JPH0214903B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a print head used in a wire dot printer, and more particularly to an improvement in a print head that minimizes and uniformizes the stress applied to each of a plurality of print wires.

For example, a printer that forms patterns such as characters by a collection of dots formed by printing wires arranged in two rows or in a matrix (hereinafter collectively referred to as printing wires). has many types of characters, and is extremely suitable and economical for applications that require copying. In order to improve printing quality, it is necessary to make the printing wires thinner and increase their number so that they can each operate independently. In addition, as its use as a computer terminal is expanding, it is required to operate at high speed.

The conventional method will be explained with reference to FIGS. 1 to 5. FIG. 1 is a plan view illustrating a wire dot printer to which the present invention is applied, and FIG. 2 is a print magnet section of the print head shown in FIG. 3 is a side view of the conventional print head with the electromagnet section removed, FIG. 4 is a rear view of FIG. 3, and FIG. 5 shows the positional relationship between the armature and pin hole in FIG. 4. FIG.

In the figure, 1 is the core, 2 is the coil, 3 is the armature, 3a is the holding part, 4 is the printing wire, 5 is the guide frame, 5a is the pin guide, 5b is the pin hole,
6 is a support spring, 7a is a yoke, 7b is a magnetic path member,
7c is a side magnetic path section, 8 is a permanent magnet, 9 is a frame,
10 is a platen, 11 is a print medium, 12a, 12
b is a sprocket, 13 is a carrier, 15 is a guide shaft, 16 is a feed screw, 17 is a belt, 1
9 is a motor, 20 is an ink ribbon cassette, 20
a is the ink ribbon, 21 is the printing head, 21a is the printing magnet, θ is the printing wire installation angle, δ ₁
~δ ₁₆ indicates the amount of deflection of the printing wire.

As shown in FIG. 1, the wire dot printer has a frame 9, on which a platen 10 is rotatably supported. Platen 1
A printing medium 11 is wound around the printing medium 0, and the medium 11 is fed in the direction of arrow A in the figure by sprockets 12a, 12b, etc. On the other hand, on the front side of the platen 10, that is, on the lower side in the figure, a carrier 13 is slidably fitted into a guide shaft 15 provided parallel to the platen 10; It is threadedly engaged with the feed screw 16. The feed screw 16 is connected to a motor 19 via a belt 17 or the like, and therefore, the feed screw 16 can move the carrier 13 in the directions of arrows C and D in the figure by rotating the motor 19 in forward and reverse directions. . Carrier 13 has ink ribbon cassette 2
0 is mounted in the cassette 20, and an endless ink ribbon 20a is built into the cassette 20 with a portion thereof exposed to the platen 10 side. Further, a print head 21 is installed in the carrier 13 surrounded by an ink ribbon cassette 20, and the print head 21 is provided with a plurality of print magnets 21a for forming prints with dots. .

As shown in FIG. 2, the printing magnet 21a is
A coil 2 is wound around a core 1, and an armature 3 is arranged so as to come into contact with the core 1. A holding part 3a with a printing wire 4 fixed to the tip is attached to the amateur 3.
is elastically supported by a support spring 6, and one end of the support spring 6 is fixed to the magnetic path portion 7a. The magnetic path sections 7a and 7b are arranged so as to sandwich the magnet 8 therebetween and surround the core 1 and the armature 3 in a U-shape. Further, side magnetic path portions 7c that engage with both sides of the armature 3 with a gap protrude from the magnetic path portion 7a.

Therefore, when the printing magnet 21a is not operating, the armature 3 is attracted to the core 1 by the magnetic force of the permanent magnet 8.

With this configuration, if current is applied to the coil 2 of the printing magnet 21a of the printing head 21 so that the NS pole of the permanent magnet 8 and the pole of the core 1 are opposite to each other, the core 1 becomes an electromagnet and the permanent magnet 8 The energy stored by the support spring 6 causes the armature 3 to fly toward the magnetic path section 7a, that is, upward in FIG. Print paper 11 on platen 10 shown in FIG. 1 protrudes in the direction of arrow E.
The two collide with each other via the ink ribbon 20a, and printing is performed. When power to coil 2 is stopped, core 1
The electromagnetic force also disappears, and the armature 3 moves in the direction of arrow F in FIG. 2 due to the attractive force of the magnet 8, is attracted to the core 1, and returns to the standby position. In this way, the plurality of print magnets 2 in the print head 21
1a, the printing head 21 and carrier 13 are moved along arrows C and D as shown in FIG.
The printing operation on the printing medium 11 is performed by moving the printing medium 11 in the direction shown in FIG.

Such a printing magnet 21a is shown in FIGS. 3 and 4.
As shown in the figure, they are arranged radially, and the printing wires 4 are concentrated in the center, with their tips protruding toward the center. It is guided by a pin hole 5b of a pin guide 5a provided in the guide frame 5.

