JPH0640627A - Curl straightening device - Google Patents

Abstract

PURPOSE:To improve curl straightening effect through a simple constitution by moving a curl straightening means in a direction opposite to the carrying direction of a sheet through an energizing means as the sheet drawn out from a winder decreases, and making the sheet act so as to be squeezed through a roll means. CONSTITUTION:A recording paper 1 drawn out from a winder 2 is sent out through a pair of feed rolls 8a, 8b, and after printed by a recording head 10, cut to a fixed length with a cutter 11. This recording device is provided with a dancer rod 3 being rotatable about a supporting shaft 4 as a curl straightening member, and a curl is straightened by squeezing action which is generated on the recording paper by a rod 3a at the tip of the dancer rod 3. The dancer rod 3 is rotated to the right by a tension spring 7 with tensile change resulting from decrease in the winding diameter of the winder 2. Thus a winding angle thetato the recording paper 1 of the dancer rod 3 is decreased, and the recording paper 1 is squeezed by a fixed roll 5a to produce excellent curl straightening effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll wound sheet generally called a roll sheet (generally, paper is used, but a thin film may be used, so it is called a sheet). The present invention relates to a device for correcting curl (hereinafter referred to as curl).

[0002]

2. Description of the Related Art Printers and facsimiles having a built-in roll of recording paper are commonly used. However, this recording paper is curled because it is wound, and this curl is one of the major causes of problems such as paper jams when the recording paper is conveyed. For this reason, there are some devices using a curl correction device for removing curl or reducing the degree of curl. An example of a printer equipped with this curl straightening device is shown in FIG. FIG. 5 is a side view showing a recording paper running system of the printer disclosed in Japanese Patent Application Laid-Open No. 2-24176.

In FIG. 5, the recording paper 1 before being recorded from the recording paper winding 2 is guided between the recording head 10 and the platen roll 9 through the curl taking rod 15 and is printed. At this time, as the recording paper is consumed, the diameter of the recording paper winding 2 becomes smaller, and the degree of curling of the recording paper sent out increases. As the degree of curl increases, the retracting means acts as a kind of moving means to move the curl removing rod 15 downward in the figure,
The degree of decurling can be increased appropriately.

[0004]

However, the retracting means for performing the above-mentioned operation needs to be provided with a driving means such as a motor and its control section, and there is a problem that the structure of the entire curl straightening device becomes complicated. The present invention has been made to solve the above problems, and an object of the present invention is to provide a curl straightening device having a simple structure without a driving unit such as a motor and a control unit.

[0005]

SUMMARY OF THE INVENTION A curl straightening device according to the present invention comprises a movable curl straightening member for straightening a curl of a sheet, which is disposed in the middle of a conveying path of a sheet sent out from a winding. Urging means for urging the curl straightening member in a direction opposite to the sheet conveying direction, and roll means arranged between the curl straightening member and the winding, the biasing means being provided to the biasing means as the number of sheets decreases. When the curl straightening member is biased and moves in the direction opposite to the conveying direction of the sheet, the roll comes into contact with the sheet, and the roll that reduces the wrap angle of the sheet with respect to the curl straightening member is smaller than that before the contact. And means.

[0006]

As the number of sheets wound for winding is reduced, the curl correcting member is moved by the biasing means in the direction opposite to the sheet conveying direction, and the wrap angle for curling is reduced.
Further, when the curl correcting member moves, the sheet comes into contact with the roll means, so that the wrap angle for further curling is reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a thermal recording device to which the curl straightening device of the present invention is applied will be described below with reference to the drawings. FIG. 1 is a sectional explanatory view showing a schematic structure of a thermal recording apparatus, and FIGS. 3 and 4 are explanatory views of the recording operation thereof.

First, a schematic structure of a recording apparatus to which the present invention is applied will be described with reference to FIG. Reference numeral 1 is a thermosensitive recording paper that is colored by heat. 2 is a winding of the thermosensitive recording paper 1 wound in a roll. A dancer rod 3 functions as a curl correcting member for correcting the curl of the thermal recording paper 1. 5a and 5b are fixed rolls. The dancer rod 3 is composed of a link 6 rotatably mounted around a support shaft 4 and a rod portion 3a provided at the tip thereof. Since the rod portion 3a at the tip of the dancer rod does not rotate about its own axis, the thermosensitive recording paper 1 is squeezed by the dancer rod 3 at the angle θ in the direction opposite to the curl. This squeezing action corrects the curl. This angle θ is hereinafter referred to as a wrap angle. Although the rod portion 3a has a round bar shape in this embodiment,
The cross section of the portion in contact with the recording paper may be a relatively smooth surface such as an ellipse as well as a circle. Also, dancer rod 3
A tension coil spring 7 is connected to a link 6 that connects the support shaft 4 with the support shaft 4 and has a function of absorbing tension applied to the thermal recording paper 1 at the time of printing and smoothly running the recording paper. Further, it has an action of absorbing a change in tension applied to the recording paper when the conveyance of the recording paper is stopped or restarted to operate the cutter 11 or the like during printing. When the recording sheet is conveyed, the resultant force F as shown in FIG. 1 acts on the dancer rod 3 due to the tension of the thermal recording sheet 1. With this resultant force F, the dancer rod 3
The tension coil spring 7 moves downward around the support shaft 4 and extends as much as the dancer rod 3 moves.

