JPH07299918A - Driving control of printing head - Google Patents

Abstract

PURPOSE:To reduce power consumption while ensuring predetermined printing pressure by reducing the time extending a current supply time and extending a regeneration time so as to compensate the lowering of printing pressure corre sponding to the reduced time. CONSTITUTION:When printing head driving time setting processing is started, the processing successively reading the drive time and cycle of the printing wire corresponding to temp. of a set level from the adjustment data stored in an ROM is performed (1f, 1g). Next, in a step 1h, correction shortening the extension DELTAT1 of the drive time DT1 for compensating the lowering of the drive current of a drive coil accompanied by a temp. rise by DELTAt1 is performed and, further, the correction extending a drive time DT2 by DELTAt2 so as to compensate the lowering of printing pressure generated when the drive time DT1 is shortend by DELTAt1 is performed. Subsequently, the data of the corrected drive times DT1, DT2 are set to a setting table (1i) and the printing operation based on these values is performed (1j).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control method for a print head which advances and retracts a print wire by energizing a drive coil.

[0002]

2. Description of the Related Art FIG. 8 is a partial sectional view illustrating a print head of a spring charge type impact printer. In this print head, an armature 82 is attached to the tip of a leaf spring 81 provided in the shape of a cantilever, and the wire 8 is attached to the tip of the armature 82.
3 is connected.

A permanent magnet 84 and a core 84b are provided on the base 84a, and a drive coil 85 is wound around the core 84b. In the non-printing state, the magnetic flux of the permanent magnet 84 is the base 84a and the core 84.
b, the armature 82 and the like form a magnetic circuit, whereby the armature 82 overcomes the bias of the leaf spring 81 and is attracted to the core 84b.

On the other hand, when printing is performed, the drive coil 8
An electric current is caused to flow through the magnet 5 to excite it, and a magnetic flux having a direction opposite to the magnetic flux of the permanent magnet 84 is generated. As a result, the suction of the armature 82 is released, and the elastic reaction force of the leaf spring 81 moves the armature 82 upward in the figure to move the wire 83.
Projects from the tip of the guide nose 83a and pushes up the ink ribbon 86. By pushing up the ink ribbon 86 by the wire 83, the ink is transferred to the paper 87 and a predetermined printing is performed.

In order to control the print head, FIG. 9 (a) is used.
The current flowing through the drive coil 85 is controlled by the circuit shown in FIG. Further, FIG. 9B is a diagram showing timings of the coil current, the armature displacement, and the printing pressure according to the printing signals S1 and S2 of the circuit in FIG. 9A.

That is, during the time T1 when both the print signals S1 and S2 are ON (energization time), the current I1 shown by the solid line in the figure flows from the + VCC side shown in FIG. The flowing coil current also increases. In addition, the print signal S1 is OFF and the print signal S2 is ON.
During 2 (regeneration time), the current I shown by the broken line in FIG.
2 circulates in the closed circuit including the drive coil 85 and is gradually attenuated. In addition, the print signal S2 also turned off T
In the state of 3, the current I3 shown by the alternate long and short dash line in FIG. 9 (a) is + VCC from the ground side through the diode and the drive coil 85.
Flowing to the side, the coil current sharply decreases to zero.

In the armature 82 shown in FIG. 8, the suction is released by canceling the magnetic flux of the permanent magnet 84 with the increase of the coil current (energization time), and the displacement thereof increases. Further, the armature 82 is opened for a while during the regeneration time after energization and the displacement increases, and the ink ribbon 86 is contacted by the wire 83 in the vicinity of the print signal S2 being turned off, thereby performing printing at a predetermined printing pressure. To do. After printing, the magnetic flux of the permanent magnet 84 attracts the core 84b again.

Conventionally, in order to control the print head, the drive times DT1 (T1) and DT2 (T1 + T) are preset.
2) and are set according to various printing conditions, and the predetermined printing pressure is secured based on these settings. For example, when the temperature of the print head rises and the resistance value of the drive coil 85 increases, it is expected that the drive current will decrease. Therefore, it is possible to correct the drive time DT1 and increase the drive current to ensure a predetermined print pressure. I have to.

FIG. 10 is a waveform for explaining conventional print control according to drive time. As shown in FIG. 10A, during normal printing, drive time DT1 = T1,
Armature 82 continuously with DT2 = T1 + T2
(See FIG. 8) is moved to obtain a predetermined printing pressure. Further, when the drive current of the drive coil 85 decreases due to changes in various conditions, drive correction is performed as shown in FIG. That is, drive time DT1 = T1 + Δ
The drive time DT1 set as T1 is extended to suppress the decrease in printing pressure by increasing the drive current.

