JPS6344069B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dot print head, and more particularly to a dot print head having an improved spring material that provides the armature with the kinetic energy necessary for printing.

As printers become faster and more compact, various improvements have been made to the printing head, which forms the core of printers.From the viewpoint of a compact, lightweight, and energy-efficient drive system, a spring-charged type that uses permanent magnets has been developed. Print heads have received particular attention.

1A and 1B show an example of a conventional spring charge type printing head, of which FIG. 1A is a plan view of a spring assembly formed by dividing one flexible plate into a plurality of pieces; FIG. 1b is a front view of the permanent magnet assembly facing the spring assembly, and their operations will be schematically explained below.

When the core 1 and armature 2 are induced magnetized by the magnetomotive force of the permanent magnet 3, each leaf spring 4 becomes
While storing elastic energy corresponding to the displacement, it is bent and restrained until it comes into contact with the core 1, as shown in FIG. 2a.

Next, when a voltage is applied to the excitation coil 5 so as to generate a magnetic field in the direction opposite to the magnetization by the permanent magnet 3, the armature 2 is released from the restraint by the permanent magnet 3.

At this time, the elastic energy stored in the leaf spring 4 is converted into the kinetic energy of the armature 2, and as a result, the printing element 6, that is, the printing element at the tip of the armature 2, prints on the ink ribbon (not shown). Through this, impact printing is performed as shown in FIG. 2b.

As can be understood from the operations described above, it is no exaggeration to say that the printing ability of the spring charge type print head is completely dependent on the unique characteristics of the leaf spring 4. That is, the effective length, thickness, and inertial mass of the leaf spring 4 determine the printing ability.

Figures 3a, b, and c are graphs for explaining this fact in detail, and in Figure 3a, the horizontal axis is h/l ² (h is the thickness of the leaf spring 4). , l is the length), and the relationship between the two is ω=A ₁ (h/l ² ), where the vertical axis is the printing repetition frequency ω of the leaf spring 4.
In addition, in Fig. 3b, when h/l ² is plotted on the horizontal axis and bending stress σ is plotted on the vertical axis, the relationship between the two is σ = A ₂
(h/l ² ) δ ₀ (δ ₀ is the amount of deflection). Furthermore, in Fig. 3c, the horizontal axis represents the bending stress σ, and the vertical axis represents the elastic energy U.
The relationship between the two when taking U = A ₃ (h/l) ³ δ ₀ = A ₃
(hl) shows δ ₀ ² .

As is known from these graphs, for example, in order to increase the printing repetition frequency ω, the spring thickness h
There is no choice but to increase the spring effective length l or reduce the effective spring length l. Furthermore, in order to effectively obtain printing energy, the elastic energy must be increased to a certain value or more. However, it must be noted that these properties of ω and U are limited by the bending stress σ of the spring.

Further, as shown in FIG. 2c, in one printing cycle, complex vibrations occur due to the release of residual energy of the spring system after impact, that is, energy not used for impact printing. Therefore, when designing the spring system, consider the printing quality, printing repetition frequency ω, breakage that occurs at higher-order node positions of the spring,
Needless to say, consideration must be given to the setting of the inertial mass, that is, the center of gravity position of the armature.
It is necessary to deal with the breakage of the spring due to the coupled vibration of the armature, the transmission of irregular vibrations to the printing strands, and the progression of wear of the strand guide (not shown) due to this. Furthermore, since the printing quality deteriorates due to the deflection of the printing strands, it is necessary to improve the spring system.

The present invention has been made in view of the above-mentioned problems, and its object is to obtain a dot printing head which has improved spring characteristics and, in particular, does not cause rotational movement. The invention is characterized in that the inertial mass, that is, the armature, is supported using two leaf springs.

Embodiments of the present invention will be described below with reference to the drawings.

4 to 6 show an embodiment of the dot printing head according to the present invention, and one unit of the spring assembly has a printing wire 7 fixed to one end by welding, as shown in FIG. an armature 8; two leaf springs 9 that support the other end of the armature 8 substantially in parallel;
It consists of a block material 10 that fixes the two leaf springs 9 and also serves as the magnetic path of the magnetic circuit, and these assemblies are divided equiangularly as shown in FIG. 4 to form a dot printing head. Configure.

The effect of supporting the armature 8 substantially in parallel with the two leaf springs 9 in this way, that is, the action of the parallel elastic fulcrum method, will be explained with reference to FIGS. 7a and 7b. By armature 8
is capable of only translational movement, and no rotational movement around the center of gravity. In other words, in the conventional support method, the elastic energy U is divided into translational motion energy (first term on the right side) and rotational motion energy (second term on the right side) as shown in the following equation.

