JPS5842121Y2 - Spoke-shaped printed wheel - Google Patents

Description

[Detailed description of the invention] The present invention relates to an improvement of a spoke-type print wheel.By reducing the rigidity of the spokes, not only the type support part but also the spokes are deformed during printing, thereby reducing the stress generated in the type support part. It is something.

A print wheel is used in which a rotating body is provided with a number of rod-shaped type support parts radially arranged, a type is attached to the tip of each type support part, and the type is struck in the direction of the axis of rotation of the rotary body using a hammer to print on paper. When the number of printed characters is 96 or less, such as a print wheel for European and American characters, a rod-shaped type support part with printed characters formed at the tip is used as shown in Japanese Patent Application Laid-Open No. 51-37725. Even in a structure in which the print wheel is provided radially from the boss portion, the value of the rotational moment of inertia of the entire print wheel is within a practical range.

However, since a print wheel for Japanese characters requires a considerably larger number of characters than this, a type support part 3 is provided radially from the boss part as in the structure disclosed in the above-mentioned publication. In this case, the length of the type support must be increased, which inevitably results in an extremely large moment of rotational inertia, and the motor rotates the print wheel at high speed, so with this structure, the type support will vibrate when the motor stops. Not only that, but the structure becomes complicated and impractical.

In order to be able to use such a print wheel for printing Japanese characters, the printer disclosed in Japanese Patent Application No. 51-25260 as shown in FIG. 1 has been improved.

The print wheel 8a is manufactured by connecting the boss portion 6a and the ring portion 3a provided with the type support portion 2a having the type 1a at the tip with spokes 7a and shortening the length of the type support portion 2a. This made the structure simple.

However, with the spoke-shaped print wheel 8a shown in FIG. 1, in order to increase fatigue strength, it is not possible to increase the media interval on the printing surface, that is, the interval at which the characters move to the platen during the printing operation with the hammer. There were problems in terms of print quality and fatigue strength.

This is because the number of spokes 7a connecting the boss portion 6a and the ring portion 3a cannot be increased because it depends on an attachment/detachment mechanism (not shown), so the type support portion 2a is bent during printing with a hammer, and the base 14 of the type support portion 2a is bent. a, 15 a
The bending stress generated at the root 14a of the type support 2a on the extension of the spokes 7a is greater than at the root 15a of the type support 2a located between the spokes 7a. Each base 14
This is thought to be because there was a difference in the stress generated at a and 15a.

In other words, the type support parts 14a, 15 during printing
The stress generated in the spokes 7 is transmitted through the ring portion 3a.
In order to receive the type at the base 14a, 1 of the type support part 2a,
5a, even if the stress is low in the static case, since the rigidity of the spokes 7a is large, in the dynamic case, only the type support part moves during printing, and the type support part 15a located between the spokes 7a and the spokes 7a move. Type support part 1 located on the extension
This is because the difference in stress from 4a becomes large.

For this reason, the vibration constant was not uniform depending on the printing location, which caused problems in terms of printing quality and fatigue strength.

By lowering the rigidity of the spoke parts, the spokes deform together with the type support part even during instantaneous printing operations, reducing the stress generated in the type support part, especially the stress generated at the base of the type support part, and at the same time reducing the stress generated at the base of the type support part. The purpose of this is to provide a print wheel with a long life by equalizing the stress generated at the base of each type support part. A plurality of spokes are provided radially and connect the ring part with a boss part having a hole that fits into the rotational drive shaft, and transmit the rotation of the rotational drive shaft to the ring part. The spokes are bent to be longer than the shortest distance between the ring part and the boss part so that the spokes are deformed together with the type support part in the axial direction of the rotary drive shaft, and the bending stress of the type support part generated during printing is reduced. It is characterized by being made smaller.

Next, an explanation will be given based on an embodiment of the present invention shown in FIGS. 2 to 4. As shown in FIG. A print wheel 8 is formed by connecting the ring part 3 to a boss part 6 which is arranged in a predetermined number of steps radially from the ring part 3 and further has a shaft hole 5 for fitting the drive shaft 4 through spokes 7. ing.

This print wheel 8 is connected to a motor 9 as shown in FIG.
The drive shaft 4 is fitted into the shaft hole 5, and the motor 9 rotates to print the desired selected type on the printing paper 11 guided to the platen 10 and the printing hammer 1 placed opposite the printing paper 11.
2, and by striking the back side of the tip of the type support 2 with the action of the hammer 12, the type 1 formed on the surface of the tip of the type support 2 is applied to the printing paper 11 via the ink ribbon 13. Printing is done.

In FIG. 2, as in the case of FIG. 1, only the two type support parts 2 on which the type characters A and B are formed are shown, and the other type support parts 2 are omitted.

The spokes 7 connecting the boss portion 6 and the ring portion 3 are not formed radially as in the conventional example shown in FIG. 1, but are bent as shown in FIG. Since the spokes 7 are made longer than the shortest distance between them and the part 3, the rigidity of the spokes 7 is reduced as a whole, so that when the hammer 12 is actuated to print, it is an instantaneous printing operation. However, only the type supporting portion 2 is bent by the hammer 12 and the collision between the type 1 and the platen 10 is not achieved, and at the same time, the spokes 7 are also deformed in the axial direction of the drive shaft by the action of the hammer 12.

Since the spokes 7 are deformed together with the type support part 2 during printing, the bending stress generated in the type support part 2, especially the stress generated at the bases 14 and 15 of the type support part 2, is reduced, and the print shown in FIG. When the spokes 8a are made rigid like the wheel 8a, stress occurs at the root 14a of the type support part 2a located on the extension of the spoke 8a and the root 15a of the type support part 2a located between the spokes 7a. However, since the spokes 7 are deformed in the axial direction during printing as shown in FIG. The difference has become smaller.

