JPH0569597A - Method for driving dot printing head - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a printing impact force and the occurrence of shortage of dots by a method wherein wire drive elements to be corrected are selected based on printing data, and on the basis of a correction value corresponding to a relational value between the selected wire drive elements, each wire drive element is controlled. CONSTITUTION:A CPU 21 writes printing data and outputs a correction signal (b). A correction pin selection circuit 22 successively selects wire drive elements to be driven on the basis of the printing data (a). A pin data comparison circuit 30 compares a correction object pin signal (c) with drive history data (k) from a pin data storage circuit 29 and outputs a correction value storage address (m) to correction value memories 24, 31. Furthermore, a correction value operation circuit 25 transmits a one pin correction completion signal (g). The correction pin selection circuit 22 transmits a correction completion signal (h). The CPU 21 drives a drive timing timer 33 and a pin drive timer 26. The pin drive timer 26 drives a printing head 28 through a drive circuit 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a dot print head in a serial printer.

[0002]

2. Description of the Related Art Conventionally, in a dot print head, a print wire is driven by the attractive force of a permanent magnet. For example, an armature to which the print wire is fixed is swingably supported by a leaf spring for biasing, The armature is previously attracted to the core by a permanent magnet against the elastic force of the leaf spring, and when printing, the coil wound around the core is excited to generate a magnetic flux in the direction opposite to the permanent magnet. The armature is released.

FIG. 2 is a sectional view of a conventional dot print head. Figure (a) shows the state when the armature is released,
(B) has shown the state at the time of armature suction. In the figure, reference numeral 1 is a base, and a permanent magnet 2, a base plate 3, a spacer 4, and a yoke 5 are sequentially laminated on an outer peripheral edge portion on the base 1. Reference numeral 6 denotes a leaf spring, the fixed end of which is sandwiched between the spacer 4 and the yoke 5. Then, the base of the guide 7 is superposed on the yoke 5 via the stopper 8, while
A cap 10 is provided on the base 1 side, and the guide 7 and the cap 10 are integrally fixed by a clamp 11.

Reference numeral 12 denotes an armature that is swingably supported at the free end of the leaf spring 6, and the base of the printing wire 13 is fixed to the tip of the armature 12. The tip of the printing wire 13 is arranged so as to project forward from the center of the guide 7. Reference numeral 14 denotes a core provided in the central portion of the base 1, and a coil 15 is wound around the core 14 to form an electromagnet. Reference numeral 16 is a substrate which is connected to the coil 15 and which energizes the coil 15.

In the dot print head having the above structure, when the coil 15 is not energized, the magnetic circuit composed of the base plate 3, the spacer 4, the yoke 5, the armature 12, the core 14 and the base 1 is generated by the magnetic flux generated by the permanent magnet 2. As a result, a suction force is generated between the core 14 and the armature 12. Then, the leaf spring 6 to which the armature 12 is attached is attracted and bent by the core 14, and strain energy is accumulated in the leaf spring 6.

When the coil 15 is energized in this state, the coil 15 generates a magnetic flux. This magnetic flux cancels the magnetic flux generated by the permanent magnet 2 in the gap between the core 14 and the armature 12, and as a result, the armature 12 is released from the core 14. At this time, the leaf spring 6 returns while releasing the accumulated strain energy, so that the tip of the printing wire 13 fixed to the armature 12 is projected from the guide 7 to fly, and an ink ribbon (not shown) is ejected. Printing is performed by hitting the printing medium via the.

In the dot print head having the above construction, the magnetic flux generated by the permanent magnet 2 returns to the permanent magnet 2 through the base 1, the core 14, the armature 12, the yoke 5, the spacer 4 and the base plate 3. Then, a wire driving element is constituted by the respective members for driving one print wire 13. By the way, in order to reduce the size and cost of the dot print head having the above-described structure, members such as the base 1, the permanent magnet 2 and the yoke 5 to which the core 14 is fixed are made common to each wire driving element and manufactured as an integral part. Often. In this case, the magnetic circuit for the wire driving element is shared in many parts. As a result, the magnetic flux generated by a certain coil 15 wraps around to the magnetic circuit of another wire driving element, and changes the magnetic circuit of the wire driving element due to magnetic interference.

