JP3280738B2 - Print head drive controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head drive control device for controlling a print head constituted by using a piezoelectric element.

In recent years, with the demand for higher speed of the wire dot type printer, a print head for printing by driving a print pin using a piezoelectric element (electrostrictive element) instead of an electromagnetic print head has been developed. It has been put to practical use.

A print head using such a piezoelectric element has an advantage that it can meet the demand for miniaturization as well as high speed. However, the print quality is degraded due to the influence of inertia due to the mechanical operation of the print pin, and the degradation becomes remarkable when high-speed operation is to be realized. Therefore, improvement in printing quality as well as high speed is desired.

[0004]

2. Description of the Related Art A conventional print head using a piezoelectric element is:
For example, it is configured as shown in FIG. Note that an actual print head is configured by providing 24 sets of the same mechanism in order to simultaneously print a plurality of dots, for example, 24 dots. However, FIG. 3 shows only a configuration for one dot for simplicity of explanation. I have.

In FIG. 3, reference numeral 30 denotes a piezoelectric element. The piezoelectric element 30 is a well-known piezoelectric element having the property of expanding when a voltage E is applied, contracting when the voltage is released, and returning to its original state.

The lower end of the piezoelectric element 30 in the figure is fixed to a frame 31. A leaf spring 32a is fixed to the upper end of the piezoelectric element 30 in the figure.
The tip of 2a is engaged with the armature 33 to form a hinge. On the other hand, a leaf spring 32b is also fixed to the upper end of the frame 31 in the figure,
3 to form a hinge portion. The above leaf spring 32
a and 32b are parallel springs 32 arranged to be parallel.

The armature 33 is arranged so as to rotate around the tip of the leaf spring 32b. A print pin 35 is fixed to the right end of the armature 33 in the figure via a wire 34.

[0008] The print head having the above configuration is driven by applying a predetermined voltage. Here, the piezoelectric element 30
Has electric characteristics similar to those of a capacitor. For example, as shown in FIG. 8, charging is performed by applying a voltage E, whereby the piezoelectric element 30 itself slightly expands. On the other hand, when the application of the voltage is released, a discharge is performed, whereby the battery contracts and returns to the original state.

The print head performs printing by controlling the charging time 1 and the discharging time 2 of the piezoelectric element 30 to extend and contract the piezoelectric element itself and to move the print pin 35 forward and backward.

That is, when the voltage E is applied, the piezoelectric element 30
Is charged and extended. Thereby, the leaf spring 32a
Presses the armature 33, and the armature 33
2b. Although the extension width of the piezoelectric element 30 is very small, the arrangement distance between the leaf springs 32a and 32b is short, so that the movement distance of the armature 33 at the right end in the drawing becomes large, and the print pin 35 moves in the direction of the arrow P in the drawing. I do.

As a result, the leading end of the print pin 35 strikes the print paper placed on the platen via an ink ribbon (not shown), and prints dots.

However, if it is attempted to control the advance / retreat of the print pin 35 only by the presence or absence of the voltage E applied to the piezoelectric element 30 in accordance with the presence or absence of the dot to be printed as described above,
When continuous dots are printed, excessive kinetic energy is stored in the print pins 35 and rebound occurs, which causes a problem that surplus dots are printed and print quality deteriorates. In view of the above, the present invention solves such a problem with the invention according to the prior application of the present applicant (Japanese Patent Application No. 282369, filed on November 10, 1988). However, the problem that the operation of the print pin 35 becomes unstable is solved. The remaining.

Therefore, the present applicant has disclosed in Japanese Patent Laid-Open No.
As shown in Japanese Patent Publication No. 54, if the dots to be printed occur independently, or continuously, or further continuously, whether the dot is the first dot or the second or subsequent dot Or, by changing the driving condition of the piezoelectric element 30, that is, the charging time and the discharging time depending on whether it is the last dot, it is possible to suppress the occurrence of rebound of the print pin 35 and to prevent the generation of an extra dot, Tried to stabilize the operation of.

[0014]

However, even if the invention disclosed in Japanese Patent Application Laid-Open No. 2-241754 is applied,
The rebound of the print pin generated after the printing of the last dot in the continuous dot row cannot be sufficiently suppressed, and the deterioration of the print quality due to the generation of extra bits cannot be avoided.

