JPS6262780A - Printing mechanism for printer - Google Patents

Abstract

PURPOSE:To stabilize the quality of print by constructing a platen roller of stacked disclike thin members of small diameter to maintain the printing pressure constant, thereby eliminating the irregular density of printing. CONSTITUTION:A platen roller 4 is composed of stacked disclike thin members 4a. A backup roller 3 and a platen roller 4 are composed of elastic members having large elasticity and large frictional coefficient. Since thus constructed, even if an irregular surface exists on a sheet to be printed, the roller 4 intrudes to the recess of the sheet by the elasticity of the roller 3 in the horizontal direction of the sheet to reduce the irregular printing pressure in one character. The individual members 4a of the roller 4 horizontally moves along the irregular surface of the sheet in the perpendicular direction of the sheet to decrease the irregular printing pressure present in one character.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a printing device, and particularly to a printing mechanism for improving printing quality.

<Conventional technology> The printing mechanism of printing devices such as thermal transfer and dot impact printing devices includes a platen with a rubber roller fitted around the outer periphery of a rod-shaped shaft, which is fixed to a frame, and a print head is mounted along this platen. Generally, a carriage moves to print on a print sheet between a platen and a print head.

In a serial dot type printing device, the printed characters are composed of a dot matrix of, for example, 16x16 or 24x24, and it is common to print one character at a time in the horizontal direction on the printing paper. be.

<Problems to be solved by the invention> In the above conventional example, the printing paper is arranged between the platen and the print head, and of course an ink ribbon is also arranged).
When printing, if there are irregularities on the paper to be printed, variations in printing pressure occur within the dot matrix of the print head.

This variation in printing pressure is absorbed to some extent by the rubber roller of the platen, but it is not enough, and due to this variation in printing pressure, the printing quality becomes poor due to the shading of the printing within one character and the lack of sharpness of the character. It had the disadvantage of being

Means for Solving the Problems> The present invention provides a platen comprising a cylindrical backup roller and a platen roller that are in contact with each other, using a platen ball,
The platen is moved to the same position as the carriage in accordance with the moving direction of the carriage, and the platen is movable, and the platen roller is composed of a stack of small-diameter disc-shaped thin members. By making the individual thin members follow the irregularities of the printing paper, variations in printing pressure within the dot matrix of the print head are eliminated and printing quality is stabilized.

<Example> Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is a schematic perspective view of a main part of a printing mechanism of a printing device according to an embodiment of the present invention.

In the figure, reference numeral 1 designates a platen support having an abbreviated cross section, and guide grooves 1b are provided on both sides of a horizontal portion 1a.

2 is a platen holder, which holds the horizontal part la of the platen holder 1.
The upper part is slidably held using the guide groove 1b as a guide.

The central part of the platen holder 2 is marked with the
As shown in FIG. 2, which is a directional view, a groove 2a is provided, and a platen 5 consisting of a cylindrical backup roller 3 and a platen roller 4 that are in contact with each other is installed in this groove 2a.
is held in a freely movable manner. The backup roller 3 and a part of the platen roller 4 are attached to the platen holder 2.
The backup roller 3 protrudes from the side surface of the vertical part of the platen holder 1 and rotates with the movement of the platen holder 2 to facilitate the movement of the platen holder 2, and the platen roller 4 serves as a printing section. .

Further, as shown in FIG. 3, which is a sectional view taken along the line Y--Y in FIG. 2, the platen roller 4 is composed of a stack of disc-shaped thin members 4a.

The backup roller 3 and the platen roller 4 are made of elastic members such as rubber and plastic that have elasticity and a large coefficient of friction.

Returning to FIG. 1, reference numeral 6 denotes a carriage body, which has a print head 7, and is movable left and right by a main shaft 8.

A belt 9 has one end fixed to one side of the platen holder 2, and the other end of the belt 9 fixed to one side of the carriage body 6 via pulleys 10, 11, and 12.

Although not shown, this belt 9 is connected to an actuator for driving the carriage, and moves the carriage and performs printing based on a printing command.

