JPH06164784A - Driver - Google Patents

Abstract

PURPOSE:To start a load to be driven smoothly and surely by applying preliminary drive to a pulse motor in a reverse direction within a range of a backlash of a transmission mechanism when the pulse motor is started forward. CONSTITUTION:When a forward pulse Pf is outputted from a control circuit 70, a pulse motor 5 is driven forward and the torque is delivered to a platen roller 3 at a reduced speed by a gear train 4 to drive a roller 3 which feeds recording paper 1 in the subscanning direction Y. When a reverse pulse Pr is outputted from the circuit 70, the motor 5 is reversed and the roller 3 feeds the recording paper 1 in a direction opposite to the direction Y. When the motor 5 is driven forward, the control circuit 70 applies preliminary drive in the reverse direction to the motor within a backlash dh of the transmission mechanism. Then the motor 5 is started at a light load condition caused by the backlash dh. Then the load such as the roller 3 is smoothly and surely started by employing the small sized pulse motor, a motor driver 6 with small power and a small power supply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for feeding a recording paper or a document in a recording device or a reading device.

[0002]

2. Description of the Related Art In a recording apparatus used in, for example, a facsimile machine or a copying machine, as shown in FIG. 6, a recording paper 1 fed from a roll is used as a recording head (thermal head) 2 and a platen roller 3. The recording paper 1 is fed and driven in the sub-scanning direction Y by sandwiching the recording paper 1 in between and performing recording in the main scanning direction X and rotating the platen roller 3 in a fixed direction in synchronization with the recording. .

As shown in FIG. 6, a drive device for performing the above-mentioned feed drive is a pulse motor 5 mechanically connected to the shaft of the platen 3 via a gear train 4 as a transmission mechanism, and a pulse motor 5 connected to the pulse motor 5. It has a motor driver 6 that gives an electric drive power and a control circuit 7 that controls this motor driver 6. The output shaft of the motor 5 is step-rotated by a pulse output from the control circuit 7, The rotation of the gear train 4 is reduced to be transmitted to the shaft of the platen roller 3.

FIG. 7 is a time chart showing the operation of the above drive device, in which (a) is a load applied to the motor shaft,
(B) is the motor rotation speed, (c) is the pulse output from the control circuit 7, the solid line curve in (d) is the rotational displacement of the motor shaft, and the broken line curve in (d) is the rotational displacement of the platen roller 3, respectively. They are shown aligned on the same time axis.

Here, the control circuit 7 outputs only the forward rotation pulse Pf for unidirectionally driving the motor 5 in the forward direction, that is, the sub-scanning direction Y, and the motor shaft rotates by the number of the forward rotation pulse Pf. To be made. The rotational displacement of the motor shaft is decelerated by the gear train 4 and transmitted to the shaft of the platen roller 3, so that the recording paper 1 is fed and driven in the sub-scanning direction Y at a predetermined pitch.

[0006]

However, according to this structure, the pulse motor generally needs to have a large size in order to reliably drive the load such as the platen roller. There is also a problem in that the power scale must be increased, which hinders the miniaturization of this type of drive device.

The above-mentioned problems occur for the following reasons. That is, as shown in FIG. 8, the output torque of the pulse motor changes depending on the speed, but the state of this change is greatly different between the time of startup and the time after startup.

The output torque at start-up, so-called pull-in torque, is smaller than the output torque after start-up, so-called pull-out torque, and the difference increases rapidly with speed.

On the other hand, in order to reliably start the load of the platen roller or the like from the stopped state, the torque of the load must be within the pull-in torque range.

For example, in FIG. 8, T1 [kg · c
m] load motor, speed F1 (PPS)
In order to start with, the coordinates (F1, T1) of the point where T1 and F1 intersect at right angles must be ensured to be inside the pull-in torque curve.

Therefore, in order to reliably start the drive load of the platen roller or the like at a constant speed, a large-sized pulse motor having a sufficient pull-in torque is required. A big one is needed.

Further, the pulse motor is apt to be a source of vibration and noise, but the vibration and noise become the largest at the time of starting.