As shown in FIG. 5, the pin hole 5 of the pin guide 5a
For example, in the case of 16 pins, the array b is arranged in two rows of eight pins each. The armatures 3 of the printing magnet 21a are arranged on the circumference (hereinafter referred to as a circular arrangement), and the distance between the position of the armature 3 and the position of the pin hole 5b, that is, the amount of deflection of the printing wire 4 δ ₁
~ δ ₁₆ are different from each other. If the mounting angle θ of the printing wire 4 fixed to the holding part 3a of the armature 3 is constant for each printing wire 4, the pin hole 5
Naturally, the bending stress applied to the printing wire 4 guided to different positions of b is different. This variation in stress due to the position of the pin hole 5b of the printing wire 4, which could be ignored in the past, has recently become impossible to ignore. In other words, the printing magnet 2 of the printing head 21 is applied to kanji printers and improves printing quality.
1a, that is, as the number of printing wires 4 increases, the diameter of the attachment position increases, and if the printing wire 4 is shortened as a way to reduce the weight of the printing wire 4 in order to increase the speed of the printer, the bending stress applied to the printing wire 4 increases. As the size increases, the printing wire 4 may break, resulting in a shortened lifespan, and the weight cannot be reduced, making it difficult to meet the demands for smaller size and higher speed. As a countermeasure for this, a method is sometimes adopted in high-speed printers in which the armature 3 of the printing magnet 21a is made to have a constant deflection with respect to the pin hole 5b to equalize the stress, but this method has the disadvantage of being difficult to manufacture. There has been a desire for a method of reducing and uniformizing stress through easy circular arrangement.

SUMMARY OF THE INVENTION The object of the present invention is to overcome the above-mentioned drawbacks and to provide an improved printing head which uniformizes the bending stress on the printing wire.

The present invention has a printing head which includes a printing wire and an armature connected to the wire, and in which a plurality of the armatures are arranged radially on a circumference. Print heads for each wire or group of wires. By doing so, the bending stress applied to the printing wire can be minimized and made uniform.

An embodiment of the present invention will be described below with reference to FIG. FIG. 6 is an explanatory diagram showing a state in which bending stress is applied to the printing wire. In the figure, D is the diameter of the circle where the joint between the armature and the printing wire is placed, l is the length of the range where stress is applied to the printing wire,
δ′ is the amount of deflection of the printing wire, M is the bending moment applied to the printing wire, P is the load applied to the printing wire, θ is the printing wire installation angle, and X is the distance from the contact point of the guide hole and the printing wire (X=o ~
l). Also, the same parts as in FIGS. 2 and 3 are indicated by the same symbols.

As shown in FIG. 6, the printing wire 4 guided by the pin hole 5b is bent so as to lie on the circumference of a diameter D at a distance l from the guide position. In other words, a bending moment M and a load P are generated in the printing wire 4 so that the amount of deflection δ' is given to the printing wire 4. The amount of deflection δ' differs for each printing wire 4 depending on the position of the pin hole 5b.

Therefore, by changing the mounting angle θ according to the amount of deflection of the printing wire 4, the bending moment M and the load P generated in each printing wire 4 can be made constant. The installation angle θ is the printing wire 4
chosen to minimize the stress generated.

The deflection curve of the printing wire is obtained from the following differential equation.

EId ² y/d ² x=M+P(l-x) Here, E is the Young's modulus of the printing wire material,
I is the moment of inertia.

The stress distribution is σx=M+Px/Z Here, Z is the section modulus.

Solving the above differential equation under the boundary conditions of x=o, y=o, dy/dx=O x=l, y=δ'dy/dx=Θ and converting it into a function of l, δ', θ yields Y= x ² /l ² (3δ′-θl)−x ³ /l ³ (2δ′-θl) σ′x＝ZEI／l ² Z{2θl−3δ′＋3x(2δ′-θl)} The maximum value of σx is Since x=o or x=l, σx=
θ is determined so that the larger of o or σx=l is constant. At the same time, consideration is given so that δx=max is minimized.

By attaching the printing wire 4 with the angle θ thus obtained, the stress applied to the printing wire 4 can be minimized and made uniform.
Although it is possible to apply the calculated angle θ to all the printing wires 4, it is convenient for manufacturing and the approximation effect to give an average angle θ to the wires whose deflection amount δ' is close to each other. is obtained.

As explained above, according to the present invention, by giving different predetermined angles to the printing wires attached to armatures arranged in a circular arrangement, the bending stress applied to the printing wires can be minimized and made uniform. Therefore, it is possible to shorten the length of the printing wire. Therefore, there is an effect that it becomes easy to reduce the weight in response to the demands for higher speed and smaller size. It also has the effect of extending the life of the printing wire.

[Brief explanation of drawings]

FIG. 1 is a plan view illustrating a wire dot printer to which the present invention is applied, FIG. 2 is a side view showing the print magnet section of the print head in FIG. 1, and FIG. 3 is a side view showing the electromagnet section of the print head according to the conventional method. Figure 4 is the rear view of Figure 3, Figure 5 is the side view of Figure 4.
FIG. 6 is an explanatory diagram showing the positional relationship between the armature and the pin hole in the figure, and FIG. 6 is an explanatory diagram showing the state in which stress is applied to the printing wire. In the figure, 1 is the core, 2 is the coil, 3 is the armature, 4 is the printing wire, 5a is the pin guide, 5
b is a pin hole, 6 is a support spring, 7a and 7b are magnetic path parts, 7c is a side magnetic path part, 8 is a permanent magnet, 21 is a printing head, 21a is a printing magnet, θ is a printing wire installation angle, and D is an armature. The diameter of the circle where the tip is placed, δ ₁ to δ ₁₆ , and δ′ indicate the amount of deflection of the printing wire.

Claims (1)

[Scope of Claims] 1. The printing pattern has n×m printing wires constituting an n×m matrix (n and m are integers) and an armature connected to the printing wires and movable in response to a printing signal, In a printing head in which a plurality of the armatures are arranged radially on a circumference and at least a printing wire is arranged so as to be able to print an n×m matrix, the printing wire and the printing wire The print head is characterized in that the angle formed by the armature to which it is connected differs for each print wire depending on the position in the matrix printed by each wire. 2. The printing head according to claim 1, wherein the angle at which the printing wire is attached to the armature is changed for each of the plurality of printing wires.