JPH10272815A - Shuttle controlling method of dot line printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a stepping motor from becoming out of step by a method wherein the number of excitations for driving the stepping motor is made larger than the number of excitations corresponding to the minimum stroke necessary for the predetermined amount of the action of a shuttle. SOLUTION: By driving a pulley 16 through a stepping motor 20 by means of a shuttle driving circuit 50, a hammer bank 10 and a counter-balancer 14 are reciprocated to the direction of a crossbeam in phases opposite to each other. During this reciprocating motions of the hammer bank and of the counter- balancer, by means of a printing controlling device 30 through a shuttle controlling circuit 40, printing hammers are controlled so as to execute a printing through an ink ribbon 100 onto the predetermined position of a printing paper 200. In a dot line printer as mentioned above, the number of excitations for driving the stepping motor 20 is set to be larger than the number of excitations corresponding to the minimum stroke necessary for the predetermined amount of the action of a shuttle. As a result, the over-running of a rotor is absorbed by the inertia forces of the hammer bank 10 and of the counter-balancer, resulting in preventing the out of step of the stepping motor 20 from developing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shuttle control system for a dot line printer that performs printing in a dot matrix format by driving a printing hammer for dot printing by a driving mechanism.

[0002]

2. Description of the Related Art FIG. 4 shows a printing principle of a dot line printer.

A hammer bank 10 having a plurality of printing hammers (not shown) and a driving mechanism for the printing hammers is mounted on a timing belt 12. Further, a counter balancer 14 that operates in a phase opposite to that of the hammerbank 10 is also coupled to the timing belt 12.

At least a pair of pulleys 16 are attached to the timing belt 12, and one of the pulleys 16 is driven by a shuttle driving circuit 50 by a stepping motor 20 which can be rotated forward and backward, so that the hammer banks 10 and The counter balancer 14 reciprocates in the digit direction with phases opposite to each other.

A linear sensor 60 is attached to the hammerbank 10, and when the hammerbank 10 moves, a signal is output at regular intervals. Based on the signal, the print controller 30 sends the signal to the printer via the shuttle control circuit 40. The hammer driving mechanism is driven, whereby the printing hammer prints at a predetermined position on the printing paper 200 via the ink ribbon 100.

[0006] When printing of a predetermined amount of one stroke of the hammerbank 10 is completed, the moving direction of the hammerbank 10 is reversed by the rotation of the stepping motor 20 in the opposite direction. The printing paper 200 is transported by a predetermined amount by a pair of paper transport tractors 400 driven by the paper transport motor 300, and printing of the next stroke is started.

On the other hand, the driving cycle of the printing hammer is a time T from when the hammer is driven by a driving circuit (not shown) to when it strikes the printing paper and returns to the original position.
r (hereinafter referred to as hammer repeatability). The shuttle speed V is determined by V = D / Tr.
Here, D represents the dot density in the digit direction. Accordingly, the printing speed depends on the reciprocating speed of the shuttle, and several steps of printing speed can be realized by changing the dot density D and the hammer repeatability Tr. Generally, 180 dpi
(dot / inch, here called mode 1 for convenience), 120d
It often consists of three modes, i.e., Pi (mode 2) and 90 dpi (mode 3).

FIG. 5 shows the relationship between the speed curve of the hammer bank 10 for one stroke and the timing of phase switching of the stepping motor 20 in a certain print mode in the prior art.

The hammerbank 10 is accelerated at a constant acceleration from a stopped state, decelerated at a constant acceleration after a predetermined amount of constant-velocity motion, and repeats acceleration, constant velocity, and deceleration immediately after the end of deceleration.

The stepping motor 20 is a motor that rotates the rotor by sequentially switching the excitation phase of the stator winding, and the rotation angle of the motor is determined by the number of times the excitation phase is switched. The number of times of switching is
It is determined by the amount of movement of the hammerbank 10 for one stroke. Therefore, it is not necessary to perform speed control or positioning while constantly monitoring the operation of the motor by an encoder, a tachogenerator, or the like, so-called open-loop control is possible, and the configuration of the device can be simplified.

