JPH0664191A - Wire dot print head - Google Patents

Abstract

PURPOSE:To eliminate oscillation of a sensor substrate and obtain stable property and high reliability at low cost without damaging the sensor substrate or without fabricating a guide nose and a guide frame additionally. CONSTITUTION:A protrusion 12e always abutting against a sensor substrate 11 such that pressure is exerted in the protruding direction of a wire 20 is provided at a guide nose 12. The oscillation of the sensor substrate 11 is restrained by the pressure of the protrusion 12e exerted on the sensor substrate 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a wire dot print head which has a sensor inside the head for monitoring the movement of an armature driving a wire, and determines the movement of the armature by a signal from this sensor for printing. It is about.

[0002]

2. Description of the Related Art Conventionally, an impact printer which drives a wire, hits a print medium through an ink ribbon, and prints by the force has a high degree of freedom in the print medium and is relatively inexpensive. It is used in various fields including output devices such as processing systems. Further, the impact printer is classified into a plunger type, a spring charge type, and a clapper type depending on the type of the wire dot print head.

Among them, in the spring charge type, an armature to which a wire is fixed is swingably supported by a leaf spring, and this armature is previously attracted to a core by a permanent magnet against the elastic force of the leaf spring. When printing, the coil wound around the core is excited to generate a magnetic flux in the direction opposite to that of the permanent magnet to release the armature, but in recent years, high-speed printing is required. However, this spring charge type wire dot print head is often used because of its fast response.

Recently, a sensor is provided inside the head, and the motion of the armature is detected by this sensor.
The drive time of the coil is controlled according to the detection result,
A method for achieving high print quality has also been proposed.

FIG. 7 is a sectional view showing an example of a conventional spring charge type wire dot print head together with its peripheral structure, and FIG. 8 is an exploded perspective view of the main part of the print head. The wire dot print head in FIGS. 7 and 8 is provided with a base 3 on the back side of which a current-carrying substrate 2 is attached via an insulating plate 1. Above the base 3, a space yoke 4 is provided at an end of the base 3. , The permanent magnet 5, the magnet yoke 6, and the spacer 7 are sequentially stacked and integrated. Further, on the spacer 7, a leaf spring 8, an armature yoke 9, a stopper plate 10, a sensor substrate 11, a guide nose 12 and a guide frame 13 are provided.
4 (see FIG. 8), and they are placed in a state of being sequentially stacked. On the other hand, on the back surface side of the base 3, a cap 15 is disposed in contact with the base 3 so as to cover and protect the conductive substrate 2. Then, the upper side surface of the guide frame 13 and the lower side surface of the cap 15 are sandwiched by the clamp spring 16 and integrated.

More specifically, the number of electromagnets formed by winding the coil 19 around the outer periphery of the core 17 via the coil bobbin 18 on the base 3 corresponds to the number of the wires 20 (in this example, 9). The thermistors 21 are provided at approximately equal intervals in a ring shape, and thermistors 21 as elements for detecting the temperature inside the head are provided in order to prevent coil burnout. Further, the terminals 22 led out from the coil bobbin 18 of each electromagnet and the thermistor 21 are soldered to the current-carrying substrate 2.
It is electrically connected at 3.

Flexible portions 8a protruding in a cantilever shape toward the center are integrally provided on the leaf spring 8 so as to correspond to the cores 17 of the electromagnets, the number of which is equal to the number of electromagnets. An armature 24 is attached to each flexible portion 8a so as to be adjacent to the armature yoke 9 and to face the core 17 of the electromagnet. The wires 20 are attached to the tips of the armatures 24,
The wire 20 is guided to the platen 26 side by a wire guide 25 fixed to the guide nose 12.

The stopper plate 10 is used for the armature 2
4 for preventing overstroke, and is provided to prevent overstroke after the armature 24 after printing is sucked by the core 17 and to prevent the leaf spring 8 from being damaged.

The sensor board 11 is provided between the guide frame 13 and the armature yoke 9, and the guide frame 1
3 and the stopper plate 10 are supported in a cantilevered manner. Further, a fixed pole 27 is provided on the surface facing the armature 24 so as to correspond to each armature 24. The fixed pole 27 forms a capacitor by opening a narrow space and facing the armature 24, and has a capacitance of a certain value. This value depends on the gap between the fixed pole 27 and the armature 24. Decided. When the armature 24 is displaced during the printing operation, the electrostatic capacitance also changes, and this change is observed by the detection control element 28 (see FIG. 8) provided on the sensor substrate 11, and the wire 20 fixed to the armature 24 is observed. You can know the behavior of.

