JPH06328741A - Print head device - Google Patents

Abstract

PURPOSE:To reduce magnetic circuits so as to make a device compact by providing a plurality of print drive mechanisms in parallel and constituting them of a magnetic drive unit having a single magnetic circuit which generates vibration and a pin drive unit which is vibrated at the whole part by the vibration. CONSTITUTION:A print head prints a dot structure pattern on a recording paper 41 through an ink ribbon 40. In this case, a plurality of print drive mechanisms 100 and 200 having the same structure are provided in a print head housing 1. The print drive mechanisms 100 and 200 are respectively constituted of a magnetic drive unit 2 having a single magnetic circuit which generates vibration and a pin drive unit 3 whose whole part is vibrated in the head direction of the print pin by the vibration. At the magnetic drive unit 2, an armature 6 is attracted to a core 5 by a drive coil 8 so as to move an arm 9. Further, each of the pin drive unit 3 communicates with a pin 9 and is respectively constituted of a plurality of pin drive plates 20, 30 and drive plate support bodies 11, 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head device for a dot impact type printer, and more particularly to a print head which realizes miniaturization.

[0002]

2. Description of the Related Art In a conventional dot impact type printer, a print head equipped with a plurality of print wires and a drive mechanism for these print wires is made to run, for example, facing the recording paper via an ink ribbon, and printing is performed simultaneously with this running. The wire is selectively driven to print a pattern of dots such as characters on the recording paper. FIG. 12 is a cross-sectional view of a conventional typical print head, and FIG. 13 is a plan view showing an arrangement state of print elements fixed in the print head. In the print head of FIG. 12, the print elements 80 shown in FIG. 14 are annularly arranged in a print head housing 81 as shown in FIG.
Each printing element 80 includes a printing wire 82, a leaf spring 83 for driving the printing wire 82, an armature 84, and a drive coil 85.
A core 86 and a yoke 87. Printing wire 8
2 is fixed to the tip of the leaf spring 83, and the tip of the print wire can be projected through the guide 88 at the tip of the print head. The armature 84 is fixed to the leaf spring 83, and the leaf spring 83 is fixed between the core 86 and the print head housing 81. The drive coil 85 is wound around the core 86 and is selectively driven according to the dot print signal.

Armature 84, core 86 and yoke 8
When a magnetic flux due to the energization of the coil 85 passes through the magnetic circuit constituted by 7, the armature 84 is attracted to the core 86. As a result, the tip of the printing wire 82 collides with the ink ribbon and the recording paper, which are not shown, and printing is performed.

[0004]

However, in the conventional print head, it is necessary to form a magnetic circuit individually for each print wire, which makes it extremely difficult to downsize the print head.

It is an object of the present invention to provide a print head which can greatly reduce the number of magnetic circuits and can be miniaturized.

[0006]

A print head device according to the present invention comprises a plurality of print pins corresponding to dots, and a plurality of first pin drive plates each having a fixed first print pin and having a first electrode on its surface. A plurality of second pin drive plates each having a second electrode facing the first electrode at a predetermined interval, and a first drive plate supporter that supports the plurality of first pin drive plates through elastic bodies, respectively. A second drive plate support for supporting the plurality of second pin drive plates. The second drive plate support repeatedly vibrates in the direction of the tip of the print pin by the drive unit. According to the timing of the vibration of the drive unit,
The drive circuit applies a voltage based on the print signal between the first electrode and the second electrode of the first and second pin drive plates to generate a Coulomb force between the first and second electrodes. As a result, the first pin drive plate, to which the print pin is fixed, is drawn to the second pin drive plate in response to the print signal, and moves in the direction of the print pin tip together with the drive unit.

With this configuration, printing can be performed on a plurality of print pins by one drive unit, the first and second pin drive plates themselves do not increase in size, and the print head can be downsized.

When the elastic body that supports the first pin drive plate to which the print pins are fixed is a material that can be energized, the first electrode of the first pin drive plate is electrically connected to the drive circuit via the elastic body. Can be connected. As a result, the elastic body not only supports the first pin drive plate but also serves as an electric cable, thereby improving the efficiency of wiring.