This magnetic interference not only changes the magnetic current value of the coil 15, but also has many influences on the operation of the armature 12, such as a deviation in the timing at which the armature 12 is released. In order to increase the speed and output of the dot print head, it is necessary to reduce the change in the operation of the armature 12 due to this magnetic interference.

Therefore, there is provided a method of driving a dot print head in which the time during which the coil 15 is energized is made variable depending on the number of coils 15 which are excited at the same time to minimize the change in the operation of the armature 12 (Japanese Patent Publication No. 63-63- 301
54 gazette). In this case, when print data is supplied to the driver that drives the dot print head, the number of coils that are excited at the same time is detected by the detection circuit, a signal corresponding to the number of coils is output, and the coil energization time Is set. That is, the larger the number of coils that are simultaneously excited, the longer the energization time.

[0010]

However, in the above-described conventional dot print head driving method, control is performed only by the number of coils 15 that are excited at the same time, so the operation of the armature 12 is not constant in practice. I won't. This is because the effect of magnetic interference varies depending on the positional relationship between wire drive elements, so the degree of magnetic interference is different between simultaneous printing by adjacent wire drive elements and simultaneous printing by wire drive elements at distant locations. Is completely different.

For example, in the case of a 24-pin dot print head, it is possible to print under a constant condition when only one arbitrary wire drive element is driven, or 24
Only when all of the wire drive elements are simultaneously driven, and when a certain number of wire drive elements of 2 to 23 are simultaneously driven, various combinations of the wire drive elements to be driven are conceivable. The printing conditions will be different.

Further, not only the magnetic flux generated by the other coil 15 which is excited at the same time wraps around, but also the magnetic flux generated by the other coil 15 which is excited before the coil 15 wraps around, or is already excited. In some cases, the residual magnetic flux of the coil 15 that has ended may go around. When the exciting period of the coil 15 is T, the exciting period of the other coils 15 is also T. However, the mutual exciting timing depends on the time T depending on the print data and the arrangement of the print wires 13.
A phase difference of / 2, T / 4, T / 6, etc. occurs, and the amount of residual magnetic flux entrainment is not constant.

FIG. 3 is an illustration of printing by a conventional dot print head. In the figure, (a) shows the print wire 13 (FIG. 2) array, (b) shows the print result printed by the print wire 13 in the (a) array, and (c) shows the array of other print wires 13. (D) shows the printing result printed by the printing wire 13 of the arrangement of (c). For example, when using a dot print head in which two print wires 13 are aligned in the vertical direction of the figure as shown in FIG. 9A and the dot print head is moved left and right to perform printing, In order to obtain a print result such as (1), each coil 15 corresponding to the print wire 13 must be excited with a phase difference of time T / 2.

Further, as shown in (c), two printing wires 1
3 uses a dot print head that is displaced by 1/120 inch in the horizontal direction in the figure, and when printing is performed by moving the dot print head to the left and right, printing is performed in order to obtain the print result as shown in (d). Each coil 15 corresponding to the wire 13 must be excited with a phase difference of time T / 4. In this way, when a certain coil 15 is excited, even if the number of coils 15 to be excited at the same time is constant, another coil 15 may be moved ahead of time T / 2 or T / 4 depending on the print data and the arrangement of the print wire 13. May be excited, and the printing conditions differ depending on the combination.

Therefore, usually, a combination of wire driving elements that are simultaneously driven or a combination of wire driving elements that is driven with a predetermined phase difference causes the armature 12 to operate worst. The energization time of the coil 15 is corrected. For this reason,
For a combination of wire driving elements that does not need to correct the energization time for the operation of the armature 12, more energy than necessary is supplied to the coil 15,
Heats up or the printing power becomes excessive.

Further, the magnetic interference also affects the time required for the operation of the armature 12 and the print wire 13. Then, the time required for the operation becomes longer, and when the coil 15 is energized at the next drive start timing before the armature 12 returns to the position of the core 14, the leaf spring 6
The flying of the print wire 13 is started in a state in which the strain is small, and the print power may be reduced or dot removal may occur.