The applicant of the present invention has disclosed, for example, Japanese Patent Application No.
As shown in Japanese Patent No. 03409, by extending the charging time for the piezoelectric element, the extended state of the piezoelectric element is extended, whereby the force applied in the striking direction of the printing pin is stored for a certain time, and the printing pin is (Platen)
We considered a method to reduce the rebound by reducing the kinetic energy of striking back and then discharging.

This was applied to the printing of the last dot in continuous dots. That is, a means for detecting the last dot in the continuous dot is provided, and when the detection means detects that the last dot, the charging time of the piezoelectric element is extended so that the printing pin hits the printing paper and tries to return. By reducing the energy and then discharging, the time for the print pin to return from the striking position to the initial position is increased to reduce rebound.

However, if the print head is operated at high speed in order to increase the printing speed, rebound cannot be prevented only by changing the driving conditions of the last dot.

That is, when the printing speed is increased, the printing cycle (the interval from the printing of a predetermined dot to the printing of the next dot) is inevitably shortened. This means that the charging time given to the piezoelectric element at the time of printing the last dot cannot be made sufficiently long, and the prevention of rebound cannot be completely prevented.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a print head drive control device capable of preventing printing of excess dots due to an increase in printing speed and improving print quality. With the goal.

[0020]

According to a first aspect of the present invention, there is provided a print head drive control device, comprising:
As shown in principle in FIG. 1, a control device for a print head 20 for a dot printer for printing by moving a print pin 35 connected to the piezoelectric element 30 by repeating charging and discharging of the piezoelectric element 30. Detecting means 1 for detecting whether or not given print data includes a continuous dot row
0, and when the detecting means 10 detects that a continuous dot row is included, the charging time of the piezoelectric element 30 as a dot to be printed later becomes a predetermined dot after the predetermined dot in the continuous dot row. Generating means 11 for generating a control signal for gradually lengthening the print head, and driving means 12 for driving the print head 20 according to the control signal generated by the generating means 11.
And characterized in that:

For the same purpose, a print head drive control device according to a second aspect of the present invention provides the print head drive control device according to the first aspect, wherein the generation unit 11 prints an intermediate dot excluding a leading dot and a trailing dot of a continuous dot row. Generates a control signal for obtaining a charging time and a discharging time in which the advance driving force and the retreat driving force of the print pin 35 are small from the leading dot in the intermediate dot to before the predetermined dot, and After the predetermined dot, to obtain a charging time in which the advance driving force of the print pin 35 gradually increases as dots to be printed later and a discharge time in which the retracting drive force of the print pin 35 becomes small. A control signal is generated.

For the same purpose, a print head drive control device according to a third aspect of the present invention provides the print head drive control device according to the first aspect, wherein the generation unit 11 advances the print pin 35 when printing the first dot of the continuous dot row. When generating a control signal for obtaining a charging time in which the driving force is sufficient and a discharging time in which the retracting driving force of the print pin 35 is short, and printing an intermediate dot excluding the leading dot and the trailing dot of the continuous dot row, A control signal for obtaining a charging time and a discharging time in which the leading driving force and the retracting driving force of the print pin 35 are small from the leading dot in the intermediate dot to before the predetermined dot is generated, and After the predetermined dot, a charging time in which the advance driving force of the print pin 35 gradually increases as dots to be printed later, and a discharge time in which the retreat driving force of the print pin 35 becomes small are obtained. When a control signal is generated to print the trailing dot of the continuous dot row, a control signal for obtaining a longer charging time than the trailing dot in the intermediate dot and a discharging time for sufficiently retracting the print pin 35 are obtained. Is generated.

[0023]

According to the first aspect of the present invention, in the case of printing a continuous dot row, the piezoelectric elements are arranged such that dots printed after a predetermined dot in the continuous dot row become dots to be printed later. The print head 20 is driven while gradually increasing the charging time of the printer 30.

