JPS5849195B2 - Hammering method in serial printers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hammering method in a serial printer.

A serial printer is a sequential type printing device that prints desired characters, symbols, etc. on various slips, bankbooks, etc.

For example, it has achieved high enough print quality and copying ability to print on unified slips, which are now rapidly becoming popular, and perform OCR processing.

In this case, printing speed is also an important factor that a serial printer should have.

Conventionally, serial printers have been equipped with a type bar and have achieved a printing speed of about 20 characters/second.

However, with the introduction of online processing by computers, the above printing speed was no longer sufficient, and in recent years, servo-type serial printers have been proposed and printing speeds of about 40 characters/second have been secured.

However, although the printing speed of 40 characters/second mentioned above is twice the printing speed of conventional printers, it does not reach the maximum printing speed that can be theoretically achieved in a servo serial printer. I haven't gotten it.

Now, in order to realize high-speed printing, it is necessary to comprehensively realize all kinds of improvements in the mechanisms and operations within the serial printer.

The present invention aims to improve the hammering system of the print head in particular.

That is, an object of the present invention is to provide a hammering method that can ensure a printing speed sufficiently higher than that which can be realized with existing serial printers.

In accordance with the above object, the present invention employs a servo-controllable DC motor in place of the conventional hammer magnet as a drive source for imparting hammer action to the print head, and furthermore, the hammer stroke of the print head is applied to a continuous fourth stroke and a fourth stroke. two strokes, such that the starting point of the first stroke is the rest point of the hammer action and the ending point of the second stroke is the point of impact on the platen supporting the print medium, where the ending point of the first stroke is In other words, the starting point of the second stroke is set as a temporary stable point, and when printing data is continuously supplied, continuous hammering is performed between the temporary stable point and the impact point, that is, during the second stroke. However, if the supply of print data is stopped, the stroke returns to the starting point of the first stroke.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a schematic structural diagram showing a part of a serial printer to which the present invention is applied.

In this figure, numeral 11 is a print medium on which desired characters are printed across several lines in a horizontal line, such as roll paper or a bankbook.

The print medium 11 is a mechanism (platen) that supports the print medium.
It is intermittently fed while being supported by 12.

The printing unit 13 impacts desired characters on the printing medium 11, and a total of 12 characters, 64 characters, are printed in two rows each on the top and bottom.
A print head 13-1 consisting of 8 characters arranged in a crown shape, and a character selection motor (
(not shown), and a drive mechanism section 13-2 housing a hammering motor (not shown) for impacting one printed character toward the medium 11.

13-3 is a ribbon cartridge containing red and black ink ribbons.

The printing unit 13 rides on the moving shaft 14 and moves in the direction of arrow A in the figure to perform a spacing operation.

The moving shaft 14 is rotated by a space motor 15, and a helical groove is formed on the moving shaft 14, so that the printing unit 13 is spaced entirely by the feeding operation of the helical groove accompanying the rotation. Do this.

Each time the printing of one horizontal line is completed, it returns to the direction of arrow A' in the figure.

Further, a control circuit (not shown) cooperates with the type selection motor to constitute a first electric servo device, which functions as a type selection means.

The space motor 15 is equipped with a potentiometer 17 on its back surface that is interlocked with the rotation shaft of the space motor.

These space motor 15 and potentiometer 1
7 constitutes a second electric servo device in cooperation with the control circuit, which device includes the print head 13-1 and the hammer drive source among the various mechanisms schematically illustrated in FIG. This is described in relation to.

Conventionally, a hammer magnet has been used without exception as a hammer drive source for causing the print head 13-1 to hammer the print medium 11 supported by the platen 12, and in the hammering method using this hammer magnet, The hammer stroke from the pause of the print head 13-1 to the point of impact on the platen is normally n(7I).
Lm) (actually several mm).

When focusing on this hammer stroke, there is still room to increase the printing speed.

