JPH02292076A - Recording paper transport device - Google Patents

Abstract

PURPOSE:To shorten the time required for the ejection of a recording paper by provid ing an ejection roller which incorporates a torque limiter and transports the paper at higher speed than does a printing section and setting a friction force between the printing section and the paper, a friction force between the ejection roller and the paper, and the maximum transport capacity of the torque limiter in a specific relation ship. CONSTITUTION:A spring 24 is energized in such a manner that friction plates 22a, 22b and sleeves 23a, 23b come in contact with each other under a constant pressure, and a torque limiter is formed on a part which slides in contact under a constant pressure. The ejection roller 2 is set at higher peripheral speed than is a platen roller 2 when the roller 16 is in free condition, that is, it does not hold a recording paper. In addition, a friction force P1 between a printing section and a recording paper 6a, a friction force PH between the ejection roller 16 and the paper 6a, and the maximum transport capacity P1 of the torque limiter are set so that the relationship of P1>PH>P1 is established. If the printing is completed and the rear end of the paper is cut off by a cutter 7, the rear end is released from the friction force in the printing section, and the ejection roller 16 rotates at the same speed as does a pulley 17. Further more, the recording paper is ejected at higher speed than its transport speed in the printing section and thus the ejection time is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a recording paper conveying device in a thermal recording device (including a thermal transfer recording device).

(Conventional technique v#) In a recording device that prints while conveying recording paper,
In order to shorten the recording time when recording is performed continuously on a plurality of sheets of recording paper, it is necessary to shorten the time from the end of printing on the preceding recording paper to the start of recording on the subsequent recording paper. Possible ways to do this include shortening the recording paper ejection distance and increasing the ejection speed.

Fig. 4 shows a conventional device of this kind, where 1 is a thermal head, 2 is a platen roller, 3 is a spring that biases the thermal head 1 against the platen roller 2, and 4 is a driving source. This motor rotates the platen roller 2 via the timing belt 5. 6 is a recording paper roll, 7 is a cutter, and has a fixed blade 7a and a rotary blade 7b.
It consists of

8 is a discharge roller, 9 is a pressure roller, and 10 is a motor, which rotationally drives the discharge roller 8 via a timing belt 11. Reference numeral 12 denotes a stacker for storing discharged recording paper. In the above configuration, the recording paper 6a pulled out from the recording paper roll 6 is guided between the thermal head 1 and the platen roller 2, and is conveyed by the platen roller 2. The image is printed and recorded by the thermal head 1 while the information is being read. The rear end of the recorded recording paper 6a is cut off by a cutter 7, and then discharged by a discharge roller 8.

In this conventional example, since the drive motor 10 of the ejection roller 8 is separate from the drive motor 4 of the platen roller 2, its rotational speed can be controlled arbitrarily. When the edges are cut, the time required for ejecting the recording paper can be shortened by increasing the conveyance speed of the recording paper at the discharge roller 8 compared to that at the printing section. However, in this case, there is a problem in that a dedicated motor must be provided for driving the wandering roller, resulting in high costs.

In another conventional example (Japanese Utility Model Application Publication No. 11646/1983) in which the driving force for the ejecting roller is extracted from the motor for driving the platen roller without providing a dedicated motor, a boss fixed to the ejecting roller shaft and a driving force for the ejecting roller are used. By installing a tension spring between the pulley and applying rotation to the yjA movable pulley at a speed faster than the transport speed of the printing section, the recording paper is held in both the printing section and the ejection roller. The spring is stretched, and when the trailing edge of the recording paper is cut, the tension of the spring is released, increasing the ejection speed.

However, in this configuration, (1) the amount of tension applied to the spring differs depending on the length of the recording paper, so the amount of forward feeding after the trailing edge of the recording paper is released differs;

(2) When the spring is fully extended, there is no place for the tension of the recording paper to escape, increasing the load on the motor. Also, slippage occurs between the recording paper and the ejection roller.

(3) If the friction coefficient of the surface of the recording paper is small, slippage is likely to occur between the recording paper and the discharge roller, and no tension is accumulated in the spring.

