JP2000085164A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regulate head pressure automatically depending on the breadth dimension of a print sheet when it is altered by providing a head pressure regulating mechanism for increasing or decreasing the head pressure based on a displacement detected by a sheet width detecting means on the side of platen roller or thermal head. SOLUTION: A head pressure regulating means, i.e., a press rod 12, has one end side secured to the upper end of an inclining plate 11 and the other end side provided with a spring receiving part 12A wherein a spring 14 is inserted, under compressed state, between the spring receiving part 12A and a thermal head 3. In order to position a print sheet 2 in the center of a sheet holder 5, a centering mechanism 7 is operated and the press rod 12 is displaced by the inclining plate 11 depending on the displacement in the interval of sheet width detecting mechanisms, i.e., flange members 10, interlocked with the centering mechanism 7 thus regulating the pressure of the thermal head 3 automatically through the spring 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus which sends out a printing paper inserted between a platen roller and a thermal head by rotating the platen roller and energizes the thermal head to perform printing. The present invention relates to a printing device for printing on such a long strip-shaped printing paper.

[0002]

2. Description of the Related Art Conventionally, as a printing apparatus using a long strip-shaped printing paper such as a label printer, a platen roller, a thermal head urged with a predetermined head pressure toward the platen roller, and a paper holding the printing paper 2. Description of the Related Art There is known a printer which includes a holder and sends out a printing sheet inserted between a platen roller and a thermal head by rotating the platen roller and energizes the thermal head to perform printing. In this type of printing apparatus, the head pressure is adjusted to a constant value (for example, 0.3 kg / cm), and this value is not structured so that it can be changed even if the width of the printing paper is changed.

[0003]

However, in the above-described printing apparatus of the prior art, the following problems occur because the head pressure is constant. That is, as shown in FIG. 7, when the printing paper 2 that is extremely narrow and extremely thin with respect to the width of the platen roller 1 is used, both ends of the platen roller 1 that do not hang on the printing paper 2 are elastically deformed. It comes into direct contact with the thermal head 3. Here, since the coefficient of friction between the thermal head 3 and the platen roller 1 is larger than the coefficient of friction between the thermal head 3 and the printing paper 2, even if the printing paper 2 having a small width is used, the friction between the thermal head 3 and the printing paper 2 is reduced. In order to rotate the platen roller 1, it is necessary to use a motor having a large torque in advance with a margin.

When a conventional printing apparatus is used as a ticket or tag issuing machine, as shown in FIG. 8, a thick printing paper 2 is used so that a platen roller 1 and a thermal head 3 are used. However, since only the printing paper 2 always slides with the thermal head 3, early wear of the thermal head 3 becomes a problem. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the related art, and an object of the present invention is to provide a printing method that can automatically adjust the head pressure according to the width when the width of the printing paper is changed. It is to provide a device.

[0005]

In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a center distributing mechanism for positioning a printing paper in a paper holder at the center between a platen roller and a thermal head. Paper width detecting means for detecting the width of the printing paper by being displaced following the center distribution mechanism, and increasing or decreasing the head pressure on the platen roller or thermal head side based on the displacement amount of the paper width detecting means. And a head pressure adjusting mechanism for adjusting the pressure.

Further, in the invention according to the second aspect, the head pressure adjusting mechanism includes a pressing rod for transmitting the displacement of the paper width detecting means via a fulcrum, and an elastic deformation of the displacement of the pressing rod. The paper width detecting means is composed of a platen roller and an elastic member serving as a pressing force between the thermal head, and the paper width detecting means abuts on the two flange members provided on the center sorting mechanism and the respective flange members. And an inclined plate for displacing the pressing rod in accordance with the separation distance.

Further, the invention according to claim 3 employs a configuration in which the inclined plate is provided with an engagement portion with which the flange is engaged.

[0008]

According to the first aspect of the invention, when the size of the printing paper is changed, the center distributing mechanism is always operated to position the printing paper at the center of the paper holder. The paper width detecting means is displaced, and the head pressure adjusting mechanism can automatically adjust the head pressure based on the displacement amount.

According to the second aspect of the present invention, the distance between the flange members of the center distributing mechanism changes with a change in the width of the printing paper. Therefore, the inclined plate of the paper width detecting means is attached to the flange member. By continuing the contact, the pressing rod is displaced in accordance with the amount of separation, and the head pressure applied to the thermal head via the elastic member can be changed.