The print head having the above-described structure is mounted on the carriage 29 for handling. The mounting of the print head covers the body portion 12a of the guide nose 12 to the carriage 29.
Of the head clamp 3 into the groove 29a of the guide nose 12 and in the gap between the wing 12b of the guide nose 12 and the carriage 29.
It is fixed by inserting 0 and tightening.

Next, the operation of this wire print head will be described. First, with this wire dot print head,
The magnetic flux of the permanent magnet 5 is generated by the magnet yoke 6, the spacer 7, the armature yoke 9, the leaf spring 8, and the armature 2.
4, a magnetic circuit that passes through the core 17, the base 3 and the space yoke 4 and returns to the permanent magnet 5 again is formed. When not energized (non-printing state), the armature 24 and the leaf spring 8 are attracted to the core 17 by the magnetic flux generated by the permanent magnet 5, and the wire 20 is drawn into the guide nose 12. FIG. 1 shows this state.

On the other hand, when the electromagnet is excited, that is, a current is passed through the coil 19 to be excited, a magnetic flux is generated in a direction opposite to the exciting circuit, that is, a magnetic flux in a direction canceling the magnetic flux of the permanent magnet 5. Then, the force of attracting the armature 24 decreases, the strain energy accumulated in the leaf spring 8 is released, and the leaf spring 8 returns. Then, upon this return, the wire 20 fixedly attached to the tip of the armature 24 projects from the guide nose 12, and the ink ribbon 31 and the print medium 32 are pressed against the platen 26. As a result, characters and graphic patterns can be printed.

Thus, after the armature 24 is once opened, the coil 19 is de-energized again. Then,
The armature 24 is again sucked and held by the core 17 together with the wire 20 that has returned after impacting the print medium 32. This completes the operation of one dot cycle, and this series of operations is performed for each electromagnet.

Further, in the wire dot print head, the internal temperature is always detected by the thermistor 21, and the heat generated from the coil 19 does not cause the temperature in the wire dot print head to rise abnormally and the coil to be burned. Therefore, the temperature of the coil 19 is maintained below the heat resistant temperature. In addition, a series of operations of the armature 24 is detected by a change in electrostatic capacitance generated between the armature 24 and the fixed pole 27, and control is performed according to the operation detected here.

[0015]

However, in the above-described conventional wire dot print head, since the sensor substrate 11 is a cantilever beam supported by the guide frame 13 and the stopper plate 10, the wire 20 is attached to the platen 26. Impact force when colliding, impact force when the leaf spring 8 collides with the core 17 after printing, or the armature 24
A shock wave due to an impact force when the colliding with the stopper plate 10 is transmitted to the sensor substrate 11, and the sensor substrate 11 changes in the direction in which the gap between the fixed pole 27 and the armature 24 changes (the direction of the arrow in FIG. 7). Vibration occurs. Therefore, the change in the electrostatic capacity in the gap between the fixed pole 27 and the armature 24 is the sum of the operation of the armature 24 and the vibration of the sensor substrate 11, and only the operation of the armature 24 is changed from the change in the electrostatic capacity. It becomes difficult to know.

To solve this problem, as shown in FIG. 9, the flange portion 12 of the guide nose 12 is larger than the dimension of the step of the guide frame 13 (the height of the inner surface of the portion 13a).
A structure in which the thickness of c is increased and the guide nose 12 presses the sensor substrate 11 is also conceivable, but since the flange end 12d of the guide nose 12 and the end 10a of the stopper plate 10 are close to each other. , Sensor board 11
The shearing force acts on the sensor substrate 11 to damage it, or the sensor substrate 11 on the fixed pole 27 side of the flange end 12d of the guide nose 12 has a cantilever shape, so that the problem of preventing vibration of the sensor substrate 11 cannot be solved.

Therefore, as shown in FIG. 10, the dimension of the step 13a of the guide frame 13 and the thickness dimension of the flange portion 12c of the guide nose 12 are made to coincide with each other so that the guide nose 12 and the guide frame 13 are on the same surface. The structure of contacting with the was considered. However, the dimensions of the step 13a of the guide frame 13 and the flange portion 12c of the guide nose 12
Since the thickness dimensions of both of the guide nose 12 and the guide frame 13 are in contact with the sensor substrate 11 on the same plane, the guide nose 12 and the guide frame 13 in the combined state are in contact with the sensor substrate 11. Must be wrapped and finished to the same plane. For this reason,
The number of man-hours for assembling the print head is increasing, which is an obstacle to lowering the price.