Thus, in each process from the predetermined dot to the last dot in the continuous dot row, the kinetic energy of the printing pin 35 striking the printing paper to return is gradually reduced. Therefore, for example, when the printing speed is increased, the charging time given to the piezoelectric element 30 at the time of printing the last dot cannot be sufficiently long, but the kinetic energy stored in the printing pin 35 at the time of printing the last dot is small. Therefore, by giving a predetermined charging time and discharging time, sufficient braking of the printing pin 35 becomes possible,
The rebound immediately after the printing of the last dot can be reduced. Therefore, printing of surplus dots is eliminated, and high printing quality can be realized.

According to the second aspect of the present invention,
When printing an intermediate dot excluding the leading dot and the trailing dot of the continuous dot row, the charging time during which the leading driving force and the retracting driving force of the print pin 35 are small from the leading dot in the intermediate dot to before a predetermined dot. And the print head 20 is driven by the discharge time, and after a predetermined dot in the intermediate dot,
The print head 20 is driven by a charging time in which the advance driving force of the print pin 35 gradually increases as dots to be printed later and a discharge time in which the retracting drive force of the print pin 35 becomes small. I have.

Thus, from the next dot after the leading dot to before the predetermined dot (dot for starting braking) in the intermediate dot, the print head 20 keeps the charge time and the retreat drive force small, The drive is performed in the discharge time, and the rebound amplification in each printing cycle is suppressed. Further, since the charging time is gradually increased after the predetermined dot, the advance driving force of the printing pin 35 is gradually increased, whereby the kinetic energy of the printing pin 35 striking the printing paper to return is gradually increased. Is reduced.

Therefore, for example, as the printing speed is increased, the charging time given to the piezoelectric element 30 at the time of printing the last dot cannot be sufficiently long, but the movement stored in the printing pin 35 at the time of printing the last dot. Since the energy is sufficiently small, the printing pin 35 can be sufficiently braked by giving a predetermined charging time / discharging time, and the rebound immediately after printing the final dot can be reduced. Accordingly, stable printing is possible from the intermediate dot to the trailing dot, and printing of surplus dots is also eliminated, so that high printing quality can be realized.

Further, in the invention according to claim 3,
When printing the first dot of the continuous dot row, the charging time at which the advance driving force of the print pin 35 is sufficient and the print pin 35
When the print head 20 is driven during the discharge time when the retreat driving force becomes small, and the intermediate dots excluding the leading dot and the trailing dot of the continuous dot row are printed, from the leading dot in the intermediate dot to before the predetermined dot. Drives the print head 20 for the charging time and the discharging time when the advance driving force and the retreat driving force of the print pin 35 are small, and after the predetermined dot in the intermediate dot, the printing is performed as the later printed dot becomes When the print head 20 is driven by the charging time in which the advance driving force of the pin 35 gradually increases and the discharge time in which the retracting driving force of the print pin 35 becomes short, and the trailing dot of the continuous dot row is printed, The print head 20 is driven in a charging time longer than the trailing dot in the dot and a discharging time in which the retreat driving of the print pin 35 is sufficient.

Thus, in printing the first dot, the print pin 35 is driven by a sufficient advance driving force and has a sufficient rising characteristic, while it is retracted by a small retraction drive force. The occurrence is controlled to be small.

In the subsequent printing of the intermediate dots, the rebound amplification in each printing cycle is suppressed up to a predetermined dot in the intermediate dots by the same operation as in the second aspect, and after the predetermined dot, The kinetic energy of the printing pin 35 striking the printing paper and returning is gradually reduced.

In this state, if the trailing dot is printed with a longer charging time than the trailing dot in the intermediate dot and a discharging time sufficient for the retracting drive of the print pin 35, the print pin 35 is printed.
Charge / discharge is performed in a state where the kinetic energy of striking and returning the printing paper is small, so that the printing pin 35 can be sufficiently braked and the rebound immediately after printing the final dot can be reduced. . From the above,
Stable printing is possible from the leading dot to the trailing dot, and printing of surplus dots is eliminated, so that high printing quality can be realized.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a print head drive control device according to the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment of the print head drive control device according to the present invention.

In FIG. 2, reference numeral 20 denotes a print head.
Since the print head 20 applied in this embodiment is the same as that already described with reference to FIG. 3, the description is omitted here. The print head 20 is provided with a drive signal from a print head drive circuit 21.
In the following description, the print head 20 is configured by arranging 24 print pins 35 in a line in the sub-scanning direction.

