JPH0332468B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an improvement in a printer that is equipped with a mechanism for feeding ribbon from a ribbon supply side to a ribbon winding side, and in which the ribbon winding member is driven by intermittent drive of a step motor. In particular, high print quality can be achieved by ensuring that the step motor, which is loaded in the opposite direction when stopped, can reliably rotate in the forward direction the next time it is driven, thereby improving the reliability of motor operation. The present invention relates to a printer in which a step motor drives a ribbon.

BACKGROUND OF THE INVENTION Generally, in order to prevent heat generation and other reasons, step motors are driven with a drive current only when they are in operation, and are excited with a holding current that is smaller than the drive current when they are stopped. In that case, when driving the motor from a stopped state,
The conventional drive method is to leave the holding current as it is in the stopped phase, and then excite it with the drive current from the next phase to rotate the motor.

However, when a force is applied to rotate the motor in the opposite direction due to the driven load, such as the film ribbon, as in the case of a ribbon feed motor,
If the holding current is reduced in a stopped state, the holding force is also reduced, and the motor is returned in the opposite direction by the reversing force of the film ribbon, causing a change in the stopped position.

FIG. 1 is a partially cutaway top view of a conventionally used film ribbon cartridge.
In the drawing, 1 is a cartridge main body, 2 and 3 are locking parts of the main body 1, 4 is a ribbon core part in which an unused film ribbon is stored, 5 is a rotating roller, and 6 and 6
A is a film ribbon, 7 is a feed gear, 8 is a winding shaft, 9 is a belt, 10 is a driven gear that is in pressure contact with the feed gear 7, 11 is a tension lever,
Reference numeral 12 indicates a spring member, 13 indicates a back tension member storage portion, 13A indicates a back tension member, arrow S indicates the feeding direction of the film ribbon 6, and arrows T and U indicate the moving direction of the belt 9.

The film ribbon 6 is fed from the ribbon core portion 4 shown on the right side in the direction of arrow S by the rotation of a feed gear 7 and a take-up shaft 8 driven by a step motor (not shown), and is fed to the take-up shaft 8 from the core portion 4 of the ribbon shown on the right side.
It is wound up one after another. In this case, the back tension member 13A is in contact with the core portion 4 from above, and the film ribbon 6 is moved in the direction of arrow S due to the frictional resistance, while back tension is applied. It is acting on

Therefore, when the ribbon is fed intermittently in conjunction with the printing operation, back tension is applied to the film ribbon 6, and at the same time, the winding state of the ribbon in the core portion 4 is prevented from being disturbed.

In addition, the feed gear 7 and the winding shaft 8 on the winding side
are configured to have different diameters, and a belt 9 made of an elastic material such as rubber is hung between the gear 7 and the shaft 8.

With this configuration, when winding the ribbon, tension is always applied to the film ribbons 6, 6A, allowing tight winding. During normal winding, the belt 9 is in a tensioned state between a and b, and is in a relaxed state between a' and b' on the opposite side.

When the feeding operation of the ribbon is completed, a force is applied to the belt 9 to keep the tension between a-B and a'-b' constant, and the feed gear 7 moves as indicated by the arrow T.
It is rotated in a direction opposite to the normal winding direction indicated by U. That is, the step motor is returned to its stop position in the opposite direction.

Next, regarding such reverse rotation of the stop position,
This will be explained in detail using the torque curve of the step motor.

FIG. 2 shows the torque curve of the step motor during normal operation.

In this Figure 2, the stop phase is φ4, and
Points Y and Z are each set at a stop position. That is, due to the previous driving, the phases φ1 to φ4 are switched and stopped at the stop point Y, and then the four pulses of the ribbon feed lock similarly switch the phases φ1 to φ4.
This shows that the switching of φ4 is performed and the motor is stopped at the stop point Z.

And, as already explained, in general,
At the stop points Y and Z, drive/hold switching is also performed to prevent heat generation in the motor, circuits, etc., and to improve operational reliability.