In other words, the hammer stroke of nm still has room to be shortened, and for example, it can be reduced to n1 (<n) m
It can be set to m.

However, for serial printers used as office machines in banks, for example, front inserters, inserter journals, etc. are prepared separately, and all printing media (passbooks) can be printed.
It is not possible to simply shorten Hammers 1 Rourke to n1 (in).

When using these front inserters, etc., a member that guides the print medium is installed between the print head 13-1 and the platen 12, so the hammer stroke is n1 (n
This is because if it is fixed in position m), there is a risk that the member may get caught on the print head 13-1.

Therefore, when inserting a print medium, etc., the hammer stroke must be set to n (7IXffl) to prevent the print head 13-1 from catching on the member.

By the way, once the medium is guided to the printing position along the guide member, the guide member is retracted downward so as not to interfere with printing.

However, after the guide member is retracted, the distance between the print head and the platen can be nIM'S.

That is, before printing starts, the distance between the print head and the platen has a stroke length of nm, but during printing, the stroke length can be set to n 1 m'tn in order to realize high-speed printing.

In other words, the hammer stroke may be 3 strokes or 6 strokes.

Now, if such a variable hammer stroke is realized using a conventional hammer magnet, the hammer speed will be increased, but the
) It is necessary to provide two hammer magnets for strokes, which is not only uneconomical, but also increases the weight of the printing unit 13, resulting in slow space movement and ultimately does not improve printing speed.

Regarding hammer energy, due to the structure of the hammer magnet, a return spring must be attached, and hammering is performed against the return spring, so the hammer energy is not used effectively. This becomes a hindrance in increasing the printing speed.

Therefore, the present invention provides n1 (mm) and n (-Ift7ft)
A servo-controllable DC motor is used instead of the conventional hammer magnet so that the hammer stroke of the hammer can be changed freely and sufficient hammer energy is supplied for hammering.

Note that no example has yet been seen in which a DC motor is used as a hammer device in a printer.

FIG. 2 is an enlarged perspective view showing only a portion of the serial printer in FIG. 1 that is related to the present invention.

In FIG. 2, numeral 21 is a DC motor adopted according to the present invention, and a potentiometer 41 is provided on the back side of the motor.

The DC motor 21 is connected to the print head 13 through a gear 22.
1 toward the platen 12 in the directions of arrows S1 and S2.

Arrow S1 means a first stroke, and arrow S2 means a second stroke.

Next, the operation will be explained with reference to the graph in FIG.

In FIG. 3, the horizontal axis represents time t, and the vertical axis represents stroke amount S, respectively.

First, when a hammer command is supplied at time to, the print head 13-1 (FIG. 2) moves toward a temporary stable point, which is the end point of the first stroke, while maintaining the speed curve C1 and being servo-controlled.

The position of this temporary stable point is shown as a dotted line P.

After this, the designated type 23 according to the supplied printing data
(Fig. 2) together with the print head 13-1 (Fig. 2),
It follows the speed curve C2 toward the impact point on the platen 12 (FIG. 2).

The position of this impact point is shown as a dotted line Q in FIG.

At this time, the DC motor is fully excited.

When the second print data is subsequently supplied, the print head 131 does not return to the starting point of the first stroke S1, but returns to the temporary stable point P while being servo-controlled while maintaining the speed curve C3, and then returns to the stable point P while being servo-controlled, and then returns to the stable point P while maintaining the speed curve C3. The second printed character is hammered together with the print head 13-1 following a speed curve.

The hammer stroke at this time is the second stroke S2, which is n1 (im).

If the second type is printed according to the conventional method, it will be hammered following the speed curve shown by the dashed line CI, and one hammer hour will be (t3 h), and one hammer hour according to the present invention (t2tt ) is naturally longer.

If the third print data is subsequently supplied, it will be hammered from the temporary stable point P toward the impact point Q in the same way.

In this way, since printing is performed by reciprocating only the second stroke S2, it is clear that printing can be performed faster than in the past.