[0009]

1 is a perspective view of a print head according to an embodiment of the present invention, and FIG. 2 is a sectional view of the print head shown in FIG. In the figure, the print head of this embodiment is shown as a recording paper 41.
Is a print head device of a dot impact type printer that prints a dot configuration pattern such as characters according to a print signal via an ink ribbon 40. The print driving mechanisms 100 and 200 having exactly the same structure are fixed in parallel in the aluminum print head housing 1. The print drive mechanism 100 (and 200) has a magnetic drive unit 2 having a single magnetic circuit that generates vibration, and the vibration transmitted from the magnetic drive unit 2 causes the entire print pin 10 to move toward the leading end of the print pin 10 (with respect to the recording paper 41). And a pin drive unit 3 that vibrates in the vertical direction).

The magnetic drive unit 2 has an arm 9 to which the pin drive unit 3 is fixed at its tip, a leaf spring 4 for supporting one end of the arm 9, a core 5 for fixing the leaf spring 4, and one side of the leaf spring 4. The armature 6 is fixed to the center of the core 5 and faces the other end of the core 5 with a predetermined gap, a yoke 7, and a drive coil 8. The core 5 is the print head housing 1
It is fixed to the base 1A which is fixed to. The yoke 7 has a U shape, and one end thereof is fixed to the core 5. As a result, the core 5, the armature 6 and the yoke 7 are magnetically coupled. Each of the core 5, the armature 6 and the yoke 7 is made of a magnetic material. The armature 6 is arranged between the forked portions of the yoke 7, but is not fixed to the yoke 7. The distance between the leaf spring 4 and the yoke 7 is larger than the moving stroke of the printing pin 10 so that the leaf spring 4 does not contact the yoke 7 during printing. Drive coil 8
Is wound around the armature of the core 5 and is fixed, and the current flows through the armature 6, causing the armature 6 to move to the core 5
Is magnetically attracted to the end of. When the armature 6 is attracted to the core 5, the leaf spring 4 bends and the arm 9 moves toward the recording paper 41.
Move in the direction of. The current flowing through the drive coil 8 is ON,
When turned off, the pin drive unit 3 fixed to the arm 9 vibrates toward the tip of the print pin 10.

The pin drive unit 3 selectively drives a plurality of print pins 10 (FIG. 2) arranged in a line for dot printing in accordance with the movement of the arm 9. The drive of each pin 10 is performed based on the print signal applied to the pin drive unit 3 according to the vibration of the arm 9. The pin drive unit 3 includes a first pin drive plate 20 to which a plurality of pins 10 are individually fixed, and an insulator first drive plate support that supports the first pin drive plate 20 via conductive elastic bodies 13, respectively. Body 1
1, a second pin drive plate 30 facing the first pin drive plate 20 at a predetermined interval, and a metal second drive plate support 12 to which the second pin drive body 30 is fixed. The first drive plate support 11 is fixed to the print head housing 1, and the second drive plate support 12 is fixed to the arm 9.

FIG. 3 is a front view of the periphery of the pin drive unit 3 when the pin drive unit 3 of the print head of FIG. 1 is viewed from the direction of arrow B. In the figure, the first with the pin 10 fixed
The pin drive plates 20 are arranged alternately with the second pin drive plates 30 fixed to the second drive plate support 12 at a predetermined interval. The first and second pin drive plates 20 and 30 have electrode films 21 and 31 on one side thereof, and the electrode films 21 and 31 face each other. As shown in FIG. 7, the first and second pin driving plates 20 and 30 have electrode films 21 and 31 formed as first and second electrodes on the ceramic plates 20A and 30A having a thickness of 1 mm or less, respectively. It is a thing. Electrode film 21, 31
Is composed of conductive films 21B and 31B and insulating films 21C and 31C formed thereon. The conductive films 21B and 31B generate a Coulomb force by the voltage applied thereto and attract each other. The insulating films 21C and 31C are the electrode films 21 and 3, respectively.
It is provided to prevent short-circuiting when the 1s contact each other by Coulomb force. However, insulating film 2
One of 1C and 31C may be omitted.

