JPH0615887A - Platen - Google Patents

Abstract

PURPOSE:To lower noise during printing by preventing paper rise in a printing device wherein a platen is employed. CONSTITUTION:A platen rubber 22 with adhesiveness is used to a platen 25 and, during printing, paper is stuck to the platen 25 through the adhesive force of the platen rubber 25, resulting in no paper rise and no vibration due to such paper rise. Thereby, paper rise is prevented and noise can thus be reduced during printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a platen for a printing device such as an impact dot matrix printer, and more particularly to a platen which reduces noise during printing by allowing the platen to have an adhesive property.

[0002]

2. Description of the Related Art A conventional example of an impact dot matrix printer will be described with reference to FIGS. FIG. 4 is a front view of a printing unit of a conventional printer capable of printing 136-digit alphabets, FIG. 5 is a cross-sectional view showing the AA cross section of FIG. 4, and FIG. 6 is a cross-sectional view showing the BB cross section of FIG. .

In FIG. 5, the platen 3 is constructed by press-fitting a platen rubber 22 made of SBR (styrene-butadiene rubber) around a platen pipe 21 made of a metal pipe. Fan hold paper 17 which is paper is the tractor 2
Is fed by the print head 4, printed on by the print head 4, and further fed to enter the paper discharge mechanism 5. The paper discharge mechanism 5 is a paper discharge roller 1 having a serrated cross section.
0, a paper discharge roller shaft 11, a paper discharge roller unit 9 including a gear 14 that is a power transmission unit, a paper discharge cover 6,
The discharge plate 7 includes a discharge roller unit 9, a discharge cover 6, screws 13 for fixing the discharge plate 7, and a frame 12 for rotatably holding the discharge roller unit 9. The positional relationship between the rib portion 6b of the paper discharge cover 6 and the paper discharge roller unit 9 does not change even if the paper discharge roller unit 9 rotates. The paper discharge cover 6 is fixed to the frame 12 with screws 13. The discharge roller unit 9 is a frame 12 having a bearing function.
It is configured to be rotatably held by the sheet discharge roller shaft 11 and its movement in the longitudinal direction is restricted. Fan hold paper 1
The paper discharge roller 10 made of rubber or a material having a high friction coefficient similar to that provided for pulling 7 is fixed to the paper discharge roller shaft 11 by fixing means such as press fitting so as not to idle. The discharge rollers 10 commonly use parts of the same shape. The gear 14 is also fixed to the paper discharge roller shaft 11.

In FIG. 5, the sheet discharge cover 6 is integrally formed with a plate portion 6a connected in a row and column direction and a rib portion 6b for guiding the fan hold sheet 17 at the ridge portion thereof. The plate portion 6a at this position in the digit extends to the bottom and has the longest length, and the rib portion 6b also extends to the same position. The paper discharge cover 6 moves toward the smaller girder side (the left side in FIG. 4) with the 40th digit as a boundary, and the plate portion 6
The height a is raised and the height is shortened, and the plate portion 6a is raised and the height is shortened as it goes to the side of the large girder (right side in FIG. 4). This is because the wide fan hold paper 17 is first guided between the paper discharge cover 6 and the paper discharge plate 7 at the 40th digit, and thereafter, as the fan hold paper 17 is sent to the downstream side, the fan hold paper 17 has a digit smaller than 40 digits. This is for gradually guiding the sheet between the sheet discharge cover 6 and the sheet discharge plate 7 on the side and the large girder side.