There were other problems.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems of the prior art by extracting the driving force for the ejection roller from the drive source of the platen roller and increasing the ejection speed faster than the speed of the printing section. It is an object of the present invention to provide a recording paper conveying device that can shorten the time required for the entire recording operation by shortening the time required to eject the recording paper.

(Means for Solving the Problems) In order to achieve the above item 1, there is a printing section consisting of a platen roller and a thermal head that sandwich the recording paper and perform conveyance and printing, and a printing section that is driven by the same rIjA rib as the platen roller. , and a discharge roller that discharges the printed recording paper, the discharge roller has a built-in torque limiter, and its conveyance speed is faster than the conveyance speed in the printing section, and the frictional force between the printing section and the recording paper is reduced to P1, Pll is the frictional force between the ejection roller and recording paper, and P is the maximum conveying force due to the torque limiter.
When M, P, > P14 > p,
Set to .

(Function) According to this configuration, when recording paper is held in both the printing section and the ejection roller, the ejection roller rotates at the same conveyance speed as the printing section because slippage occurs in the torque limiter, but the recording paper rotates at the same conveyance speed as the printing section. When the trailing edge of the paper is released, there is no more slippage in the torque limiter, and the conveyance speed of the discharge roller becomes faster than that of the printing section. (Example) Examples will be described below with reference to the drawings. It will be explained in detail.

Fig. 1 shows an embodiment of the present invention, and the same reference numerals as in Fig. 4 indicate the same parts, and 1
5 is a timing belt, 16 is a wandering roller, 17 is a pulley, and 18 is a guide member for conveying recording paper. The discharge roller 16 is rotationally driven by a motor 4, which is the same driving source as the platen roller 2, via a timing bell 1/15 and a pulley 17.

FIG. 2 shows the discharge roller, and the wandering roller 16
is provided rotatably with respect to the shaft 19 to which the pulley IJ17 is fixed; 21a, 2lb are thrust stop members fixed to the shaft 19; 22a, 22b are discharge rollers 16;
The sliding plate 1 is in sliding contact with the sleeves 23a and 23b fixed to both ends of the shaft 19, and cannot be rotated about the shaft 19, but can be moved in the axial direction. Reference numeral 24 denotes a spring that urges the friction plate and the sleeve to press against each other with a constant pressure. A torque limiter is constituted by the portion that slides into contact with this constant pressure. Now, when the shaft l9 is rotated via the pulley IJl7, the load on the protruding roller l6 is applied to the sleeves 23a,
When the frictional force is greater than that between the friction plates 23b and the friction plates 22a and 22b, slipping occurs at the sliding contact portions. Here, the circumferential speed of the discharge roller 16 is set to be faster than the circumferential speed of the platen roller in a free state in which no recording paper is loaded.

Furthermore, the frictional force P1 between the printing section and the recording paper 6a is P+=
(μτ+μp) x'r, ...(1) where μT: Coefficient of friction between the thermal head 1 and recording paper μI,: Coefficient of friction between platen roller 2 and recording paper T1: Pressing force between the thermal head and platen roller The frictional force Pl+ between the discharge roller 16 and the recording paper 6a is PII
= μ,. XT. ...(2) However, μ11: Coefficient of friction between the ejection roller and the recording paper 1゛H
: Maximum conveying force P due to the suppressing force torque limiter of the discharge roller and pressure roller. P. =Tbu/r
...(3) However, when r* is the limit torque of the torque limiter and r is the radius of the discharge roller, the above Pl+PH+p. Between P+ >
Set so that the relationship Pi > Pi...{4) holds. Next, the operation of this embodiment will be explained. First, the recording paper 6a pulled out from the recording paper roll 6 is guided between the thermal head 1 and the platen roller 2, and is printed and recorded by the thermal head 1 while being conveyed by the platen roller 2. The leading edge of the recording paper 6a is moved by the cutter 7 as printing progresses.
The paper is conveyed along the guide member 18 and held between the discharge port roller 16 and the pressure roller 9.
Here, as described above, the ejection roller l6 rotates at a faster circumferential speed than the platen roller 2 when it is not holding the recording paper in its mouth, but when it is holding the recording paper 6a in its mouth, it rotates at a circumferential speed of (4
), the recording paper is stretched between the printing section and the ejection roller, slippage occurs in the torque limiter of the ejection roller, and the circumferential surface of the ejection roller 16 rotates with the conveyance speed at the printing section. do.