In the graph of Figure 3, if the supply of print data is interrupted, it is assumed that a new print medium will be inserted next, so after the last print is completed, the print head 13
-1 is lowered to the rest point of the print head 13-1 (starting point of the first stroke S1) while maintaining the speed curve C5 and being servo-controlled, and the distance between the platen 12 and the print head 13-1 is set to the nearest n( mm).

Therefore, at this rest point, it is possible to lift the side member between the print head and the platen, and then eject the printed bankbook or the like and insert a new bankbook or the like to be printed.

A specific example of a circuit that implements the two-stage switching hammering described above will be described.

FIG. 4A shows 1 to which the hammering method of the present invention is applied.
4B is a block diagram showing an example of the circuit, and FIG. 4B is a time chart for explaining the operation of the circuit of FIG. 4A.

In FIG. 4A, 21 is the DC motor M for the hammer shown in FIG. attached.

The output voltage Vs of the potentiometer 41 is determined by the differential amplifier 42.
is input to one terminal of

On the other hand, the output voltage vR from the variable reference voltage generation circuit 43 is applied to the ten terminals ζ, and the difference voltage (VR, V
S) is connected to the DC motor 2 via a phase compensation circuit 44, a clamp circuit 45, a switch 46 and a current amplifier 47.
1.

Then, the DC motor 21 is servo-controlled so that the differential voltage (VR, VS) becomes zero.

Next, the operation of the circuit shown in FIG. 4A will be explained with reference to the time chart shown in FIG. 4B.

First, a printing command a is supplied from a central control device (not shown) at time T1 (a in Fig. 4A and a in Fig. 4B).
reference).

As a result, the switch Sa of the variable reference voltage generation circuit 43
is closed, and the group R of the circuit 43
R quasi-voltage ■R becomes vcc'.

This ■cc-R+, aR+ra ? The reference voltage is shown as ■Ra in FIG. 4B d.

Due to the voltage difference between this v average and the potentiometer 41, t
During period a (see FIG. 4B, a), the current amplifier 47 is controlled to supply the drive current IM8 (see FIG. 4B, f) to the DC motor 21.

In this case, the drive current 'Mal is supplied only in the first half of the period t8, and after a predetermined time has passed, the drive current 'Mal becomes negative IMa1 (4th B
A braking current of (see figure f) is supplied.

In other words, when starting with the drive current positive (■Ma), the current becomes negative (I) at an appropriate timing by servo control.
Mal1), and the DC motor stably stops at the target position.

The DC motor 21 is servo-controlled by the drive currents ■Ma and 'Ma'1, and accordingly, the output voltage vs of the potentiometer 41 changes as shown in FIG.
It changes like ■sa in .

When this sa matches the reference voltage vRa (=vcc·) of R, the R+ra temporary stable point P (see FIG. 4B e) is reached.

This temporary stable point P is the same as P in FIG.

Further, the change in ■sa described above corresponds to the speed curve C1 in FIG.

In FIG. 4B, IMax maintains a constant peak level, which is defined by the clamp circuit 45 of FIG. 4A.

This makes it possible to achieve uniform speed of the DC motor 21.

■Ma'l has a predetermined waveform that goes from negative to zero level, and this predetermined waveform is shaped by the phase compensation circuit 44.

In other words, the circuit 44 adds a certain amount of speed obtained by differentiating the actual amount of change (corresponding to Vs) to achieve more stable servo control.

Next, at time T2 after the period ta, the impact command b is supplied from the central control device (see FIG. 4B b).

As a result, the switch Sb of the variable reference voltage circuit 43 in FIG. 4A is closed, and the reference voltage becomes 8, and the voltage VFl.
It rises to the level shown by b.

As a result, the DC moke 21 is fully energized during period tb (see FIG. 4B) and causes the print head to fly toward the platen with high energy.

This state of flight is represented by a waveform vsb in FIG. 4B, which corresponds to the speed curve MC2 in FIG.

