JPH06135089A - Wire dot printer - Google Patents

Abstract

PURPOSE:To provide a wire dot printer performing printing corresponding to the number of printing media by the optimum printing force and generating no printing density difference. CONSTITUTION:In a wire dot printer equipped with a gap adjusting means 22 adjusting the gap between a printing head constituted by attaching a large number of printing elements 4 to the same frame 12 and a platen 11 and driving the wires 1 of the printing head to allow them to protrude to the printing medium 10 inserted in the gap between the printing head and the platen 11 to perform printing constituting a character by a dot matrix, a detection means 23 detecting the gap adjusting quantity of the gap adjusting means 22 and a pulse sending-out means 24 increasing and decreasing the width of the drive pulse for driving the wires of the printing head are provided and the width of the drive pulse sent out from the pulse sending-out means 24 is determined corresponding to the number of simultaneously printed printing media 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire dot printer for forming a character in a dot matrix for printing by striking a print medium by driving a wire forward and backward, and particularly when printing a character, a print medium. The present invention relates to a wire dot printer capable of performing printing with an optimum printing force corresponding to the number of sheets, and preventing a print density difference from occurring.

In recent years, line printers equipped with a plurality of print heads each composed of a plurality of print elements and printing a plurality of characters at the same time have come to be used. Although the weight of the movable part for carrying out is reduced, it is necessary that no obstacle occurs for this purpose.

Also, when a print head having a plurality of printing elements mounted on a front frame and a rear assembly having a plurality of printing elements mounted on a rear frame is used, it is used for the rear assembly. The length of the wire of the printing element to be used is longer than the length of the wire of the printing element used for the front assembly, but it is necessary that a difference in printing density does not occur.

[0004]

2. Description of the Related Art FIG. 3 is a diagram illustrating an example of a printing element. FIG. 3A is a perspective view of the printing element,
FIG. 3B is a side sectional view of the printing element, showing an example of the printing element used in the release type wire dot printer.

The print element 14 of the release type wire dot printer comprises a permanent magnet 6 and a yoke 5a forming a magnetic path.
And 5b, the spring 4 and the armature 3, the coil 7 for canceling the attractive force of the permanent magnet 6, the beam 2 attached to the armature 3 for transmitting the movement of the armature 3 to the wire 1, and the forward / backward drive attached to the beam 2. Wire 1
Composed of.

Since no current is flowing through the coil 7 during non-printing, the magnetic flux generated by the permanent magnet 6 is generated by the yoke 5a.
The armature 3 configured to flow through the spring 4, the armature 3 and the yoke 5b and to be separated from the yoke 5b by the spring 4 is attracted to the yoke 5b.

Therefore, the strain energy is stored in the spring 4, and when the current is supplied to the coil 7 to cancel this magnetic flux, the armature 3 is separated from the yoke 5b by the strain energy of the spring 4, so that the armature 3 is removed. Three
Is transmitted to the wire 1 via the beam 2, and the wire 1 guided by the pin guide 8 strikes the platen 11 via the ink ribbon 9 and the print medium 10, and the print medium 1
Dot printing is performed at 0.

The printing element 14 is attached to the frame 12 with screws 13. FIG. 4 is a diagram illustrating a first configuration example of the print head.

The print head 15 shown in FIG. 4 has a plurality of print elements 14 described in FIG.
For example, it is configured by attaching 24 pieces, and the frame 1
The pin guide 8 fixed to 2 is provided with 12 guide holes in the upper part and 12 in the lower part. Then, twelve printing elements 14 are provided on the frame 12 and the frame 1
Twelve printing elements 14 are attached to the lower part of each of the two, and each wire 1 of each printing element 14 is guided to the corresponding guide hole of the pin guide 8.

Therefore, the print head 15 divides one character into upper and lower parts, prints the upper character region with the print element 14 mounted on the upper part of the frame 12, and prints the lower character region on the lower part of the frame 12. Printing is performed by the printing element 14.

FIG. 5 is a diagram for explaining a second configuration example of the print head. The print head 16 shown in FIG. 5 has the print element 14 described in FIG.
a plurality of, for example, 24 pieces are attached to b,
The front frame 12a and the rear frame 12b are positioned and connected by a pole 17, and the pin guide 8a fixed to the front frame 12a has two guide holes adjacent to the upper portion at six positions, and two guide holes adjacent to the lower portion. Six guide holes are provided.

