JP2003025673A - Method of controlling shuttle of dot line printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost dot line printer having a high performance. SOLUTION: A shuttle is driven by a trapezoidal wave. The angle velocity operation at a time after the excitation of the motor during the driving is set by controlling motor phase excitation.

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a shuttle control method for a dot line printer which performs printing in a dot matrix format using a printing hammer for dot printing. 2. Description of the Related Art The printing principle of a dot line printer will be described with reference to FIGS. A hammer bank 1 on which a plurality of printing hammers (not shown) are mounted is connected to a hammer block 2 and supported by a shaft 3 via a linear bearing 7. Similarly, a counter balancer 6 driven in a phase opposite to that of the hammerbank 1 is supported on the shaft 3 via a linear bearing 7. One end of each of the pair of cranks 4 is connected to the hammer block 2 and the counter balancer 6, respectively.
The other ends are respectively connected to the shaft of the stepping motor 5. When the stepping motor 5 is excited, the motor is driven and the two cranks 4 are arranged 180 degrees out of phase, so that the hammerbank 1 and the counter balancer 6 reciprocate in opposite phases. A sensor 8 is attached to the hammer bank 1. When the hammer bank 1 moves, a signal is output at regular intervals, and a print control device drives a print hammer for printing via a shuttle control circuit, and an ink ribbon is provided. The printing is performed at a predetermined position on the printing paper 9 via the. In the crank 4, the difference between the center position of the crank and the center of the shaft of the stepping motor 5 (hereinafter referred to as the amount of eccentricity b) and the center distance of the crank 4 (hereinafter referred to as the crank length a) are on the horizontal axis. The rotation starts from the maximum position, and the hammerbank 1 is at a position where the eccentricity b and the crank length a are minimum on the horizontal axis (a position rotated 180 ° from the rotation start).
When the printing of one stroke is completed, the above operation is reversed, and the moving direction of the hammerbank 1 is reversed. During,
The printing paper 9 is transported by a predetermined amount by the pair of paper transport tractors 11 driven by the paper transport motor, and printing of the next stroke is started. Here, a time Tr (hereinafter referred to as hammer repeatability) from when a printing hammer (not shown) is driven by a printing hammer driving circuit to when it strikes the printing paper 9 and returns to the original position again. , The maximum shuttle speed is determined by Vx1 = D / Tr. D represents the dot density in the digit direction. Therefore, the maximum speed of the shuttle operation is determined by the hammer repeatability of the hammer itself, since D is determined by each print mode pattern. Therefore, it is premised that the shuttle maximum speed Vx1 does not exceed this value during operation. In order to improve the printing speed, the shuttle reciprocating time (hereinafter, referred to as scan time) is driven by the shortest driving time. Although there are many means for reciprocating motion, here, the crank mechanism will be described. By providing the crankshaft of the crank mechanism with a predetermined eccentricity, the eccentricity b
Perform double distance reciprocation. In addition, since the reciprocating motion can be performed by rotation in one direction, forward / reverse rotation control is not required, and thus the mechanism has been widely used in other fields. Basically, a crank mechanism is a means for converting a rotary motion into a linear motion and transmitting it. Since the inertia (hereinafter referred to as inertia) of the rotary system and the linear system is different, it is difficult to analyze the load torque applied to the motor. In general, the motor is driven at a constant driving angular velocity ω. The shuttle speed waveform of the crank of the hammer bank 1 at the constant angular speed ω is a sine wave. The hammery repeatability T described above
The maximum shuttle speed Vx1 determined from r and the maximum shuttle speed Vx obtained from the equation of the shuttle waveform of the crank.
2 basically does not match. Therefore, if the hammer repeatability Tr of the printing hammer ability has already been determined, it is impossible to obtain a shuttle maximum speed Vx2 higher than the printing hammer ability, so that Vx1 ≦ Vx2. Therefore, in order to satisfy the above condition, since the maximum speed of the velocity waveform sine wave is at the vertex 1, the scanning time has to be extended. If the reciprocating distance (hereinafter referred to as a stroke) is the same, the scanning time can be shortened by changing the speed waveform of the hammer to a trapezoidal waveform while maintaining a constant speed near the maximum speed. However, in the crank mechanism, hammerbank 1