Further, the plate portion 6a and the rib portion 6b of the paper discharge cover 6 extend to the bottom at the 40th digit because the paper is discharged between the paper discharge cover 6 and the paper discharge plate 7 even when a narrow paper is used. It is to guide to. The fan hold paper 17 is configured to be discharged and held by the pressure applied between the discharge cover 6 and the roller unit 9. When the front end of the fan hold paper 17 is sent downstream from the front surface of the print head 4, the fan hold paper 17 is guided along the rib portion 6b of the paper discharge cover 6, and the fan hold paper 17 enters between the rib portion 6b and the paper discharge roller 10. As shown in FIG. 4, the rib portion 6b and the paper discharge roller 10 are arranged on both sides of the paper discharge roller 10 with a gap of L and with an overlap amount of M as shown in FIG. The force for pressing the fan hold paper 17 against the paper discharge roller 10 is determined by the gap L, the overlap amount M, and the spring property of the fan hold paper 17. The dynamic friction coefficient when the discharge roller 10 is in contact with the fan hold paper 17 and rotating and the pressing force determine the discharge force of the fan hold paper 17 due to friction. Paper ejection roller 1
When 0 is stopped and printing is being performed, the fan hold paper 17 is wound around the platen 3, and therefore a restoring force is applied to return to the original flat shape. Due to this restoring force, the fan hold paper 17 is fixed because its upstream is positioned by the tractor 2, so that the fan hold paper 17 on the downstream side tries to return to the upstream side. The force with which the fan hold paper 17 returns is called the paper return force. When the fan hold paper 17 is pulled back, the force for pressing the fan hold paper 17 against the paper discharge roller 10 (fan hold paper 1
7) to the rib portion 6b), the first static friction force, which is the product of the static friction coefficient between the fan hold paper 17 and the rib portion 6b, and the fan hold paper 17 to the discharge roller 1
A second static friction force, which is the product of the force of pressing to 0 and the static friction coefficient between the fan hold paper 17 and the paper discharge roller 10, acts. The frictional force obtained by adding the first static frictional force and the second static frictional force is called the total static frictional force. 6 is a cross-sectional view of the cross section BB in FIG. 4, and the contact length V between the rib portion 6b and the fan hold paper 17 is shorter than the AA cross section shown in FIG. The discharge force of the fan-hold paper 17 affects not only the gap L but also the contact length V between the rib portion 6b of the fan-hold paper 17 in the traveling direction and the fan-hold paper 17. If the contact length V is long, the fan-hold paper 17 is likely to be restrained, which has the effect of apparently increasing the spring property of the fan-hold paper 17. When the contact length V is short, the degree of freedom of the fan hold paper 17 is increased, and the elasticity of the fan hold paper 17 is apparently reduced.
The paper discharging force on the small girder side is large because the contact length V is long, and the paper discharging force on the large girder side is small because the contact length V is short. Regarding the static frictional force of the fan hold paper 17 in the traveling direction, the contact length V between the fan hold paper 17 and the rib 6b is V.
Is long, the static frictional force is large, and when the contact length V is short, the static frictional force is small. The static frictional force on the small girder side is large because the contact length V is long, and the static frictional force on the large girder side is small because the contact length V is short. In the conventional paper ejection mechanism 5 in which the paper ejection rollers 10 are used and the heights of the plate portion 6a and the rib portion 6b of the paper ejection cover 6 are changed depending on the girder position, the girder side and the girder side where the paper ejection force and static friction force are small are large. Is unbalanced, and the fan hold paper 17 is skewed and wound around the platen 3 when pulled unbalanced by the discharge force, so that the paper floats from the platen 3 on the large girder side to cause paper floating, Further, since the total static friction force on the girder side is smaller than the paper return force, the fan hold paper 17 returns on the larger girder side and further floats from the platen 3.
It was a bigger paper float.

[0006]

When the fan-holding paper 17 in the paper-floating portion floated from the platen 3 is hit by the wire of the head 4 as described above, the fan-holding paper 17 vibrates in a large area according to the paper-floating amount. It was making a lot of noise.

[0007]

In order to solve the above problems, the present invention is characterized by using a sticky rubber for the platen.