In addition to the increase in the resistance value of the drive coil 85, the drive current decreases when the drive voltage changes, for example, when the drive voltage changes. Therefore, the drive time DT1 is extended to secure a predetermined printing pressure. We are making corrections. In addition, even when the number of simultaneous prints is large and magnetic interference occurs, or when the gap between the wire 83 and the paper 87 is wide, the drive time DT is similarly set in order to secure the print pressure.
Correction is made to extend 1.

When the correction for extending the drive time DT1 is thus performed, the return time of the armature 82 due to the attraction of the permanent magnet 84 is delayed because the excitation of the drive coil 85 is not completed even after printing. Therefore, in order to cope with this, when the correction for extending the drive time DT1 is performed, the setting (cycle down) for delaying the repetition (cycle) of printing is simultaneously performed.

[0012]

However, when the drive time DT1 is corrected according to various conditions and the cycle is reduced, the current value increases and the power consumption also increases (see FIG. (See W1 'and W2' in 10 (b)). As a result, the coil temperature rises, which causes a problem that the printing operation for cooling, for example, bidirectional printing is changed to one-directional printing, or the number of processing such as temporary stop of printing is increased and the throughput for printing is lowered.

Further, when the cycle is reduced, rebound occurs due to the inertia of the armature when the armature is again attracted to the core between printing, which affects the printing pressure of repeated printing (continuous printing). Become. In other words, the next printing is performed before the rebound is attenuated, and when the displacement amount of the armature is reduced, the predetermined printing pressure cannot be obtained and the printing quality is deteriorated.

[0014]

SUMMARY OF THE INVENTION The present invention is a print head drive control method which has been made to solve such problems. That is, according to the present invention, in a print head that drives a print wire based on energization of a drive coil to perform predetermined printing, an energization time for flowing a current to the drive coil according to changes in various conditions and a drive coil after energization. A method of controlling a print head for controlling a regeneration time for circulating an electric current in a closed circuit including a print wire and ensuring a predetermined print pressure by a print wire, when the current amount of a drive coil is reduced due to changes in various conditions. When the energization time is extended by a predetermined amount to compensate for the decrease in printing pressure, the extension time is shortened and the regeneration time is extended so as to compensate for the decrease in printing pressure according to the reduced time.

Further, when the print wire is continuously driven, it is also a drive control method of the print head in which the print pressure of the print wire is secured by the second and subsequent drives by controlling the regeneration time.

[0016]

According to the present invention, when the amount of current flowing through the drive coil is reduced due to changes in various conditions, the energization time to the drive coil is extended by a predetermined amount to reduce the printing pressure to compensate for the reduction in printing pressure. The current value of the drive coil is not raised too much. Furthermore, by extending the regeneration time in accordance with the amount of extension of the energization time, it is possible to compensate for the printing pressure drop due to the reduction of the current value of the drive coil, and to reduce the power consumption and secure the predetermined printing pressure. Both can be achieved.

Further, when the print wire is continuously driven, the rebound time can be controlled so that the rebound of the armature generated between prints does not affect the next print. Even in continuous printing, it is possible to obtain a reliable printing pressure.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a print head drive control method according to the present invention will be described below with reference to the drawings. FIG. 1 shows the first of the present invention.
2 is a block diagram of the control system, FIG. 3 is a temperature detection circuit diagram, and FIG. 4 is a waveform for explaining the first embodiment of the present invention. 5 to 6 are flowcharts for explaining the second embodiment of the present invention, and FIG. 7 is a waveform for explaining the second embodiment of the present invention. In the following, drive control of a spring-charge type print head as shown in FIG. 8 will be described as an example.

First, prior to describing the drive control method for the print head of the present invention, a control system for performing drive control will be described. As shown in FIG. 2, this control system includes a CPU (central processing unit) 21 that controls the entire impact printer, and a ROM (read-only memory) 22 that stores a control program and adjustment data to be described later.
A RAM (read / write memory) 23 for temporarily storing data received from the outside, a temperature detecting circuit 24 for the print head, and a setting table 2 for setting the drive time and cycle of the print wire in response to a command from the CPU 21.
5, a print head driver 26 for driving the print head in response to a command from the CPU 21, and a bus line 27 for connecting each part.

The setting table 25 is not provided separately by a storage device or the like, but is a firmware given by an operation for reading the optimum print wire drive time and cycle described later from the adjustment data in the ROM 22. It will be realized.