And the lateral inertial force of the counter weight 6 and the inertial force of the rotating system of the motor 5 and the crank 4 act, so that simply bringing the waveform closer to a trapezoidal waveform will result in excessive torque (hereinafter, required torque) required for driving the motor. Become. Therefore, it is necessary to employ a large motor and a high torque motor, and an appropriate means for reducing the required torque has been determined by a trial and error of drive control by an actual machine. As described above, in the conventional shuttle control, the required torque is high when the hammerbank speed waveform is trapezoidal, so that the cost is increased by adopting a high torque motor or the like. It was difficult to reduce the torque and the scan time. An object of the present invention is to provide a hammer bank having a plurality of print hammers, a counter balancer operating in a phase opposite to that of the hammer bank, and interlocking the hammer bank and the counter balancer. A dot line printer including a crank, a hammer bank including a stepping motor for rotating the crank, and a shuttle mechanism for reciprocating a counter balancer, the hammer bank and the counter balancer acting on the motor shaft of the stepping motor Is achieved by controlling the motor phase excitation under the driving condition in which the rotational force due to the driving of the stepping motor is minimized by utilizing the inertia force of the stepping motor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG. FIG. 1 shows an angular velocity B, a hammerbank velocity waveform A, and a required torque diagram C according to the present invention. The horizontal axis in the figure indicates the time axis. The left side of the excitation cutting point D is a hammerbank velocity waveform A driven by a trapezoidal wave, and the right side shows the locus of shuttle driving due to inertia. When driving with a trapezoidal waveform, the required torque C
Greatly fluctuates near the reversal, so a motor exceeding this required torque is required. When the excitation is cut off at the point D, the hammerbank and the crank continue to be driven without being stopped instantaneously due to inertia. Since the crank and the hammerbank after the excitation cutting are not affected by the external force and continue to move only by the inertial force, the required torque C becomes almost zero at D. If the angular velocity B at that time is adopted as the drive control, it is possible to perform control using the inertia force to minimize the required torque. That is,
With a shuttle driven by trapezoidal waves, the angular velocity operation after the excitation to the motor is cut off during driving is set as control of the motor phase excitation control. At this time, since the waveform after cutting changes depending on the cutting point of the applied current and the driving waveform before cutting, it is necessary to set the shuttle speed not to exceed the maximum shuttle speed corresponding to each print mode. According to the control method of the shuttle mechanism of the present invention, the allowable torque of the stepping motor can be used to the maximum, so that the load torque of the stepping motor can be reduced and the cost of the motor can be reduced. Leads to Also,
The printing speed can be improved by reducing the scanning time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an angular velocity, shuttle speed, and load torque diagram of the present invention. FIG. 2 is a schematic diagram of a crank structure. FIG. 3 is a perspective view of a shuttle mechanism of the dot line printer. FIG. 4 is a schematic perspective view of a dot line printer. [Description of References] 1 is a hammer bank, 2 is a hammer block, 3 is a shaft, 4 is a crank, 5 is a stepping motor, and 6 is a counter balancer.

Claims (1)

Claims: 1. A hammer bank having a plurality of print hammers, a counter balancer operating in an opposite phase to the hammer bank, a crank for interlocking the hammer bank and the counter balancer, and the crank A dot line printer having a shuttle mechanism for reciprocating a hammer bank and a counter balancer configured by a stepping motor for rotating a stepper motor, wherein the inertia of the hammer bank and the counter balancer acting on the motor shaft of the stepping motor is used A shuttle control method for the dot line printer, wherein the motor phase excitation is controlled under a driving condition in which the rotational force generated by driving the stepping motor is minimized.