Reference numeral 8a is a feed roll for feeding the thermosensitive recording paper, and 8b is a feed roll for feeding the thermosensitive recording paper 8a.
It is a roll that holds down. This feed roll 8a
With the press roll 8b, the thermosensitive recording paper can be stably run. Therefore, the thermal recording paper 1 pulled out from the winding 2 is recorded by the recording head 10 which is a recording means after the curl is corrected by the dancer rod 3. The recording head 10 has a plurality of heating elements arranged in a line to generate electric current in accordance with recording information, and is configured to be in pressure contact with the surface of the platen roll 9.
Therefore, the platen roll 9 and the feed roll 8a are rotated in the direction of the arrow to convey the thermosensitive recording paper 1 and, in synchronization with this, heat the heating elements of the recording head 10 in accordance with the recording information to generate thermal recording paper. Information can be recorded. The thermal recording paper that has been recorded is the cutter 11
It is cut by the set length.

By the way, as the winding diameter φ of the winding 2 changes from the maximum diameter immediately after the start of use to the minimum diameter at the end of use, the degree of curling of the thermal recording paper fed out increases. There is no end. Therefore, the inventors measured how the degree of the curl changes as the winding diameter φ of the winding 2 decreases. The specifications of the thermal recording paper actually used for the measurement are as follows. Paper width 300 mm, tsubo 105
g / m ² , maximum winding diameter 140 mm, minimum winding diameter 62 mm. It should be noted that even recording papers having specifications other than this specification exhibited curl characteristics as described below.

The measurement results are shown in FIG. In FIG.
The horizontal axis represents the winding diameter φ, and the vertical axis represents the relative degree of curl indicating curl characteristics. Relative curl means cutting a sample piece of paper of a certain length at each winding diameter of the roll, and then, when one end of the piece of paper is stopped on a horizontal table, from the table at the other end of the piece. The height of is expressed as a relative value.

As can be seen from FIG. 2, when the winding diameter is relatively large, the degree of curl changes gently. When the winding diameter becomes small to some extent, the degree of curl changes rapidly. That is, it was found that there was an inflection point A in the change in the degree of curl.

Next, the curl correction operation of the thermal recording paper 1 when the winding diameter of the winding 2 changes with the use of the thermal recording paper will be described with reference to FIGS. 3 and 4. FIG. 3 shows an operation state when the recording operation is started, that is, when the diameter of the winding 2 is large. In FIG. 3, the feed roll 8a, the pressing roll 8b, and the platen roll 9 try to feed the thermal recording paper 1 in the direction of the arrow. At this time, the stationary winding 2 is at the beginning of use, and since the winding diameter is maximum and the weight is heavy, the tension applied to the thermal recording paper 1 becomes strong. When the tension applied to the thermosensitive recording paper 1 becomes strong, the resultant force acting on the dancer rod 3 also becomes large, and the dancer rod 3 moves largely downward around the support shaft 4. As the dancer rod 3 moves downward, the tension coil spring 7 extends in the flow direction of the thermal recording paper 1. Then, when the tension coil spring 7 is suspended from the force to pull it back, the dancer rod 3
Stands still, and the curl of the thermosensitive recording paper 1 is corrected at the wrapping angle θ 1. The winding angle θ1 is also maximum when the winding diameter φ is maximum. That is, when the winding diameter φ of the winding is large and the curl is weak, the curl correcting effect is weakened. afterwards,
As the winding diameter of the winding paper decreases, the tension applied to the thermal recording paper 1 also decreases, and the dancer rod 3 gradually moves in the direction opposite to the conveying direction of the recording paper. The winding angle θ
Also gradually decreases. The above-mentioned FIG. 1 shows an example of a state in which θ decreases.