On the other hand, since the printing speed of the dot line printer is substantially determined by the moving speed of the hammer bank 10,
I want to operate the hammerbank 10 as fast as possible and in a short cycle. For that purpose, it is necessary to increase acceleration / deceleration, but on the other hand, the inertia force applied to the rotor increases. Particularly, in the acceleration / deceleration section, the maximum inertial force is generated, and even when the phase switching of a predetermined amount at the time of deceleration is completed, the rotor cannot stop at the predetermined position and overruns, and the operation shown in FIG. do. Here, the solid line represents the movement of the rotor of the stepping motor 20, the dotted line represents the ideal curve of the hammerbank 10, and the dashed line represents the movement of the hammerbank 10.

If the overrun of the stepping motor 20 is too large, a phenomenon occurs in which the rotor cannot follow the switching frequency of the next excitation phase and steps out. In the figure, (X
1) is the amount of overrun of the rotor with respect to the ideal stop position, and (X2) is the amount of overrun due to the extension of the timing belt 12. For example, in the case of two-phase excitation, (X2)
1) Step out when overrun by ≧ 4 steps.

On the other hand, the hammerbank 1 which is a movable part
0 and the counter balancer 14 operate slightly later than the movement of the rotor due to elongation of the timing belt 12 or play of the mechanism, etc., so that when the rotor stops and starts accelerating in the opposite direction, it has not stopped yet, An inertial force in a direction opposite to the rotation direction of the rotor is generated. When the inertial force exceeds the maximum output torque of the motor, the motor loses synchronism.

Such a step-out phenomenon may rarely occur due to a temporary load change or a successive change in the mechanical section even if the normal shuttle reversal operation is performed without any problem.

Therefore, in general, a shuttle mechanism of a dot line printer is provided with a motor that generates a torque enough to withstand the inertial force of an object that reciprocates even with a temporary load change or a continuous change. It was necessary to perform closed-loop control for controlling the rotational speed and positioning while always monitoring the operation of the motor using an encoder or a tachogenerator.

[0016]

As mentioned above, the step-out of the stepping motor reduces the reliability of the device. In addition, there is a problem that using a stepping motor having a high torque output or performing closed loop control using an encoder or the like increases the cost of equipment.

[0017]

An object of the present invention is to provide a hammer bank having a plurality of printing hammers and a driving mechanism for the printing hammer, and a counter balancer which operates in the opposite phase to the hammer bank. Combined with a belt,
The stepping motor connected to one of the pulleys is driven forward and reverse by repetition of acceleration and deceleration, so that printing is performed while the hammer bank and the counter balancer are reciprocated on a slide shaft provided in the spar direction. In a dot line printer, this is achieved by exciting the excitation number for driving the stepping motor more than the excitation number corresponding to the minimum stroke required for the operation of the predetermined amount of shuttle.

The phase excitation added to prevent the stepping motor from stepping out is achieved by being applied after the stepping motor deceleration phase excitation is completed or during the stepping motor deceleration process.

It is preferable that the frequency of the added phase switching be as high as possible in terms of control processing.

Further, the number of additional phase excitations may be changed according to the speed of the shuttle.

As described above, by performing the phase switching of the stepping motor so as to absorb the overrun of the rotor due to the inertial force of the movable object of the hammerbank or the counter balancer by the shuttle operation, the stepping motor does not lose synchronism. .

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to FIGS.

FIG. 1 shows a stepping motor 2 according to the present invention.
7 shows a flowchart at the time of zero drive.

In FIG. 1, one of the operation modes 1, 2, and 3 having different shuttle speeds described in the prior art described above is selected by a shuttle start command from the controller, and the stepping motor 20 is operated in accordance with preprogrammed data. Phase switching is performed, and the rotor performs acceleration, constant velocity, and deceleration movements. After the end of the last phase switching of the deceleration movement in the series of operations, the phase switching for step-out prevention of the stepping motor 20 according to the present invention is selectively executed, and the acceleration, the constant velocity, and the deceleration movement are repeated again with the end. By performing the step-out prevention phase switching, the overrunning rotor can be instantaneously stopped at a stable position, and the inertial force of the rotor can be eliminated.

Also, when the shuttle operation is stopped, the phase switching for preventing loss of synchronism is performed so that the stop time of the rotor can be shortened, and the time until the restart can be shortened. The printing speed can be improved under the printing conditions.

FIG. 2 is an example showing the speed curve of the hammer bank 10 and the timing of the phase switching of the stepping motor 20 during the deceleration to the acceleration during the shuttle operation of the present invention.

