JPH0432286Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an apparatus for adjusting left and right print density unevenness in a thermal printer.

[Conventional technology]

In a thermal printer that prints using a heating element (hereinafter referred to as a thermal head) in which heating elements are arranged in a straight line and a platen that presses thermal paper against the heating elements of the thermal head, both ends of the heating elements in a straight line are used. In order to equalize the printing density, it is necessary to bring the platen into contact with the heat generating element with the same pressing pressure at both ends. For this purpose, a pressure contact force adjusting device as shown in FIG. 4 has been required in the past. This prior art will be explained below with reference to the drawings.

The drawing is a side view, and 1 is a platen, 2 is a platen shaft of this platen 1, 3 is a side plate that rotatably supports this platen shaft 2, and 4 is a top cover.

Further, the side plate 3 is located parallel to the axis of the platen 1 and is rotatably supported by a center piece 6 fixed to the side frame 5. It has a structure that opens as a fulcrum.

8 is a lock lever post, which is fixed to the side plate 3. Reference numeral 9 denotes an adjuster plate, which can be freely attached to the side frame 5 vertically and forwardly on the plane of the side frame 5. Reference numeral 10 designates a lock lever that rotatably engages with the adjuster plate 9, and the lock lever post 8 engages with this lock lever 10 so that the platen 1 can be fixed.

11 is a thermal head, which is fixed to a head mount 12;
A shaft 13 is fixed to the shaft hole 5a of the side frame 5, and the head mount 12 is fitted into the shaft hole 5a of the side frame 5.
It is rotatable about a as a fulcrum.

In addition, the head mount 12 is connected to the thermal head 1.
In order to press the thermal head 11 against the platen 1, the thermal head 11 is pressed against the platen 1 by a head pressure spring 15 via a spring bracket 14 attached to a head mount 12. Note that 16 is a heating element and 17 is thermal paper.

According to the above configuration, adjustment of left and right print density unevenness is achieved by moving the platen 1 by moving the mounting position of the adjuster plate 9, which causes the lock lever post 8 engaged with the claw portion 10a of the lock lever 10 to move. can be moved up and down and back and forth. As a result, the platen 1 is brought into contact with the heat generating element 16 of the thermal head 11, and the pressing force is equalized at both left and right ends of the platen 1 and the heat generating element 16, thereby making it possible to equalize the print density on the left and right sides of the printing paper.

[Problem that the invention attempts to solve]

According to the above-mentioned conventional technology, since the platen can freely move up and down and back and forth, the printing density on both sides can be made equal by positioning the platen on the heating element and applying equal pressing pressure on the left and right sides. There is a problem that double adjustment is required and adjustment is difficult.

[Means for solving problems]

In order to solve the above problems, this invention consists of a platen placed on the side frame, a head mount that is rotatably supported by the side frame via fulcrums provided at one end on both sides, and a heat generating device that prints on thermal paper. A thermal printer comprising: a thermal head in which elements are arranged in a straight line and held by the head mount; and urging means for urging the thermal head to press the heating elements against the platen via the thermal paper. In the device for adjusting left and right print density unevenness in The side frame is movably supported within an arc-shaped hole provided in the side frame so as to be located on the circumference of a circle whose radius is the distance to the one fulcrum, and the other fulcrum is located in the arc-shaped hole. The present invention is characterized in that an adjuster plate for fixing it in any position is attached to the side frame.

[Effect]

In the present invention having the above-described configuration, the other fulcrum of the head mount is moved along the arc-shaped hole without being fixed, so that both left and right ends of the row of heating elements of the thermal head are uniformly pressed against the platen. Then, fix the other fulcrum at that position with an adjuster plate.

Therefore, according to this, the pressing force of the heating element array against the platen can be made uniform, so that the left and right densities of characters or images printed on thermal paper can be made equal.

In addition, no matter where the other fulcrum of the head mount is fixed in the arc-shaped hole, the platen and the heating element of the thermal head are always in contact with each other, so the printing quality does not deteriorate due to adjustment, and the head Since adjustment can be made only on the other fulcrum side of the mount, adjustment work is also facilitated.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view, FIG. 2 is a side view of the main part, and FIG. 3 is a plan view of the main part. In the figure, 18 is a platen, 19 is a platen shaft of this platen 18, and 20a and 20b are this platen shaft 19.
A side plate rotatably supports the
is a top cover, and this side plate 20a,
20b is attached on both sides. The side plates 20a, 20b are located parallel to the axis of the platen 18, and are rotatably supported by center pieces 23a, 23b fixed to the side frames 22a, 22b.
Due to this, the top cover 21 is attached to the center pieces 23a, 2.
It has a structure that opens using 3b as a fulcrum.