The first pin drive plate 20 is fixed to the connector 14 via the elastic body 13, as shown in FIG. The connector 14 is fixed to the first drive plate support 11 and electrically connected to the cable 15. As shown in FIG. 6, a pair of thin plates 13A of the elastic body 13 are connected by a pair of spring bodies 13B. One of the thin plates 13A is inserted into and fixed to the gap 14A provided in the connector 14,
The other is fixed on the side opposite to the surface of the first pin drive plate 20 on which the electrode film 21 is formed. Conductive film 21B of electrode film 21
(FIG. 7) is electrically connected to the conductive elastic body 13,
As a result, the cable 15 is electrically connected. Therefore, the elastic body 13 has a function of supporting the first pin driving body 20 and moving the print pin 10 in the vertical and horizontal directions with respect to the recording paper 41, and also having a function of electrically connecting the electrode film 21 to the cable 14. .

The second pin drive plate 30 facing the first pin drive plate 20 is fixed to the metal second drive plate support 12 together with the electrode film 31, and the cable 16 connected to the second drive plate support 12. Grounded through.

The drive signal (print signal) is the cable 15 or 1.
When the voltage is supplied via 6, the voltage is selectively applied between the plurality of electrode films 21 and 31 according to the print signal, and the first and second pin drive plates 20 and 30 are attracted by the Coulomb force. That is, the first pin drive plate 20 to which the print pin 10 is fixed is deformed by the elastic body 13 to cause the second pin drive plate 30 to move.
Attracted to. In this case, the Coulomb force F is assumed to be a voltage between the electrode films 21 and 31 is V, a distance between the electrode films is d, an area of the conductive films 21B and 31B of the electrode films 21 and 31 is S, and a dielectric constant is ε. , Is expressed by the following equation.

F = V ² · ε · S / 2 · d ² (1) An arm to which the second drive plate support 12 is fixed in a state where the first pin drive plate 20 is attracted to the second pin drive plate 30. 9
When the drive coil 8 is energized to move toward the tip of the print pin 10, as shown in FIG.
The first pin drive plate 20 attracted to 0 moves together with the arm 9. At this time, the tip of the pin 10 projects below the bottom plate 1B of the print head housing 1. However, the first pin drive plate to which the voltage is not applied to the electrode film does not move down even when the arm 9 moves down and does not move from the position before printing, and thus does not protrude from the bottom plate 1B. Therefore, only the pins protruding from the bottom plate 1B push out the ink ribbon 40 and transfer the ink to the recording paper 41. As described above, in this embodiment, the drive coil 8 of the magnetic drive unit 2 is driven in synchronization with the timing of the print signal, and at the same time or a little earlier than that, the plurality of first and second pin drive plates of the pin drive unit 3 are driven. When 20 and 30 are selectively activated based on the print signal, the pin 10 transfers ink to the recording paper 41 according to the print signal.

The Coulomb force F in equation (1) depends on the force with which the pin 10 presses the ink ribbon 40. For example, 10
When the pin 10 presses the ink ribbon with the force of gram,
The voltage V is 100 volts, the area S is 1 to 2 square mm, and the interval d is about 0.1 mm.

When the print pin 10 reciprocates in the direction perpendicular to the recording paper 41, the print pin 10 is prevented from causing lateral shake.
It is desirable to reciprocate in a narrow guide hole.

In the print head of this embodiment, it is not necessary to provide a drive coil, a core and an armature for each pin 10,
Only one or two magnetic drive units are required. Further, since the pin drive unit 3 can be downsized, the size can be greatly reduced as compared with the conventional print head.