Six printing elements 14 are attached to the upper part of the front frame 12a and six printing elements 14 are attached to the lower part of the front frame 12a to form a front assembly, and the printing elements 14 are attached to the upper part of the rear frame 12b. Six printing elements 14 are attached to each of the lower portion of the rear frame 12b to form a rear assembly, and each wire 1 of each printing element 14 is formed.
Are guided to the corresponding guide holes of the pin guide 8a.

Therefore, the horizontal width of the print head 16 can be reduced to half that of the print head 15. Therefore, a combination of a plurality of print heads 15 or 16 is used as a print head for a line printer.

FIG. 6 is a diagram for explaining the wire driving of the print head. Taking the wire displacement, the printing force, the coil current, and the printing drive pulse on the vertical axis, and taking the time on the horizontal axis,
The time when the print drive pulse is indicated by Tp, the coil 7 shown in FIG.
The waveform of the current flowing through the coil 7 when it is supplied to
It becomes as shown in the coil current of.

Therefore, when the magnetic flux of the permanent magnet 6 shown in FIG. 3 is canceled and the armature 3 separates from the yoke 5b,
When the beam 2 causes the wire 1 to project toward the platen 11 and the magnetic flux of the permanent magnet flows through the magnetic path again, the wire 1 returns to its original position. The displacement state of the wire 1 at this time is as shown in FIG.
The wire displacement is as shown in.

Therefore, the impact force of the wire 1 when the impact force measuring device is placed at the position of the platen 11 is as shown in the printing force of FIG.

[0017]

FIG. 7 is a diagram for explaining the problems of the prior art. When the print force Fp is plotted on the vertical axis and the print drive pulse width Tp is plotted on the horizontal axis, the print force Fp increases as the print drive pulse width Tp increases as shown by the curve when there are six print media. However, the conventional print drive pulse width Tp1 is set so as to have the optimum print pressure Fp6 when six 34 kg sheets of paper are used as the print medium.

By the way, in the case of one sheet, as shown by the curve, the printing force Fp increases as the printing drive pulse width Tp increases, but the optimum printing pressure Fp6 is obtained when there are six sheets. Set print drive pulse width Tp1
Therefore, when the wire 1 is driven, the printing force becomes too large.

That is, the optimum printing power when there is one sheet is
It is necessary that the magnitude is Fp1, and the print drive pulse width at this time is Tp2. However, conventionally, even when the print drive pulse width is one sheet, it remains at Tp1, so that the print power remains excessive.

Therefore, when the plate thickness of the beam 2 shown in FIG. 3 is thinned to reduce the mass of the movable portion of the printing element in order to increase the speed, the reaction force against the excessive printing force and the beam 2 can be reduced. There is a problem that the stress due to shaking increases at the connecting point between the beam 2 and the armature 3, and the beam 2 is broken during printing when there is only one print medium.

Further, in the case of the print head 16 shown in FIG. 5, as described above, the front assembly and the rear assembly are
It is positioned and connected by a pole 17. FIG. 8 is an exploded perspective view of a second configuration example of the print head.

FIG. 8 shows a state in which the print head 16 shown in FIG. 5 is separated into a front assembly 20 and a rear assembly 21. As shown in FIG. 8, the length of the wire 1 of the printing element 14 forming the rear assembly 21 is longer than the wire of the printing element 14 forming the front assembly 20.

Therefore, the frame 1 of the rear assembly 21
2b is provided with a nose portion 18, and the wire 1 penetrates an intermediate guide 19 accommodated in the nose portion 18 with a play.

Although the intermediate guide 19 is provided to prevent the long wire 1 from bending, the intermediate guide 19 has a printing force higher than that of the wire 1 of the printing element 14 constituting the front assembly 20 due to the influence of buckling. Therefore, there is a problem in that there is a difference in print density between the printing by the front assembly 20 and the printing by the rear assembly 21.