The present invention has been made in view of the above-mentioned problems, and a drive load such as a platen roller can be reliably and smoothly started by a relatively small pulse motor, a motor driver having a small power scale, and a power source. It is an object of the present invention to provide a drive device configured as described above.

[0014]

In order to solve the above-mentioned problems, the present invention is designed so that, when a pulse motor connected to a load via a transmission mechanism such as a gear train is started in the forward direction, the pulse motor is transmitted to the transmission. It is provided with a structure for preliminarily driving in the reverse direction within the range of the backlash of the mechanism.

[0015]

According to the present invention, because of the above-described structure, the motor is started under the very light load condition caused by the backlash of the transmission mechanism. Therefore, the pulse motor having a relatively small size and the motor having a small power scale can be used. The load such as the platen roller can be surely and smoothly activated by the driver and the power source.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

In the drawings, the same reference numerals indicate the same or corresponding parts. FIG. 1 shows a schematic structure of a driving device according to an embodiment of the present invention.

The drive device shown in the figure constitutes a sub-scan feed drive part of a thermal recording device, wherein 1 is a recording paper such as thermal paper fed from a roll and 2 is a main scanning direction X. A recording head such as a thermal head for recording, 3 is a platen roller for feeding and driving the recording paper 1 in the sub-scanning direction Y at a recording position, 4 is a gear train as a transmission mechanism including a large number of reduction gears a to h, 5 Is a pulse motor that rotationally drives the platen roller 3 in a fixed direction via the gear train 4, 6 is a motor driver that gives electric drive power to the pulse motor 5, and 70 is a pulse motor of the pulse motor 5 through the motor driver 6. It is a control circuit for controlling rotation by pulse.

Here, the control circuit 70 is configured to output two kinds of pulses, a forward rotation pulse Pf and a reverse rotation pulse Pr, as a pulse for driving the pulse motor 5 to rotate.

When the normal rotation pulse Pf is output from the control circuit 70, the pulse motor 5 is rotationally driven in the forward direction, and when the rotation of this motor is decelerated and transmitted to the platen roller 3 via the gear train 4, the platen 5 is rotated. A roller 3 feeds and drives the recording paper 1 in the sub-scanning direction Y.

On the other hand, when the reverse rotation pulse Pr is output from the control circuit 70, the pulse motor 5 is rotationally driven in the opposite direction to the above, and the rotation of this motor is transmitted to the platen roller 3 through the gear train 4 to reduce the speed. Then, the platen roller 3 feeds the recording paper 1 backward in the direction opposite to the sub-scanning direction Y.

In addition to the configuration described above, the control circuit 70
At the time of starting the pulse motor 5 connected to the platen roller 3 which is a drive load via the gear train 4 which is a transmission mechanism, the reverse rotation is performed before the motor 5 is driven in the forward direction by the forward rotation pulse Pf. The driving operation in the reverse direction is instantaneously performed in advance by the pulse Pr.

At this time, the reverse drive amount by the reverse rotation pulse Pr is set so as to be within the range of backlash generated in the transmission system such as the gear train 4.

The operation of the motor drive device constructed as described above will be described below. FIG. 2 is a flowchart showing the operation of the above-described drive device.

FIG. 3 is a time chart showing the operation of the above-mentioned driving device, in which (a) is a load applied to the motor shaft,
(B) is the motor rotation speed, (c) is the pulse output from the control circuit 7, the solid line curve in (d) is the rotational displacement of the motor shaft, and the broken line curve in (d) is the rotational displacement of the platen roller 3, respectively. They are shown aligned on the same time axis.

In FIGS. 2 and 3, when the start of the motor is commanded in the stop section (section B) in which the platen roller is not driven, first, every 1 second at a predetermined time.
The reverse rotation pulse Pr for the step is output to drive the motor in reverse.

The reverse rotation of the motor at this time is performed within the range of the backlash dh of the transmission system. This allows
The motor is rotated in the reverse direction, but the platen roller remains stopped (B1 section).

