JP2002002034A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a good print by oscillating a platen properly to come into face contact with a thermal head when they are brought into pressure contact. SOLUTION: The thermal printer comprises a thermal head 7 mounted, on a carriage 5 to reciprocate in the widthwise direction of a recording sheet 100, and a platen 32 disposed to touch the thermal head 7 separably through the recording sheet 100. A low friction member 34 is provided on the upstream side of the platen 32 in the print line direction and pressure contact of the thermal head 7 and the low friction member 34 is started thereat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer of the serial type, and more particularly to a thermal printer in which a thermal head is pressed against a platen with a predetermined pressing force to enable high-quality printing and recording.

[0002]

2. Description of the Related Art Conventionally, a plurality of heating elements formed on a thermal head are energized to appropriately heat the heating elements to melt ink on an ink ribbon and transfer a part of the ink to recording paper. Therefore, thermal printers that perform desired print recording are often used.

As shown in FIG. 8, in a general thermal printer, almost at the center of a frame 1 of the printer,
A platen 2 having a flat rectangular shape is disposed so that its print recording surface is substantially at a right angle, and a carriage shaft 3 is disposed below and in front of the platen 2 of the frame 1 in parallel with the platen 2. ing. A flange-shaped guide portion 4 is formed on the front edge of the frame 1. A carriage 5 is attached to the carriage shaft 3 and the guide portion 4 so as to be able to reciprocate along the carriage shaft 3 and the guide portion 4.

A thermal head 7 is attached to one end of the carriage 5 so as to be able to contact and separate from the platen 2, and an ink ribbon is stored on the upper surface of the carriage 5.
A ribbon cassette for guiding the ink ribbon between the thermal head 7 and the platen 2 is mounted. Further, on the upper surface of the carriage 5, a take-up bobbin 8 for taking up the ink ribbon of the ribbon cassette and a delivery bobbin 9 for sending out the ink ribbon are provided, respectively.

[0005] Behind the platen 2, a recording paper 10
0 (see FIG. 9) to the front of the platen 2
In the vicinity of the paper insertion slot 11, a paper feed roller 12 for transporting the recording paper 100 at a predetermined speed is provided. Below the paper feed roller 12, a pressure roller 13 that is pressed against the paper feed roller 12 is rotatably provided. On one side surface of the frame 1, a paper feed motor 15 for driving the paper feed roller 12 to rotate, and a gear group 14 for transmitting the rotational driving force from the paper feed motor 15 are connected to each other. By rotating the paper feed roller 12, the recording paper 100 inserted from the paper insertion port 11 is inserted.
Is transported while being sandwiched between the paper feed roller 12 and the pressure roller 13.

In such a printer, when the recording paper 100 is inserted from the paper insertion slot 11 and the paper feed roller 12 is rotationally driven through the gear group 14 by the rotational drive of the paper feed motor 15, the recording paper 100 is The recording paper 100 is sandwiched between the feed roller 12 and the pressing roller 13, and is conveyed at a predetermined speed in a paper feed direction orthogonal to the moving direction of the carriage 5. The thermal head 7 is pressed against the upper surface on one end side of the platen 2 with a predetermined pressure. In this state, the carriage 105 is moved, the thermal head 7 slides on the recording paper 100, and the winding bobbin 8 is rotated to wind the ink ribbon of the ribbon cassette (not shown). , The print recording is performed on the recording paper 100 as desired. Then, the recording paper 100 on which the print recording is performed is discharged to the outside by the discharge roller 16 (see FIG. 9).

Next, the configuration of the platen 2 portion of the printer and the relationship between the platen 2 and the thermal head 7 will be described in more detail with reference to FIGS.
Are a plate-shaped platen base 2b and a platen base 2
b, and a platen rubber 2a attached to the upper surface of the platen. On the back (lower surface) side of the platen base 2b, a platen holder 18 having a self-adjustment (fulcrum) projection 18b formed on the surface thereof with plastic or the like is attached to the frame 1. On the upper and lower edges of the platen holder 18, bent portions 18a having a hook-like cross section are formed along the longitudinal direction thereof. The center portion of the back (lower) surface of the platen base 2b is swingably supported by the self-adjustment (fulcrum) projection 18b.
The upper and lower edges of b are regulated within the bent portion 18a.

