JPS61283577A - Platen - Google Patents

Abstract

PURPOSE:To provide a low-vibration low-noise platen, by a construction wherein a platen is provided with a double cylinder construction comprising an outer cylinder the material thickness of which is constant and an inner cylinder the material thickness of which is varied, the inner cylinder is fixed to a printer chassis through a platen shaft, and the outer cylinder is so supported that it can be rotated relative to the outer peripheral surface of the inner cylinder. CONSTITUTION:Since the outer cylinder 4 and the inner cylinder 1 are in perfect contact with each other, a reduction in the vibration level of the platen with the result of a reduction in noise level can be achieved by reducing the vibrational amplitude of the inner cylinder 1 which is the dominant factor in determining the amplitude of vibration of the platen. Namely, the inner cylinder 1 is provided with such a cross section that the material thickness in Z-axis direction is larger than that in Y-axis direction, thereby providing a major axis in the direction of higher stiffness and a major axis in the direction of lower stiffness. The platen is so disposed that the Z-axis direction is directed to a printing material supplying part of the printer, whereby the vibrational amplitude in the Z-axis direction is reduced, resulting in that the noise generated is also reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a platen, and particularly to a platen with low vibration and low noise.

[Prior art and its problems]

Typical output devices for information processing equipment such as computers and word processors include CRTs, printers, plotters, and other file devices. Among these, printers are positioned as the most common output device because they can output information as printed information such as characters or figures, and can also leave a note copy.

Such printers can be broadly divided into so-called impact type printers, which apply impact to a printing material such as paper through an ink ribbon, and make the ink stick to the printing material, and printers that use inkjet or thermal paper. There is also a non-impact type used. Among them, impact printers use impact force to make multiple copies at once.
It is widely used in fields such as slip processing. There are two types of impact type: the type type, which prints using type, and the wire dot type, which combines several wires to form characters as a collection of extremely fine dots.

The basic printing method for both methods is the same, in which a wire or type drive unit collides with a printing object on a platen via an ink ribbon, and the impact transfers ink to the printing object. FIG. 5 is a cross-sectional view showing the schematic structure of a general impact printer. The general printing configuration of this printer is shown in FIG. 5, as shown in FIG.
It consists of a platen 11 covered with 0, a type simple 12, a printing hammer 13 for striking the type simple, and an ink ribbon 14 disposed between the platen II and the type simple 12. Printed material 15 is printed by platen 11.
is sent, and when the printing hammer 13 is driven, the simple type 12 is pushed toward the printing object 15 side, and further collided with the printing object 15 on the outer rubber 10 via the ink ribbon 14, and at that time, the ink is released by the pressing force. The ink contained in the ribbon 14 is transferred to the printing medium 15.

The printing method of an impact printer is as follows: The printing hammer 13 and the platen 11 covered with the outer rubber 10
The printer is characterized by a hammer drive that collides with the printer, and by using this method, the printing mechanism becomes extremely simple. However, the kinetic energy of the hammer drive
As a result, a large impact force is applied to the platen, and as a result, the platen vibrates greatly. This vibration of the platen not only deteriorates printing quality but also causes a big problem in terms of noise generation. In particular, the noise generated from the platen is one of the factors that determines the level of the noise generated by the impact type blink, and therefore, reducing the noise generated from the platen realizes a reduction in the noise of the impact type printer. For this purpose, it goes without saying that it is effective to reduce the kinetic energy of the printing hammer 13 to reduce the excitation energy generated by the hammer drive to the platen. One of the important features is the ability to make multiple copies, and this requires a certain amount of kinetic energy from the hammer, and there is a limit to how much kinetic energy can be reduced.

If some of the platens are designed to have a low vibration response to the same excitation energy, the generated noise can be reduced. Such conventional planar planes are shown in FIGS. 6, 7, and 8. 6 is a front view including a partial cross section of the platen, FIG. 7 is a partially enlarged sectional view of part 0 of FIG. 6, and FIG. 8 is a sectional view taken along the line DD' of FIG. 6.