The print head drive circuit 21 includes, for example, two transistors Tr as shown in FIG.
1 and Tr2 and a resistor R. FIG.
1 shows only a drive circuit corresponding to one piezoelectric element 30 (that is, a print pin 35) as the print head drive circuit 21, but actually, the two transistors Tr1 and Tr2 and the resistor R are connected to each other. One set is realized by 24 sets of drive circuits.

The collector of the transistor Tr1 is connected to a power source (not shown) (for example, 120 volts), and the emitter is connected to the collector of the transistor Tr2. The base of the transistor Tr1 has a selection signal supplied from the drive pin selection unit 53 of the print head control circuit 22 and a charge signal supplied from the drive time setting unit 54 for defining the timing and time of the charge start. A signal obtained by ANDing TA with the AND gate G1 is supplied.

As described above, the collector of the transistor Tr2 is connected to the emitter of the transistor Tr1,
The emitter is grounded. Also, this transistor T
At the base of r2, a selection signal supplied from the drive pin selection unit 53 of the print head control circuit 22 and a discharge signal TB, which is also supplied from the drive time setting unit 54 and defines the discharge start timing and time, are ANDed. A signal obtained by performing an AND operation on the gate G2 is supplied.

Further, a resistor R is connected to the emitter of the transistor Tr1 (collector of the transistor Tr2).
A signal passed through the resistor R is output to the print head drive circuit 21.
Is supplied to the piezoelectric element 30 as a drive signal output from the piezoelectric element 30. Note that the resistor R limits the current when the piezoelectric element 30 is charged, and defines the charging speed of the piezoelectric element 30.

The print head drive circuit 21 having the above configuration operates as follows. That is, the drive circuit is selected by making the selection signal supplied from the drive pin selection unit 53 of the print head control circuit 22 active (H level). In this state, the charging signal TA rises from the drive time setting unit 54 of the print head control circuit 22, and is supplied to the base of the transistor Tr1 via the AND gate G1. As a result, the transistor Tr1 is turned on. At this time, the discharge signal TB is maintained at the L level, so that the transistor Tr2 remains off.

When the transistor Tr1 is turned on,
Charging of the piezoelectric element 30 via the resistor R is started. The charging speed is performed according to a time constant determined by the resistance value of the resistor R and the capacitance of the piezoelectric element 20. As a result, the piezoelectric element 20 is extended and the print pin 35 is moved in the hitting direction,
Dots are printed.

Next, the charge signal TA output from the drive time setting section 54 of the print head control circuit 22 falls, and the output of the AND gate G1 is set to L level. On the other hand, at the same time as the fall of the charge signal TA, the discharge signal TB rises, so that the transistor Tr2 is turned on. As a result, the electric charge charged in the piezoelectric element 30 is discharged via the resistor R and the transistor Tr2, and the piezoelectric element 20 contracts to move the print pin 35 to the original state.

By repeating this operation, dots are printed through the forward and backward movements of the print pin 35.

In FIG. 2, the print head control circuit 22
Is composed of a line buffer 50, a print pattern detection unit 51, a dot appearance pattern determination unit 52, a drive pin selection unit 53, a drive time setting unit 54, and a memory 55.

The line buffer 50 temporarily stores one line of print data sent as code data from an external device such as a host computer. The print data temporarily stored in the line buffer 50 is
The print pattern is sent to the print pattern detection unit 51.

The print pattern detector 51 develops print data as code data sent from the line buffer 50 into dot patterns indicating characters, symbols, figures, etc. corresponding to each code. Each print pin 35 of the print head 20 is driven according to the dot image data developed by the print pattern detection unit 51, and actual printing is performed.

The dot image data generated by the print pattern detection unit 51 is used by the dot appearance pattern determination unit 5.
2. It is supplied to the drive pin selection unit 53 and the drive time setting unit 54.

The dot appearance pattern judging section 52 refers to the dot image data generated by the print pattern detecting section 51, and selects the preceding dot, the next dot, and the next dot with respect to the dot position in the main scanning direction to be printed next. This is to determine whether or not there is a dot to be printed at the position. The result determined by the dot appearance pattern determination unit 52 is sent to the drive time setting unit 54.