As shown in FIG. 9, a recording paper 100 sandwiched between a rotating paper feed roller 12 and a pressing roller 13 is provided.
When the paper feed roller 12 is further rotated in a counterclockwise direction (the direction of the arrow in FIG. 9), the leading end side of the recording paper 100 in the paper feed direction is inserted between the thermal head 7 and the platen 2, and the print recording start position The recording paper 100 is placed at the bottom.
Subsequently, as shown in FIG. 10, the thermal head 7 is moved in the direction of the platen holder 18 (in the direction of the arrow in FIG. 10), and is directly pressed against the longitudinal end of the upper surface of the platen rubber 2 a separated from the recording paper 100. Subsequently, the thermal head 7 is moved along the longitudinal direction of the platen 2 while being pressed against the platen 2. Then, a part of the ink of the ink ribbon is transferred onto the recording paper 100 by the heating element which generates heat in accordance with the print recording information, and prints and records along the printing line within the printing digit range of the recording paper 100. . The recording paper 100 after the printing and recording is performed by the rotating discharge roller 1.
6, etc., are discharged outside the printer.

[0009]

By the way, when the thermal head 7 presses against the platen rubber 2a to start print recording, the upper surface of the platen rubber 2a does not necessarily coincide with the surface of the thermal head 7 on which the heating elements are arranged. As the thermal head 7 moves in the row direction of the recording paper 100, the recording paper 100 and the ink ribbon intervene therebetween,
Gradually, the entire platen 2 swings on the basis of the projection 8b for self-adjustment, and their surfaces come to coincide. However, in the initial stage in which the thermal head 7 is pressed against the platen rubber 2a and starts moving in each row of the recording paper 100, even if the thermal head 7 moves in the row direction of the recording paper 100,
The swing of the platen 2 stops, and the thermal head 7
There is a possibility that the ink of the ink ribbon may be transferred to the recording paper 100 obliquely with the platen rubber 2a, that is, without making a uniform surface contact. For this reason, the print density in the vertical direction of the print recording surface differs,
There was a risk that good printing could not be obtained due to print unevenness such as fading. In particular, in print recording of images and the like in recent years, higher and higher image quality has been demanded, and the deterioration of print recording quality due to the uneven printing has had a great influence.

[0010] An object of the present invention is to provide a print head (printing) on a recording sheet by appropriately swinging the platen so that the thermal head and the platen come into surface contact with the thermal head when the thermal head comes into pressure contact with the platen. An object of the present invention is to provide a thermal printer which can be obtained.

[0011]

As a first means for solving the above problems, a head mounted on a carriage reciprocally movable in the width direction of the recording paper, and a head interposed by the recording paper. A low friction member is provided upstream of the platen in the printing line direction, and a pressure contact start position at which the head presses against the low friction member is provided.

As a second solution, the platen comprises a plate-shaped platen base and an elastic member attached to the platen base, and a low friction member is provided on the upper surface of the elastic member. It is.

As a third solution, the low-friction member is made of a plastic sheet member such as PET or vinyl chloride, and is attached to a platen.

As a fourth solution, the low-friction member is made of a plastic block member such as polyacetal, and is arranged on an end of the elastic member on the platen base so as to be flush with the elastic member. Thus, one surface of the block member is used as a pressure contact start position at which the head is pressed.

As a fifth solution, a coating member having a low friction coefficient is further laminated on the surface of the low friction member.

As a sixth solution, a self-adjusting (fulcrum) projection is provided on the front side of the platen on the rear side, which serves as a fulcrum for the forward and backward swinging of the platen. A platen holder for holding a platen swingably is provided.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A thermal printer according to an embodiment of the present invention will be described below with reference to FIGS.
Note that the same components as those of the above-described conventional device are denoted by the same reference numerals, and detailed description thereof is omitted. 1 to 3
As shown in FIG. 2, the platen 32 is a long plate-like metal platen base 32b such as an iron plate, and a rubber or the like attached to the front surface (upper surface) of the platen base 32b so as to be slightly narrower than the platen base 32b. And a platen rubber (elastic member) 32a. An adhesive such as a double-sided adhesive tape (not shown) is interposed between the platen base 32b and the platen rubber 32a. On the upstream side of the platen rubber 32a in the printing row direction X, a low friction member 34 having a low friction coefficient is provided at an upper end of the platen rubber 32a. The low friction member has a thickness of about 0.1
It is a film-like plastic sheet 34 such as PET (polyethylene terephthalate) or vinyl chloride having a friction coefficient (μ) of about 0.2 to 0.4 mm, and is placed on the platen rubber 32a from the tip of the platen rubber 32a. The thermal head 7 is formed up to the left edge of the conveyed recording paper 100 in the width direction, that is, at a portion where the thermal head 7 goes down.