The present invention has been made in view of the above problems, and an object thereof is to eliminate vibration of the sensor substrate without damaging the sensor substrate or additional machining of the guide nose and the guide frame, and to make it inexpensive and stable. An object of the present invention is to provide a wire dot print head having the above characteristics and high reliability.

[0019]

In order to achieve the above object, a wire dot printing head according to the present invention has an armature fixed to the free end side of a leaf spring with a wire fixed to the tip and an outer peripheral portion fixed. The armature and a sensor substrate that is disposed facing the moving direction of the armature while being held in a cantilever shape, a fixed pole that is disposed on the sensor substrate so as to face the armature, and the armature. Magnetic flux means for attracting / releasing the leaf spring with bending, and means for detecting the operation of the armature by replacing it with a capacitance value generated between the fixed pole and the armature. In addition, a protrusion is provided on the fixing member side so that pressure is always applied to the sensor substrate in the wire protruding direction. In this case, the pressure applied to the sensor substrate by the protrusion can suppress the vibration of the sensor substrate. Further, in order to eliminate the influence of the provision of the protrusion on the wiring on the sensor substrate, the protrusion can be provided by escaping the wiring pattern on the sensor substrate. As another means to achieve the above object, an armature having a wire fixed to the tip and attached to the free end side of a leaf spring, and an armature with the outer peripheral portion fixed and held in a cantilever shape are provided. A sensor substrate arranged to face the moving direction, a fixed pole arranged to face the armature on the sensor substrate, and a magnetic flux means for attracting / releasing the armature with the bending of the leaf spring. And a means for detecting the movement of the armature by replacing it with a capacitance value generated between the fixed pole and the armature, the wire escape passing through the wire in the center of the sensor substrate. The hole may be provided, and the protrusion, which is always arranged in pressure contact with the inner surface of the wire escape hole, may be provided on the side of the fixing member that fixes the sensor substrate. In this case, the vibration of the sensor substrate can be suppressed by the frictional force generated by the protrusion applied by pressure contact to the inner surface of the wire escape hole.
Further, as still another means for achieving the above object, an armature having a wire fixed to a tip end and attached to a free end side of a leaf spring, and an outer peripheral part being fixed and being held in a cantilever shape are described above. A sensor substrate arranged so as to face the moving direction of the armature, a fixed pole arranged on the sensor substrate so as to face the armature, and the armature is attracted and released while the leaf spring is bent. Magnetic flux means, means for detecting the operation of the armature by replacing it with a capacitance value generated between the fixed pole and the armature, and corresponding to the other end side of the armature to which the wire is attached. In a device including a ring-shaped stopper plate interposed between the armature and the sensor substrate, the stopper plate is attached to the stopper plate. A plurality of protrusions are provided in a comb-teeth shape in a state of protruding between the fixed poles adjacent to each other from the inner periphery of the base and protruding downward from the fixed poles, and the protrusions form the armature and the fixed poles. You may make it prevent contact. In this case, if the armature tries to move toward the fixed pole by more than a predetermined amount, it will not hit the protrusion and stop further movement, and the armature will not directly hit the sensor substrate. You can

[0020]

According to this structure, even if the armature vibrates, the sensor substrate does not vibrate significantly, and the fixed pole on the sensor substrate does not move more than the fixed position. Therefore, the change in the electrostatic capacitance in the gap between the fixed pole and the armature is only an element of the armature operation, and there is no element due to the vibration of the sensor substrate. Therefore,
It is possible to obtain stable characteristics and high reliability. Also,
By simply providing the protrusions, it is possible to realize the structure at a low cost without significantly changing the conventional structure.

[0021]

Embodiments of the present invention will be described in detail below with reference to the drawings. 1 and 2 show a first embodiment of a wire dot print head according to the present invention. FIG. 1 is a sectional view showing the peripheral structure thereof and FIG. 2 is an exploded perspective view of a main part of the print head. . In addition, in FIG. 1 and FIG. 2, the same reference numerals as those in FIGS.
Shows the same thing as, and its operation is also the same.

Therefore, only the points different from the structure shown in FIGS. 7 to 10 will be described. In the wire dot print head according to the first embodiment, the protrusion 12e is formed on the surface of the guide nose 12 facing the sensor substrate 11. Is provided. The dimension L of the protrusion 12e in the wire movement direction from the contact surface with the guide frame 13 to the tip is the guide frame 13.
Is provided in the vicinity of the wire escape hole 33 of the sensor substrate 11 so as to minimize the shearing force of the sensor substrate 11 generated from the stopper plate end portion 10a and the bending of the sensor substrate 11 which are slightly larger than the dimension of the step 13a. . The protrusion 12e is arranged in a state of being always in contact with the sensor substrate 11 so that pressure is applied to the sensor substrate 11 in the protruding direction of the wire 20.