This conventional platen has a cylindrical pipe 16,
Side rolls 17 are fixed to both ends of this cylindrical pipe. The outer peripheral surface of the cylindrical pipe 16 and a part of the outer peripheral surface of the side roll 17 are covered with an outer rubber 18,
A platen shaft 19 is fixed to the side roll 17. The assembly of the cylindrical pipe 16, side roll 9, and outer rubber 18 is generally called a platen roll.

The platen roll and the platen shaft 19 have an integral structure, and the printing surface on the surface of the outer rubber 18 can be rotated by the transmission force from a line feed mechanism (not shown) rotating the platen shaft 19.

In the platen having the above structure, the cylindrical pipe 16 has a concentric circular cross section, so the value of the second moment of area of the cylindrical pipe 16 is the same regardless of the direction in which the main axis of the cross section is selected. In other words, even if the line feed is performed by the platen, the vibration characteristics of the platen, which are determined by the value of the second moment of area, do not change and remain constant at first glance.

Considering the noise radiated from the platen in an impact printer, since the platen has a cylindrical surface, the noise is radiated over the entire circumference of the platen. This radiated noise can be reduced by covering the printer with a printer housing, but there is usually a portion above the printer where the platen cannot be covered with the housing in order to supply the printing medium. Therefore, conventional printers have the disadvantage that noise generated by the vibration of the platen is radiated from this portion.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned conventional drawbacks and provide a platen with low vibration and low noise.

[Structure of the invention]

The present invention provides a platen comprising a platen roll and a platen shaft fixed to both end faces of the platen roll and coupled to a printer chassis frame to support the platen roll, in which the platen roll is connected to an outer shaft having a constant wall thickness and a cross section. The printer has a double cylindrical structure consisting of a cylinder and an inner cylinder having a cross section with varying wall thickness, and the inner cylinder is fixed to the printer chassis frame via the platen shaft,
The outer cylinder is characterized in that it has a structure in which it is held in close contact with the outer peripheral surface of the inner cylinder and is rotatably held.

〔Example〕

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

FIG. 1 is a front view including a partial cross section showing one embodiment of the platen of the present invention, and FIG. 2 is an end portion of the platen shown in FIG.
FIG. 3 is an enlarged cross-sectional view of the line feed mechanism and platen fixing section, and FIG.
It is a cross-sectional view when cut along the -B' line, and Y and Z are coordinate systems.

The platen of this embodiment has an inner cylinder 1 , an end of which is connected to an inner roll 2 , and this inner roll is connected to a platen shaft 3 . The platen is
In addition, an outer cylinder 4 that is in close contact with the inner cylinder 1 but can rotate relative to the inner cylinder 1
and an outer roll 5 which is in close contact with the platen shaft 3 but is capable of relative rotation, and the outer cylinder 4 and the outer roll 5 are connected. The outer peripheral surface of the outer cylinder 4 is covered with an outer rubber 6, and a line feed pulley 7 is coupled to the outer roll 5.

The platen shaft 3 is fixed to the printer chassis frame 8, and therefore the inner roll 4 and the inner cylinder 1 are fixed to the printer chassis frame 8 and do not rotate. On the other hand, the portion composed of the outer rubber 6, the outer cylinder 4, and the outer roll 5 is rotatably held by a line feed mechanism (not shown) via a line feed pulley 7. In this embodiment, the platen roll refers to an assembly of the outer rubber 6, outer cylinder 4, inner cylinder 1, inner roll 2, and outer roll 5.)
shall be.

In order to reduce the vibration level of the platen, and thus the noise level, it is necessary to reduce the vibration mode amplitude of the pipe section inside the platen, which largely determines the vibration modes of the platen. In this embodiment, since the outer cylinder 4 and the inner cylinder l have a structure in which they are completely in close contact with each other, it is sufficient to reduce the vibration amplitude of the inner cylinder 1, which is dominant in determining the vibration amplitude. It goes without saying that increasing the rigidity of the pipe that makes up the inner cylinder 1 is effective in reducing vibration amplitude, but if the wall thickness of the pipe is made uniformly thick in order to increase the rigidity, the overall weight will increase. The torque required for line feed increases, which requires a larger line feed motor, which is not preferable.