The drive pin selection unit 53 refers to the dot image data generated by the print pattern detection unit 51, and determines the number of dots at the next dot position in the main scanning direction to be printed.
Of the four dots, a process for activating a selection signal corresponding to a dot to be printed (H level) is performed. Only the drive circuit in the print head drive circuit 21 in which the selection signal supplied from the drive pin selection unit 53 is activated drives the print pin 35 as described above.

When printing the dot image data supplied from the print pattern control circuit 51, the drive time setting section 54 reads the charge time and discharge time from the memory 55 based on the determination result supplied from the dot appearance pattern determination section 52. Is read out, a charge signal TA and a discharge signal TB are generated based on the data, and output at a predetermined timing.

Based on the charge signal TA and the discharge signal TB output from the drive time setting section 54, the drive circuit in the print head drive circuit 21 described above, which is selected by the selection signal, is driven. , Print head 2
The dot printing is performed by operating the print pin 35 in the middle.

The memory 55 is formed of, for example, a ROM. Data indicating the charging time for each dot driving condition as shown in the memory configuration example of FIG.
To A4) and data indicating the discharge time (B0 in the illustrated example).
B4) is stored.

Here, it is assumed that the charging time in the present embodiment satisfies the relationship of A0>A4> A3 = A1> A2 as an example. The charging time is not limited to satisfying the above relationship. In order for the present invention to exhibit a predetermined effect, at least “A4>
It is sufficient if the relationship of "A3>A2" is satisfied.

The discharge time in this embodiment is:
As an example, it is assumed that the relationship of B0 = B4> B1 = B2 = B3 is satisfied. Note that the discharge time is not limited to satisfying the above relationship, but can be determined by an arbitrary relationship suitable for preventing the print pin 35 from rebounding.

Next, the operation of this embodiment in the above configuration will be described in detail with reference to the flowchart shown in FIG.

First, when print data is set in the line buffer 50, the print pattern detecting section 51 develops the print data into dot image data, and outputs a dot appearance pattern determining section 52, a drive pin selecting section 53, and a drive time. It is sent to the setting unit 54. Since the operation of the drive pin selecting unit 53 has already been described, the description here is omitted.

The dot appearance pattern judging section 52 receives the dot image data, judges whether there is a preceding dot, a next dot, and a dot after the next to be printed, and outputs the judgment result to the driving time setting section 54. To send to.

The drive time setting section 54 first checks whether there is a preceding dot for the next dot to be printed (step S10). This is performed by examining the determination result sent from the above-described dot appearance pattern determination unit 53. The following judgment on the presence or absence of dots before and after is performed in the same manner. If it is determined that there is no previous dot, then it is checked whether there is a next dot (step S11).

Here, if it is determined that there is no next dot, it is recognized that printing is a single dot, and a single dot driving condition is set (step S12). That is, charge time and discharge time data A0 and B0 for the single dot drive condition are read from address 0 of the memory 55, and based on the data, a charge signal TA and a discharge signal TB are created. Sent to As a result, the print head drive circuit 21 performs
A predetermined printing pin 35 is driven.

The waveforms of the charging and discharging of the piezoelectric element 30 and the operation waveforms indicating the transition of the print pin 35 in this case are shown at timings T0 and T1 in (2) and (3) of FIG. 7, respectively. That is, after the piezoelectric element 30 is charged with a sufficiently long charging time A0, and thus the kinetic energy of the printing pin 35 striking and returning the printing paper is reduced,
Discharge is performed in a relatively long discharge time B0. As a result, rebound during printing of a single dot is suppressed, and printing of a surplus dot is avoided.

If it is determined in step S11 that there is a next dot, it is recognized that the next dot to be printed is the first dot of the continuous dot row, and the first dot drive condition is set (step S13). . That is, 1 of the memory 55
The charge time and discharge time data A1 and B1 for the leading dot drive condition are read from the address. Based on the data, a charge signal TA and a discharge signal TB are created and sent to the print head drive circuit 21. Thus, the print head drive circuit 21 drives the predetermined print pin 35 by the above-described operation.