FIG. 3 is a torque curve of the step motor when switching between drive and hold.

As shown in FIG. 3, the motor is switched from φ4 DRIVE to φ4 HOLD at a stop position, for example, point Y, and is held with a relatively weak torque.

When the motor is in a detented state with such a relatively weak torque, if reverse rotational torque is applied from the driven load side such as a ribbon cartridge, as explained earlier, the motor will move toward the left in the drawing, that is, at the point. It will be returned to the direction of X.

Assume that this reverse rotation torque and the hold torque of φ4HOLD are in equilibrium at point X, and this position is the stop position of the motor.

In this state, when a normal drive operation is performed and the drive phase is switched to φ1, as is clear from FIG. 3, the torque of φ1 at this point X is zero. Therefore, the motor will not rotate at all, or
Or, even if it moves somewhat in either the forward or reverse direction, sufficient torque necessary for rotation cannot be obtained, and as a result, it is hardly rotated.

Next, when the phase is switched to φ2, it begins to rotate in the opposite direction, and when φ3 is selected, rotation in the forward direction is performed for the first time at this point, and the next φ4 also rotates normally in the forward direction. can continue.

The torque from φ1 to φ4 generated in this way is
It is shown in FIG. 3 by a thick line with an arrow. The stopping position after driving φ1 to φ4 is point Y again.

Furthermore, even if the motor stop position is between points X and Y, if the motor rotates in the forward direction and is not moved to the right from point Y during the first drive phase As in the case where the motor is stopped at point X, the stopping position after driving becomes point Y again.

Therefore, in ribbon feed control using the conventional drive method, due to the shift in the stop position of the step motor caused by the force that tries to rotate it in the opposite direction, it is difficult to ensure the proper starting torque at the next drive. Therefore, rotation errors often occurred.

In this way, in the conventional drive system, if the amount of return in the opposite direction from the stop position when the motor is stopped is large, the starting torque during the next drive is reduced.
It becomes impossible to drive the load.

As a result, on the printing surface, uneven density of characters, missing characters, etc. occur, and the printing quality deteriorates.

Problems to be Solved by the Invention The present invention solves these inconveniences in conventional printers, and uses the ribbon pull-back force that the step motor receives when the step motor is stopped, so that even if the motor is rotating in the opposite direction, To improve the reliability of a printer and to obtain high-quality printing by generating a starting torque that can reliably rotate the printer in the original rotation direction when driving the printer.

Means for Solving the Problems According to the present invention, in a printer that is equipped with a mechanism for feeding the ribbon from the ribbon supply side to the winding side, and in which the ribbon winding member is driven by intermittent drive of a step motor, the stop phase is excited with a holding current. When driving the motor from a stopped state, prior to exciting the excitation phase that should be stepped with the drive current, the stopped phase that is being excited with the holding current is excited with the drive current for a predetermined period of time to make it normal. After returning to a predetermined position, the next excitation phase to be stepped is excited with a drive current.

Effects In the printer of the present invention, with the above configuration, the stop phase is once excited with a drive current before the motor rotates, so that the stop position of the motor returned in the opposite direction by the load can be adjusted to the normal stop position. Since the motor is returned to the stop position and then the next phase is excited with the drive current, the original starting torque required to drive the motor is generated.

In other words, the stop position is corrected using a simple drive method in which the stopped phase is once excited by the drive current, and even if the motor's stop position shifts in the opposite direction due to the load, rotation errors will be avoided during the next drive. It becomes possible to perform the desired rotation without causing any distortion.

Also, in the printer of this invention, similarly to the conventional drive system, when the printer is stopped, the switch is made so that a small holding torque is generated by φ4HOLD, and the stop position is moved in the opposite direction by the reverse rotation torque of the ribbon, which is the driven load. This ensures that accurate rotational drive is always possible even when the shaft is returned to the original position.