The present invention solves the problems of the conventional method of driving a dot print head, and in the case of a combination of wire drive elements which does not require correction of the energization time of the coil, the coil requires more energy than necessary. It is an object of the present invention to provide a method for driving a dot print head that does not supply the print wire and that does not cause a decrease in printing power due to a change in the drive time of the print wire or dot removal.

[0018]

Therefore, in the method of driving a dot print head according to the present invention, the dot print head has an armature having a print wire fixed to the tip thereof, and a core provided so as to face the armature, A leaf spring to which the armature is joined and supported in a cantilever manner, a permanent magnet that generates a magnetic flux and attracts the armature to the core against the elastic force of the leaf spring, and is wound around the core. A coil is provided for generating a magnetic flux from the core upon energization and canceling the magnetic flux of the permanent magnet to release the armature.

When the print data is sent to the printer having the dot print head having the above-mentioned configuration, the correction pin selection circuit selects the wire drive element to be corrected based on the print data, and is subsequently selected. For each wire drive element, the number of wire drive elements that are simultaneously driven, the relative position with respect to other wire drive elements that are simultaneously driven, and drive history data are calculated.

Then, the correction values for the drive time and the drive timing are preset based on the relationship between the wire drive elements that are simultaneously driven, and the set correction values are stored in the correction value memory. .. Therefore, the correction value calculation circuit reads the correction value stored in advance in the correction value memory based on the calculated value, and calculates the drive time and the drive start timing for each wire drive element based on the correction value. To do.

The output of the correction value calculation circuit is sent to a drive circuit via a pin drive timer, and the dot print head is driven at a predetermined drive start timing and drive time. Further, the driving time and the driving start timing can be corrected by the past history of other wire driving elements. In this case, the number of simultaneously driven wire drive elements and the number of other wire drive elements that were driven before the set time were calculated based on the print data, and the correction values were calculated in advance based on the calculated values. The drive time and drive start timing stored in the memory are read out.

[0022]

According to the present invention, as described above, the dot print head is a cantilever type in which the armature having the print wire fixed to the tip thereof, the core provided to face the armature, and the armature are joined together. A leaf spring supported by, a permanent magnet that generates a magnetic flux to attract the armature to the core against the elastic force of the leaf spring, and is wound around the core to generate a magnetic flux from the core by energization, A coil is provided to cancel the magnetic flux of the permanent magnet and release the armature.

Therefore, the armature is released by passing an exciting current through the coil in accordance with the print data, the print wire fixed to the tip of the armature is caused to fly, and the print medium is hit through the ink ribbon. Printing is performed. Then, when the print data is sent to the printer having the dot print head having the above-mentioned configuration, the correction pin selection circuit selects the wire drive element to be corrected based on the print data. Then, for each selected wire drive element, the number of wire drive elements that are simultaneously driven, the relative position with respect to other wire drive elements that are simultaneously driven, and drive history data are calculated.

Then, the correction values for the drive time and the drive timing are preset based on the relationship between the wire drive elements that are simultaneously driven, and the set correction values are stored in the correction value memory. .. Therefore, the correction value calculation circuit reads the correction value stored in advance in the correction value memory based on the calculated value, and calculates the drive time and the drive start timing for each wire drive element based on the correction value. To do. In this case, various correction values for the drive time and the drive timing are stored corresponding to each relative position, and the calculation is performed using the correction values.

The output of the correction value calculation circuit is sent to the drive circuit via a pin drive timer, and an exciting current is supplied to the coil at a predetermined drive start timing and drive time. Also,
When the drive time and the drive start timing are corrected based on the past history of other wire drive elements, the number of wire drive elements that are simultaneously driven based on the print data and the drive time is set before. The number of other wire drive elements is calculated, and the drive time and drive start timing stored in advance in the correction value memory are read based on the calculated values.

Also in this case, similarly, the output of the correction value calculation circuit is sent to the drive circuit via the pin drive timer, and the exciting current is supplied to the coil at a predetermined drive start timing and drive time. Therefore, it is possible to prevent the influence of the winding of the magnetic flux generated in the past by the coil of the other wire driving element.