In view of such problems, the present invention makes it possible to always perform printing with an appropriate printing force by adjusting the printing force according to the number of print media.
It is an object of the present invention to prevent breakage of the beam 2 so as to be able to cope with speeding up / down driving of the wire 1.

Furthermore, in the print head 16 shown in FIG. 5, the print drive pulse width is changed between the front assembly 20 and the rear assembly 21 to eliminate the print density difference.

[0027]

FIG. 1 is a block diagram for explaining the principle of the present invention. In FIG. 1 (A), the wire dot printer is composed of a print head and a platen 1 each having a plurality of print elements 14 mounted on the same frame 12.
1 is provided with a gap adjusting means 22 for adjusting the gap between the print head and the platen 11, and the wire 1 of the print head is driven to project onto the print medium 10 inserted between the print head and the platen 11, Characters are composed by dot matrix and printed.

Then, the detecting means 23 for detecting the distance adjustment amount of the distance adjusting means 22, and a pulse for adjusting the width of the drive pulse for driving the wire of the print head based on the detection result of the detecting means 23. The sending means 24 is provided, and the width of the drive pulse sent by the pulse sending means 24 is determined according to the number of the print media 10 to be printed at the same time.

When the number of the print media 10 is smaller than the predetermined number, the width of the drive pulse is narrowed as compared with the case where the number of the print media 10 is the predetermined number or more.
In FIG. 1 (B), the wire dot printer has a plurality of printing elements 14 attached to a front frame 12a.
4 is mounted on the rear frame 12b and is provided with a rear assembly. Spacer adjusting means 22 for adjusting the space between the print head and the platen 11 is provided, and is inserted between the print head and the platen 11. The wire 1 of the print head is driven to be projected onto the print medium 10 to form a character in a dot matrix for printing.

Then, the detecting means 23 for detecting the distance adjustment amount of the distance adjusting means 22, and a pulse for adjusting the width of the drive pulse for driving the wire of the print head based on the detection result of the detecting means 23. The sending means 24 is provided, and the width of the drive pulse sent by the pulse sending means 24 is determined according to the number of the print media 10 to be printed at the same time.

When the number of the print media 10 is smaller than the predetermined number, the width of the drive pulse is narrower than when the number of the print media 10 is the predetermined number or more.
Further, when the number of the print media 10 is a predetermined number or more, the width of the drive pulse of the front assembly is made narrower than the width of the drive pulse of the rear assembly.

[0032]

With the above configuration, the printing power can be adjusted according to the number of print media.
Printing can be performed with an appropriate printing force corresponding to the number of print media. Therefore, the breakage of the beam can be prevented, and the forward / backward drive of the wire 1 can be speeded up.

Further, in the print head composed of the front assembly and the rear assembly, it becomes possible to change the print drive pulse width and equalize the printing power, so that the print density difference can be eliminated.

[0034]

FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention. The print unit 30 is a combination of eight print heads 15 shown in FIG. 4, and is driven by a motor (not shown) to print while moving back and forth in the direction of arrow CD.

The shaft 32 of the platen 11 is crimped by a spring (not shown) to an eccentric cam 31 which is rotated by a lever 25 which rotates in the direction of arrow AB.
The distance between the printing unit 30 and the platen 11 is adjusted by the lever 25 operated by the operator according to the number of print media.

The switch 26 detects the rotational position of the lever 25, and when the print medium is, for example, 34 Kg paper,
It is off when the number of sheets is one or two, and is on when the number of sheets is three or more.

The controller 29 sends a signal to the print drive pulse generator 27 to send a drive pulse to the print element to be driven by each print head 15 of the print unit 30 based on print information input from a host device (not shown). Is sent.

Therefore, the print drive pulse generator 27 sends a drive pulse to the print element driver 28 by this signal, and the drive pulse width is adjusted depending on the ON / OFF state of the switch 26 at this time.

That is, for example, the drive pulse width is set to 116 μs when the number of sheets of 34 Kg is 1 to 2 and is set to 128 μs when the number of sheets is 3 or more. Therefore, the print element drive unit 28 sends a pulse current having a given drive pulse width to the coils of the print elements of the print heads 15 of the print unit 30 to be driven.