The waveforms of the charging and discharging of the piezoelectric element 30 and the operation waveforms indicating the transition of the print pins 35 in this case are shown at timings T2 in (2) and (3) of FIG. 7, respectively. That is,
The piezoelectric element 30 is charged in a relatively long charging time A1, and thus the print pin 35 is driven with sufficient rising characteristics. On the other hand, since the discharge time B1 is performed in a short time, a brake is applied to the force of the print pin 35 to return, thereby reducing rebound and preventing the amplitude of the print pin 35 from increasing. I have.

If it is determined in step S10 that there is a previous dot, then it is checked whether there is a next dot (step S14). Here, when it is determined that there is a next dot, it is further checked whether or not there are dots one after another (step S15).

Here, if it is determined that there are dots one after another, it is recognized that the next dot to be printed is a dot in the middle of a continuous dot, and a dot driving condition is set (step S16). That is, the data A of the charge time and the discharge time with respect to the halfway dot drive condition from address 2 of the memory 55
2 and B2 are read out, and based on the data, a charge signal TA and a discharge signal TB are created and sent to the print head drive circuit 21. Thereby, the print head drive circuit 2
1 drives a predetermined print pin 35 by the above-described operation.

The waveforms of the charging and discharging of the piezoelectric element 30 and the operation waveforms indicating the transition of the print pin 35 in this case are shown at timings T3 and T4 in (2) and (3) of FIG. 7, respectively. That is, the piezoelectric element 30 is charged in a short charging time A2, and the print pin 35 is driven in a manner that the energy due to the small charge is added to the kinetic energy remaining in the print pin 35. On the other hand, since the discharge time B2 is short, the rebound is reduced and the print pin 3
5 is prevented from being increased.

If it is determined in step S15 that there are no more dots one after another, it is recognized that the next dot to be printed is the dot immediately before the trailing dot of the continuous dot, and the trailing dot drive condition is set. (Step S17). That is,
Data A3 and B3 of the charge time and the discharge time with respect to the last dot drive condition are read from the address 3 of the memory 55, and based on the data, the charge signal TA and the discharge signal TB
Is sent to the print head drive circuit 21. Thus, the print head drive circuit 21 drives the predetermined print pin 35 by the above-described operation.

The waveforms of the charging and discharging of the piezoelectric element 30 and the operation waveform indicating the transition of the print pin 35 in this case are shown at timings T5 in (2) and (3) of FIG. 7, respectively. That is,
The piezoelectric element 30 is charged in a charging time A3 longer than the charging time A2 for the intermediate dot and shorter than the charging time A4 for the trailing dot, and the printing pin 35 is driven in a manner to slightly reduce the kinetic energy of the printing pin 35. On the other hand, since the discharge time B3 is short, the rebound is reduced and the increase in the amplitude of the print pin 35 is prevented, as described above.

On the other hand, if it is determined in step S14 that there is no next dot, it is recognized that the next dot to be printed is the trailing dot of the continuous dot, and the trailing dot drive condition is set (step S18). ). That is, the memory 55
, Data A4 and B4 of the charging time and the discharging time with respect to the trailing dot drive condition are read out, and based on the data, a charging signal TA and a discharging signal TB are created.
It is sent to the print head drive circuit 21. Thus, the print head drive circuit 21 drives the predetermined print pin 35 by the above-described operation.

The waveforms of the charging and discharging of the piezoelectric element 30 and the operation waveforms indicating the transition of the print pin 35 in this case are shown at timings T6 and T7 in (2) and (3) of FIG. 7, respectively. That is, the piezoelectric element 30 is charged for a charging time A4 longer than the charging time A3 for the front dot, and the print pin 35 is charged.
The printing pin 35 is driven in such a manner as to reduce the kinetic energy of the printing. On the other hand, the discharging time B4 is performed in a relatively short time, and all the electric charges of the piezoelectric element 30 are discharged.

As a result, the printing pin 35 is driven in a state in which the kinetic energy of the printing pin 35 striking and returning the printing paper is reduced, and the discharge is performed for a relatively long discharge time B4. Even if the printing cycle is shortened due to the increase in speed, the occurrence of rebound can be suppressed, and the printing of an extra dot at the dot position next to the trailing dot, that is, at timing T7 can be avoided. Further, since all the electric charges stored in the piezoelectric element 30 are discharged, the initial condition at the time of the next printing becomes constant, and the disadvantage that the operation becomes unstable can be eliminated.