[0027]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a control block diagram of a serial printer in which the dot print head driving method of the present invention is adopted, and FIG. 4 is an explanatory diagram of a printing operation in the dot print head driving method of the present invention.

In FIG. 4, # 1 to # 24 denote 24 wire driving elements, and the wire driving elements are arranged in a ring shape. (A) and (b) of the figure show the drive state of the wire drive element at some point during the printing operation.
The wire drive element indicated by is being driven, and the wire drive element indicated by is not being driven. In addition, (a) of the figure
In, the wire driving elements of # 1, 2, 5 are simultaneously driven, and in FIG. 5B, the wire driving elements of # 1, 21, 24 are simultaneously driven.

Here, the printing operation when printing is performed in the drive state of the wire drive element shown in FIG. 4A will be described with reference to FIG. In FIG. 1, reference numeral 21 is a CPU for controlling the entire printer, 22 is a correction pin selection circuit for selecting a wire driving element to be subjected to correction processing, and 23.
24 is a relative position calculation circuit for calculating the relative position between the wire drive elements that are simultaneously driven, and the number of wire drive elements that are simultaneously driven, that is, the number of simultaneously driven pins.
Is a correction value memory for storing a correction value which is a basis for the correction of the drive time of the wire drive element, 25 is a correction value calculation circuit for calculating the correction value stored in the correction value memory 24, 2
6 is a pin drive timer for generating the drive time of the wire drive element, 27 is a drive circuit for supplying a drive current to the wire drive element, and 28 is a dot print head.

Further, 29 is a pin data storage circuit for storing the data of the driven wire drive element, 30 is a pin data comparison circuit for comparing drive history data, and 31 is a correction of the drive start timing of the wire drive element. A correction value memory for storing a correction value serving as a basis of the correction value calculation circuit 32, a correction value calculation circuit for calculating the correction value stored in the correction value memory 31, and a correction value calculation circuit 33 for correcting the drive start timing of the wire drive element. It is a drive timing timer.

First, the CPU 21 stores the print data a in the correction pin selection circuit 22, the inter-pin relative position calculation circuit 23, the correction value calculation circuit 25, the pin drive timer 26, the pin data storage circuit 29, and the pin data comparison circuit 30. Write to a register (not shown). Next, the CPU 21 turns on the correction processing start signal b, and thereby the correction processing is started.

The correction pin selection circuit 22 uses the wire drive elements driven based on the print data a as # 1 in FIG.
# 2, # 3, ..., # 24 are selected in this order. Figure 4 (a)
In the case of # 1, the wire driving element of # 1 is first selected, and the correction target pin number c is sent to the inter-pin relative position calculation circuit 23 and the pin data comparison circuit 30. The inter-pin relative position calculation circuit 23 calculates the number of simultaneously driven pins based on the print data a, and the relative position between the correction target pin number c and the driven wire drive element in the print data a is # 1 ,. #
2, # 3, ..., # 24 are calculated in the order of the wire driving elements,
The storage address d of the correction value corresponding to each simultaneous drive pin number and relative position is output. In the case of FIG. 4A, the number of simultaneous drive pins is 3, and the wire drive elements # 1, # 2, and # 5 to be driven are driven with respect to the wire drive element # 1 to be corrected. The relative positions of are 0, 1, and 2, respectively.

Further, the pin data comparison circuit 30 uses the correction target pin number c and the driving history data read from the pin data storage circuit 29, for example, the pin of the wire driving element driven last time or the wire driving element driven two times before. The number k is compared, and the storage address m of the correction value corresponding to the comparison result is output. The storage addresses d and m are input to the correction value memories 24 and 31. Therefore, by inputting the storage addresses d and m of the correction value, the correction value memories 24 and 31 are
The correction values e and n stored in advance corresponding to the simultaneous driving pin number 3 and the relative positions 0, 1 and 2 are output to the correction value calculation circuits 25 and 32, respectively. In this case, the relative positions are 0, 1, 2, ..., 12 and the maximum relative position with respect to the wire driving element of # 1 is 12 in the case of the wire driving element of # 24. Further, by inputting the storage address m of the correction value, the correction value memories 24 and 31 change the correction table corresponding to the history data of the drive, and the correction values e and n
To the correction value calculation circuits 25 and 32, respectively.

