JP3454399B2 - Dot line printer shuttle control system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a speed control method in a shuttle mechanism of a dot line printer using a printer. 2. Description of the Related Art FIG. 4 shows the printing principle of a dot line printer. In FIG. 4, a printing hammer (not shown) is used.
Hammerbank 200 equipped with a timing belt 2
The pulley 260 is attached to the two pulleys 260 via the bracket 70. When one of the pulleys 260 is driven by the stepping motor 210, the pulley 260 reciprocates horizontally with a predetermined stroke width. In the course of the reciprocation of the hammer bank 200, the printing hammer is driven by a printing control device (not shown), and performs printing at a predetermined position on the printing paper 230 via the ink ribbon 220. Hammerbank 2
When the printing of one stroke of 00 is completed, the stepper motor 210 rotates in the opposite direction, so that the hammer bank 200 is inverted and the paper transport motor is moved until it moves to the next printing position. The printing paper 230 is transported by a predetermined amount by the paper transport tractor 250 driven by the printer 240, and printing of the next stroke starts. As described above, the hammerbank 200 is inverted,
In a print pattern in which the conveyance of the paper is completed before moving to the next printing position, the printing speed of the printer is determined by the reciprocating time of the hammer bank 200. FIG. 5 shows a speed waveform of the hammerbank 200 for one round trip. In FIG. 5, the vertical axis represents a hammerbank 200.
+ V indicates the speed when the hammerbank 200 is moving from left to right, and -v indicates the speed when the hammerbank 200 is moving from right to left. The horizontal axis is the hammerbank 200
Represents the position of. In order to increase the printing speed of the printer, the round trip time of the hammerbank 200 may be reduced. However, the maximum speed of the hammerbank 200 is determined by the time during which a hammer can print one dot and then print the next dot (hereinafter referred to as hammer response time). For example, when printing 180 dots per inch,
If the hammer bank 200 moves 1/180 inch faster than the response time of the hammer, the hammer cannot follow and print. Therefore, when the response time of the hammer is constant, it is necessary to minimize the moving distance of the hammer bank 200 in order to increase the printing speed of the printer. On the other hand, there are two driving systems for the stepping motor: an open loop drive and a closed loop drive. In the open loop drive, the motor is driven by sequentially switching the excitation phase of the motor at predetermined intervals, so that devices such as an encoder and a tachogenerator are unnecessary, and the equipment can be manufactured at low cost. Can be configured. However, during rotation of the stepping motor, the stator and the rotor are always displaced at a certain angle,
This angle varies depending on the load on the motor and the rotation speed. Therefore, during the open loop drive, it is difficult to accurately grasp the position of the rotor while the motor is rotating. In particular, in the case of the shuttle mechanism of the dot line printer as shown in FIG. 4, the Hanbank 200 does not always reciprocate on the same track due to the load fluctuation due to the expansion and contraction of the timing belt 270 and the change of the printing pattern. If the hammerbank 200 has turned inside out of the ideal trajectory as shown by the dotted line (.....) in FIG. 5, the hammerbank 200 is ready before the next printing is completed. 200 reaches the printing start position, printing cannot be performed, and one stroke is wasted. For this reason, in the conventional open loop drive, taking into account the load fluctuation due to the expansion and contraction of the timing belt 270 and the change of the printing pattern, the hammer bank 200 is used as shown by a broken line (----) in FIG. Must be controlled to flip outside the ideal orbit,
The printing speed decreased accordingly. As a general means for solving the above problem, there is a closed loop drive. In this method, a pulse generator such as an encoder or a tachogenerator is mounted on a rotor shaft, and the excitation phase of the motor is switched based on a signal from the pulse generator. With the closed loop drive, the position of the rotor can be accurately grasped, so that the hammerbank 200 can reciprocate on an ideal orbit. However, the closed loop drive requires a pulse generator and a device for processing a signal from the pulse generator, and has a disadvantage that the equipment is expensive. [0011] In the case of the open loop drive,
Although the device can be configured at low cost, the hammerbank 200 needs to be inverted outside the ideal trajectory, so that there is a problem that the printing speed is reduced accordingly. Further, in the case of closed loop control, the hammerbank 20 moves on an ideal orbit.
