JP2001232884A - Shuttle control method of dot line printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive dot line printer good in performance. SOLUTION: In the shuttle mechanism of the dot line printer, the angular velocity in one stroke of a hammer bank is controlled so as to be suddenly increased at a time of the reversal of a shuttle, suddenly decreased after reversal and decreased in a printing range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art The printing principle of a dot line printer will be described with reference to FIGS.

In FIG. 4, a hammer bank 1 having a plurality of printing hammers (not shown) is provided with a hammer block 2.
And is supported by the shaft 3 via the slide bearing 7. Further, a counter balancer 6 that operates in a phase opposite to that of the hammerbank 1 is also supported by the shaft 3 via a slide bearing 7. In addition, as shown in FIG.
Are arranged 180 degrees out of phase. One of the cranks 4 is connected to the hammer block 2 and the counter balancer 6, respectively, and the other is connected to the shaft of the stepping motor 5. In the above configuration, when the motor 5 is driven by the excitation of the stepping motor 5,
The hammer bank 1 and the counter balancer 6 reciprocate in opposite phases.

A sensor (not shown) is attached to the hammer bank 1. When the hammer bank 1 moves, a signal is output at regular intervals, and a printing control device drives a printing hammer via a shuttle control circuit. The printing is performed at a predetermined position on the printing paper 9 via the ink ribbon 8 shown in FIG.

In FIG. 4, the distance between the center of the crank 4 and the center of the stepping motor shaft (hereinafter referred to as the eccentricity b) and the distance between the centers of the crank 4 (hereinafter referred to as "b").
The position where the crank length a is minimum on the horizontal axis is the initial position, the rotation starts from this initial position, and the eccentricity b
When printing of one stroke of the hammerbank 1 is completed at a position where the crank length a becomes maximum on the horizontal axis (a position rotated by 180 ° from the start of rotation), the above operation is then reversed, and the movement of the hammerbank 1 is performed. The direction is reversed. During this reversal, the printing paper 9 is transported by a predetermined amount by the pair of paper transport tractors 11 driven by the paper transport motor 10 shown in FIG. 6, and printing of the next stroke is started.

Next, a shuttle control method according to the prior art will be described.

In general, the print hammer is a time Tr (hereinafter referred to as hammer repeatability) unique to the hammer from when the hammer is driven by the printing hammer drive circuit to when it strikes the printing paper 9 and returns to its original position. ) Determines the printing speed. Also, the shuttle maximum speed Vx1
Is determined by the following equation. Here, D represents the dot density in the digit direction. Therefore, the printing speed depends on the shuttle reciprocating speed, and several stages of printing speed can be realized by changing the dot density D and the hammer repeatability Tr.

[0008]

(Equation 1)

On the other hand, as described above, in the shuttle operation by the crank mechanism, by giving the crankshaft of the crank mechanism a predetermined eccentricity, the eccentricity b can be reduced.
Reciprocating movement of twice the distance can be performed. In addition, the mechanism has been widely used in other fields because reciprocating movement in one direction of rotation is possible and forward / reverse rotation control is unnecessary. Therefore, generally, when a crank mechanism is used, a motor that does not require forward / reverse rotation (such as a DC servomotor) has been used. However, since fine speed control cannot be performed by a DC servo motor or the like, it is common to rotate the motor at an angular speed close to a predetermined constant. The shuttle speed waveform of the crank of the hammer bank 1 at the constant angular speed ω can be expressed by the following equation. As is clear from the following equation, the velocity waveform is a sin wave.

[0010]

(Equation 2)

As is apparent from the equations, the shuttle maximum speed Vx1 determined from the above-mentioned hammer repeatability Tr does not basically match the shuttle maximum speed Vx2 determined from the above-described equation of the shuttle mechanism of the crank mechanism. . In particular, when the hammer repeatability Tr of the printing hammer ability is already determined in terms of configuration, it is impossible to output the shuttle maximum speed Vx2 higher than the printing hammer ability, so that Vx1 ≦ Vx2. Therefore, it is necessary to lower the angular velocity ω in order to obtain Vx1 = Vx2 in order to obtain the maximum performance of the hammer. Further, in a section where the print hammer prints (hereinafter, referred to as a print range), if the velocity waveform is a sin wave, there is a disadvantage that the hammering characteristics of the hammer are not stable.