In the above embodiment, the recharging time of the dot immediately before the trailing dot (the dot before the trailing dot) is made longer than the charging time of the middle dot, and the charging time of the trailing dot is further lengthened. However, the dot for starting the process of extending the charging time is not limited to the dot before the tail. That is, by gradually increasing the charging time from a plurality of dots before the trailing dot, the same operation and effect as in the above embodiment can be obtained.

[0071]

As described in detail above, according to the present invention, there is provided a print head drive control device capable of preventing the printing of extra dots due to the increase in printing speed and improving the printing quality. Can be.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of a print head drive control device according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of a print head drive control device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a conventional dot printer and a print head according to the present invention.

FIG. 4 is a circuit diagram showing a configuration of a print head drive circuit of the present invention.

FIG. 5 is a diagram showing a configuration example of a memory of the present invention.

FIG. 6 is a flowchart showing the operation of the present invention.

FIG. 7 is a diagram for explaining the operation of the present invention.

FIG. 8 is a diagram for explaining a charge / discharge operation of a piezoelectric element used in the present invention and a conventional print head.

[Explanation of symbols]

 Reference Signs List 10 detecting means 11 generating means 12 driving means 20 print head 21 print head drive circuit (drive means) 22 print head control circuit 30 piezoelectric element 35 print pin 50 line buffer 51 print pattern detection section (detection means 10) 52 dot appearance pattern judgment Section (detection means 10) 53 drive pin selection section 54 drive time setting section (generation means 11) 55 memory (generation means 11)

Continuation of the front page (72) Inventor Shuichi Yamaki 1405 Daimaru, Inagi-shi, Tokyo Fujitsu Isotec Co., Ltd. (56) References JP-A-5-185617 (JP, A) JP-A-2-241754 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/30

Claims (3)

(57) [Claims] A print head (2) for a dot printer that performs printing by repeating a charge and a discharge of a piezoelectric element (30) to advance and retreat a print pin (35) connected to the piezoelectric element (30).
(0), a detecting means (10) for detecting whether or not the given print data includes a continuous dot row, and detecting that the continuous dot row is included in the detection means (10). In this case, after the predetermined dot in the continuous dot row, the piezoelectric element becomes
(30) generating means (11) for generating a control signal for gradually increasing the charging time, and driving means (10) for driving the print head (20) in accordance with the control signal generated by the generating means (11). 12) A print head drive control device comprising: 2. A method according to claim 1, wherein said generating means comprises:
When printing an intermediate dot excluding the leading dot and trailing dot of the continuous dot row, the leading driving force and the retracting driving force of the print pin (35) are small from the leading dot in the intermediate dot to a point before the predetermined dot. A control signal for obtaining a charging time and a discharging time is generated, and after a predetermined dot in the intermediate dot, a printing pin (35)
The charging time when the advance driving force gradually increases and the printing pin (3
5) A print head drive control device for generating a control signal for obtaining a discharge time in which the retraction drive force is short. 3. The generating means (11) according to claim 1, wherein:
Is the print pin when printing the first dot of the continuous dot row.
(35) Charging time and printing pin (35) for sufficient driving force
When a control signal for obtaining a discharge time in which the retreat driving force becomes small is generated and an intermediate dot other than the leading dot and the trailing dot of the continuous dot row is printed, a predetermined dot from the leading dot in the intermediate dot is printed. Until before, a control signal for obtaining a charging time and a discharging time in which the advance driving force and the retreat driving force of the print pin (35) become small, and after a predetermined dot in the intermediate dot, a dot to be printed later Print pin (35)
The charging time when the advance driving force gradually increases and the printing pin (3
5) Generate a control signal for obtaining a discharge time at which the retreat driving force is short, and when printing a trailing dot in the continuous dot row, when the trailing dot in the intermediate dot is longer than the trailing dot and the print pin ( 35)
A printhead drive control device for generating a control signal for obtaining a discharge time sufficient for retraction drive of the printhead.