0 can be reciprocated, but there is a problem that the equipment becomes expensive. The above-mentioned object is achieved by providing a sensor for detecting that the hammer bank 200 has passed the deceleration start position, and controlling the stepping motor at the timing when a signal is output from the sensor. Is switched from constant speed control to deceleration control. Hereinafter, the present invention will be described in detail with reference to the drawings. Hammerbank 20 for dot line printer
0 moves on a symmetrical trajectory with the center of the trajectory as the center of the maximum printing range regardless of the actual printing range as shown in FIG. Therefore, if the stepping motor is decelerated while the hammerbank 200 is always at the same position, the hammerbank 200 always reverses at the same position, so that the hammerbank 200 can be moved on an almost ideal orbit. FIG. 1 shows a shuttle mechanism of a dot line printer according to the present invention, and its basic configuration is the same as that of FIG. In FIG. 1, the hammerbank 200 has 2
There are two concave portions (concave portion 1 and concave portion 2), and when this concave portion passes over the photo sensor 10 provided at the center of the maximum printing range, the stepping motor 210 is at the deceleration start position. FIG. 2 shows the operation of the photosensor 10, and FIG. 3 shows a circuit diagram of the shuttle control unit according to the present invention. In FIG. 2, the photo sensor 10 comprises a light emitting diode 11 and a photo transistor 12. In FIG. 3, the signal from the phototransistor 12 is connected to the control circuit 30 and becomes "0" when the phototransistor 12 is turned on and "1" when the phototransistor 12 is turned off. Control circuit 3
0 switches the order of excitation of the motor coil 40 by controlling the transistor 50 in accordance with a signal from the phototransistor 12, and switches the rotation direction of the stepping motor 210. When the flat portion of the hammerbank 200 passes over the photosensor 10, as shown in FIG. 2A, the light of the light emitting diode 11 is reflected by the hammerbank 200 and the phototransistor is turned off. At 12, the phototransistor 12 is turned on. On the other hand, when the recess of the hammerbank 200 passes over the photosensor 10, the light from the light emitting diode 11 does not hit the phototransistor 12, as shown in FIG. The phototransistor 12 turns off. The control circuit 30 includes a stepping motor 210
After switching the rotation direction, the stepping motor 210 is decelerated when the phototransistor 12 is turned off twice. Accordingly, when the hammer bank 200 is moving from left to right in FIG. 1, the control circuit 30 controls the stepping motor 210 when the recess 1 passes after the recess 2 has passed over the phototransistor 12. The control circuit 3 decelerates when the hammerbank 200 is moving from right to left.
0 indicates that the stepping motor 210 has passed when the recess 2 has passed after the recess 1 has passed over the phototransistor 12.
Slow down. As a result, the control circuit 30 can always start the deceleration of the stepping motor 210 at the same position, and the hammer bank 200 always moves on an almost ideal orbit. Although a photo sensor is used in the above embodiment, a mechanical switch such as a micro switch or a magnetic sensor may be used. As described above in detail, according to the present invention, the stepping motor can be controlled with almost the same cost as the open loop drive and with the same accuracy as the closed loop.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a shuttle mechanism of a dot line printer showing an example of the present invention. FIG. 2 is a diagram showing the operation of a photo sensor of the present invention. FIG. 3 is a dot line showing an example of the present invention. Circuit diagram of the shuttle control unit of the printer. [FIG. 4] Diagram showing the printing principle of the dot line printer. [FIG. 5] Diagram showing the speed waveform of the hammerbank. Photosensor, 11 is a light emitting diode, 12 is a phototransistor, 20 is a resistor, 30 is a control circuit, 40 is a motor coil, 50 is a transistor, 200 is a hammerbank, 210 is a stepping motor, and 220 is an ink ribbon. , 230 is a printing paper, 240 is a paper transport motor, 250 is a paper transport tractor, 260 is a pulley, and 270 is a timing belt.

Claims (1)

(57) [Claim 1] Two pulleys are connected by an endless carrier to which a hammer bank having a printing hammer is attached, and one of the pulleys is a stepping motor. In the shuttle mechanism of the dot line printer that reciprocates the hammerbank by being driven by the hammerbank, the shuttle mechanism has means for detecting that the hammerbank has passed the deceleration start position. A shuttle control system for a dot line printer, wherein the stepping motor is switched from constant speed control to deceleration control.