The correction value calculation circuits 25 and 32 are # 1,
The correction values e and n of the wire driving elements # 2 and # 5 are received, a predetermined calculation is performed on each correction value e and n, and the correction values e and n of the last wire driving element # 5 are received. rear,
The calculation results f and p are respectively written in the channels corresponding to the wire drive elements to be corrected in the pin drive timer 26 and the drive timing timer 33.

Then, the correction value calculation circuit 25 sends the 1-pin correction end signal g to the correction pin selection circuit 22 to notify the end of the correction process for each wire drive element. Subsequently, the correction pin selection circuit 22 outputs the next correction target pin number c,
Similar correction processing is performed. When this operation is repeated up to the last wire drive element in the print data a, the correction pin selection circuit 22 sends the correction end signal h to the CPU 21 to notify the end of the correction process.

When the predetermined timing comes after the completion of the correction processing, the CPU 21 turns on the timer start signal i to cause the drive timing timer 33 to start counting, and the timer output q to start driving the wire drive element. Then, the pin drive timer 26 starts counting. Then, the pin drive timer 26 counts the value corresponding to the drive time, and the dot print head 28 is driven via the drive circuit 27 during this period to perform printing.

FIG. 5 is a waveform diagram of the exciting current of the coil according to the dot print head driving method of the present invention. In the figure, the broken line α is the exciting current in the driving state as shown in FIG. 4A, and the solid line β is the exciting current in the driving state as shown in FIG. 4B. Next, a case where the correction process is performed to print an actual character will be described.

FIG. 6 is a diagram showing a dot pattern of characters to be printed, FIG. 7 is a diagram showing an example of a timing chart after correction processing, and FIG. 8 is a diagram showing an example of a correction table. FIG. 8A shows a correction table based on the number of simultaneously driven pins, and FIG.
Shows a correction table based on drive history data, (c) shows a correction table depending on the presence or absence of an adjacent drive pin, and (d) shows a correction table of drive start timing based on the sum of correction values of drive timing.

In FIG. 6, the character "B" has 12 columns × 2.
It is developed as a pattern on a 4-pin dot matrix. In this case, the odd-numbered pins and the even-numbered pins are grouped in timing, and each odd-numbered pin or each even-numbered pin is placed in a state in which they can be simultaneously driven by receiving respective drive currents. Actually, the wire drive element corresponding to the print data is selectively driven.

For example, in the case of the ninth column, the third, fourth, fifth,
The 9th, 10th, 12th, 13th, 19th, and 20th pins are driven, but the odd-numbered 3rd, 5th, 9th, 13th, and 19th pins are driven simultaneously. Then, the even-numbered fourth, tenth, twelfth, and twentieth pins are simultaneously driven at the next timing. In FIG. 4, first, # 3, # 5,
The wire drive elements of # 9, # 13, and # 19 are followed by # 4,
The wire drive elements # 10, # 12, and # 20 are simultaneously driven. Then, the drive time and the drive timing are corrected for each of the wire drive elements that are simultaneously driven.

In FIG. 7, standard drive time and standard drive
Driving time of each wire drive element after timing correction and
The drive timing is shown. For example, the third in the eighth row
For pins, the drive time is corrected and the standard drive time is
Δt₁And the fourth pin of the 9th row is
Due to the correction, Δt from the standard drive timing due to correction ₂
Just being late. In this way, the third, fourth, and
5, 9th, 10th, 12th, 13th, 19th, 20th
All wire drive elements in the
Each drive time and drive timing are set.

Next, each correction value which is the basis of the calculation for setting the driving time and the driving timing of the wire driving elements which are simultaneously driven will be described. In FIG.
(A) shows a correction value for correcting the drive time and drive timing depending on the number of simultaneous drive pins. For example, when the standard drive time is 76 ms and the standard drive timing correction value is 0 ms, the third, fifth, ninth, and first are simultaneously performed.
When the 3rd and 19th pins are driven, the number of pins driven at the same time is 5, so the correction value of the drive time is +3 ms and the correction value of the drive timing is +3 ms.