Next, the recording paper is consumed, and the winding diameter φ of the winding 2 is
FIG. 4 shows the operating state when the value becomes smaller. At this time,
Since the winding 2 itself is light in weight and the tension applied to the thermosensitive recording paper 1 is small, the resultant force acting on the dancer rod 3 is also weakened and the pulling back force of the tension coil spring is increased. Then, the dancer rod 3 is attracted by the tension coil spring and moves in the direction opposite to the recording paper conveyance direction. When the dancer rod 3 moves in this direction, the thermosensitive recording paper 1 comes into contact with the fixed roll 5a, and the curl is corrected at the winding angle θ2. When the thermal recording paper 1 starts to come into contact with the fixed roll 5a in this manner, the wrapping angle θ at which the curl is corrected sharply decreases. Since this winding angle θ2 is smaller than the above-mentioned θ1,
The wrapping of the thermal recording paper 1 with the dancer rod 3 becomes stronger, and the curl correction effect also becomes stronger.

That is, the winding diameter φ of the winding becomes small,
Immediately before the point of curl sharply increases beyond the inflection point A described above in FIG. 2, the dancer rod 3, so that the recording paper 1 starts to contact the fixed roll 5a as described above,
The fixed roll 5a and the like are designed and arranged. By doing so, it is possible to make the wrapping angle θ at which the curl is corrected sharply small when the winding is reduced to a winding diameter at which the degree of the curl sharply increases. When the degree of curl is strongest, that is, when the winding diameter φ of the winding 2 is the minimum diameter, the winding angle θ2 is the minimum angle. A stopper 12 is provided to define the range in which the dancer rod 3 moves to the right in the figure.

According to the above construction, by the dancer rod 3 and the fixed roll 5a which change the position in the sheet conveying direction, the winding diameter is changed from the maximum diameter of the winding with a weak curl to the minimum diameter of the winding with a strong curl. Even if it decreases with the use of recording paper, the wrapping angle θ of the recording paper squeezed by the dancer rod decreases according to the degree of decrease in the winding diameter, and a curl correction effect corresponding to the curl strength is obtained. You can Furthermore,
The fixed roll 5a and the recording paper are brought into contact with each other immediately before the degree of curl increases sharply due to the decrease of the winding diameter, so that the curl straightening effect that further follows the change of the degree of curl can be obtained. Obtainable. Further, when the thickness of the paper and the strength of the waist are changed by changing the recording paper, the position of the fixed roll 5a is adjusted, or the diameter or cross section of the dancer rod 3 is changed to adjust the curl correction effect. It is also possible to take appropriate measures. Changing the cross section means that the rod section 3a in contact with the recording paper is formed of a relatively smooth surface such as an ellipse in addition to the circle, as described above.

[0017]

As the number of sheets wound for winding is decreased, the curl correcting member is moved in the direction opposite to the sheet conveying direction by the biasing means, and the wrap angle for correcting the curl is also reduced. Furthermore, by moving the curl correction member,
The contact between the sheet and the roll means also reduces the wrap angle for further curl correction. As described above, the curl of the sheet, which sharply increases as the number of sheets decreases, can be corrected by the simple configuration of the curl correcting member that does not require a motor or the like, the biasing unit, and the roll unit.

[Brief description of drawings]

FIG. 1 is a side view showing the configuration of an embodiment of a heat-sensitive recording apparatus to which a curl straightening apparatus of the present invention is applied.

FIG. 2 is a diagram showing a relationship between a degree of curl and a winding diameter φ of winding.

FIG. 3 is a side view of a recording operation of the thermal recording apparatus shown in FIG. 1 when the winding diameter is large.

FIG. 4 is a side view of the thermal recording apparatus shown in FIG. 1 during a recording operation when the winding diameter is small.

FIG. 5 is a side view showing a recording paper running system of a printer including a conventional curl straightening device.

[Explanation of symbols]

 1 Thermal recording paper 2 Winding 3 Dancer rod 3a Rod part 4 Spindle 5a, 5b Fixed roll 6 Link 7 Pulling coil spring 8a Feed roll 8b Pressing roll 9 Platen roll 10 Recording head 11 Cutter 12 Stopper

Claims (1)

[Claims] 1. A movable curl straightening member for straightening a curl of a sheet, which is disposed midway along a sheet transporting path of a sheet fed from winding, and the curl straightening member is provided in a direction opposite to a sheet transport direction. Urging means for urging, and roll means arranged between the curl correcting member and the winding, the urging means being urged by the urging means as the number of sheets decreases so that the sheet is conveyed in a direction opposite to the sheet conveying direction. A curl straightening device comprising: a roll unit that contacts the sheet and the roll unit when the curl straightening member moves to reduce a wrap angle of the sheet with respect to the curl straightening member compared to before the contact.