Embodiments Next, embodiments of the printer of the present invention will be described in detail with reference to the drawings.

FIG. 4 shows the step motor and torque curve in the printer of this invention.

In the printer of this invention, when the motor is stopped in a state where it is returned from the normal stopping position Y to the point In this case, the phase change to the rotary drive phase is not performed immediately. That is, as already explained, the phase at the current stop position, that is, the phase of φ4 in the previous embodiments, is first switched from the hold torque φ4HOLD to the drive torque φ4DRIVE, and then the phase is changed from φ1 to φ4 so that the desired rotation is performed. The φ4 phase is switched.

Therefore, at the time of start, the torque for the stop phase is switched from hold to drive, and the motor that was stopped at point The starting torque generated by the motor enables normal rotational operation of the motor.

FIG. 5 is a block diagram showing the configuration of a conventional ribbon feed control circuit. In the drawings, 14
is a delay circuit, 15 is a mono multivibrator for hammer, 16 is a hammer driver, 17 is a set-reset flip-flop circuit, 18 is a clock generation circuit, 19 is a counter, 20 and 21 are AND gate circuits, 22 and 23 are delay flip-flop circuits, 24 indicates a ribbon feed driver.

The following FIG. 6 is a time chart for explaining the operation of the circuit shown in FIG. The symbols A to K assigned to each signal in the drawing correspond to the same symbol position in the circuit of FIG.

Now, when the character selection or carriage movement operation associated with the printing operation of the printer is completed, an input pulse A is input from a control section (not shown) to the hammer and ribbon feed control circuit.

This input pulse A is applied to the delay circuit 14, and after a preset time delay B has elapsed, the operations of the hammer and ribbon feed are started. The reason for providing such a time delay B is to secure the time from the end of character selection or carriage movement until the device comes to a complete mechanical standstill.

Then, at the fall of this time delay B, the hammer mono multivibrator 15, the reset/flip-flop circuit 17, and the clock generation circuit 18 start operating.

That is, the printing operation is performed via the hammer driver 16 in response to the hammer drive signal C generated from the mono-multivibrator 15 . Also,
A ribbon feed drive signal D is applied from the flip-flop circuit 17 to the ribbon feed driver 24, and at the same time, a ribbon feed clock E is generated from the clock generation circuit 18.

Ribbon feed clock E rotates the motor to the next stop position with four pulses. counter 19
is used to count these four pulses, and during that time it generates an output G and opens the gate of the AND gate circuit 21. Therefore, the output F of the gate circuit 21 is transferred to the delay flip-flop circuit 2.
2 and 23 to generate ribbon feed phase excitation signals J and K.

In the conventional control circuit shown in FIG. 5, the phase switching signal J is changed to the drive signal D as shown in FIG.
They are generated at the same time, and when the motor starts, the next phase is immediately excited by the drive current.

Therefore, as explained in detail in relation to Figure 3 above, if the stop position is returned to the opposite direction due to the reverse rotation torque from the ribbon, which is the driven load, then the normal starting torque is applied at the time of start. cannot be generated reliably, leading to rotation errors. As a result, the ribbon feed operation becomes inaccurate, resulting in uneven density of characters, missing characters, etc. on the printed surface.

Note that even after the output F of the AND gate circuit 21 ends, the ribbon feed clock E continues to operate twice.
The two clocks are used to compensate for the inconvenience in ribbon feed operation.

FIG. 7 is a block diagram showing one embodiment of the ribbon feed control circuit in the printer of the present invention. The symbols in the drawings are the same as in Fig. 5,
Further, 25 is a delay circuit, 26 is an inverter, 27
indicates an AND gate circuit.

The following FIG. 8 is a time chart for explaining the operation of the circuit shown in FIG. 7. The symbols A, L to Q, etc. attached to each signal in the drawing correspond to the same symbol position in the circuit in FIG. 7, and the signals B and C, which are common to the circuit in FIG. 6, have been omitted. There is.

