JPH0143247Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a pressing roll for pressing recording paper against a thermal head of a thermal recording device.

In thermal recording devices used in printers such as word processors and telefaxes, the first
As shown in the figure, heat-sensitive recording paper that develops color when heated or plain paper overlaid with an ink donor sheet is passed through the heat-generating resistors arranged in a line on the surface of the thermal head 4 while being pressed by the press roll 1. recording is performed.

The pressing roll 1 has bearings 5 that support both ends of the core shaft 2.
is pressed toward the heat-sensitive head by a spring 6.

The conventional pressing roll 1 has a cylindrical solid rubber layer 3 formed around the outer periphery of the core shaft 2 so that the recording paper comes into close contact with the thermal head. Due to disturbances in feed speed,
There were cases where the printing was blurred, the outline was unclear, or the lines were disordered.

In order to prevent blurred printing and unclear outlines, the surface rubber layer of the pressing roll has a low compression set, is resistant to abrasion with the paper, has a stable coefficient of friction with the paper, and has a high pressing pressure. Rubber hardness is required to be small so that it can be sufficiently deformed even if it is small, and that the physical properties change little due to environmental changes such as temperature and humidity. Rubber hardness is in the range of 20° to 50° on the JIS A scale. things are used.

However, even if the physical properties of the pressing roll are improved, blurred printing or irregularities in the pattern may still occur.
The cause of this is uneven pressure distribution in the axial direction between the roll and the thermal head, which can lead to blurred prints, especially at the edges of the recording paper, and in severe cases, uneven and overlapping prints.

In addition, since the shape of the heat-sensitive head is not straight in the length direction but has a tapered tip, there are cases where the pressure applied to the paper by the end of the roller changes.

The present invention relates to a pressing roll that has improved this drawback, and is characterized in that, as shown in FIG. 2, ring-shaped grooves are formed on both end surfaces of a rubber roll 7 that is integrated with a core bar 9.

Because this ring-shaped groove is formed, even if the tip of the heat-sensitive head used is tapered, its elastic deformation makes it easy to equalize the pressing pressure, resulting in blurred printing, unclear outlines, etc.
There is no disturbance between the lines.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a thermal recording device, and FIG. 2 is a sectional view of a pressing roll for a thermal recording device according to the present invention. 1... Pressing roll, 2... Core shaft, 3... Solid rubber layer, 4... Thermal head, 5... Bearing, 6...
Spring, 7...Rubber layer, 8...Ring-shaped groove, 9...
Metal core for rolls.

Claims (1)

[Scope of utility model registration request] In a pressure roll for a heat-sensitive recording device made of natural rubber or synthetic rubber such as silicone rubber or chloroprene rubber with a JIS A scale of 20° to 50°, the roller is used to make the axial pressure distribution between the roll and the heat-sensitive head uniform. A pressing roll for a thermal recording device characterized by having ring-shaped grooves formed on both end faces.