<Effect> Next, the effect will be explained.

When the carriage body 6 moves in the direction of arrow A based on the command, the belt 9 fixed to the carriage body 6 is pulled in the direction B, and this belt 9 is pulled by the pulley 12.11.1.
-0 and is sequentially pulled in the C, D, and E directions. Therefore, the platen holder 2 moves in the E direction along the guide groove 1b on the horizontal portion la of the platen support 1.

The entry direction and the E direction are the same direction, and the carriage body 6 and the platen holder 2 move in the same direction and the same distance. The platen roller 4 of the platen 5 is always at the same position and printing is possible.

Further, the platen roller 3 as a printing section is composed of a disc-shaped thin member 4a, and is held movably in the groove of the platen holder 2, and furthermore, a backup roller is in contact with the platen roller 4. 3 is also movable and made of an elastic member, so even if there are irregularities on the printing paper, the elasticity of the backup roller 3 prevents the platen roller 4 from being covered in the horizontal direction of the printing paper, as shown in FIG. It penetrates into the recesses of the printing paper and reduces variations in printing pressure within one character.

In addition, in the vertical direction of the printing paper, as shown in FIG. On the side of the platen roller 4, the elasticity of the backup roller 3 causes the individual thin members 4a of the platen roller 4 to move horizontally along the unevenness of the printing paper, reducing variations in printing pressure within one character.

In this embodiment, the backup roller and the platen roller are made of an elastic member such as rubber or plastic that has elasticity and a large coefficient of friction, but they may also be made of a metal material such as Bs or SUS. Of course, a combination of each may be used.

<Effects of the Invention> As described above in detail, according to the present invention, even if there are irregularities on the paper to be printed during printing, the thin member constituting the platen roller as a printing section does not conform to the irregularities in the paper to be printed. Since the printing moves in a patterning manner, the printing pressure is always constant, which eliminates the shading of the printing and stabilizes the printing quality.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing the main part of a printing mechanism of a printing device according to an embodiment of the present invention, FIG. 2 is a view taken along the X arrow in FIG. 1, and FIG. 4 is a diagram illustrating the action of the platen and the paper to be printed in the horizontal direction, and FIG. 5 is a diagram illustrating the action of the platen and the paper to be printed in the vertical direction. 1...Platen holder, 2...Platen holder, 3...
・Backup roller, 4...Platen roller, 5・
...Platen, 6...Carriage body, 7...Print head, 8...Main shaft, 9...Belt, 1
o, 11, Figure 3 Figure 4

Claims (5)

[Claims] (1) A carriage on which the print head, ink ribbon, etc. are mounted, a platen holder with an approximately L-shaped cross section, a platen holder that moves left and right on the horizontal part of the platen holder, and a central part of the platen holder. It consists of a platen consisting of vertically provided cylindrical backup rollers that touch each other and a platen roller, one end of the belt is fixed to one end of the platen holder, and the platen holder is connected to the platen holder via a plurality of pulleys. By fixing the belt to one end of the carriage body on the opposite side to the side on which the belt is fixed, the platen holder can be moved in accordance with the moving position of the carriage body, and the print head and the platen can always be kept at the same position. A printing mechanism of a printing device characterized in that printing is performed in such a manner that (2) The platen holder has a groove in the center thereof into which the platen is inserted, and the groove is larger than the platen, and a backup roller of the platen and a part of the platen roller are connected to the platen holder. 2. A printing mechanism of a printing device according to claim 1, wherein said platen has a structure protruding from said platen and is movable. (3) The printing mechanism of the printing device according to claims 1 and 2, wherein the platen roller is constructed of a disc-shaped thin member. (4) The backup roller is made of an elastic member such as rubber or plastic having elasticity and a large coefficient of friction, and the platen roller is made of a metal material such as Bs or SUS. A printing mechanism of the printing device according to items 1, 2, and 3. (5) The backup roller and the platen roller are made of an elastic member such as rubber or plastic that has elasticity and has a large coefficient of friction. Printing mechanism of the printing device described in Section 1.