Next, the drive circuit of the print head shown in FIGS. 1 and 2 will be described. FIG. 8 is a circuit diagram of the print head drive circuit, and FIG. 9 is a timing chart showing the operation of the print head drive circuit of FIG. In the figure, the print head drive circuit is a drive coil drive circuit 50 that drives the drive coil 8.
And a pin drive plate drive circuit 51 for driving the first and second pin drive plates 20 and 30, and a drive control circuit 52.
The print head drive circuit is mounted on the electric circuit board of the printer. The drive control circuit 52 generates control signals 55, 56, 57 and 58 based on the print signal as shown in FIG. The control signals 55 and 56 are repeatedly generated in synchronization with the print cycle of the print signal, and are supplied to the base terminals of the transistors Tr1 and Tr2 of the drive coil drive circuit 50. The transistors Tr1 and Tr2 are simultaneously turned on by the rising edges of the control signals 55 and 56, and after the lapse of t1 time,
First, the transistor Tr1 is turned off, and the transistor Tr2 is turned off after a delay of t2. Since the transistors Tr1 and Tr2 are on during the time t1, the power supply E
The current from 1 flows through the path of the transistor Tr1, the drive coil 8 and the transistor Tr2, the armature 6 (FIGS. 1 and 2) is attracted to the core 5, and the arm 9 descends. After the transistor Tr1 is turned off, the transistor Tr2
The power source E1 is cut off by the transistor Tr1 until the power is turned off (end of time t2). However, the energy stored in the drive coil 8 is transferred to the drive coil 8 and the transistor Tr1.
2 through the ground to the diode D1. Therefore, until the transistor Tr2 is turned off, the arm 9
Keeps falling. Transistor Tr2 is Tr
The reason for turning off after 1 is to make the current waveform of the drive coil close to a rectangular wave and stabilize the operation of the magnetic circuit. As described above, the drive coil 8 is driven at every constant time t3 which is equal to the printing cycle.

On the other hand, the control signals 57 and 58 are respectively supplied to the switches S1 and S2 of the pin drive plate drive circuit 51 to turn on and off the switches. Pin drive plate drive circuit 51
Are connected in parallel to the power source E2 in the same number as the number of the printing pins 10, but only one is shown in FIG. The control signals 57 and 58 are pulse signal trains that become high or bottom level based on the print signal at constant time intervals t3, and each print pin 10 is selectively driven by these signals. One terminal of the switch S1 is connected to the power source E2, and the other terminal is connected to the electrode film 21 of the first pin drive plate 20 via the resistor Rs.
Connected to. The electrode film 31 of the second pin driving plate 30 and the switch S2 are connected to the ground of the power source E2,
2. The resistors Rp and Rs and the electrode films 21 and 31 form a closed circuit. Here, in the cable 15 of FIGS. 1 and 2, the resistor Rs is connected to the electrode film 21, and the cable 16 is the electrode film 31.
Is connected to the ground of the power supply E2.

As shown in FIG. 9, the control signals 57 and 55 are completely synchronized, but the control signals 58 and 57 are not. Therefore, while the current flows through the drive coil 8, the switch S
1 is closed, a voltage is applied between the electrode plates 21 and 31,
The Coulomb force causes the electrode films 21 and 31 to attract each other, and FIG.
Printing is performed as shown in. Of course, in this case, the switch S1 may not be closed depending on the print signal.

On the other hand, when the switch S1 is turned off and the switch S2 is turned on, the charges accumulated in the electrode films 21 and 31 are discharged through the resistors Rs and Rp. in this way,
The switches S1 and S2 are turned on and off in synchronization with the operation of the drive coil 8.

In the embodiment described above, the print signal voltage is applied to the electrode film 21 via the elastic body 13, and the electrode film 31 is connected to the ground of the power source via the second drive plate support 12. The voltage application and grounding may be reversed. In this case, an insulator is used for the second drive plate support 12 and each electrode film 31 has a resistance R of the pin drive plate drive circuit 51.
s, and all the electrode films 21 are connected to the ground of the power source E1 via the elastic body 13.