On the other hand, the torque required to rotate the motor (hereinafter referred to as load torque) includes a force Fc for rotating the crank mechanism 4 and a force Fh for reciprocating the hammer bank 1 and the counter balancer 6. Since the sum of the inertial force Fcc of the hammerbank 1 and the inertial force Fhc of the counter balancer 6 acts on the center of the crank eccentricity, the load torque is given by the following equation.

[0013]

(Equation 3)

Here, Fc and Fh are forces that depend on their respective masses and do not change with the rotation of the crank. However, the magnitude of the inertial forces Fcc and Fhc can be changed by the rotation of the crank. Therefore, when the angular velocity ω is constant, Fcc and Fhc have fixed values, and it has been difficult to reduce them.

Further, the printing speed is represented by the following equation. In the formula, S is the number of shuttle reciprocations for hitting one line of characters, and Ts is the travel time of the hammerbank 1 for one stroke (hereinafter, referred to as one scan time).

[0016]

(Equation 4)

That is, in order to increase the printing speed, it is necessary to shorten one scan time Ts. In the above-described crank mechanism, when the angular velocity ω is constant, one scan time is a time for the motor shaft to make a half rotation, so that Ts = ω / π
Is determined.

As described above, in the shuttle operation using the crank mechanism, the maximum shuttle speed, the load torque,
Since all printing speeds depend on the angular speed ω, it has been difficult to implement each condition with the minimum required specifications.

As described above, the conventional shuttle control method in the crank mechanism cannot perform fine speed control, and therefore always reciprocates in a sine wave operation. , The maximum shuttle speed and one scan time all depend on a constant angular speed, and it was not possible to reduce the load torque without changing the motor and the like, stabilize the shuttle speed, and improve the printing speed. .

Accordingly, an object of the present invention is to provide a shuttle control method which solves the above-mentioned problem and reduces the printing speed and can reduce the cost as a result.

[0020]

SUMMARY OF THE INVENTION An object of the present invention is to provide a hammer bank having a plurality of printing hammers, a counter balancer operating in a phase opposite to the hammer bank, and a motor serving as a drive source for the hammer bank and the counter balancer. And a dot line printer having a shuttle mechanism connected to the motor and transmitting a torque of the motor to interlock the hammerbank and the counter balancer in opposite phases, and having a shuttle mechanism for reciprocating the hammerbank. Immediately before the hammerbank and the counter balancer switch the moving direction, the angular speed of the crank mechanism is sharply increased to a value equal to or higher than the angular speed at the time of steady rotation, and after the reversal, the angular speed is rapidly decreased. Achieved by controlling to keep it lowered That.

[0021]

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

FIG. 3 is a schematic view of the crank structure of the shuttle mechanism used in the present invention.

In the figure, a hammer bank 1 is connected to a hammer block 2 and reciprocates on a shaft 3. The motor 5 for driving the crank mechanism can be controlled at a small angle.
A stepping motor whose rotation speed is variable is selected. In this figure, the crank mechanism is omitted, and the hammer block 2 mechanically shows the crank length a and the eccentricity b. When the motor 5 rotates clockwise, the hammerbank 1 is configured to move in the direction C in the drawing.

As shown in the figure, one stroke of the hammer bank 1 is a half of the distance during which the sheet is being conveyed (hereinafter referred to as a reversal section), and is one of the reversal sections through the printing section.
/ 2 distance.

The specific shuttle operation in the present invention is as follows.

In the case of the conventional steady rotation, the angular velocity of the motor shaft connected to the crank mechanism is fixed.
In the present invention, during the paper feed distance (reversal section) at the end of one stroke, the rotation angular velocity of the motor shaft is gradually increased, and when the rotation reaches the reversal point E (or D) of the crank mechanism, the reciprocation is performed. Control is performed so as to reduce the angular velocity of the crank mechanism by using the inertial force of the hammer bank 1 and the counter balancer 6 that are moving.

Next, a specific method of the shuttle control method of the present invention will be described.