When the reverse rotation drive of the motor is completed, after waiting for a predetermined time, the forward rotation pulse Pf for one step is output every predetermined time to drive the motor in the forward direction.

At this time, the motor, which has started the normal rotation, rotates without rotating the platen roller while the rotational displacement is within the range of the backlash dh of the transmission system. The motor drives the platen roller to rotate because the amount of rotational displacement of the motor causes the backlash d of the transmission system.
It is after exceeding the range of h. That is, the motor is started in the backlash section where the load of the platen roller is not applied (B2 section).

When the amount of rotational displacement of the motor exceeds the range of the backlash dh, from this point on, the motor starts rotating while driving the platen roller which is the actual load (section C).

As described above, the pulse motor 5 connected to the platen roller 3 via the gear train 4 which is a transmission mechanism is operated before the forward rotation is started by the forward rotation pulse Pf. Backlash d that occurs in the transmission system
Within the range of h, it is driven in the reverse direction by the reverse rotation pulse Pr.

Here, it should be noted that even if the pulse motor 5 is driven in the reverse direction, if the reverse drive amount is within the range of the backlash dh generated in the transmission system, the reverse drive is absorbed by the backlash dh. That is, it is not transmitted to the platen roller 3. Therefore, even when the pulse motor 5 is driven in the reverse direction, the feeding operation by the platen roller 3 can be maintained in the stopped state.

Further, it should be noted that, as shown in FIG. 4, the backlash d generated in the transmission system of the gear train 4 or the like.
The rotational displacement of the output shaft of the motor 5 within the range of h
The output shaft of the motor has a platen roller 3 which is an actual load.
Is that the torque is not applied.

Therefore, as shown in FIG. 5, the pulse motor 5 is started under a load torque T2 that is significantly smaller than the actual load torque T1 including the platen roller 3. As a result, even at the speed F1 that cannot be started under the actual load T1, it can be started reliably. This is indicated by the broken line in FIG.
It has the same effect as the pull-in torque and pull-out torque of the pulse motor are increased substantially.

As a result, the driving load such as the platen roller can be reliably and smoothly started by a relatively small pulse motor, a motor driver having a small power scale, and a power source.

Although the embodiments in which the present invention is applied to the recording apparatus have been described above, the present invention can have various modes other than the above-mentioned embodiments.

For example, the gear train 4 forming the transmission mechanism can be replaced with a transmission component such as a chain or a timing belt.

[0038]

As is apparent from the above description, according to the present invention, when the pulse motor connected to the driving load via the transmission mechanism such as the gear train is started in the forward direction, the pulse motor is moved to the transmission mechanism. By pre-driving in the reverse direction within the range of the backlash of the motor, the motor is started under the very light load condition caused by the backlash of the transmission mechanism. Even with a small-scale motor driver or power supply, the drive load such as the platen roller can be activated reliably and smoothly.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a recording device to which a motor driving device according to an embodiment of the present invention is applied.

FIG. 2 is a flowchart showing the operation of the device of the present invention.

FIG. 3 is a time chart showing the operation of the device of the present invention.

FIG. 4 is a diagram showing a relationship between a shaft displacement of a motor and a load torque in the device of the present invention.

FIG. 5 is a diagram showing pull-in torque and pull-out torque of a motor.

FIG. 6 is a schematic configuration diagram of a recording device using a conventional motor drive device.

FIG. 7 is a flowchart showing the operation of the device of the present invention.

FIG. 8 is a diagram showing pull-in torque and pull-out torque of a motor.

[Explanation of symbols]

 1 recording paper 2 recording head 3 platen roller 4 as a driving load 4 gear train as a transmission mechanism ah gear 5 pulse motor 6 motor driver 70 control circuit X main scanning direction Y sub-operation direction dh backlash Pf forward rotation pulse Pr reverse rotation pulse

Claims (1)

[Claims] 1. A pulse motor connected to a drive load via a transmission mechanism such as a gear train, and a reserve in the reverse direction within the backlash range of the transmission mechanism when the pulse motor is started in the forward direction. A drive device comprising: a control means for driving.