Next, when l pages of printing are completed and the trailing edge of the recording paper is cut by the cutter 7, the trailing edge is released from the frictional force in the printing section, so the torque limiter no longer slips, and the ejection roller l6 rotates at the same speed as the rotation speed of pulley 17,
Therefore, the recording paper is ejected at a faster speed than the conveyance speed at the printing section. That is, the time required to eject the recording paper can be shortened.

Note that the above formula ignores the frictional force between the recording paper and its conveyance path (guide member, etc.) and the load caused by the pressure roller 9 for the sake of simplicity, so in practice, there is sufficient margin. It is necessary to make a difference in size by holding . FIG. 3 shows another embodiment of the present invention, in which a cut sheet 25 is used as the recording paper and an ink sheet 26 is used as an example of a thermal transfer recording method. 2
7 is a recording paper table on which the cut sheet 25 is set; 2;
8 is a pre-feed roller, 29 is a feed roller, 30
is the separation roller. The feed roller 29 receives its driving force from the motor 4 which is the driving force of the platen roller 2, and the pre-feet roller 28 receives its driving force from the motor 4, which is the driving force of the platen roller 2.
It is connected to work with 9. Feed roller 2
9 and the separation roller 30 work together to separate the cut sheets 25 one by one and supply them. In the printing section, the supply roll 31
The ink sheet 26 fed out from the thermal head 1
The cut sheet 25 is passed between the ink sheet 25 and the platen roller 2, and is set to be taken up by a take-up roll 32, and the supplied cut sheet 25 is overlapped with an ink sheet 26 and sent to the printing section. Note that the ink sheet 26 is fed by being taken up by a take-up roll 32 connected to the platen roller 2. The printed cut sheet 25 is delivered to the ejection roller 1
6 and discharged to stacker 12. Ejection roller l
6 has the same handle structure as that shown in FIG.

In this embodiment configured as described above, as well as in the embodiment shown in FIG. Slippage occurs and the cut sheet 25 is conveyed at the conveyance speed of the printing section, but when the rear end of the cut sheet is released from the grip of the printing section, the torque limiter no longer slips and is set faster than the printing section. The paper is discharged at the conveyance speed of the wandering roller.

As described above, in this embodiment, as in the case of using roll paper, the time for ejecting the recording paper can be shortened.
Furthermore, in the case of a thermal transfer method that uses cut sheets,
By shortening the time for ejecting the recording paper, the gap between the preceding recording paper and the following recording paper can be reduced, so that the waste of ink sheets during that time can be reduced.

(Effects of the Invention) As explained above, according to the present invention, (1) the ejection speed of the recording paper can be made faster (several times) faster than the transport speed of the printing unit, so the time required for ejection can be Therefore, the time required for the entire recording operation can be shortened.

(2) Since one motor is commonly used to drive the platen roller and the discharge roller, it is possible to reduce the size and cost.

(3) In the thermal transfer recording method, the interval between recording sheets can be reduced by shortening the ejection time, thereby reducing the waste of ink sheets during that time and reducing running costs.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is a perspective view of the discharge roller, FIG. 3 is a horizontal view of another embodiment of the present invention, and FIG. 4 is a conventional It is a block diagram of an example. 1... Thermal head, 2... Platen roller, 4... Motor, 6... Recording paper roll, 7
... Cutter 15 ... Timing belt, 16
...Discharge roller, 17...Pulley, 19...
Shaft, 22a, 22b... Friction plate, 25... Cut sheet, 26... Ink sheet, 29... Feed roller, 30... Separation roller. Diagram

Claims (1)

[Scope of Claims] A printing section consisting of a platen roller and a thermal head that sandwich recording paper and carry out conveyance and printing, and a discharge roller that is driven by the same drive source as the platen roller and discharges the printed recording paper. The ejection roller has a built-in torque limiter, and its conveyance speed is faster than the conveyance speed in the printing section, and the frictional force between the printing section and the recording paper is P_I, and the frictional force between the ejection roller and the recording paper is P_I. is P_H, and the maximum conveying force by the torque limiter is P_l, then P_I>P_H>
A recording paper conveyance device characterized in that P_l is set.