On the back (lower surface) side of the platen base 32b, a platen holder 38 provided with a self-adjustment (fulcrum) projection 38b made of plastic or the like at the center is mounted on the frame 1. Further, the platen holder 3
8 is a bent portion 38a having a hook-shaped cross section at the upper and lower edges.
Are formed along the longitudinal direction of the platen 32, and two protruding platen locking hooks 38d, 38d are provided on the back side thereof. The central portion on the back surface of the platen base 32b is swingably supported by a self-adjusting (fulcrum) projection 38b, and the platen base 32b
The upper and lower edges are restricted within the groove of the bent portion 38a so as not to come off. The frame 1 is provided with a platen insertion hole 1b having a size large enough to allow the platen engagement hooks 38d, 38d to be inserted smoothly, and connected to the platen insertion hole 1b.
A platen mounting hole (not shown) having a size enough to lock 8d is formed. And the platen insertion hole 1
The platen locking hook 38d is inserted into the platen b, a part of the platen locking hook 38d is fitted into a platen mounting hole (not shown), and the platen 32 is locked to the frame 1.

Next, the operation of the thermal printer according to the present embodiment will be described with reference to FIGS. As shown in FIG. 4, first, the carriage 5 to which the thermal head 7 is attached is positioned at a position deviating from one edge of the recording paper 100, which is a print recording start position, in a width perpendicular to the paper feeding direction of the recording paper 100. In the direction (print line X direction). At this time,
By rotating and driving the paper feed roller 12 and the pressure roller 13, the recording paper 100 is arranged at a predetermined position of the line where the print recording is started, facing the thermal head 7. Subsequently, the thermal head 7 is pressed against the platen 32 via the ink ribbon R (see FIGS. 4 and 5), and a so-called head-down state is set. In this head down, the surface on which the heating elements of the thermal head 7 are disposed is the platen 32.
Is pressed against the plastic sheet 34 provided on the upstream side in the print line direction X.

As shown in FIG. 6, after the thermal head 7 is pressed against the plastic sheet 34 on the platen 32,
The thermal head 7 moves in the print line direction X of the platen 32. Then, the plastic sheet 34 having a low friction coefficient
The surface of the thermal head 7 on which the heating element is disposed smoothly slides in contact with the upper surface of the thermal head 7, and the platen 32 swings on the basis of the self-adjustment projection 38b. Face to face and match. Then, as shown in FIG. 5, when the carriage 5 starts moving in the print line direction X on the recording paper 100 in this head down state, the plastic sheet 34
In the state where the pressure of the thermal head 7 against the platen 32 is already uniform, the surface on which the heating element is arranged slides. Platen rubber 32 for thermal head 7
a, even if there is a difference in the pressure between the upper edge and the lower edge of the plastic sheet 34 at the initial stage of the sliding, that is, until the thermal head 7 reaches the recording paper 100. The thermal head 7 slides, and the unevenness of the pressing pressure becomes uniform.

Then, on the recording paper 100, the thermal head 7 moves the carriage 5 in the row direction X while transferring a part of the ink to the recording paper 100 by the heat via the ink ribbon R via the ink ribbon R to the upper surface of the platen rubber 32a. Move with.
While rotating the winding bobbin 8 to wind the ink ribbon R onto which a part of the ink has been transferred, the heating elements of the thermal head 7 are selectively heated based on predetermined print recording information, and The desired print record is made. Then, at the end of one row of the recording paper 100, the thermal head 7 separates from the upper surface of the platen rubber 32a,
The paper feed roller 12 and the pressure roller 13 are rotated to feed the recording paper 100 in the paper feed direction and feed a new line. Then, the carriage 5 to which the thermal head 7 is attached is moved to a start position for printing a next line. That is, the recording sheet 100 comes into pressure contact with the plastic sheet 34 on the platen rubber 12a which is separated from one edge in the width direction, and the above-described operation is repeated.

After the print recording is performed as described above and the print recording arbitrarily set in advance is completed, the recording paper 100 is discharged to the outside of the printer by rotating the discharge roller 16. Note that a coating member such as Teflon (registered trademark) having a still lower coefficient of friction may be formed on the plastic sheet 34 stuck on the platen rubber 32a. Alternatively, the upper surface of the platen rubber 32a may be satin-finished to suppress sticking. Further, the hardness of the plastic sheet 34 is set to 100 kg / mm.
Two or more are preferred.

Next, a modification of the platen of the thermal printer according to the present embodiment will be described below with reference to FIG. FIG.
As shown in the figure, the low friction member is composed of a plastic block member 44 such as polyacetal (having a friction coefficient μ of 0.2 or less and a Young's modulus of 100 kg / mm 2 or more), and a platen rubber 32a on a platen base 32b. They are arranged at the end of the platen rubber 32a so as to be flush with each other. One surface of the block member 44 is set as a press-contact start position at which the thermal head 7 presses. The operation of the block member 44 in printing and recording is the same as when the above-mentioned plus sheet 34 is used. By arranging the block member 44 made of polyacetal or the like at the end of the platen rubber 32b in this way, even if the thermal head 7 is pressed, the thermal head 7 is harder than the rubber and is not easily deformed. Make rocking more reliable. Further, the block member 44 having a low friction coefficient is simply provided at the end of the platen rubber 32a.
Since it is only necessary to mount the device, assembly is further simplified. Further, since the platen rubber 32a and the block member 44 have the same height, the thermal head 7 can be smoothly moved in the printing line direction.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.
Changes can be made without departing from the spirit of the invention.