The adjustment data stored in the ROM 22 is
In some temperature ranges of the print head, the optimum drive time and cycle of the print wire for ensuring the print quality are experimentally obtained and are associated with each other. Also,
As shown in FIG. 3, the temperature detection circuit 24 includes a thermistor 31 mounted inside the print head, and the thermistor 3.
The comparators 32 and 33 that compare the resistance change of No. 1 with the reference voltages Va and Vb, and the reference voltages Va and Vb with the constant voltage V
It is composed of resistors R1, R2, R3, and R4 for dividing the voltage from.

Then, from the comparators 32 and 33 of the temperature detection circuit 24, two-stage temperature detection signals Sa of a first level and a second level corresponding to a preset temperature,
Sb is output and sent to the CPU 21 shown in FIG.
With such a temperature detecting circuit 24, the temperature of the print head can be digitally detected. That is, the detected temperatures are K1 and K2 (K1 <K2), and K
The resistors R1, R2 and R3 are so arranged that the first level signal Sa is output when it is 1 and the second level signal Sb is output when it is K2.
, R4 values are set.

Next, a first embodiment of the present invention based on the above-described control system will be described. First, as shown in step 1a of FIG. 1A, the CPU 21 determines whether or not the first level signal Sa is output, and then the first level signal Sa is output.
Is not output, that is, when the temperature of the print head is less than K1, the process proceeds to step 1b, and the normal print operation without drive adjustment is performed.

If it is determined that the first level signal Sa is output, that is, if the temperature of the print head has reached K1, the process proceeds to step 1c, and the printing operation based on the print head drive time setting process described later. I do. Step 1
After advancing to c, the CPU 21 determines whether or not the second level signal Sb is output in step 1d. If it is determined that there is no signal output, that is, if the temperature of the print head is less than K2, the process returns to step 1a to repeat the determination. On the other hand, when it is determined that the second level signal Sb is output, that is, when the temperature of the print head becomes K2 or higher, the process proceeds to step 1e, and the printing operation based on the print head drive time setting process is performed in the conventional cooling. Performs the cooling printing operation with the operation added.

After performing step 1e, the procedure returns to the determination of step 1d, and the determination of the presence / absence of the second level signal Sb is repeated. Then, the printing operation selected as described above, that is, the normal printing operation (step 1b), the printing operation based on the print head drive time setting process (step 1)
c), cooling printing operation with cooling operation added (step 1
While executing any one of e), the first level signal Sa
Then, the presence / absence of the second level signal Sb is determined, and when the determination is changed, the printing operation is immediately switched to the determination.

Next, the print head drive time setting process which is a main part of the control method of the first embodiment will be described. As shown in FIG. 1 (b), when this process is started, first, the temperature of the set level, in this case K1 or more and K2
The process of sequentially reading the drive time and the cycle of the print wire corresponding to the temperature lower than the temperature from the adjustment data stored in the ROM 22 (see FIG. 2) is performed (steps 1f, 1).
g).

Next, the drive time corresponding to the read cycle is corrected (step 1h). That is, in the first embodiment, the drive coil 85 due to temperature rise and the like
(See FIG. 8) A correction is made to shorten the extension ΔT1 of the drive time DT1 for compensating for the drive current decrease by Δt1. Furthermore, with the correction of this drive time DT1,
A correction is made to lengthen the drive time DT2 by Δt2 so as to compensate for the decrease in the printing pressure due to the decrease of the drive time DT1 by Δt1.

Then, the values of the respective drive times DT1 and DT2 thus corrected are set in the setting table 25 (see FIG. 2) (step 1i), and the printing operation based on these values is performed (step 1j). As a result, the drive coil 85 (see FIG. 8) changes due to changes in various conditions such as temperature rise.
Even when the drive current is decreased, the control for ensuring the predetermined printing pressure can be performed without performing the correction for unnecessarily increasing the drive current.

Next, a specific example of the control method in the first embodiment will be described with reference to FIG. Figure 4 (a) shows the case of normal printing
That is, the coil current when not cycle down,
The waveforms of the armature displacement and the printing pressure are shown in FIG.
(B) shows the waveforms of the coil current, armature displacement, and printing pressure when the drive correction is performed and the cycle is reduced.

As shown in FIG. 4 (a), during normal printing, once the armature displacement is released and the operation of returning is completed, the operation of the next printing is started for an extremely short time or at the same time. The cycle time is limited. For this reason, printing is controlled by the drive time DT1 and the drive time DT2 so that one operation is completed within the time limit.