Further, when the print head 16 shown in FIG. 5 is used in the print unit 30, the difference in print density between the front assembly and the rear assembly is caused by the paper 3
Since there is more than one sheet, the print drive pulse generator 27
Causes the coil of the printing element to output a pulse having a drive pulse width of 116 μs when the switch 26 is off.

When the switch 26 is turned on, a pulse having a drive pulse width of 128 μs is sent to the coil of the print element on the front assembly side, and the drive pulse is sent to the coil of the print element on the rear assembly side. A pulse with a width of 136 μs is emitted.

Although the present embodiment has been described based on the print element of the release type wire dot printer, it is needless to say that the present invention can be applied to a suction type or piezo type print element.

[0043]

As described above, according to the present invention, since excessive printing reaction force is eliminated, it is possible to prevent beam breakage. Therefore, it is possible to reduce the plate thickness of the beam to reduce the weight thereof, and it is possible to realize high-speed forward / backward drive of the wire.

Further, since the printing forces on the front assembly side and the rear assembly side can be made uniform, it is possible to eliminate the print density difference.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating the principle of the present invention.

FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a print element.

FIG. 4 is a diagram illustrating a first configuration example of a print head.

FIG. 5 is a diagram illustrating a second configuration example of a print head.

FIG. 6 is a diagram illustrating wire driving of a print head.

FIG. 7 is a diagram for explaining the problems of the conventional technology.

FIG. 8 is an exploded perspective view of a second configuration example of the print head.

[Explanation of symbols]

 1 wire 2 beam 3 armature 4 spring 5a, 5b yoke 6 permanent magnet 7 coil 8, 8a pin guide 9 ink ribbon 10 print medium 11 platen 12 frame 12a front frame 12b rear frame 13 screw 14 print element 15, 16 print head 17 pole 18 Nose 19 Intermediate guide 20 Front assembly 21 Rear assembly 22 Interval adjusting means 23 Detecting means 24 Pulse sending means 25 Lever 26 Switch 27 Printing drive pulse generating section 28 Printing element driving section 29 Control section 30 Printing unit 31 Eccentric cam 32 Axis

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 9113-2C B41J 7/92 B

Claims (5)

[Claims] 1. A print head and platen (11) comprising a plurality of print elements (14) mounted on the same frame (12).
A print medium (1) provided with a space adjusting means (22) for adjusting the space between the print head and the platen (11).
(0) is a wire dot printer for projecting by driving the wire (1) of the print head to form characters in a dot matrix for printing, and the space adjustment amount of the space adjusting means (22). Detection means (2
3) and pulse sending means (24) for adjusting the width of the driving pulse for driving the wire of the print head based on the detection result of the detecting means (23), and the printing medium for printing at the same time. A wire dot printer characterized in that the width of a drive pulse sent by the pulse sending means (24) is determined in accordance with the number of sheets (10). 2. When the number of print media (10) is smaller than a predetermined number, the width of the drive pulse is narrower than when the number of print media (10) is a predetermined number or more. The wire dot printer according to claim 1, wherein: 3. A front assembly having a plurality of printing elements (14) mounted on a front frame (12a) and a rear assembly having a plurality of printing elements (14) mounted on a rear frame (12b). A gap adjusting means (22) for adjusting the gap between the constituted print head and the platen (11) is provided, and for the print medium (10) inserted between the print head and the platen (11), A wire dot printer for projecting by driving a wire (1) of a print head to form a character in a dot matrix for printing, the detecting means (detecting means for detecting an interval adjustment amount of the interval adjusting means (22) ( 2
3) and pulse sending means (24) for adjusting the width of the driving pulse for driving the wire of the print head based on the detection result of the detecting means (23), and the printing medium for printing at the same time. A wire dot printer characterized in that the width of a drive pulse sent by the pulse sending means (24) is determined in accordance with the number of sheets (10). 4. When the number of print media (10) is less than a predetermined number, the width of the drive pulse is narrower than when the number of print media (10) is a predetermined number or more. The wire dot printer according to claim 3, wherein 5. The width of the drive pulse of the front assembly is made narrower than the width of the drive pulse of the rear assembly when the number of print media (10) is a predetermined number or more. The wire dot printer according to claim 3 or 4.