[0025]

According to the thermal printer of the present invention described above, the head mounted on the carriage which can reciprocate in the width direction of the recording paper and the head can be separated from the head via the recording paper. With a disposed platen, a low friction member is provided on the upstream side of the platen in the printing line direction, and a pressure contact start position where the head is pressed against the low friction member,
In the initial state of pressing the head against the platen, the head comes into contact with the low-friction member having a low friction coefficient, so that the head operates smoothly and printing on recording paper can be performed uniformly.
In particular, the effect is further enhanced when printing and recording images and the like.

The platen is composed of a plate-shaped platen base member and an elastic member adhered on the platen base member. By providing a low friction member on the upper surface of the elastic member, the platen is simply an elastic member. It is only necessary to stick a low friction member on the upper part, and the mounting can be performed easily.

The low-friction member is made of a plastic block member such as polyacetal, and is arranged on the platen base at the end of the elastic member so as to be flush with the elastic member. Is set as the pressure contact start position where the head is pressed, so that the head can slide more smoothly from the low friction member composed of the block member to the platen at the boundary portion thereof, and the hardness of the block member increases the reliability. It is possible to obtain a suitable pressing pressure.

Further, by coating a coating member having a low friction coefficient on the surface of the low friction member, the head operates more smoothly with respect to the platen, so that printing on the recording paper becomes more uniform. It can be carried out.

On the back side of the platen, there is provided a self-adjustment (fulcrum) projection on the front surface, which serves as a fulcrum for swinging the platen back and forth. The upper and lower edges hold the platen so as to be able to swing. The self-adjustment of the oscillating platen is adjusted satisfactorily by the provision of the platen holder, and the pressing pressure of the head against the platen becomes uniform, without causing print unevenness from the printing start position on the recording paper. Clear print records can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a principal part of a platen in a thermal printer according to an embodiment of the present invention, showing a state in which recording paper is fed.

FIG. 2 is a front view of a platen portion of the thermal printer according to the embodiment of the present invention.

FIG. 3 is a schematic sectional view of a platen portion of the thermal printer according to one embodiment of the present invention.

FIG. 4 is a plan view of a platen portion showing a printing start state of a platen and a thermal head in the thermal printer according to one embodiment of the present invention.

FIG. 5 is a plan view of a platen portion showing a print recording state in the thermal printer according to one embodiment of the present invention.

FIG. 6 is a side view of a platen portion showing a print recording state in the thermal printer according to one embodiment of the present invention.

FIG. 7 is a perspective view of a main part of a platen portion illustrating a modification of a platen of the thermal printer according to the embodiment of the present invention and showing a state where recording paper is fed.

FIG. 8 is an external view of a generally known thermal printer.

FIG. 9 is a schematic configuration diagram of a main part during a paper feeding operation of a conventional thermal printer.

FIG. 10 is a schematic configuration diagram of a main part during a printing operation of a conventional thermal printer.

[Explanation of symbols]

 Reference Signs List 5 carriage 7 thermal head (head) 32 platen 32a elastic member (platen rubber) 32b platen base 34 low friction member (plastic sheet) 38 platen holder 38b self-adjustment (for fulcrum) projection 44 block member 100 recording paper

Claims (6)

[Claims] 1. A print head, comprising: a head mounted on a carriage that can reciprocate in the width direction of a recording sheet; and a platen disposed so as to be able to contact and separate from the head via the recording sheet. By providing a low friction member on the upstream side in the row direction,
A thermal printer wherein a pressure contact start position at which the head is pressed against the low friction member is provided. 2. The apparatus according to claim 1, wherein the platen comprises a plate-shaped platen base and an elastic member attached to the platen base, and the low friction member is provided on an upper surface of the elastic member. Item 4. The thermal printer according to Item 1. 3. The thermal printer according to claim 1, wherein the low friction member is made of a sheet member made of plastic such as PET or vinyl chloride, and is attached to the platen. 4. The low-friction member is made of a plastic block member such as polyacetal, and is disposed on an end of the elastic member on the platen base so as to be flush with the elastic member. 3. The thermal printer according to claim 2, wherein one surface of the block member is a pressing start position at which the head is pressed. 5. The thermal printer according to claim 1, wherein a coating member having a low friction coefficient is further laminated on a surface of the low friction member. 6. A self-adjustment (fulcrum) projection, which is a fulcrum for swinging the platen back and forth, on the back side of the platen, and the platen can be swung by an upper edge and a lower edge. The thermal printer according to any one of claims 1 to 5, wherein a platen holder for holding the platen is provided.