(B) shows a correction value set depending on whether or not the previous dot row is driven. For example, in the correction process for the third pin in the ninth row, the third pin is also driven in the eighth row, so the correction value for the drive time is −2 ms and the correction value for the drive timing is +1.
ms. Further, (c) shows a correction value set in order to eliminate the influence caused by driving the adjacent wire drive element. For example, in the correction processing for the third pin in the ninth row, the fourth pin is driven simultaneously and is in the one-sided adjacent state, so the correction value for the drive time is +2 ms and the correction value for the drive timing is +2 ms.

Further, (d) is for delaying the drive start timing from the standard drive timing when the total of the correction values of the drive timing obtained by the correction tables of (a) to (c) exceeds a certain value. It is a correction table for showing a set correction value. For example, in the correction process for the third pin in the ninth column, +3 ms when the correction value of the drive timing is (a), +1 ms when (b), and (c)
, The sum of them is +6 ms. Therefore, the drive start timing correction value is +2 m
s. On the other hand, although not shown, there is also provided a correction table for changing the standard drive time in accordance with the total value of the correction values of the drive time obtained by the correction tables of (a) to (c), The driving time is changed by the correction table.

In this way, the drive time and drive timing are corrected for each wire drive element in each dot row. Next, a second embodiment of the present invention will be described. FIG. 9 is a control block diagram of a serial printer that employs the dot print head driving method according to the second embodiment of the present invention.

In the figure, 21 is a CPU for controlling the entire printer, 36 is a simultaneous drive pin number calculation circuit for calculating the number of wire drive elements that are simultaneously driven, 3
7 indicates the data of the simultaneous drive pin number calculated by the simultaneous drive pin number calculation circuit 36 from the next drive timing at time T / N.
(N: integer) T / N pre-driving pin number storage circuit for storing the previous driving pin number data, 38 is a correction value memory for storing the driving time of the wire driving element,
26 is a pin drive timer for generating the drive time of the wire drive element, 27 is a drive circuit for supplying a drive current to the wire drive element, and 28 is a dot print head.

Further, 39 is a correction value memory for storing the drive start timing of the wire drive element, and 33 is a drive timing timer for correcting the drive start timing of the wire drive element. The CPU 21 first determines the time T
When the print data a for driving the wire driving element is written at a timing of every / 4 in the simultaneous drive pin number calculation circuit 36 and the register (not shown) in the pin drive timer 26, the correction process is started.

The simultaneous drive pin number calculation circuit 36 calculates the data of the simultaneous drive pin number based on the print data a,
The storage address s of the correction value corresponding to this is output. Further, in preparation for the next timing, the calculated data is stored in the T / N front drive pin number storage circuit 37. The T / N pre-driving pin number storage circuit 37 has already stored in the previous timing (before time T / 4) and the timing before the last time (time T / 2).
The data of the number of drive pins in the previous) is stored, and the storage address r of the correction value corresponding to these is output from the T / N previous drive pin number storage circuit 37.

The storage addresses s and r are input to the correction value memories 38 and 39. When the storage addresses s and r are input to the correction value memories 38 and 39, the number of simultaneously driven pins, T
/ 4 drive pin number and T / 2 drive pin number corresponding to the pre-stored calculation result f, that is, the corrected drive time, to the pin drive timer 26, and the calculation result p, that is, the corrected drive timing, is driven. Timing timer 33
Output to.

At a predetermined timing, the CPU 21 turns on the timer start signal i to cause the drive timing timer 33 to start counting, and the wire output is driven by the timer output q generated after a predetermined time based on the calculation result p. The driving of the elements is started, and the pin driving timer 26 starts counting the value corresponding to the calculation result f, and the driving circuit 27 is driven by the signal j output during this period.
The dot print head 28 is driven to print by.

