JPH04129761A - Line dot thermal printer - Google Patents

Abstract

PURPOSE:To make a rubber part of a sheet-feeding rubber roller less flexible in the direction of rotation by reducing the elasticity thereof in the direction of rotation while maintaining the axial elasticity of the same. CONSTITUTION:A sheet-feeding rubber roller 10 is composed of a core metal 11 and a rubber part 12, and radially installed fins 13 in comb teeth shape are provided round the core metal 11 so that they cover the whole length of the core metal. The rubber part 12 is finished in such a way where a cylindrical rubber material with a hole provided along its longitudinal direction in a shape corresponding to the sectional shape of the core metal is forcibly fitted to the outside of the core metal, or crude rubber with the core metal 11 placed in the center is put in a cylindrical mold and is heated and vulcanized and after this, grinding is applied to its exterior. As the fins 13 in the comb teeth shape are provided axially on the core metal 11, they are resistant against the flexibility of the rubber in the direction of rotation, making the rubber part 12 less elastic in such direction, while the axial elasticity of the same is kept almost the same as in the case where the fins are not provided.

Description

[Detailed Description of the Invention] [Summary] Regarding line dot thermal printers used in output devices such as computer terminal devices, the noise generated when the paper feed roller discontinuously feeds the paper due to the flexure of the rubber portion is prevented. In a line dot thermal printer that is equipped with at least a line dot thermal head and a paper feed rubber roller that also serves as a platen roller, the paper feed rubber roller retains the axial flexibility of the rubber part and rotates. It is configured to provide means for stiffening the directional flexibility.

[Industrial application field]

The present invention relates to a line head printer used as an output device such as a terminal device of an electronic computer.

[Conventional technology]

A conventional line dot thermal printer is shown in FIG.

As shown in the figure, it consists of a stepping motor 1, a reduction gear section 2, a rubber roller 3 for platen/paper feeding, a thermal head 4, a housing 5, etc. The rubber roller 3 for platen/paper feeding is a reduction gear section. stepper motor 1 through 2
The recording paper 6 is fed out while being pressed against the thermal head 4. Since the thermal head 4 requires a large amount of electricity to print one dot line at a time, the one dot line is usually divided into a plurality of parts and sequentially driven to print one dot line.

Problems that this project aims to solve] In line dot thermal printers like the one mentioned above,
In the field of measurement and medical equipment, printing speeds ranging from high to low are required. However, as shown in FIG. 5, the torque of the stainless steel motor decreases rapidly at high speed.

Therefore, as a design value, the required torque in the high speed range is 1
I try to divide and use the Tonto line as much as possible.

However, the number of divisions S of one dot line is limited, as can be determined by the following equation.

d × π However, f: paper feeding force T, required motor torque μ: friction coefficient between the head and paper d: outer diameter of comb roller η; gear efficiency C: reduction ratio M, number of divisions of chipping motor S: division of 1 ton trine Number P: Dot Pitch Also, as shown in FIG. 6, during printing, the rubber roller rotates with the rubber portion 8 having a certain degree of deflection θ relative to the core metal portion 7 of the rubber roller to perform printing.

Especially when printing at low speed, the printing and paper feeding cycles become longer and paper 6
and the thermal head 4 will stick together. At that time, the motor rotates and attempts to feed the paper, rotating the core metal 7 of the rubber roller, but the deflection θ of the rubber portion 8 increases, and the repulsive force becomes greater than the sticking force between the paper 6 and the thermal head 4. Sometimes, the paper is fed for the first time and goes beyond the stable flexure of the rubber part (the flexure of the rubber part during high-speed stamping).

In this way, during low-speed printing, the deflection of the rubber portion of the rubber roller repeatedly increases and decreases.

At this time, there is a problem in that due to the discontinuity of the mechanical part and the paper, the members, paper, etc. resonate, generating a loud noise that is not typical of a thermal printer.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, it is an object of the present invention to provide a line dot thermal printer that can prevent the noise generated when the paper feed roller discontinuously feeds the paper due to the deflection of the comb portion.

[Means to solve the problem]

In order to achieve the above object, the line dot thermal printer of the present invention includes at least a paper feed rubber roller that also serves as a platen roller and a line dot thermal head. It is characterized by providing means for increasing the flexibility in the rotational direction while keeping the flexibility in the axial direction as is.