As shown in FIG. 4 (b), during drive correction, the drive time DT1 of the drive coil 85 (see FIG. 8) and the drive time DT2 are corrected according to cycle down of the print head performed under various conditions. I do. That is, in order to compensate for the coil current of the drive coil 85 (see FIG. 8) that decreases due to changes in various conditions, the drive time DT1 has conventionally been corrected so as to extend the energization time T1 by ΔT1 (FIG. 10 (b)). reference). In the first embodiment, the drive time DT1 that shortens this ΔT1 by Δt1
Is corrected to suppress an unnecessary increase in coil current.

Further, as the drive time DT1 is shortened by Δt1 compared to the conventional one, in order to compensate the printing pressure drop by that amount, the regenerative time T2 of the drive coil 85 (see FIG. 8) is extended by Δt2 to drive. The time DT2 is being corrected. As a result, the armature 82 (Fig. 8
(See FIG. 8), the required printing pressure can be secured by supplementing the stroke, and the coil current of the drive coil 85 (see FIG. 8) does not rise too much in response to changes in various conditions, and power consumption can be reduced (FIG. (See W1 and W2 in 4 (b)).

Further, in the control method in the first embodiment,
When performing drive correction according to cycle down, the coil current can be made lower than in the prior art, so the drive coil 85
(Refer to FIG. 8) The number of cooling printing operations for cooling the printer is reduced, and the throughput for printing is improved.

Next, the flow of the second embodiment of the present invention will be described with reference to FIGS.
It will be described with reference to FIG. First, step 5 in FIG.
As shown in a, the CPU 21 (see FIG. 2) determines whether or not the first level signal Sa is output by the temperature detection circuit 24 (see FIG. 2). Here, when the first level signal Sa is not output, that is, when the temperature of the print head is K1.
If it is less than this, the process proceeds to step 5b, and the normal printing operation without drive adjustment is performed.

When it is determined that the first level signal Sa is output, that is, when the temperature of the print head has reached K1, the process proceeds to step 5c and the print operation based on the print head drive time setting process described later. I do. Step 5
After advancing to c, the CPU 21 determines whether or not the second level signal Sb is output, advancing to step 5d. If it is determined that there is no signal output, that is, if the temperature of the print head is less than K2, the process returns to step 5a to repeat the determination. On the other hand, when it is determined that the second level signal Sb is output, that is, when the temperature of the print head becomes K2 or more, the process proceeds to step 5e, where the printing operation based on the print head drive time setting process is performed and the conventional cooling is performed. Performs the cooling printing operation with the operation added.

After performing step 5e, the process returns to the determination of step 5d and the determination of the presence / absence of the second level signal Sb is repeated. Then, the printing operation selected as described above, that is, the normal printing operation (step 5b), the printing operation based on the print head drive time setting process (step 5)
c), cooling printing operation with cooling operation added (step 5
While executing any one of e), the first level signal Sa
Then, the presence / absence of the second level signal Sb is determined, and when the determination is changed, the printing operation is immediately switched to the determination.

Next, the print head drive time setting process which is a main part of the control method of the second embodiment will be described. As shown in FIG. 6, when this process is started, first, the drive time and cycle of the print wire corresponding to the temperature of the set level, in this case, the temperature of K1 or more and less than K2 are stored in the ROM 22 (see FIG. 2). ) Is sequentially read out from the adjustment data stored in () (steps 6a and 6b).

Next, it is judged whether or not the read cycle is within the cycle range in which rebound due to the return of the armature 82 (see FIG. 8) obtained by the experiment remains (step 6c). If the cycle is outside the range where the rebound remains, set the value in the setting table 25.
(See FIG. 2) (step 6e), and the printing operation is performed based on the setting (step 6f).

On the other hand, if the read cycle is within the range where the rebound remains, correction is made by adding ΔT2 to the regeneration time T2 of the drive coil 85 (see FIG. 8) (step 6d), and the drive time after the correction is performed. Is set in the setting table 25 (step 6e), and the printing operation is performed based on the set drive time and cycle (step 6f). As a result, even in the cycle where the rebound of the armature 82 remains, it can be reduced by the correction of adding ΔT2 to the regenerative time T2, and the control for ensuring the predetermined printing pressure can be performed.

Next, a specific example of the control method in the second embodiment will be described with reference to FIG. FIG. 7A shows the case of normal correction
That is, the waveforms of the coil current, the armature displacement, and the printing pressure when the cycle is lowered are shown in FIG.
(B) shows the waveforms of the coil current, armature displacement, and printing pressure when the drive time DT2 is corrected.

As shown in FIG. 7A, in order to cope with changes in various conditions, the cycle CTa during normal correction is set longer than the cycle CT during normal printing (see FIG. 10A). . However, in cycle CTa, a rebound occurs between the first armature displacement and the second armature displacement, and the second printing operation starts when the armature 82 (see FIG. 2) descends due to the rebound. As a result, a predetermined printing pressure cannot be obtained.

