JP3256609B2 - Print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a print head used in a printer.

[0002]

2. Description of the Related Art Conventionally, an impact printer which drives a printing wire, impacts a printing medium via an ink ribbon, and performs printing with the force, has a high degree of freedom of the printing medium and is relatively inexpensive. It is used in various fields, including output devices such as processing systems.

The impact printer uses a wire dot print head of a plunger type, a spring charge type, a clapper type or the like. Of these, the spring-charged print head supports the armature to which the print wire is fixed by a plate spring for bias so as to be able to swing freely, and this armature is formed by a permanent magnet magnetic flux against the elastic force of the plate spring for bias. Side, the coil wound around the core is excited when printing, and a magnetic flux is generated in the coil in a direction opposite to that of the permanent magnet, thereby releasing the armature. This spring-charged wire dot print head has been widely used in recent years because of its good high-speed response.

[0004] Also, this wire dot print head includes:
There is a type in which a clamp is hooked and held between hook portions provided on a frame on the spring assembly side and a frame on the magnet assembly side to be integrally formed. Hereinafter, such a conventional wire dot print head will be described with reference to the drawings. FIG. 7 is a partial side sectional view showing a conventional wire dot print head.

In FIG. 7, a spring-charged wire dot print head 1 includes a guide frame 2, an armature yoke 3, a plate spring 4 for bias, a magnetic spacer 5, an armature 6, a guide nose 7, a dot wire 8 for printing, It comprises a spring assembly 10 composed of a wire guide 9 and a magnet assembly 22 composed of a magnet yoke 11, a permanent magnet 12, a yoke 13, a base yoke 14, an electromagnet 18, a printed circuit board 19, a thermistor 20, and fins 21. The electromagnet 18 includes a rod-shaped core 15 having a substantially trapezoidal cross section, and a bobbin 16 around which an exciting coil 17 is wound and having a pair of terminals 16a.

The clamp 23 is provided with a hook 24 on the outer wall of the guide frame 2 which constitutes the spring assembly 10.
Hook one end 23a to the magnet assembly 2
The other end 23b formed of a hole (not shown) is hooked on the hooking portion 25 of the fin 21 constituting the fin 2, and the wire dot print head 1 is sandwiched and integrally formed. In addition, the clamp 23
The wire dot print head 1 is provided at four locations.

Next, the printing operation of the wire dot print head 1 as described above will be described. The wire dot print head 1 is driven by turning on / off a current to the exciting coil 17. That is, the current to the exciting coil 17 is cut off when printing is not performed, and is turned on when printing is performed.

In the non-printing state where the excitation coil 17 is not energized, the magnetic flux of the permanent magnet 12
3, the base yoke 14, the core 15, the biasing leaf spring 4, the armature 6, the armature yoke 3, the magnetic spacer 5, the magnet yoke 11, and the permanent magnet 1 again.
Flow on the route back to 2. Further, the armature 6 is attracted to the core 15 while biasing the biasing leaf spring 4 by the magnetic attraction generated at this time, whereby the entire dot wire 8 is drawn inside the guide frame 2.

On the other hand, when a current flows through the exciting coil 17 to excite it, a magnetic flux opposite to the magnetic flux of the permanent magnet 12 is generated in the core 15. As a result, the magnetic flux of the permanent magnet 12 is canceled, and the biasing leaf spring 4 that has been attracted to the core 15 in a biased state is opened. Then, the armature 6 is rotated about the other end toward the platen (not shown) by the elastic reaction force of the biasing leaf spring 4, and the dot wire 8 attached to the free end is instantaneously protruded. Then, the protruding dot wire 8 impacts a printing medium (not shown) via an ink ribbon (not shown), and printing is performed. Also, once the armature 6 is released, the energization of the exciting coil 17 is stopped again, and the core together with the dot wire 8 that has returned after the armature 6 has finished impacting the print medium.
It is held by suction on the 15 side.

Therefore, this operation is performed by a plurality of dot wires 8.
If the selection is made every time and the operation is performed while moving the wire dot print head 1 in the row direction, a character or graphic pattern having a dot configuration is printed on the print medium.

[0011]

In a conventional wire dot print head, when a dimensional error occurs in each part during processing and assembly of each part, the parts of the wire dot print head sandwiched by a clamp are stacked. There is a problem in that the length in the direction varies, and the tightening force of the clamp at each position is not constant, and the flexure of each leaf spring and the impact of each dot wire also vary, thereby deteriorating the printing quality. was there.

[0012]

In order to solve the above-mentioned problems, the present invention is provided on a first frame and a second frame.
Hook the clamp on the hooked part and pinch it to form one
In the print head, the clamp is attached to the hook by the first frame.
And an interval adjusting unit that makes the length for holding the frame and the second frame variable .

[0013]

The first head of the print head constructed as described above.
When one end of the clamp is hooked on one of the hooks provided on the frame and the second frame, and the other end of the clamp is hooked on the gap adjusting unit provided on the other hook, the clamp is brought into the first position. The length for holding the frame and the second frame varies according to the length in the stacking direction, and the print head is held with a fixed tightening force.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals. FIG. 1 is a side view showing a first embodiment of the present invention, and FIG. 2 is a perspective view showing a first embodiment of the present invention.

In FIG. 1, a step portion 31 is formed in a hook portion 25 provided on a fin 21 constituting a magnet assembly of a wire dot print head. The step portion 31 is composed of an upper stage 31a, a middle stage 31b, and a lower stage 31c.
It is composed of steps. Other components of the wire dot print head are the same as in the prior art,
Description is omitted.