At this time, the drive current is 1Mbt (see Fig. 4B, f).

Furthermore, at time T3, an excitation stop signal C is supplied from the central controller (see FIG. 4B, C), and the switch 46
Open.

As a result, the drive current becomes ■MCI (see Fig. 4B, f), which has a current value of zero.

As a result, the period t.

During this period, the print head flies at a constant speed, collides with the platen at time T4, and printing is performed.

This uniform flight is a process inserted in order to obtain constant printing energy regardless of the thickness of the printing medium and to prevent ink shading from appearing.

After this, if print data continues to be supplied, the print head will move to the rest point O (O in Figure 4B e), S=O in Figure 3).
Back off at the temporary resting point P without returning to the previous point.

This downward movement to point P is caused by the drive current 'M('1
It is stabilized at point P by the bank-to-bank control described above.

After further printing is repeated and a series of print data has been processed, neither the print command a nor the impact command b is supplied from the central control device, so the switch Sa in FIG. 4A
, Sb are both open and vR becomes zero (vR in Figure 4B d)
See o).

This causes the DC motor 21 to rotate in reverse until it reaches its rest point.

The output Vs of the potentiometer 41 at this time is as shown by C in FIG. 4B, which corresponds to C5 in FIG.

As explained above, according to the present invention, two-stage switching hammering by the DC motor 21 is achieved, and the two-stage switching is performed by the potentiometer 4 interlocked with the DC motor 21.
1, and by switching the reference voltage to be compared in three stages for servo control.

[Brief Description of the Drawings] Fig. 1 is a schematic structural diagram showing a part of the serial printer to which the present invention is applied, and Fig. 2 is a schematic structural diagram showing only the part of the serial printer shown in Fig. 1 according to the present invention. FIG. 3 is a graph for explaining the hammering method of the present invention, FIG. 4A is a block diagram showing an example of a circuit implementing the method of the present invention, and FIG. 4B is an enlarged perspective view of FIG. 4A. This is a time chart 1 showing the waveform of the main part. In the figure, 11 is a print medium, 12 is a platen 13-1 is a print head, 21 is a DC motor, 41 is a potentiometer, 42 is a differential amplifier, 43 is a variable reference voltage generator, 4
4 is a phase compensation circuit, 45 is a clamp circuit, and 47 is a current amplifier.

Claims (1)

[Scope of Claims] 1. A serial printer comprising a print head formed by arranging a large number of printed characters, a hammer drive source that applies a hammer action to the print head, and a platen that supports a print medium, comprising: The hammer driving source is a DC motor, and means for detecting the amount of rotation of the motor and means for generating a voltage difference between the output voltage of the detection means and a predetermined reference voltage are provided, A hammering method in a serial printer, characterized in that the DC motor is servo-controlled to perform printing. 2. A hammering method in a serial printer according to claim 1, wherein the detection means is a potentiometer. 3. In a serial printer comprising a print head for distributing a large number of printed characters, a hammer for imparting a hammer action to the print head, a drive source, and a platen for supporting a print medium, the hammer drive source is a DC motor, and is provided with means for detecting the amount of rotation of the motor, and means for generating a voltage difference between the output voltage of the detection means and a predetermined reference voltage. The hammer action is applied by servo-controlling the motor, and the reference voltages are v1, v2 and v3 (■1<■2<v3
), the printhead is selectively set to a value such that at the reference voltage V1, the print head is stabilized at its rest position, and at the reference voltage V2, the print head is servo-controlled to a temporary stable point located between the rest position and the platen. A hammering method for a serial printer, characterized in that the print head is servo-controlled to be stabilized, and the print head is controlled to impact the platen at the reference voltage (3). 4. A patent claim comprising a differential amplifier that outputs a differential voltage, a phase compensation circuit connected to the differential amplifier, and a clamp circuit connected to the phase compensation circuit, and driving a DC motor with the output of the clamp circuit. A hammering method in the serial printer described in scope 3.