JPS5816872A - Heat-sensitive recorder - Google Patents

Abstract

PURPOSE:To simplify a pushing mechanism for making the cost of a heat-sensitive recorder lower by a method in which plural pressure rolls are piercingly provided to a common shaft and the diameter of the central pressure roll is made larger. CONSTITUTION:The outside diameter of an intermediate roll 11C is made larger than that of side rolls 11A and 11B by as much as the total flextion of the flextion of the central part of a counter roll 3 when not acted by a pressure roll 1 and the flextion of the central part of the support shaft 12 of the pressure roll 11. Thus, the counter roll 3 can be pressingly contacted with a heat-sensitive recording head 2 with uniform pressure distribution in its longitudinal direction without having nothing to do with the flextions of the counter roll 3 by compression springs 7 and 8 and also of the support shaft 12 of the pressure roll 11 by compression springs 13 and 14.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording device for performing thermal recording,
In particular, the present invention relates to a thermal recording device that prevents deflection of a facing roll disposed facing a thermal recording head.

In a recording device such as a facsimile or a printer that records information using a thermal recording method, a recording paper or a recording paper and a thermal recording medium are passed between a thermal recording head and an opposing roll placed opposite the head. It looks like this. At this time, the recording paper is pressed against the thermal recording head by the opposing roll, and thermal recording is performed by the heat pulses supplied from the thermal recording head.

FIG. 1 shows the main parts of such a conventionally used recording apparatus. A rotatably supported opposing roll 3 is in pressure contact with the thermal recording head 2 placed on the mounting base 1, and a support shaft 4 provided on each side of the opposing roll 3 is in pressure contact with the thermal recording head 2 placed on the mounting base 1.
, 5 are pressed downward with a considerable pressure in the figure by compression springs 7 and 8, one end of which is pressed against the immovable member 6.

In this conventional recording apparatus, the pressing force of the compression springs 7 and 8 caused a deflection dl in the center of the opposing roll 3, as shown in FIG.

When the deflection dl occurs, both ends of the recording paper passing between the thermal recording head 2 and the opposing roll 3 are strongly pressed against the thermal recording head 2, while the center is weakly pressed. . For this reason, there is a problem that unevenness occurs in the recording density of the recording paper, and the image quality of the recording surface deteriorates. 4g became more significant as the length of the thermal recording head became longer and the length of the opposing roll became correspondingly longer.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thermal recording device that can uniformly press recording paper against a thermal recording head.

In the present invention, a plurality of rolls, each having a common axis in a plane including the +ll+ center of the opposing roll and arranged in the center at a position facing the thermal recording head across the opposing roll, have a diameter larger than that of the peripheral part. The above-mentioned object is achieved by arranging pressure rolls, which are pressed against counter-rolls by means of compression springs.

The present invention will be described in detail with reference to Examples below.

In FIG. 3, a pressure roll, generally designated by the reference numeral 11, is arranged so as to cooperate with the thermal recording head 2 and sandwich the counter roll 3. The pressure roll 11 includes a pair of side rolls 11. which are in pressure contact with both sides of the opposing roll 3. A, I
It consists of a small roll IB and an intermediate roll IIC disposed in between. Each role II
Each end of the spindle 12 to which A to 11C are fixed] 2
A.

A pair of compression springs 13 and 14, one end of which is pressed against the immovable member 6, are respectively locked at the other ends of the spring 12B. It is pressed against the surrounding surface.

By the way, the support shaft 12 is deflected by the elasticity of the compression springs 13 and 14 themselves. The deflection of the central portion of the support shaft 12 is assumed to be d2. As described above, when the pressure roll 11 is not acting on the opposing roll, the deflection at the center of the opposing roll is dl. The outer diameter of the intermediate roll IIC is increased by an amount corresponding to the sum of this deflection d and the deflection d2 at the center of the pressure roll 11 (support shaft) d=d, +d2. It is formed to be larger than the outer diameter of. In this way, the outer diameter of the intermediate opening 11C of the pressure roll 11 is adjusted to the side roll 1. I
By correcting and forming it in advance to be larger than A, 1-IB, the deflection dll of the opposing roll 3 due to the compression springs 7 and 8 and the deflection of the support shaft 12 of the pressure roll 11 due to the compression spring 13, 1/l are The opposing roll 3 can be brought into pressure contact with the thermal recording head 2 with uniform pressure distribution in the longitudinal direction without being affected by the deflection d2. Therefore, it is possible to prevent uneven recording density on the recording paper from occurring.

As described above, according to the present invention, a plurality of pressure rolls are arranged in a skewer shape around a common shaft, and the diameter of the pressure roll arranged in the center is made larger than that of the peripheral part. Compared to a device that corrects the deflection of the opposing rolls by pressing a plurality of pressure rolls individually against the circumferential surface of the opposing rolls, the suppression mechanism that presses each pressure roll against the opposing rolls is simplified, and the device can be manufactured at a lower cost. It has the advantage of being possible. Of course, the same effect as the present invention can be obtained even if the pressure roll is formed by one roll, and the diameter of the center part is made gradually larger than that of the side parts so as to compensate for the deflection occurring in the opposing roll. However, it is very expensive to process a single roll in this way.

It becomes the value. In this sense as well, according to the present invention, an economical device can be constructed.

In the example, a total of three pressure rolls were arranged on the same axis, but the number of pressure rolls, their diameters, and arrangement relationship may be changed as appropriate depending on the length and deflection state of the opposing rolls. Of course it's a good thing.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the recording section of a conventional thermal recording device, FIG. 2 is an explanatory diagram for explaining the degree of deflection of the opposing roll in this device, and FIG. 3 is a thermal recording in an embodiment of the present invention. FIG. 3 is a front view of the device. 2...Thermal recording head 3...Opposing roll 7.8...Compression spring 11...Pressure roll 11A, IIB...Side roll ■IC...Intermediate Part roll 12 ... Support shaft 13.14 ... Compression spring applicant Fuji Xerox Co., Ltd. Representative patent attorney Umeo Yamauchi 7- Figure 2 Diagram 3 Figure 451

Claims (1)

[Claims] 1. The elasticity of the compression springs acting on both ends of the opposing roll presses the opposing roll against the thermal recording head disposed opposite to it, and the recording paper passing between them is heated. In a recording device, a plurality of pressure rolls, each having a common axis in a plane including the axes of the opposing rolls and a roll placed in the center having a diameter larger than that of the peripheral part, are heated. A feature is that a counter roll is placed in a position facing the recording head so as to sandwich the counter roll, and a compression spring is installed between the shaft of these pressure rolls and a stationary member to press these pressure rolls into contact with the counter roll. A thermal recording device. 2. The diameter of the pressure roll attached to the center is fixed on both sides by the deflection d, which is the sum of the deflection d at the center of the roll facing the thermal recording head and the deflection d2 at the center of the pressure roll. The thermal recording device according to claim 1, characterized in that it is formed to have a much larger diameter.