FIG. 1 shows waveforms of the angular velocity, load torque and shuttle speed of one revolution in the crank mechanism of the present invention.
FIG. 2 shows waveforms of the angular speed, load torque, and shuttle speed of one revolution of the crank 4 during rotation at a constant angular speed (hereinafter, referred to as steady rotation).

In the steady rotation shown in FIG. 2, the angular velocity (A2)
Is constant, and the shuttle speed waveform becomes a sin waveform (B2). The load torque at that time becomes like C2, and the peak point D after the inversion of the hammerbank at the center of one scan time.
Plus torque (acceleration torque) required up to 2,
And a negative torque (hereinafter, brake torque) required from the center position to the peak point E2 acts alternately.

On the other hand, in the present invention, the angular velocity (A1) of the motor shaft is increased immediately before and immediately after the reversal of the crank mechanism, and is decreased during the printing section. Therefore, the shuttle speed waveform at that time becomes a waveform close to the trapezoidal wave (B1), and a constant speed can be obtained in the printing section.

Also, in FIG. 1 according to the present invention, the acceleration torque and the brake torque act alternately on the load torque at the center line of one scan time similarly to the steady rotation. However, the aforementioned acceleration torque D2 and brake torque E
Acceleration torque D1 and brake torque E over torque 2
The unit torque decreases.

This is explained theoretically as follows.

In the section before the inversion of the hammerbank 1,
Since the angular velocity of the crank mechanism is rapidly increased, the inertial force of the hammer bank 1 and the counter balancer 6 is increased, and the rotational energy immediately before the reversal is increased. Will be spent after the reversal. Therefore, after the reversal, the acceleration torque can be reduced by the rotational energy of the inertial force.

On the other hand, since the angular speed of the crank mechanism is sharply reduced after the inversion of the hammerbank 1, the shuttle speed is reduced, and the rotational energy of the inertial force is reduced accordingly.
Therefore, the brake torque may be small due to the rotational energy of a small inertial force, and the brake torque itself is reduced.

As described above, by performing the shuttle control method of the present invention, the maximum shuttle speed can be reduced.
There is an advantage that the maximum shuttle speed can be determined while checking the hammer repeatability of the printing hammer described above.

In addition, since the printer can operate at a constant shuttle speed even in the printing section, stable hammering characteristics can be obtained.

Further, if the allowable load torque of the motor can be given a margin by reducing the load torque,
One scan time can be reduced, and the printing speed can be improved.

[0038]

As described above, according to the present invention, the motor for driving the crank mechanism is a stepping motor, and the rotational angular velocity of the crank mechanism is increased only in the reversal region, so that the load torque of the motor, the maximum shuttle speed, and Since the scan time can be reduced and the specifications of the motor and the hammer can be reduced, the cost can be reduced as a result. In addition, the printing speed can be improved by reducing one scanning time.

[Brief description of the drawings]

FIG. 1 shows the angular velocity in the shuttle control method of the present invention;
6 is a graph showing changes in shuttle speed and load torque.

FIG. 2 is a graph showing changes in angular velocity, shuttle speed, and load torque in a shuttle control method during steady rotation.

FIG. 3 is a schematic view showing a crank structure of the present invention.

FIG. 4 is a side view showing a shuttle mechanism.

FIG. 5 is a plan view of FIG. 4;

FIG. 6 is a perspective view showing the printing principle of a dot line printer.

[Explanation of symbols]

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 (2)

[Claims] 1. A hammer bank having a plurality of print hammers, a counter balancer operating in a phase opposite to the hammer bank, a motor serving as a drive source for the hammer bank and the counter balancer, and connected to the motor; The hammerbank and the counter balancer are constituted by a crank mechanism that transmits the torque of the motor so as to interlock in opposite phases,
In a dot line printer having a shuttle mechanism for reciprocating the hammerbank, the angular velocity of the crank mechanism is rapidly increased to an angular velocity at the time of steady rotation immediately before the hammerbank and the counter balancer switch the moving direction, and sharply after reversal. And controlling the angular velocity of the crank mechanism to be kept low in a low speed region of the hammerbank. 2. A shuttle control method for a dot line printer according to claim 1, wherein said motor is a variable speed stepping motor.