Numerals 25a and 25b are lock lever posts, which are fixed to the side plates 20a and 20b and can engage lock levers 26a and 26b rotatably attached to the side frames 22a and 22b to fix the platen 18, top cover 21
The position of the platen 18 is fixed when it is closed.

27 is a thermal head, and 28 is a head mount that holds this thermal head 27. One fulcrum 29a of the head mount 28 is rotatably fixed to the side frame 22a, and the other fulcrum 29b is movable on the circumference of a radius r centered on the axis of the platen 18. It fits into an arc-shaped hole 30 formed in the side frame 22b. Further, the head mount 28 includes a spring bracket 3 attached to the head mount 28 in order to press the thermal head 27 against the platen 18.
1, the thermal head 27 is brought into pressure contact with the platen 18 by a head pressure spring 32.

Reference numeral 33 designates an adjustment plate rotatably attached to the side frame 22b by a fulcrum 34, and has an abutment surface 35 formed thereon and abuts against the fulcrum 29a of the head mount 28. By rotating the fulcrum 29b of the head mount 28, the contact surface 35 can move the fulcrum 29b, thereby allowing the platen 18 and the thermal head 27 to come into contact on the heating element 36. The heating elements 36 are arranged in a straight line on the thermal head 27.

The two supporting points will be further explained with reference to FIG. The position of the fulcrum 29a is the position where the thermal head 27 contacts the platen 18 on the heating element 36, and the distance between the fulcrum 29a and the axis of the platen 18 is r. The other fulcrum 29b is supported by an adjuster plate 33 within the hole 30 of the side frame 22b on a radius r centered on the axis of the platen 18 shown in FIG. 37 is thermal paper.

According to the fulcrum support structure of the head mount that holds the thermal head described above, one fulcrum 29a is rotatably supported at a distance r from the axis of the platen 18, and the other fulcrum 29b is rotatably supported on the platen 18.
By manipulating the position of the adjusting plate 33, the thermal head 27 can be moved on the heat generating element 36 while keeping the thermal head 27 in constant contact with the platen 18 on the heat generating element 36.
It can be adjusted so that the pressure contact force at both the left and right ends of can be equalized.

[Effect of idea]

As explained above, in the present invention, one fulcrum of the head mount holding the thermal head is supported by the side frame at a position where the heating element of the thermal head can come into contact with the platen, and the other fulcrum is supported by the side frame. The side frame is movably supported within an arc-shaped hole provided in the side frame so as to be located on a circumference having a radius of the distance from the axis to the one fulcrum, and the other fulcrum is movably supported in the arc-shaped hole. An adjustment plate is attached to the side frame to fix the heat generating element array at any position in the hole of the thermal head. Since the fulcrum is fixed by the adjuster plate, the pressing force of the heating element row against the platen can be made uniform, which makes it possible to equalize the left and right densities of characters or images printed on thermal paper. You can get the effect that you can.

In addition, no matter where the other fulcrum of the head mount is fixed in the arc-shaped hole, the platen and the heating element of the thermal head are always in contact with each other, so the printing quality does not deteriorate due to adjustment, and the head Since adjustment can be made only on the other fulcrum side of the mount, the adjustment work is also easy.

[Brief explanation of drawings]

Figure 1 is a side view showing one embodiment of the present invention;
The figure is a side view of the main part, FIG. 3 is a plan view of the main part, and FIG. 4 is a side view of a conventional example. 18...platen, 27...thermal head,
28... Head mount, 29a, 29b... Fulcrum, 30... Hole, 33... Adjustment plate,
35...Abutting surface, 36...Heating element.

Claims (1)

[Scope of Claim for Utility Model Registration] A platen placed on a side frame, a head mount rotatably supported by the side frame via fulcrums provided on both sides of one end, and a heating element for printing on thermal paper are connected in one line. A thermal printer comprising: thermal heads arranged in a line and held by the head mount; and biasing means for biasing the thermal head so as to press the heating element into contact with the platen via the thermal paper. In the device for adjusting print density unevenness, one fulcrum of the head mount is supported by the side frame at a position where the heat generating element of the thermal head can come into contact with the platen, and the other fulcrum is positioned from the axis of the platen to the one above. The side frame is movably supported within an arc-shaped hole provided in the side frame so as to be located on the circumference of a circle whose radius is the distance to the fulcrum of A device for adjusting left and right print density unevenness in a thermal printer, characterized in that an adjustment plate for fixing the printer in position is attached to the side frame.