In such a case, in the second embodiment, the drive time DT2 is controlled so that the rebound of the armature 82 does not affect the printing pressure after the second time. That is, when the cycle CTa is within the range where the influence of the rebound of the armature 82 remains, as shown in FIG. 7 (b), the regeneration time T2 is set to ΔT.
2 Correct the drive time DT2 to extend it. The range of the cycle in which the rebound affects the next printing is determined by experimentally obtaining the relationship between the drive time DT1 and the armature displacement and the cycle in advance. Further, .DELTA.T2 is determined and set so that the rebound does not affect the next printing (a range of 1 <(T2 + .DELTA.T2) / T2 <2 is suitable).

As described above, by extending the drive time DT2, the cycle CTb is established, the rebound between the first armature displacement and the second armature displacement is controlled, and the predetermined printing pressure is applied in the second printing operation. You will be able to secure. For example, if .DELTA.T2 is set to a value such that the rebound between the first armature displacement and the second armature displacement converges, the second armature displacement is not affected and a predetermined printing pressure can be secured.

When high speed printing is supported, ΔT2 is set at a timing such that the influence on the second armature displacement is reduced even before the rebound converges.
By setting, it becomes possible to increase the printing throughput. In the second embodiment, the print operation is performed in a stable state of the armature 82 of the print head, and it is possible to always secure a sufficient print pressure even when repeatedly printing.

In the first and second embodiments, the spring charge type print head has been described as an example, but the present invention is not limited to this. In other words, the present invention can be applied to a plunger type or clapper type print head that energizes the drive coil and sucks the armature to perform printing.

[0046]

As described above, the print head drive control method of the present invention has the following effects. That is, in the present invention, when performing the correction to extend the drive time of the drive coil according to various conditions, it is possible to secure a predetermined printing pressure and reduce power consumption by reducing the extension of the energization time and extending the regeneration time. It becomes possible. As a result, the rise in coil temperature can be suppressed and the number of printing operations for cooling can be reduced, so that the throughput for printing can be improved. Even when the cycle is reduced, the effect of rebound of the armature can be reduced by controlling the regeneration time, so continuous printing can be performed with stable printing pressure, and it is possible to improve the printing quality. Become.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating a first embodiment of the present invention.

FIG. 2 is a block diagram of a control system.

FIG. 3 is a temperature detection circuit diagram.

4A and 4B are waveforms for explaining the first embodiment, in which FIG. 4A shows normal printing and FIG. 4B shows drive correction.

FIG. 5 is a flowchart (part 1) for explaining the second embodiment.

FIG. 6 is a flowchart (part 2) explaining the second embodiment.

7A and 7B are waveforms for explaining the second embodiment, where FIG. 7A shows a normal correction time and FIG. 7B shows a drive time DT2 correction time.

FIG. 8 is a partial cross-sectional view illustrating a print head.

FIG. 9 is a diagram illustrating print control, in which (a) is a circuit diagram,
(B) shows the signal timing and the waveform.

10A and 10B are waveforms for explaining a conventional example, in which FIG. 10A shows normal printing and FIG. 10B shows drive correction.

[Explanation of symbols]

 21 CPU 22 ROM 23 RAM 24 Temperature Detection Circuit 25 Setting Table 26 Print Head Driver 27 Bus Line 81 Leaf Spring 82 Armature 83 Wire 84 Permanent Magnet 85 Drive Coil

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Noboru Oishi 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Koichi Ando 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Yuhiko Shimosugi 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (2)

[Claims] 1. In a print head which drives a print wire based on energization of a drive coil to perform predetermined printing, an energization time for supplying a current to the drive coil according to changes in various conditions, and the drive after energization. A drive control method for a print head for controlling a regeneration time for circulating an electric current in a closed circuit including a coil to secure a predetermined print pressure by the print wire, the current amount of the drive coil depending on changes in the various conditions. When decreasing, the energizing time is extended by a predetermined amount to compensate for the decrease in the printing pressure, and the extending time is reduced, and the regeneration time is extended to compensate for the decrease in the printing pressure according to the reduced time. Characteristic print head drive control method. 2. In a print head which drives a print wire based on energization of a drive coil to perform a predetermined printing, an energization time during which a current is applied to the drive coil according to changes in various conditions, and the drive after energization. A drive control method of a print head for controlling a regeneration time of circulating a current in a closed circuit including a coil to secure a predetermined print pressure by the print wire, in which the drive of the print wire is continuously performed, A drive control method for a print head, characterized in that the print pressure of the print wire is secured by the second and subsequent drives by controlling the regeneration time.