JPH01320185A - Printing head travel controller - Google Patents

Abstract

PURPOSE:To inhibit a speed fluctuation vibration occurring in acceleration/ deceleration to improve a printing quality and to reduce a distance required for acceleration by transmitting a speed instruction value signal obtained by a sine-wave function generator to a drive controller controlling the acceleration/ deceleration speed of a drive motor. CONSTITUTION:A carriage 2 loading a printing head 1 thereon is bonded to a power transmission mechanism 3. The power transmission mechanism 3 is supported by an idle pulley 4 and a motor pulley 5 at the ends thereof. The carriage 2 is so constructed as to travel between both the pulleys. The motor pulley 5 is bonded to the output shaft of a drive motor 6. Furthermore, a drive controller 9 is connected to the drive motor 6. The drive controller 9 drives the drive motor 6 according to a speed profile signal instructed by a sine-wave function generator 10 connected thereto. In this manner, a speed fluctuation vibration occurring in acceleration/deceleration can be inhibited. As a result, a printing head travel controller for a printer printable with a high quality at a high speed can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a movement control device for moving a print head of a printer.

[Conventional technology]

In printers that print while moving a carriage carrying a print head, the driving force of the motor is usually transmitted through a power transmission mechanism such as a belt or wire between the motor and the carriage, and the carriage is moved along the guide. The printing position is controlled by a structure that moves by moving.

Current printers generally have a structure that allows them to print many character patterns such as kanji and alphanumeric characters, so the carriage movement speed is set to multi-speed mode according to the difference in dot density of the character font structure. .

In addition, in order to improve printing throughput, the print head movement speed has been increased to a maximum of 1 m.
Devices with speeds exceeding per second are also being put into practical use. As the moving speed increases, even if the motor applies the same acceleration to the carriage on which the print head is mounted as when the moving speed is low, the acceleration distance required to reach the maximum speed increases.

As a result, the length of the printer in the width direction becomes longer.
Therefore, in high-speed printers, it has become necessary to set the acceleration distance to the same length as in the case of low-speed printers, increase the front speed accordingly, and quickly raise the print head to the desired speed.

FIG. 4 is a diagram illustrating a print head movement mechanism in a conventional general printer. A carriage 2 carrying a print head 1 is connected to a power transmission mechanism 3.

The power transmission mechanism 3 has an idle pulley 4 at both ends thereof.
The carriage 2 is supported by a motor pulley 5 and a motor pulley 5, and the carriage 2 is movable between both pulleys. The motor pulley 5 is connected to the output shaft of the drive motor 6.

Drive control of the drive motor 6 is performed by a motor driver 7 connected to the drive motor 6. In order to start the motor at a desired speed, a speed command value generated by a speed bump generator 8 that specifies the speed for each time after the start of startup is transmitted to the motor driver 7, and the motor speed is recorded in the time history. controlled.

When a stepping motor is used as the motor, for example, the speed command value from the speed bang generator corresponds to the time axis of the switching pulse timing that specifies the switching timing of phase excitation. That is, the pulse time width becomes longer at low speeds, and decreases as the speed increases. When it is necessary to start up a large load quickly in a short time, such as in a printer, for example, as described in ``Basics and Applications of Stepping Motors'' published by General Electronic Publishing Co., Ltd., by adjusting the pulse switching timing. As the motor speed profile, a trapezoidal acceleration/deceleration ramp as shown in FIG. 5 is often used. The reason for this is that the acceleration is constant on one side of the trapezoid, that is, the part where the speed increases linearly during acceleration, and the maximum torque characteristic of the motor can be utilized.

[Problem to be solved by the invention]

If the printing speed of the printer is low, if you apply a trapezoidal speed bump to the motor as shown in Figure 5, the speed of the motor will be controlled along the trapezoidal speed bump, and the carriage carrying the print head will also act as a power transmission mechanism. The speed can be controlled almost faithfully through. However, as the printing speed increases, such a trapezoidal speed bump becomes less suitable as a motor speed control command. As the speed increases, the inertial force on the carriage and print head increases, so a vibration system consisting of the carriage including the motor and print head, and the power transmission mechanism or spring mass interposed between them, is required. Vibration is more likely to occur at the end of acceleration when the motor acceleration suddenly changes.
As a result, fluctuations in speed occur in the carriage, so
During printing, the print wire is driven on the assumption that the print head is moving at a constant speed, so variations in speed appear as errors in the positioning of print dots, resulting in characters being crushed or stretched in the horizontal direction. This may lead to deterioration in print quality such as If this type of vibration that occurs between the carriage and the motor is simply due to a sudden change in acceleration at the end of acceleration, then if the change in acceleration is made small at the end of acceleration, it can be reduced to some extent. Although vibration can be expected to be suppressed, reducing the rate of change in acceleration causes the following problems.