U = 1/2Kδ ² = 1/2Mδ〓 ² + 1/2JΘ〓 ² where, K: Spring constant, δ: Deflection amount, M: Mass, δ〓: First derivative of deflection amount, J: Moment of inertia, Θ 〓; is the first derivative of the deflection angle.

However, according to the present invention, since Θ = 0, the elastic energy U stored in the leaf spring 9 is
are all converted into translational kinetic energy 1/2Mδ〓 ² , and δ
〓 is large, so it has excellent high speed.

In addition, in the spring assembly according to the present invention, the bending rigidity is given by 24EI/l ³ (E: Young's modulus, I: second moment of area, l: effective length of the leaf spring 9), but conventional l is 1/2 compared to the one with one spring.
Therefore, eight times the stiffness can be obtained. This means that in addition to the above-mentioned high speed, the charge amount of the leaf spring 9, that is, the printing force against the distance traveled while being restrained, that is, the impact force also increases.

Furthermore, the printing wire 7 fixed to the armature 8
Even in this case, the movement is only a translational movement, so the sliding resistance between the wire guide (not shown) and the printing wire 7 can be reduced to almost zero, thereby reducing the print quality caused by abrasion between the two. Deterioration can be prevented. Furthermore, since the bending moment acting on the printing wire 7 can be reduced to zero, the bending vibration that occurs during one printing cycle of the printing wire 7 is also reduced, thereby ensuring good printing quality and Breakage of the printed wire 7 can also be prevented.

8a and 8b schematically show another embodiment, in which the load acting on the leaf spring 11 (in this case,
An oval hole 13 is formed in the leaf spring 11 along the direction of the neutral axis 12 of the leaf spring 11 with respect to the bending moment M).
This plate spring 11 is used in a spring assembly to construct a dot printing head, similar to the embodiment described above. To be more specific, as mentioned above, the leaf spring 11 is used as a spring charge type head by generating a bending moment M, but in this case,
As shown in Figure 9, in addition to deflection occurring along the
Also known as BENDING. Therefore, as in a spring charge type head, if both ends of a spring material are rigidly connected by brazing welding or the like, and then a bending moment M is applied thereto, the spring material may cause a buckling phenomenon or the welded portions at both ends may break. This may cause peeling or even breakage.

Therefore, in the present invention, the curvature in the y-axis direction is corrected by providing the oval hole 13 along the direction of the neutral axis 12, and the armature 8 is formed using two such leaf springs 11. By supporting it, good operating characteristics can be realized and printing quality can be further improved.

As described above, according to the dot printing head according to the present invention, the armature is supported using two leaf springs installed substantially in parallel, so that the elastic energy is converted into only the energy of translational motion. Since it can be converted, printing quality can be improved, and the lifespan and speed of equipment can be increased.

[Brief explanation of the drawing]

1A and 1B show an example of a conventional spring charge type printing head, of which FIG. 1A is a plan view of a spring assembly formed by dividing one flexible plate into a plurality of pieces; In addition, FIG. 1b is a front view of the spring assembly facing the permanent magnet assembly, FIG. 2a,
b, c are partial front views for explaining the printing process; Fig. 3 a, b, c are graphs for explaining the spring characteristics; Figs. 4 to 6 are diagrams according to the present invention. An embodiment of the dot printing head is shown, in which FIG. 4 is a plan view of the spring assembly, and FIG.
FIG. 4 is a sectional view taken along the - line, FIG. 6 is an exploded perspective view, FIGS. 7 a and b are schematic diagrams for explaining the parallel elastic fulcrum method, and FIGS. 8 a and b are other embodiments. A plan view and a perspective view, FIG. 9, for explaining the
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view for explaining ANTICLASTIC BENDING. 7... Printing wire, 8... Armature, 9,1
1... Leaf spring, 10... Block material, 12... Neutral shaft, 13... Oval hole.

Claims (1)

[Scope of Claims] 1. An armature having a dot element at its tip is supported by a spring material, and the armature is restrained and selectively released against the spring force of the spring material. In a dot printing head that prints dot characters by moving the armature using a repulsive force, the direction of movement of the armature is the direction of deflection,
A dot printing head characterized in that the armature is supported by two leaf springs arranged parallel to each other and facing each other in the bending direction.