The protrusion 12e is formed on the sensor substrate 11
When the pattern is wired on the surface on the side opposite to the guide nose 12, the pattern may be damaged by repeated microvibrations, and therefore the pattern is arranged at a position away from the pattern.

3A and 3B, the sensor substrate 11 has protrusions 12
2 shows a vibration state of the structure of the present embodiment in which the guide nose 12 is brought into contact via e and the conventional structure in which the sensor substrate 11 and the guide nose 12 are not in contact with each other. That is, in FIG. 3A, the protrusion 1 is formed on the sensor substrate 11.
2B shows the structure of the present embodiment in which the guide nose 12 is in contact with the guide nose 12 via 2e, and FIG. 3B shows the conventional structure in which the sensor substrate 11 and the guide nose 12 are not in contact with each other. As shown in (a) and (b) of FIG.
In the case of (a), since the guide nose 12 is in contact with the sensor substrate 11 via the protrusion 12e, the protrusion 12e
Suppresses the vibration f of the sensor substrate 11 to make it small, and in the case of (b), since the guide nose 12 is not in contact with the sensor substrate 11, the protrusion 12e increases without suppressing the vibration F of the sensor substrate 11. I understand.

In this embodiment, the structure in which the protrusion 12e is formed integrally with the guide nose 12 is disclosed, but it may be provided on a member fixed to the guide nose 12 side.

FIG. 4 is a sectional view showing a second embodiment of the wire dot print head according to the present invention together with the peripheral structure. Further, in FIG. 4, the components denoted by the same reference numerals as those in FIGS. 1 and 2 indicate the same components as those in FIGS. 1 and 2, and their operations are also the same.

Therefore, only the points different from the structure shown in FIGS. 1 and 2 will be described. The wire dot print head shown in the second embodiment is a projection protruding downward from the inner wall of the guide nose 12. Bar part 12f
And a wire escape hole 3 on the sensor substrate at the other end.
It has a structure inserted in 3. In addition, the pair of rod-shaped portions 12f has a spring property, and a structure that constantly applies pressure to the inner surface of the wire escape hole 33 in the outer circumferential direction of the print head, that is, a structure in which the pair of rod-shaped portions 12f is pressed into the inner surface of the wire escape hole 33 Has become.

Therefore, according to the structure of the second embodiment, since the pair of rod-shaped portions 12f is always in pressure contact with the wire escape hole 33, the sensor is provided between the pair of rod-shaped portions 12f and the wire escape hole 33. A frictional force is generated in a direction that hinders the vibration of the substrate 11. Therefore, vibration of the sensor substrate 11 can be prevented by this frictional force, and stable sensor output can be achieved, resulting in high reliability.

Although the rod-shaped portion 12f is integrally formed with the guide nose 12 in this embodiment, the rod-shaped portion 12f may be provided on a member fixed to the guide nose 12 side. There is no problem if there is at least one.

FIG. 5 is a sectional view showing the third embodiment of the wire dot print head according to the present invention together with the peripheral structure. Further, in FIG. 5, the components denoted by the same reference numerals as those in FIGS. 1, 2 and 4 indicate the same components as those in FIGS. 1, 2 and 4, and the operation thereof is also the same.

Therefore, only the points different from the structure shown in FIGS. 1, 2 and 4 will be explained. The wire dot printing head shown in the third embodiment is the stopper plate 1
A protrusion 10a is provided on the inner peripheral side of 0. here,
Detects a change in electrostatic capacitance generated between the armature 24 and the fixed pole 27 when a voltage V is applied. Since the stopper plate 10 is made of metal and has the same potential as the armature 24, the stopper plate 10 contacts the fixed pole 27. Then,
It is not possible to accurately detect a change in electrostatic capacitance due to the operation of the armature 24. Therefore, the stopper plate 1
A plurality of protrusions 10a of 0 are provided between the fixed poles 27 so as to escape the fixed poles 27 of the sensor substrate 11 in a comb-teeth shape so as to protrude from the inner surface of the outer peripheral portion. Also,
The thickness of each protrusion 10a is formed to be larger than the thickness of the fixed pole 27, and in the assembled state, the lower surface (the surface facing the armature 24) protrudes below the fixed pole 27 as shown in FIG. Will be placed. In addition, in FIG. 6, the broken line indicates the inner circumference of the conventional stopper plate.