[For production]

Since the flexibility of the paper feed rubber roller 10 in the axial direction is the same as that of the conventional one, it is possible to secure the pressing area of the paper 6 against the thermal head 4 as a platen, and by making the flexibility rigid in the rotation direction, a stable amount of deflection can be achieved. It is possible to follow the rotation of the core metal 7 and prevent the generation of noise.

〔Example〕

FIG. 1 is a diagram showing a first embodiment of the present invention, (a)
is a front view, and (b) is a side view.

In the figure, reference numeral 10 denotes a paper feed rubber roller consisting of a core metal 11 and a rubber portion 12, and the core metal 10 is provided with radial comb-teeth-shaped fins 13 over the entire length of the rubber portion 12. The rubber part 12 is made by press-fitting cylindrical rubber having a hole corresponding to the cross-sectional shape of the core metal into the core metal, or by inserting raw rubber into the core metal 1.
1, placed in a cylindrical mold, heated and vulcanized, and then finished by polishing the outer diameter.

In this embodiment configured as described above, since the comb-shaped fins 13 of the core bar 11 extend in the axial direction, the flexibility of the comb portion 12 is almost the same as when there are no fins 13 in the axial direction. Similarly, since the fins 13 resist the bending of the rubber in the direction of rotation, the flexibility becomes stiff. As a result, when the paper is pressed against the thermal head, the rubber part 12 deforms in the axial direction to secure the pressing area of the paper against the thermal head, and when paper is fed, the flexibility in the rotational direction is stiff, so it is not possible to Noise generation is prevented because the rotation of the core bar 11 can be followed with a stable amount of deflection without being significantly deflected.

FIG. 2 is a diagram showing a second embodiment of the present invention.

In this embodiment, disks 14 are formed on a core metal 11 at appropriate intervals, and a rubber portion 12 is molded thereon. Note that the outer diameter of the disk 14 is made slightly smaller than the outer diameter of the rubber portion 12.

In this embodiment configured in this way, the flexibility of the rubber part 12 between the discs 14 is not very stiff, but since it is dragged by the discs 14 in the rotational direction, the flexibility becomes stiff. It has become. This provides the same effect as the previous embodiment.

FIG. 3 is a diagram showing a third embodiment of the present invention.

In this embodiment, a suitable pinched spiral fin 15 is provided on a core metal 11, and a comb portion 12 is molded thereon. The outer diameter of the spiral fin 15 is set to be slightly smaller than the outer diameter of the rubber portion 12.

In this embodiment configured in this manner, the flexibility of the rubber portion 12 is not very stiff in the axial direction but becomes stiff in the rotational direction, as in the previous practical example. Therefore, the same effects as in the previous embodiment can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, the flexibility in the axial direction of the paper feeding rubber roller is maintained as is, and the flexibility in the axial direction is made rigid, thereby reducing the deflection of the rubber portion in the rotational direction when feeding the paper. This makes it possible to prevent discontinuity in paper feeding due to stenciling between the paper and the thermal head, thereby preventing the generation of noise.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment of the invention, FIG. 2 is a diagram showing a second embodiment of the invention, FIG. 3 is a diagram showing a third embodiment of the invention, and FIG. 4 is a diagram showing a third embodiment of the invention. Figure 5 shows a conventional line dot thermal printer, Figure 5 shows the output torque characteristics of a stepping morph, and Figure 6 explains the problem to be solved by the invention. In the figure, 10 is a paper feeding rubber roller, 11 is a metal core, 12 is a rubber portion, 13 is a radial comb-shaped fin, 14 is a disk, and 15 is a spiral fin. Front view and side view (b) Diagram showing the first embodiment glj of the present invention Fig. 1 10...Paper feed rubber roller 11...Core 12...Rubber portion 13...Radial comb-shaped fin of the present invention Figure 3 shows the second embodiment of the present invention Figure 3 shows the third embodiment of the present invention...Paper feed rubber roller 11...Core 12...Rubber portion 14...Disc 15... Diagram showing a traditional line dot thermal printer with spiral fins

Claims (1)

[Claims] 1. In a line dot thermal printer comprising at least a paper feed rubber roller that also serves as a platen roller and a line dot thermal head, the paper feed rubber roller (10) has a rubber portion (12) that is flexible in the axial direction. This line dot thermal printer is characterized in that it has a means for increasing its flexibility in the direction of rotation while maintaining its properties as is.