According to the third aspect of the present invention, since the inclined plate is stably supported on the flange member by the engagement of the engagement portion with the flange member, the detecting operation of the sheet width detecting means is stabilized. Can be done.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The same components as those described in the related art are denoted by the same reference numerals, and description thereof will be omitted. In the drawing, reference numeral 4 denotes a printing apparatus according to the first embodiment of the present invention. The printing apparatus 4 includes a platen roller 1 described in the related art and a thermal head 3 urged against the platen roller 1 with a predetermined head pressure. The platen roller 1 is driven to rotate in the direction indicated by an arrow by a motor (not shown). Further, a roll of thermo-sensitive paper formed in a long strip shape as the printing paper 2 is held by a paper holder 5 described later.
One end of the printing paper 2 drawn out of the printer is inserted between the platen roller 1 and the thermal head 3 so as to be sent out of the printing device 4 by rotation of the platen roller 1 and to be printed by energizing the thermal head 3. Has become.

Reference numeral 5 denotes a paper holder. The paper holder 5 includes a shaft 6 and a center distributing mechanism 7 provided with the centers of the platen roller 1 and the thermal head 3 aligned with each other. The printing paper 2 is rotatably held together with a flange member 10 described later.

The center distributing mechanism 7 has two racks 8, 8 provided opposite each other, and a pinion 9 provided between the racks 8 so as to mesh with the racks 8.
And a shaft hole 1 attached to each rack 8 at the center.
0A is provided with two flange members 10, 10. And each flange member 10 has each shaft hole 10A.
The rack 6 is attached to each of the racks 8 so as to face each other with the shaft 6 inserted therethrough.

The paper holder 5 configured as described above is attached to the flange member 10 when the roll-shaped printing paper 2 is inserted into the shaft 6 and the width is shifted by one flange member 10 of the center sorting mechanism 7. The rack 8 rotates the pinion 9, moves the other flange members 10 in parallel through the other rack 8, and sandwiches the roll between the flange members 10 so that the printing paper 2 is positioned between the platen roller 1 and the thermal head 3. Is positioned.

Numeral 11 designates an inclined plate which constitutes a sheet width detecting means together with each of the flange members 10. As shown in FIG. 2, the inclined plate 11 is notched in an inverted V-shape on the lower side, and is directed from both ends toward the center. The inclined portion 11A has a reduced vertical width. The inclined plate 11 is supported in the vicinity of the center of the inclined portion 11A when the distance between the flange members 10 is small (FIG. 2) by the inclined portion 11A abutting on the upper end of each of the flange members 10, When the separation distance between the flange members 10 is large (FIG. 3), the flange members 10 are supported near both ends of the inclined portion 11A.

Reference numeral 12 denotes a pressing rod as head pressure adjusting means. The pressing rod 12 is swingably disposed above the paper holder 5 via a fulcrum 13. One end of the pressing rod 12 is It is fixed to the upper end of the inclined plate 11. A spring receiving portion 12A is formed at the other end of the pressing rod 12, and a spring 14 as an elastic member is inserted between the spring receiving portion 12A and the thermal head 3 in a compressed state. .
The spring 14 constantly urges the thermal head 3 toward the platen roller 1 between the pressing rod 12 and the thermal head 3, and when the spring receiving portion 12 </ b> A of the pressing rod 12 is displaced vertically about the fulcrum 13. It is appropriately deformed and applies a pressing force to the platen roller 1 to the thermal head 3.

The first embodiment of the present invention has the above-mentioned configuration, and its operation will be described below. Printing paper 2
When the width dimension of each flange member 10 is small, as shown in FIG.
The distance between the flange members 10 is small, and each flange member 10 comes into contact with the vicinity of the center of the largely cut-out inclined portion 11A, and
To support. At this time, the pressing rod 12 is at the position shown in FIG. 1, and the spring 14 urges the thermal head 3 toward the platen roller 1 with a head pressure corresponding to the deformation d1.

Next, when printing paper 2 having a large width is used, as shown in FIG. 3, each flange member 10 comes into contact with and supports near both ends of the inclined plate 11. At this time, the pressing rod 1
2 is displaced to the position shown in FIG. 4, and the spring 14 has a deformation d2 larger than d1, so that the thermal head 3 is urged toward the platen roller 1 with a larger head pressure.

As described above, according to the present embodiment, the center distributing mechanism 7 is operated to position the printing paper 2 at the center of the paper holder 5, so that each flange member is linked with the center distributing mechanism 7. When the printing paper having a small width is used, since the separation distance of the head 10 changes and the inclined plate 11 displaces the pressing rod 12 according to the separation distance and the head pressure can be automatically adjusted via the spring 14. The friction between the platen roller 1 and the thermal head 3 can be reduced by reducing the head pressure, and a motor having a small torque can be used as a motor for driving the platen roller 1.