Therefore, with such a shape, as shown in FIG. 5, when the sensor substrate 11 vibrates, the vibration on the stopper plate 10 side hits the protrusion 10a and is stopped, so that the supporting portion 10b serves as a fulcrum. However, it is possible to make a small vibration of one-way swing to the opposite side of the stopper plate 10, and the armature 24 does not directly collide with the fixed pole 27, so that the influence on the sensor output can be reduced.

[0033]

As described above, according to the wire dot print head of the present invention, even if the armature vibrates, the sensor substrate does not vibrate greatly, and the fixed pole on the sensor substrate is displaced more than the fixed position. There is no need to Therefore, the change of the electrostatic capacitance in the gap between the fixed pole and the armature becomes only an element of the operation of the armature, and there is no element due to the vibration of the sensor substrate, so that stable characteristics and high reliability can be obtained. Further, by simply providing the protrusion, it is possible to expect an effect that the conventional structure can be realized at a low cost without making a great change.

[Brief description of drawings]

FIG. 1 is a sectional view of a wire dot print head according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of essential parts of the same print head as shown in FIG.

FIG. 3 is a vibration explanatory view of a sensor substrate.

FIG. 4 is a cross-sectional view of a wire dot print head according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a wire dot print head according to a third embodiment of the present invention.

6 is a plan view of a main part of the same print head as shown in FIG.

FIG. 7 is a sectional view showing an example of a conventional wire dot print head.

8 is an exploded perspective view of a main part of the same print head as shown in FIG.

9 is an enlarged cross-sectional view of a main part of the same print head as shown in FIG.

FIG. 10 is an enlarged view of a main part showing another example of a conventional wire dot print head.

[Explanation of symbols]

 5 Permanent magnet 8 Leaf spring 10 Stopper plate 10a Protrusion 11 Sensor substrate 12 Guide nose 12e Protrusion 12f Rod-shaped part (protrusion) 17 Core 19 Coil 20 Wire 24 Armature 27 Fixed pole 33 Wire escape hole

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Noboru Oishi 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Takanori Mimura 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (4)

[Claims] 1. An armature having a wire fixed to its tip and attached to the free end side of a leaf spring, and an armature opposed to the moving direction of the armature with its outer peripheral portion fixed and held in a cantilever shape. A sensor substrate arranged, a fixed pole arranged on the sensor substrate so as to face the armature, magnetic flux means for attracting and releasing the armature with the bending of the leaf spring, and an operation of the armature. In a wire dot print head having means for replacing and detecting with a capacitance value generated between the fixed pole and the armature, in order to always apply pressure to the sensor substrate in the wire protruding direction. A wire dot print head, characterized in that the protrusions arranged in a line are provided on the fixing member side. 2. The wire dot print head according to claim 1, wherein the protrusion is provided by escaping a wiring pattern on the sensor substrate. 3. An armature having a wire fixed to the tip and attached to the free end side of a leaf spring, and an armature opposed to the moving direction of the armature with its outer peripheral part fixed and held in a cantilever shape. A sensor substrate arranged, a fixed pole arranged on the sensor substrate so as to face the armature, magnetic flux means for attracting and releasing the armature with the bending of the leaf spring, and an operation of the armature. In a wire dot print head having means for replacing and detecting with a capacitance value generated between the fixed pole and the armature, wherein a wire escape hole through which the wire passes is provided in the center of the sensor substrate. At the same time, a protrusion that is constantly arranged in pressure contact with the inner surface of the wire escape hole is provided on the side of the fixing member that fixes the sensor substrate. The print head. 4. An armature having a wire fixed to the tip and attached to the free end side of a leaf spring, and an armature facing the moving direction of the armature with its outer peripheral part fixed and held in a cantilever shape. A sensor substrate arranged, a fixed pole arranged on the sensor substrate so as to face the armature, magnetic flux means for attracting and releasing the armature with the bending of the leaf spring, and an operation of the armature. Is detected by replacing with a capacitance value generated between the fixed pole and the armature, and the armature and the sensor substrate corresponding to the other end of the armature to which the wire is attached. A wire dot print head including a ring-shaped stopper plate interposed between the stopper plate and the inner circumference of the stopper plate. A plurality of protrusions are provided in a comb shape in a state of protruding between adjacent fixed poles and protruding downward from the fixed poles, and the protrusions prevent contact between the armature and the fixed poles. A wire dot print head characterized in that