In FIG. 2, the rotor is decelerated at the same acceleration, and after the last phase switching T1, the phase switching of several steps shown in the part A of FIG. 2 is performed in a short time, and the next acceleration is started. . The number of phase switching performed in the part A of FIG. 2 varies depending on the specification of the stepping motor 20, the configuration of the device, the acceleration of the shuttle, and the top speed, but is about several steps capable of absorbing the delay of the hammerbank 10 and the counter balancer 14. You can send it. For example, according to the operation mode selected in the flowchart of FIG. 1, mode 1 is performed once, mode 2 is performed three times, mode 3 is performed five times, and so on. The optimum number of phase switching at this time can be easily determined by experiment.

The additional phase excitation provided to prevent the rotor from overrunning during the shuttle reversal is an effective means even during the shuttle deceleration process.

As shown in FIG. 3, the brake is applied to the stepping motor 20 even during the shuttle deceleration process. In addition, the moving speed of the hammerbank 10 increases due to the inertial force.

In order to make the rotor catch up with the hammerbank 10 during the deceleration process, a phase switch for instantaneously moving the rotor is additionally performed as shown in FIG. Can be stopped. The phase excitation added during the deceleration process may be performed at a plurality of points.

The time (frequency) of the phase switching added to prevent the step-out described above is preferably as short as possible in terms of shuttle operation control and desirably a time that does not affect the operation of the movable part. . The longer the phase switching time and the greater the number of times, the longer the shuttle cycle, and the lower the printing speed. In the case of this example, about 100 μs is good.

[0032]

The shuttle mechanism according to the present invention as described above can prevent loss of synchronism even with temporary load fluctuations and continuous fluctuations. And a low-cost shuttle mechanism can be provided. Further, a shuttle mechanism with good response can be provided even in printing including a large number of line feeds, and the printing speed can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of the present invention.

FIG. 2 is a diagram showing a speed waveform of a hammer bank and a phase switching timing of a stepping motor, showing an example of the present invention.

FIG. 3 is a diagram showing a speed waveform of a hammer bank and a phase switching timing of a stepping motor according to another example of the present invention.

FIG. 4 is a schematic diagram illustrating a printing principle of a dot line printer.

FIG. 5 is a diagram showing a speed waveform of a hammerbank and a phase switching timing of a stepping motor according to the related art.

FIG. 6 is an operation diagram of a hammer bank and a rotor at the time of shuttle deceleration reversal.

[Explanation of symbols]

10 is a hammer bank, 12 is a timing belt, 14 is a counter balancer, 16 is a pulley, 20 is a stepping motor, 30 is a print control device, 40 is a shuttle control circuit, 50 is a shuttle drive circuit, 60 is a linear sensor,
00 is an ink ribbon, 200 is a printing paper, 300 is a paper transport motor, and 400 is a paper transport tractor.

Continuing from the front page (72) Inventor Masafumi Hiratsuka 1060 Takeda, Hitachinaka-shi, Ibaraki Prefecture Within Hitachi Koki Engineering Co., Ltd.

Claims (5)

[Claims] 1. A hammer bank having a plurality of printing hammers and a driving mechanism for the printing hammer, and a counter balancer operating in an opposite phase to the hammer bank are coupled to a pair of pulleys and an endless transport band. A dot line printer that performs printing while reciprocatingly moving the hammerbank and the counter balancer on a slide shaft arranged in the digit direction by driving the stepping motor connected to one side forward and reverse by repeating acceleration and deceleration. In the above, the stepping motor is driven by exciting the excitation number more than the excitation number corresponding to the minimum stroke necessary for the operation of the predetermined amount of shuttle, thereby preventing stepping out of the stepping motor. Dot line printer shuttle control system. 2. A shuttle control system for a dot line printer according to claim 1, wherein phase excitation added to prevent step-out of said stepping motor is applied after completion of deceleration phase excitation of said stepping motor. Dot line printer shuttle control system. 3. A shuttle control system for a dot line printer according to claim 1, wherein phase excitation added to prevent step-out of said stepping motor is added in a step of deceleration of said stepping motor. Dot line printer shuttle control system. 4. A shuttle control system for a dot line printer according to claim 1, wherein the frequency of the added phase switching is made as high as possible in control processing. . 5. A shuttle control system for a dot line printer according to claim 1, wherein the number of phase excitations to be added is changed according to the speed of the shuttle.