FIG. 10 is a diagram showing a dot pattern of characters to be printed in the second embodiment of the present invention, FIG. 11 is a time chart when no correction process is performed, and FIG. 12 is a view of the second embodiment of the present invention. FIG. 13 is a time chart after the correction processing, and FIG. 13 is a diagram showing an example of the correction table in the second embodiment of the present invention. 11 and 12, S1 is the standard drive signal of the first to twelfth pins, and S2 is the thirteenth to second pins.
The standard drive signal of pin 4 is shown. 13A shows a correction table based on the number of simultaneously driven pins, FIG. 13B shows a correction table based on the number T4 of previous driving pins, and FIG. 13C shows a time T / 2.
The correction table by the number of front drive pins is shown.

In FIG. 10, the character "B" has 13 columns x
It is developed as a pattern in a 24-pin dot matrix. In the case of a dot print head in which the first to twelfth pins and the thirteenth to twenty-fourth pins are respectively arranged on a grid of 1/180 inch and the grids are displaced from each other by 1/360 inch, 1st to 12th pins and 13th
The 24th to 24th pins are grouped in drive timing, and in response to the respective timing signals, the 1st to 12th pins or the 13th to 24th pins are placed in a state in which they can be driven simultaneously. Actually, the wire drive element corresponding to the print data a is selectively driven.

For example, in the case of the fifth row, the three pins of the fourth, twelfth and nineteenth pins are driven, but as shown in FIG. 11, the fourth and twelfth pins are driven simultaneously and the nineteenth pin is driven. The pin is driven at another timing, that is, a delay of time (3/4) T. Then, the drive time and the drive timing are corrected every time T / 4. In FIG. 12, the drive time and drive timing of each pin after correction are shown.

For example, in the case of the fourth pin and the twelfth pin of the fifth row, the drive timing is corrected and delayed by Δt ₁ from the standard drive timing, and the drive time is corrected by Δt ₂ from the standard drive time. Has been long. In this way, the correction process is performed for all the pins every time T / 4, and the drive time and the drive timing are set.

Next, based on FIG. 13, each correction value which is the basis of the calculation for setting the drive time and drive timing of the driven pin will be described. Figure (a) shows
The correction values for correcting the drive time and the drive timing depending on the number of simultaneous drive pins are shown. For example, the standard drive time is 100 μs, and the standard drive timing correction value is 0.
Assuming μs, when the fourth and twelfth pins are driven simultaneously, the number of pins driven at the same time is 2. Therefore, the correction value of the drive time is +2 μs and the correction value of the drive timing is +2 μs.

FIG. 6B shows the correction value set by the number of driven pins at the drive timing before time T / 4. For example, since seven pins of the 13th to 19th pins were driven before the time T / 4 when the 4th and 12th pins were simultaneously driven, the correction value of the driving time was + 4μ.
s, and the correction value of the drive timing is +5 μs.

Further, (c) in the figure is the time T as in (b).
It shows the correction value set by the number of pins driven at the driving timing before / 2, for example, only the third pin is driven before the time T / 2 when the fourth and twelfth pins are simultaneously driven. Therefore, the correction value of the drive time and the correction value of the drive timing are both 0 μs. The addition result of each correction value obtained as described above is previously stored in the CPU 2
1 is written in the correction value memories 38 and 39 of FIG. 9, and the storage address r is input from the T / N pre-driving pin number storage circuit 37 and the storage address s is input from the simultaneous driving pin number calculation circuit 36. Can be read.

FIG. 14 is a time chart showing an example of drive current waveforms in the second embodiment of the present invention. In the figure, i ₃ is the drive current waveform of the 3rd pin, i ₁₂ is the drive current waveform of the 12th pin, i ₁₃ is the drive current waveform of the 13th pin, F is the flight waveform of the 12th pin, and S ₁₂ is It is a drive signal waveform of the 12th pin. The numbers added in the vicinity of the respective waveforms indicate the columns of each data forming the print data a.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0060]

As described in detail above, according to the present invention, the wire drive element to be corrected is selected based on the print data, and the value of the relationship between the selected wire drive elements is calculated. The drive time and drive start timing for each wire drive element are calculated based on the correction value corresponding to the calculated value.

