 is a drive current variable means, 40 is a temperature detection circuit, 50 is a hold current setting means, and 60 is a drive current setting means. Patent applicant: BFN Co., Ltd. Agent Patent attorney: 1) Hiroshi (2 others) Motor drive stop signal Pulse motor drive circuit 10,! : Diagram for explaining the principle of the hold current control circuit of the invention: Figure 1: Diagram for explaining the principle of the drive current control circuit of the invention: Figure 2: Figure 3

Claims (2)

[Claims] (1) In the pulse motor drive circuit (10) that holds the pulse motor by passing a hold current through a predetermined excitation coil of the pulse motor, there is a temperature detection circuit (40) that detects the ambient temperature, and a temperature detection circuit (40) that detects the ambient temperature. The pulse motor drive circuit (10) includes a hold current setting means (50) for setting a hold current according to the ambient temperature detected by the pulse motor drive circuit (40), and the pulse motor drive circuit (10) is configured to vary the hold current flowing through the excitation coil of the pulse motor. The hold current variable means (20) controls the hold current setting means (20) when the pulse motor is in a stopped state.
50) A pulse motor control circuit characterized in that a small hold current is controlled to flow through an excitation coil of a pulse motor as the ambient temperature increases, according to the setting of item 50). (2) A temperature detection circuit (40) that detects ambient temperature in a pulse motor drive circuit (10) that drives a pulse motor by passing a drive current through an excitation coil of the pulse motor according to a predetermined phase excitation sequence; The pulse motor drive circuit (10) includes a drive current setting means (60) for setting a drive current according to the ambient temperature detected by the temperature detection circuit (40), and the pulse motor drive circuit (10) is configured to drive a drive current flowing through the excitation coil of the pulse motor. The drive current variable means (30) is provided with a drive current variable means (30) for variably controlling the current, and when the pulse motor is in the drive state, the drive current variable means (30) adjusts the pulse current according to the setting of the drive current setting means (60). A pulse motor control circuit characterized in that a small drive current is controlled to flow through an excitation coil of a motor as the ambient temperature increases.