[0008]

EXAMPLE An example of the platen of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a platen of the present invention, in which a platen rubber 22 made of SBR (styrene butadiene rubber) having an adhesive property is press-fitted around a platen pipe 21 made of a metal pipe to form a platen 25. The method of giving tackiness to synthetic rubber such as SBR is to add coumarone indene resin and colesine, which are organic chemicals of resinous substances, and other xylene-based, phenol-based, styrene-based, and terpene-based resins as tackifiers. Good. Regarding the adhesiveness of the platen rubber 22, a 1 cm square test piece of 55 kg paper is brought into contact with a flat rubber for testing for 10 seconds at a load of 500 g for 10 seconds, and the test piece side is faced down so that gravity acts in the direction of peeling the test piece. It is sufficient that the test piece has at least tackiness so that the test piece does not come off. As the adhesiveness, such a condition is described as the adhesiveness (tackiness) measuring method at present, the method of Beavan et al., The method of Pickup et al., And the peeling test by a peeling tester are introduced. This is because there are large variations, the measured values differ depending on the test conditions such as load and contact time, and the adhesiveness required for the present invention is very small. FIG. 2 is a sectional view of the same portion as FIG. The fan hold paper 17, which is a paper, is sent by the tractor 2 and wound around the platen 25, and the fan hold paper 17 is weakly attached to the platen 25 due to the adhesiveness of the platen rubber 22. When the fan-hold paper 17 is printed by the print head 4 (a wide concept including numbers, letters, graphs, image prints, etc.), the adhesive force increases as the load increases, so the printing pressure exerts a strong force on the platen 25. Then, the fan hold paper 17 does not float when printing, and the fan hold paper 17 does not vibrate due to the paper float. With this strong adhesive strength, the printing pressure disappears, and after a short time the adhesive strength weakens and becomes weak. When the paper is further sent, the fan hold paper 17 is wound around the platen 25, so that a restoring force for returning to the original flat shape acts. Due to this restoring force, the fan hold paper 17 separates from the platen 25 and enters the paper discharge mechanism 5. By using an adhesive rubber for the platen rubber 22, the fan hold paper 17 at the time of printing
It is possible to eliminate the above-mentioned paper floating, and to reduce the vibration of the fan-hold paper 17 due to the paper floating. Regarding the strength of the adhesive force of the platen rubber 22, the adhesive force does not work at the time of feeding the paper, and the paper floating at the time of printing can be eliminated even if the platen rubber 22 sticks for a short time when the printing pressure is applied. That is, the same effect is exhibited even with pressure-sensitive adhesiveness.

In the description of the present invention, the paper is a fan hold paper 1.
7 has been described as an example, the same effect can be obtained with a cut sheet, a postcard, or an envelope. Although the platen 25 of the present invention has been described by taking the case where the core is a metal pipe as an example, the same effect can be obtained with a solid core material, and the same effect can be obtained with a plastic material. SB of the platen rubber 22 of the present invention
Although R has been described as an example, other NBR (nitrile rubber), CR (chloroprene rubber), EPT (ethylene
Similar effects can be obtained with propylene / terpolymer) and Si (silicon rubber).

FIG. 3 is a sectional view showing another embodiment of the platen of the present invention. Platen pipe 2 made of metal pipe
The first platen rubber 24 made of SBR having desired hardness or durability is press-fitted around the periphery of 1, and the second platen rubber 23 made of SBR having adhesiveness is press-fitted to the outside thereof to form the platen 26. ing. This is because when the hardness and durability of the platen 26 which is optimum for printing cannot be obtained by the second platen rubber 23 alone, the platen rubber is composed of a plurality of layers and the first platen rubber 24 has appropriate hardness and durability characteristics. The use of rubber is effective when desired platen characteristics are obtained as the combined characteristics of the first platen rubber 24 and the second platen rubber 23.

[0011]

As described above, in the platen of the present invention, by using the rubber having the adhesive property, it is possible to eliminate the paper floating of the paper at the time of printing, eliminate the vibration due to the paper floating of the paper, and reduce the noise. is there.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a platen of the present invention.

FIG. 2 is a cross-sectional view of a printing unit when the platen of the present invention is used.

FIG. 3 is a sectional view of another embodiment of the platen of the present invention.

FIG. 4 is a front view of a printing unit of a conventional printer.

5 is a cross-sectional view showing a cross section AA of FIG.

6 is a cross-sectional view showing a cross section BB of FIG.

[Explanation of symbols]

 17 Fan Hold Paper 22 Platen Rubber 25 Platen

Claims (1)

[Claims] 1. A platen using a rubber having an adhesive property.