Therefore, since it is determined for each wire driving element to be driven whether or not the driving time and the driving start timing need to be corrected, it is not only necessary to supply unnecessary energy to the coil. Also, the driving time of the printing wire is not changed and the printing power is not reduced, and dot removal does not occur. When the drive time and the drive timing are corrected based on the past history of other wire drive elements, the number of wire drive elements that are simultaneously driven based on the print data, and the drive time is set before the drive time. The number of other wire drive elements is calculated, and the drive time and drive timing stored in advance in the memory are read based on the calculated values.

Then, when the residual magnetic flux in the coil of another wire driving element which has already been excited has sneak in, unnecessary energy is not supplied to the coil, and it is necessary for the operation of the printing wire. It is possible to prevent the printing power from being reduced due to a change in a specific time, and dot removal or the like from occurring.

[Brief description of drawings]

FIG. 1 is a control block diagram of a serial printer in which a method for driving a dot print head according to the present invention is adopted.

FIG. 2 is a cross-sectional view of a conventional dot print head.

FIG. 3 is a printing explanatory view of a conventional dot print head.

FIG. 4 is an explanatory diagram of a printing operation in the dot print head driving method of the present invention.

FIG. 5 is a waveform diagram of an excitation current of a coil according to the dot print head driving method of the present invention.

FIG. 6 is a diagram showing a dot pattern of a character to be printed.

FIG. 7 is a diagram showing an example of a timing chart after correction processing.

FIG. 8 is a diagram showing an example of a correction table.

FIG. 9 is a control block diagram of a serial printer that employs a dot print head driving method according to a second embodiment of the present invention.

FIG. 10 is a diagram showing a dot pattern of characters to be printed in the second embodiment of the present invention.

FIG. 11 is a time chart when the correction process is not performed.

FIG. 12 is a time chart after the correction process in the second embodiment of the present invention.

FIG. 13 is a diagram showing an example of a correction table in the second embodiment of the present invention.

FIG. 14 is a time chart showing an example of a drive current waveform according to the second embodiment of the present invention.

[Explanation of symbols]

 21 CPU 22 Correction pin selection circuit 23 Inter-pin relative position calculation circuit 24, 31, 38, 39 Correction value memory 25, 32 Correction value calculation circuit 26 Pin drive timer 27 Drive circuit 28 Dot print head 29 Pin data storage circuit 30 pin data Comparison circuit 33 Drive timing timer 36 Simultaneous drive pin number calculation circuit 37 T / N Previous drive pin number storage circuit

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Claims (2)

[Claims] 1. An armature having a printing wire fixed to its tip, a core provided to face the armature, a leaf spring to which the armature is joined and supported in a cantilever manner, and magnetic flux is generated. A permanent magnet that attracts the armature to the core against the elastic force of the leaf spring;
A method for driving a dot print head, which comprises a coil wound around the core and generating a magnetic flux from the core when energized to cancel the magnetic flux of the permanent magnet to release the armature, comprising: (a) correcting based on print data (B) For each selected wire drive element, the number of wire drive elements simultaneously driven, the relative position with respect to other wire drive elements simultaneously driven, and The history data is calculated, (c) the correction value stored in advance in the memory is read out based on the calculated values, and (d) the drive time and the drive start for each wire drive element are performed based on the correction value. A method for driving a dot print head, characterized in that timing is calculated and printing is performed. 2. An armature having a printing wire fixedly attached to its tip, a core provided to face the armature, a leaf spring to which the armature is joined and supported in a cantilever manner, and magnetic flux is generated. A permanent magnet that attracts the armature to the core against the elastic force of the leaf spring;
A method of driving a dot print head, which comprises a coil wound around the core and generating a magnetic flux from the core upon energization to cancel the magnetic flux of the permanent magnet to release the armature, and (a) at the same time based on print data, The number of wire drive elements to be driven and the number of other wire drive elements that have been driven before the set time are calculated, and (b) the drive time and the drive time previously stored in the memory based on the calculated values. A method for driving a dot print head, wherein printing is performed at a drive start timing.