In the illustrated embodiment, 128 characters (including peripheral symbols, etc.) of JIS C6250 (OCRB-■) matrix type are installed,
The length of the type support part from the type part to the ring part is 14mm.
, when the plate thickness excluding the boss part is Q, 5 mm, the rotational moment of inertia when made of synthetic resin and when the type surface is plated is approximately 41.0 in the case of Fig. 1, with the outer diameter being the same.
g cm2, 41.4 g cm2 in the case of FIG. 2, and 50 g cm2 in the case where the type supporting parts were provided radially directly from the boss part.

In order to reduce the rotational moment of inertia, it is effective to reduce the number of spokes, reduce the plate thickness, and increase the diameter of the ring when the outer diameter is constant. This reduces the stress generated at the base of the print wheel with the ring part, but this reduces the rigidity of the entire print wheel, which becomes a source of vibration and causes so-called side print, where adjacent characters are also printed. Therefore, the result will not be good.

Therefore, in order to avoid side prints and to reduce the stress generated at the base of the type support, the limits of the length of the type support are approximately 14 mm and the width is approximately 1 mm, according to the embodiment.

In the present invention, we focused on the fact that the stress generated at the ring roots 14 and 15 of the type support part 2 changes depending on the rigidity of the spokes 7 that connect the boss part 6 and the ring part 3. In order to reduce the stiffness of
By increasing the length of the spokes 7, the type support portion 2
The aim is to reduce the stress generated at the ring roots 14° and 15.

In order to reduce the rigidity of the spokes, other than increasing the length of the spokes 7 as in the present invention, there is a method of reducing the thickness or width of the spokes 7.

However, when integrally molding a plastic print wheel, the thickness is limited by the ratio of the width to the length, so it is not easy to reduce the thickness, and it is difficult to reduce the width. Unless the number of spokes is increased, a uniform vibration constant cannot be obtained at any position in the circumferential direction, and at the same time, the print wheel attachment/detachment mechanism is restricted, resulting in a problem in operability, which is undesirable.

By bending the spokes 7 to form a branch shape as in the present invention, the spokes 7 become longer than the shortest distance between the ring part 3 and the boss part 6, and the overall state is the same as increasing the number of spokes in the circumferential direction. The vibration constants at arbitrary positions became almost equal.

At the same time, this reduces the rigidity of the spokes 7, and when the type support part 2 is bent by the hammer 12 during printing, the spokes 7 are also bent together with the type support part 2, so bending stress generated in the type support part, especially the type This will reduce the stress generated at the base of the support.

According to experiments, in the print wheel 8a shown in FIG.
The stress generated at the base 14a of the type support portion 2a located on the extension of the spoke 7a is greater than the stress generated at the base 14a of the type support portion 2a located on the extension of the spoke 7a.
However, in the print wheel of the present invention shown in FIG. 2, the degree of increase in the stress generated at the root 14 with respect to the stress generated at the root 15 was reduced to 1.2 times.

In addition, a comparison of the spokes on both spokes shows that the print wheel in FIG. 1 tends to have 1.5 times greater distortion than the print wheel in FIG. 2.

In the case of high-speed printing, the stiffness of the entire print wheel is particularly problematic, and reducing it too much will make the operation unstable.

Therefore, as in another embodiment of the present invention shown in FIG. 4, a damper material 16 for eliminating residual vibrations may be installed between the spokes.

This makes it possible to remove vibrations.

According to the present invention, the spokes that connect the boss part and the ring part are bent and formed into a branch shape, which is longer than the shortest distance between the ring part and the boss part, so that the rigidity of the spokes is reduced, and when printing, the type Since the spokes are also deformed in the axial direction of the rotary drive shaft along with the support part, the bending stress of the type support part that occurs during printing, especially the bending stress at the base, is reduced, and the stress generated at the base of each type support part is reduced. The difference was reduced, the life of the print wheel could be extended, and the vibration characteristics at any position in the circumferential direction could be made uniform.

Additionally, the distance traveled by the hammer-driven characters toward the platen during printing, that is, the distance between the media, can be increased, thereby improving the versatility of the print wheel.

Furthermore, since it has a planar shape, it can be etched or pressed if it is made of metal, and it can be integrally molded if it is made of synthetic resin, which has the advantage of being mass-producible and reducing costs.

[Brief explanation of drawings]

FIG. 1 is a front view showing a conventional print wheel, FIG. 2 is a front view showing a print wheel according to an embodiment of the present invention,
Fig. 3 is a side view showing the state in which the print wheel of the present invention is used, Fig. 4 is a front view showing the print wheel of another embodiment of the present invention, in the drawings, 1 is a matrix type, and 2 is a type 3 is a ring portion, 4 is a drive shaft, 5 is a shaft hole, 6 is a boss portion, 7 is a spoke, and 14 and 15 are the roots of the type support portion.

Claims (1)

[Scope of utility model registration request] A ring part is provided with a plurality of type support parts each having a printing type character at the tip thereof radially from the ring part, and the ring part is connected to a boss part having a hole that fits with the rotational drive shaft to prevent rotation of the rotational drive shaft. The spokes that transmit the information to the non-glue portion are arranged at a distance from the shortest distance between the ring portion and the boss portion such that the spokes are deformed together with the type support portion in the axial direction of the rotational drive shaft during printing due to a decrease in the rigidity of the spokes. 1. A spoke-shaped print wheel, characterized in that the spoke-type print wheel is formed by bending it into a long length so that the bending stress of the type supporting portion that occurs during printing is reduced.