FIG. 10 is a sectional view showing the print head of the second embodiment of the present invention. In this embodiment, the magnetic drive unit 6
0 is different from the magnetic drive unit 2 of FIG. 1, and the others are the same as the previous embodiment. Core 6 of magnetic drive unit 60
1, a permanent magnet 62 is fixed in series, and a leaf spring 63 is fixed below the core 61. The leaf spring 63 and the core 61 are fixed to the print head housing 68. Armature 6
4 is fixed on the leaf spring 63, and a gap is formed between the core 61 and the armature 64. Core 61
The permanent magnet 62, the yoke 66, and the armature 64 form a magnetic circuit. Armature 6 with permanent magnet 62
4 is always attracted to the core 61, and the leaf spring 63
The arm 69 fixed to the leading end of the recording paper 41 moves to the side opposite to the recording paper 41. The drive coil 65 is wound around the core 61 so that a magnetic force is generated in a direction in which the magnetic force of the permanent magnet 62 is canceled when a drive signal is supplied.

When no current flows through the drive coil 65, the leaf spring 63 bends to the side opposite to the print pin 10 and the print pin 10
Is located at a position away from the recording paper 41 and printing is not performed. However, when a current synchronized with the print signal flows through the drive coil 65, the attraction of the armature 64 by the permanent magnet 62 is released, and at that moment, the second drive plate support 12 moves toward the recording paper 41. Simultaneously with the movement, as shown in FIG. 4, the electrode films 2 of the first and second pin driving plates 20 and 30 are formed.
When a voltage based on the print signal is applied to the first and the third pins 31, the first and second pin drive plates 20 and 30 attract each other. As a result, as shown in FIG. 10, while the elastic body 13 bends, the print pin 10 moves together with the movement of the second drive plate support 12, and prints on the recording paper 41 via the ink ribbon 40.
The same drive circuit as the drive circuit of FIG. 9 is used.

In this embodiment, the length of the arm fixed to the leaf spring can be shortened and the movement of the arm can be made more stable as compared with the above-mentioned embodiments.

FIG. 11 is a sectional view of a print head showing a third embodiment of the present invention. Although the magnetic drive unit is used in the first and second embodiments, the piezoelectric element is used in the drive unit in the present embodiment. In the figure, a drive unit 70 includes a piezoelectric element 71, a support body 72 that fixes one end of the piezoelectric element 71, and the other end of the piezoelectric element 71, and expands the expansion and contraction operation of the piezoelectric element 71. Vibration magnifying member 73 to which the second drive plate support 12 is fixed
Have and. One end of the vibration magnifying member 73 is fixed to the support body 72. The support 72 is fixed to the print head housing 74. Since the configuration other than the drive unit 70 is the same as that of the first embodiment, the description thereof will be omitted.

Before the drive signal is applied to the piezoelectric element 71,
Since the print pin 10 is located away from the recording paper 41, printing is not performed. When the drive signal synchronized with the print signal is supplied to the piezoelectric element 71, the piezoelectric element 71 expands, and at that moment,
The second drive plate support 12 moves toward the recording paper 41.
Simultaneously with the movement, when a voltage according to a print signal is applied to the electrode films 21 and 31 of the first and second pin drive plates 20 and 30, as shown in FIG.
Is printed on the recording paper 41 via. As the drive circuit, a piezoelectric element drive circuit may be used instead of the drive coil drive circuit 50 used in the drive circuit of FIG. 9, and the piezoelectric element 71 may be driven at the same timing as the control signal 56.

This embodiment has the advantage that no magnetic circuit is required and that the vibration amplifying member 73 serves both as an arm and a leaf spring, so that the number of parts can be reduced.

The embodiments of the present invention are not limited to the first to third embodiments described above, and various modifications can be made within the scope covered by the claims. For example, the first and second pin drive plates 20 and 30 may have any plate-like shape. Also, the print pin 10
Was fixed to the first pin drive plate 20, but may be formed as a part of the first pin drive plate 20.

[0032]

As described above, according to the present invention, it is not necessary to provide a drive unit such as a magnetic circuit or a piezoelectric element for each print pin, and a plurality of second pin drive plates are combined into one drive unit. It can be miniaturized because it can be driven.

[Brief description of drawings]

FIG. 1 is a perspective view of a print head according to an embodiment of the present invention.