As mentioned above, in a general printer, it is necessary to provide a supply section for the printing medium, and therefore, a large amount of platen noise is emitted from the printing medium supply section. Therefore, if the vibration amplitude of the platen surface corresponding to the printing medium supply section is reduced, the noise reduction effect will be increased. Based on this idea, the platen of this embodiment is designed to have the highest bending rigidity in the Y-axis direction, as shown in FIG. In other words, the pipe wall thickness in the Y-axis direction of the inner cylinder 1 is made larger than the pipe wall thickness in the Y-axis direction, and instead of a pipe with a constant wall thickness, the pipe has a cross section with varying wall thickness, so that the pipe thickness in the direction of high rigidity is increased. It is differentiated into a main axis and a lower direction main axis.

If the platen is installed so that the Y-axis direction faces the printing material supply section of the printer, the vibration amplitude in the Y-axis direction is small, and as a result, the radiated noise is also reduced.

Needless to say, the inner cylinder 1 is fixed to the printer chassis frame 8 via the inner roll 2 and the platen shaft 3, so even if the outer cylinder 4 is line fed, the direction in which the platen is highly rigid will always remain constant. . The direction in which the high-rigidity shaft is set may be set in the direction that is optimal for noise reduction. Furthermore, although the platen is made to have high rigidity, the pipe wall thickness of the inner cylinder 1 is not made uniformly thick, so the weight is also light.

FIG. 4 is a diagram showing the mobility transfer functions of the platen of this embodiment and the conventional platen under the same conditions.

The solid line in the figure is the transfer function of the platen of this embodiment, and the broken line is the transfer function of the platen of the conventional example. Normally, the problem of print noise in printers is in the frequency range up to approximately 0 KHz.When considering the transfer function in Figure 4 from this perspective, this embodiment has a higher vibration level than the conventional example. It can be seen that the level is decreasing.

Note that this embodiment does not limit the present invention, and it goes without saying that any changes can be made without departing from the spirit of the present invention.

〔Effect of the invention〕

As explained above, the platen roll has a double cylindrical structure consisting of an outer cylinder with a cross section of constant wall thickness and an inner cylinder with a cross section of varying wall thickness, and the inner cylinder is fixed to the blink chassis frame via the platen shaft. By having a structure in which the outer cylinder is rotatably held relative to the outer peripheral surface of the inner cylinder, high rigidity can be achieved while being relatively lightweight, and as a result, a platen with low vibration and low noise can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a front view including a partial cross section showing one embodiment of the platen of the present invention, FIG. 2 is a partially enlarged sectional view of section A in FIG. 1, and FIG.
A cross-sectional view taken along the line B-B' in the figure. Figure 4 is a diagram showing the transfer function showing the vibration characteristics of the platen of the embodiment shown in Figure 1 and the platen of the conventional example. Figure 5 is a diagram showing the general impact. 6 is a front view including a partial cross section showing a platen of a conventional example; FIG. 7 is a partially enlarged sectional view of part 0 in FIG. 6; and FIG.
It is a sectional view taken along the line D-D'' in the figure. 1. Inner cylinder 2 Inner roll 3 Platen shaft 4.・Outer cylinder 5 ・・・・・・Outer roll
)6...Outer rubber 7...Line feed pulley 8...
... Blink chassis frame 11 ... Platen 12 ... Simple type 13 ... Printing hammer 14 ... Ink ribbon agent Patent attorney Yoshiyuki Iwasa 3 tools Figure 2 Figure 5 C Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] (1) In a platen consisting of a platen roll and a platen shaft fixed to both end faces of the platen roll and connected to a printer chassis frame to support the platen roll, the platen roll is connected to an outer cylinder having a constant wall thickness and a cross section. and an inner cylinder having a cross section with varying wall thickness, the inner cylinder is fixed to the printer chassis frame via the platen shaft, and the outer cylinder is in close contact with the outer peripheral surface of the inner cylinder. A platen characterized by having a structure in which it is rotatably held.