Further, since the head pressure can be adjusted according to the size of the paper width, when thick printing paper such as a ticket or a tag is used, uneven wear of the thermal head 3 can be prevented, and the economy and durability can be improved. I can do it.

Next, FIG. 5 shows a second embodiment. This embodiment is similar to the first embodiment described above, and is a paper holder comprising a center distribution mechanism 7 including a flange member 10 and a shaft 6. 15, an inclined plate 16, a pressing rod (not shown), and a spring are included, but the feature of the present embodiment is that a step-shaped engagement portion 16B, 1
6B,...

The present embodiment having the above configuration is also the first embodiment.
In this embodiment, the inclined plate 16 is stably supported on the upper end side of each flange member 10, but the sheet width can be stably detected. .

The present invention is not limited to the above embodiments, but can be variously modified within the scope of the technical idea described in the claims. As an example, the long strip-shaped printing paper 2 may not be wound in a roll shape, but may be folded in a zigzag manner as shown in FIG. 6, or a coiled spring 14 as an elastic member. Instead, a leaf spring or a rubber member may be used. Further, the configuration in which the head pressure adjusting mechanism urges the thermal head 3 toward the platen roller 1 may alternatively urge the platen roller toward the thermal head, or the inclined portion 11 of the inclined plate 11.
A illustrates a linear shape, but may be a curved shape.

[0024]

As described in detail above, according to the present invention, the head pressure can be automatically adjusted according to the width dimension of the printing paper. Therefore, even when the paper width is small and the platen roller and the thermal head are in partial contact with each other, Paper can be fed by a motor with a small torque, which can simplify design and reduce costs. In addition, since the head pressure can be automatically adjusted, uneven wear of the thermal head can be prevented and the life can be extended even when the printing paper is thick and only the paper is in sliding contact with the thermal head.

[Brief description of the drawings]

FIG. 1 is an overall view showing a printing apparatus according to a first embodiment of the present invention.

FIG. 2 is a right side view showing a positional relationship between a paper holder and an inclined plate when printing paper having a small width is used in the printing apparatus shown in FIG. 1;

FIG. 3 is a right side view showing a positional relationship between a paper holder and an inclined plate when printing paper having a large width is used in the printing apparatus shown in FIG. 1;

4 is an overall view of the printing apparatus in the state of FIG.

FIG. 5 is a right side view similar to FIG. 3 showing a second embodiment.

FIG. 6 is an overall view showing a modification of the first and second embodiments.

FIG. 7 is a partially enlarged view showing a relationship between a thermal head and a platen roller when printing paper having a small width is used in a conventional printing apparatus.

FIG. 8 is a partially enlarged view similar to FIG. 7, showing a case where thick print paper is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Platen roller 2 Printing paper 3 Thermal head 4 Printing device 5, 15 Paper holder 6 Shaft 7 Center distribution mechanism 8 Rack 9 Pinion 10 Flange member (Paper width detection mechanism) 11, 16 Inclined plate (Paper width detection mechanism) 12 Pressing rod 13 fulcrum 14 spring (elastic member) 16B engaging part

Claims (3)

[Claims] A platen roller; a thermal head biased against the platen roller with a predetermined head pressure;
A printing apparatus that includes a paper holder that holds printing paper inserted between the thermal head and the platen roller, and that sends out the printing paper by rotating the platen roller and energizes the thermal head to perform printing. The holder is provided with a center distribution mechanism for positioning the print paper at the center of the platen roller and the thermal head, and a paper width detection means for detecting the width of the print paper by being displaced following the center distribution mechanism. A printing apparatus, further comprising a head pressure adjusting mechanism for increasing or decreasing the head pressure based on the amount of displacement of the sheet width detecting means on the thermal head side. A pressure rod for transmitting the displacement of the paper width detecting means via a fulcrum; and a pressing force between the platen roller and the thermal head by elastically deforming the displacement of the pressure rod. And an elastic member,
The paper width detecting means includes two flange members provided on the center distributing mechanism, and an inclined plate which comes into contact with each of the flange members and displaces the pressing rod according to a separation distance between the respective flange members. The printing device according to claim 1, comprising: 3. A printing apparatus according to claim 2, wherein said inclined plate is provided with an engaging portion with which said flange member is engaged.