2 is a cross-sectional view of the print head of FIG. 1 taken along the line AA.

3 is a plan view of the vicinity of the pin drive unit before printing when the print head of FIG. 1 is viewed from the direction of arrow B. FIG.

4 is a plan view of the periphery of the pin drive unit during printing when the print head of FIG. 1 is viewed from the direction of arrow B. FIG.

5 is a perspective view showing the connection between the first drive plate support and the first pin drive plate of the print head of FIG. 1. FIG.

6 is an exploded perspective view of a first drive plate support and a first pin drive plate shown in FIG.

7 is a cross-sectional view of first and second pin drive plates of the print head of FIG.

FIG. 8 is a circuit diagram of a drive circuit of the print head of FIG.

9 is a timing chart showing the operation of the drive circuit shown in FIG.

FIG. 10 is a sectional view of a print head according to a second embodiment of the present invention.

FIG. 11 is a sectional view of a print head according to a third embodiment of the present invention.

FIG. 12 is a sectional view of a conventional print head.

FIG. 13 is a plan view showing an arrangement state of a plurality of printing elements of the conventional print head of FIG.

FIG. 14 is a front view of one printing element of the conventional print head of FIG.

[Explanation of symbols]

 1 Print head housing 2 Magnetic drive unit 3 pin drive unit

Claims (11)

[Claims] 1. A print head device for a dot impact type printer, which prints a pattern of dots or the like on a recording paper in accordance with a print signal, wherein a plurality of print pins corresponding to the dots and the print pins are fixed respectively. A plurality of first pin drive plates each having a first electrode on its surface, a plurality of second pin drive plates each having a second electrode facing the first electrodes at a predetermined interval, and the first pin drive plate A first drive plate support for supporting each of the two via elastic bodies, a second drive plate support for supporting the plurality of second pin drive plates, and a second drive plate support for supporting the second drive plate support in the tip direction of the print pin. A drive unit that repeatedly vibrates, and the first unit according to the timing of vibration of the drive unit.
A print head device comprising: a drive circuit that applies a voltage based on the print signal between an electrode and a second electrode to generate a Coulomb force between the first and second electrodes. 2. The printhead device according to claim 1, wherein the elastic body is made of an electrically conductive material. 3. The print head device according to claim 2, wherein the first electrode is electrically connected to the drive circuit via the elastic body. 4. The printhead device according to claim 3, wherein the first drive plate support has a connector connected to the drive circuit, and the elastic body is connected to the connector. 5. The printhead device according to claim 3, wherein the second electrode is electrically connected to the drive circuit via the second drive plate support. 6. The printhead device of claim 3, wherein the second electrode is individually connected to the drive circuit. 7. The printhead device according to claim 1, wherein at least one of the first and second electrodes has an insulating layer on its surface. 8. The drive unit includes a core, a drive coil wound around the core, an armature arranged at a predetermined interval on the core, an elastic body to which the armature is fixed, and the elastic body. The print head device according to claim 1, further comprising a member that is coupled to the second drive plate support, wherein the drive circuit switches a current flowing through the drive coil. 9. The drive circuit includes a coil drive circuit that repeatedly supplies a current to the drive coil at the same cycle as the print signal, and between the first electrode and the second electrode according to a timing of supplying the current. 9. The print head device according to claim 8, further comprising: a pin drive circuit that applies a voltage based on the print signal to generate a Coulomb force between the first and second electrodes. 10. The drive unit comprises: a core; a permanent magnet connected in series to the core; a drive coil that is wound around the core to generate a magnetic flux that degausses the magnetic flux of the permanent magnet; The drive circuit includes an armature arranged with a gap, an elastic body to which the armature is fixed, and a member that connects the elastic body and the second drive plate support to each other. The printhead device of claim 1 that is switched. 11. The drive unit includes a piezoelectric element, and a member fixed to the other end of the piezoelectric element and fixing the second drive plate support to an action point where expansion and contraction of the piezoelectric element is transmitted. The print head device according to item 1.