Next, the clamping operation of the clamp 23 in the first embodiment will be described. When manufacturing a wire dot print head, first, the spring assembly 1 shown in FIG.
The wire dot print head 1 is assembled by laminating the magnet assembly 22 and the wire assembly 0, and is integrally formed by being clamped by the clamp 23 by an automatic machine such as an automatic head clamping machine. At this time, the automatic machine operates so that the tightening force of the clamp 23 and the stroke of the dot wire at each position are constant even if the length in the stacking direction varies due to the dimensional error of each component.

The wire dot print head 1 is clamped 23
First, one end 23a of the clamp 23 is hooked on the hook 24 on the outer wall of the guide frame 2 shown in FIG. Next, the other end 23b of the clamp 23 is pressed in the direction of arrow A, and the other end 23b is hooked on the step 31 of the hook 25 as shown in FIG.

At this time, when the length of the wire dot print head 1 in the laminating direction is longer than a specified length, the other end 23b of the clamp 23 is hooked on the upper step 31a of the step portion 31. When the length of the wire dot print head 1 in the stacking direction is substantially the same as the specified length, the other end 23b is hooked on the middle step 31b of the step portion 31 as shown in FIGS. If the length of the wire dot print head 1 in the stacking direction is shorter than the specified length, the other end 23b is hooked on the lower portion 31c of the step portion 31. In this manner, the length of the clamp 23 that clamps the wire dot print head 1 is adjusted according to the length of the wire dot print head 1 in the stacking direction, and the tightening force of each clamp 23 is made constant.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a side view showing a second embodiment of the present invention. In FIG. 3, an inclined portion 32 is formed in a hook portion 25 provided on a fin 21 constituting a magnet assembly of a wire dot print head.
The other components of the wire dot print head 1 are the same as those in the first embodiment, and a description thereof will be omitted.

In the second embodiment, the clamp 23
When the wire dot print head 1 is clamped by the automatic machine, as in the first embodiment, even if the length in the stacking direction is varied due to the dimensional error of each component, the tightening force of the clamp 23 at each position, And it operates so that the stroke of a dot wire may be constant. That is, the automatic machine adjusts the length by which the clamp 23 clamps the wire dot print head 1 in accordance with the length of the wire dot print head 1 in the stacking direction, and makes the clamp 23 The other end 23 b is hooked on the inclined portion 32.

Here, a method of setting the taper angle of the inclined portion 32 will be described. FIG. 4 is an explanatory view showing a force acting on the inclined portion, FIG. 5 is a table showing a coefficient of static friction and an allowable taper angle by each metal material, and FIG. 6 is a side view showing a modification of the second embodiment.

When the hole 23c of the clamp 23 is hooked on the inclined portion 32, a tightening force P of the clamp 23 is applied to the surface 32a as shown in FIG. In addition, a reaction force H (Pcos θ) is applied in the vertical direction of the surface 32a, and a force P ′ (Psin θ) that tries to slide in the direction of the arrow acts on the surface 32a. At the same time, the frictional force μ
sH occurs. Since the condition for clamping the wire dot print head 1 without the clamp 23 sliding on the surface 32a is P '<μsH (1), Psinθ <μsPcosθ (2) tanθ <μs ( 3)

From equation (3), the allowable taper angle for each metal material is a value as shown in FIG. In the second embodiment, an aluminum fin 2 having a static friction coefficient of 0.45 was used.
1 and the hook 25, and the taper angle of the inclined portion 32 is 6 °, so that the height of the inclined portion 32 is 1
In the case of mm, an adjustment between about 0.1 mm can be made. By providing the inclined portion 32 in this manner, the length of the clamp 23 holding the wire dot print head 1 can be adjusted with higher accuracy than in the first embodiment.

If the taper angle of the inclined portion 32 is further increased, it is possible to widen the adjustment range of the length in which the clamp 23 clamps the wire dot print head 1. In this case, as shown in FIG.
When hooking b on the inclined portion 32, the clamp 23 is strongly pressed in the direction of arrow A. Since the clamp 23 is made of stainless steel, the engaging portion 33 is formed by plastically deforming the surface 32 a, whereby the other end 23 b of the clamp 23 can be fixed to the inclined portion 32.

[0025]

Since the present invention is configured as described above, it has the following effects.

That is, the clamp is provided with the first
Variable length between the frame and the second frame
By providing the interval adjustment unit , due to the dimensional error of each part that occurs when processing and assembling each part of the print head,
Even if the length of the components in the stacking direction varies, the length of the clamp sandwiching the first frame and the second frame changes in accordance with the length in the stacking direction, and the print head has a fixed tightening force. , The bending degree of each leaf spring and the printing operation are stabilized, and the printing quality is improved.

[Brief description of the drawings]

FIG. 1 is a side view showing a first embodiment of the present invention.

FIG. 2 is a perspective view showing a first embodiment of the present invention.

FIG. 3 is a side view showing a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a force acting on an inclined portion.

FIG. 5 is a table showing a coefficient of static friction and an allowable taper angle for each metal material.

FIG. 6 is a side view showing a modification of the second embodiment.

FIG. 7 is a partial side sectional view showing a conventional wire dot print head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wire dot print head 23 Clamp 24, 25 Hook part 31 Step part

Continuation of front page (72) Inventor Masayuki Ishikawa 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (56) References JP-A-6-262775 (JP, A) 41797 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/235

Claims (4)

(57) [Claims] 1. A print head integrally formed by hooking a clamp on a hook provided on a first frame and a second frame to form a clamp, wherein the clamp is provided on the hook and the first frame. No.
A print head provided with an interval adjustment unit that makes a length for holding the second frame variable. 2. The print head according to claim 1, wherein said interval adjusting section is a step. 3. The print head according to claim 2, wherein the step portion has three steps. 4. The print head according to claim 1, wherein said interval adjusting section is an inclined section.