The drive control of the hammer is similar to the conventional circuit shown in FIG. 5.

On the other hand, in ribbon feed control, since the input pulse A is directly input to the reset flip-flop circuit 17, the ribbon feed drive signal L is immediately generated.

Therefore, the stop phase of the ribbon feed motor, which had been excited by the hold current, is now excited by the drive current, and the motor returns from the stop position in the opposite direction due to the reverse rotation torque of the driven load to the normal stop position. It will be.

In this way, in the printer of the present invention, the input pulse A generates a drive current to the stop phase, so the stop position error is corrected prior to the start, and during subsequent rotational driving,
Normal starting torque is generated.

In FIG. 7, the time delay M of the delay circuit 25 is set to the same time as the time delay B of the delay circuit 14, and the subsequent phase switching is different from that shown in FIGS. 5 and 6, which show conventional examples. The same is done.

That is, after the time delay M has elapsed, the gate of the AND gate circuit 27 is opened, and a signal N corresponding to the conventional drive signal D is generated from the AND gate circuit 27.

In response to this signal N, the clock generating circuit 18 starts operating, a ribbon feed clock O is generated, and the counter 19 counts four pulses thereof. The motor is rotated to the next stop position by these four pulses of clock O.

The phase excitation signals J' and K' of the ribbon feed are generated at the same timing as the phase excitation signals J and K of the conventional example.

Incidentally, in the printer of the present invention, inconveniences in the ribbon feed operation can be corrected with one clock, so after the gate of the AND gate circuit 21 is closed by the output P of the counter 19, the next fifth clock O is At the rising edge, the output signal N of the gate circuit 27 is brought to L level.

Effects of the Invention According to the printer of the present invention, it is possible to always perform normal rotational drive even if the stop position when stationary is deviated from the normal position due to the reverse rotational torque generated by the ribbon, which is the driven load. becomes.

As a result, the reliability of the printer is significantly improved, and the occurrence of uneven density of printed characters and missing characters caused by rotational errors is completely prevented, resulting in the excellent effect of obtaining high-quality printing. can be achieved.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway top view of a conventionally used film ribbon cartridge, Figure 2 is the step motor torque curve during normal operation, and Figure 3 is the drive/hold switching. Torque curve of step motor when
FIG. 4 is a torque curve of the step motor in the printer of the present invention, FIG. 5 is a block diagram showing the configuration of a conventional ribbon feed control circuit, and FIG.
5 is a time chart for explaining the operation of the circuit shown in FIG. 5, FIG. 7 is a block diagram showing an embodiment of the ribbon feed control circuit in the printer of the present invention, and FIG. 8 is the circuit shown in FIG. 7. Time chart to explain the operation. In the drawing, 1 is a cartridge body, 4 is a ribbon core, 5 is a rotating roller, 6 and 6A are film ribbons, 7 is a feed gear, 8 is a winding shaft,
9 is a belt, 10 is a driven gear, 11 is a tension lever, 12 is a spring member, 13 is a back tension member storage area, 13A is a back tension member, 14 is a delay circuit, 15 is a mono-multivibrator for hammer , 16 is a hammer driver, 17 is a reset flip-flop circuit, 18 is a clock generation circuit, 19 is a counter,
22 and 23 are delay flip-flop circuits, 24 is a ribbon feed driver, and 25 is a delay circuit.

Claims (1)

[Scope of Claims] 1. In a printer that is equipped with a mechanism for feeding the ribbon from the ribbon supply side to the winding side and whose ribbon winding member is driven by intermittent drive of a step motor, a stop phase in which the stop phase is excited with a holding current is provided. When driving the motor from a state, prior to exciting the excitation phase that should be stepped with the drive current, the stop phase that is excited with the holding current is excited with the drive current for a predetermined period of time to return it to its normal predetermined position. 1. A printer characterized in that, after the step, the next excitation phase to be stepped is excited by a drive current.