In other words, if the maximum acceleration is constant, that is, if the slope of the velocity profile during acceleration is constant, then by reducing the change in acceleration near the end of acceleration, the overall acceleration time will become longer, and as a result, the distance required for acceleration will decrease. As a result, the length of the printer in the width direction must be increased, and at the same time, the overall printing speed decreases because the acceleration time increases. In this case, if the time required for acceleration is set to be the same as in the case of linear acceleration, the magnitude of the maximum acceleration must be increased, and the motor must be made more powerful, resulting in the large size of the equipment. This will lead to Furthermore, in reality, the vibrations that occur between the carriage and the motor during acceleration are not only due to rapid acceleration changes at the end of acceleration, but also due to the overall acceleration change from the start to the end of acceleration. History influences. Therefore, simply smoothing out the change in acceleration at the end of acceleration will not solve the problem.

[Means to solve the problem]

According to the present invention, a carriage carrying a print head is movably held via a guide mechanism, and a drive motor is provided for moving the carriage, and the carriage and the drive motor are coupled by a power transmission means. In the printer having a carriage moving mechanism, a sine wave function generator is provided that generates a profile in which the speed command value of the drive motor is a part of a sine wave function expanded on a time axis, and the sine wave function generator There is obtained a print head movement control device characterized in that a speed command value signal obtained by the above is given to a startup control device that controls the acceleration/deceleration speed of the drive motor.

[Action of the invention]

When accelerating or decelerating a carriage to a steady printing speed using a drive motor, a drive that controls the acceleration/deceleration speed of the drive motor based on the speed profile on the time axis that is determined according to the target acceleration state. For the control device,
The speed fluctuation vibration that occurs during acceleration and deceleration in printer head movement control is generated by a sine wave function generator according to a profile in which the speed command value of the drive motor is a part of a sine wave function expanded on the time axis. As a result, it is possible to realize a print head movement control device for a printer that has high print quality and is capable of printing at high speed.

〔Example〕

Next, the present invention will be described in more detail with reference to the drawings showing one embodiment of the present invention.

Referring to FIG. 1, in one embodiment of the invention, a carriage 2 carrying a print head 1 is joined to a power transmission mechanism 3. The power transmission mechanism 3 is supported by an idle pulley 4 and a motor pulley 5 at both ends, and the carriage 2 is movable between the two pulleys.

The motor pulley 5 is connected to the output shaft of the drive motor 6. Furthermore, a drive control device 9 is connected to the drive motor 6. The drive control device 9 drives the drive motor 6 according to a speed profile signal commanded by a sinusoidal function generator 10 connected thereto.

FIG. 2 shows the time history speed command value for motor drive generated by the sine wave function generator 10. A solid line in the figure indicates a speed command value given to the drive control device 9 by the sine wave function generator 10. The broken line indicates a certain sine wave shape on the time axis, and indicates that a part of it is used as an actual speed command value in the acceleration region of the drive motor 6. The drive control device 9 drives the motor according to the speed command value signal given by the sine wave function generator 10. For example, when a stepping motor is used as the drive motor, phase excitation of the motor may be switched using pulse timing that approximates a command signal.

In addition, the fundamental period and phase relationship for composing the sine wave generated in the sine wave generator depend on the carriage, print head, and inertia of the motor that serve as loads, as well as the dynamic characteristics of the drive mechanism that exhibits spring action. It should be appropriate.

FIG. 3 compares how the starting speed of the carriage changes according to a computer simulation between this embodiment and the conventional configuration. Figure 3 (A) shows the speed response of the carriage section when the motor is started up using normal trapezoidal drive, and Figure 3 (B) shows the speed response when the motor is driven using three types of sine wave functions. . Figure 3 (B
) indicates that speed fluctuations in a constant speed range can be minimized by using a sine wave function that shows the response of function (3) within ).

〔Effect of the invention〕

As explained above, according to the present invention, speed fluctuation vibrations that occur during acceleration and deceleration can be suppressed in print head movement control of a printer, resulting in high print quality and shortening the distance required for acceleration. This makes it possible to control the movement of the print head of a printer that allows high-speed printing.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a diagram explaining a speed signal generated by a sine wave function generator in this embodiment, and Fig. 3 is a diagram showing a case in which this embodiment is required. FIG. 4 is a block diagram of a conventional printer head movement control device, and FIG. 5 is a diagram showing an example of a speed signal from a conventional speed bang generator. 1: Print head, 2: Carriage, 3: Power transmission mechanism,
4: Idle pulley, 5: Motor pulley, 6: Drive motor, 7: Motor driver, 8: Speed slam generator, 9:
Drive control device, 10: sine wave function generator. Agent Patent Attorney Uchihara Sound No. 1I21 Process 2 Closed Figure 3 (Part 5 Kasumi

Claims (1)

[Claims] Carriage movement in which a carriage mounted with a print head is movably held via a guide mechanism, and has a drive motor for moving the carriage, and the carriage and the drive motor are coupled by a power transmission means. In a printer having a mechanism, a sine wave function generator is provided that generates a profile in which the speed command value of the drive motor is a part of a sine wave function expanded on a time axis, and the speed obtained by the sine wave function generator is A print head movement control device characterized in that a command value signal is given to a startup control device that controls acceleration/deceleration speed of the drive motor.