JPH08318652A - Printer - Google Patents

Abstract

PURPOSE: To provide a printer feeding paper accurately and stably to eliminate printing shift to obtain an image of excellent printing quality and capable of reducing the front and rear blanks of the paper. CONSTITUTION: A printing is constituted so that auxiliary rolls 28a, 28b are brought into contact with a thermal head 22 under predetermined pressure on the extension line of the linear printing element formed to the thermal head 22 to perform the forward and reverse feed of paper. For example, even if forward/reverse direction feed is repeated three times in order to perform the printing processing of yellow (Y), magenta (M) and cyan (C), accurate printing can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus, and more particularly to a printing apparatus for printing by printing a print head having printing elements arranged in a line on a platen roller via a sheet of paper.

[0002]

2. Description of the Related Art Today, a printing device is widely used, for example, as a terminal device of a computer for printing data output from the computer. In particular, a printing apparatus using a so-called thermal head is widely used because of its low noise and simple structure. Hereinafter, a conventional printing device will be described with reference to FIGS. 6 and 7.

(A) FIG. 6 is a diagram for explaining an example of a conventional printing device. In the figure, the paper P is unloaded from the paper feed cassette 1 by the paper feed roller 2, is conveyed between the thermal head 3 and the platen roller 4 which are in pressure contact, and is ejected out of the machine via the conveyance roll 5. The ink ribbon 6 is wound around the feed roll 7 and is fed in the same direction as the paper P by the winding driving force of the winding roll 8. During this time, the heat of the thermal head 3 is generated by the ink ribbon 6 at the pressure contact portion t. The ink is melted and the melted ink is transferred to the paper P. By repeating this process, for example, printing is performed on the paper P according to the data output from the computer. During the above-mentioned printing, the thermal head 3 presses the contact force (f) in the direction of arrow b.
At this time, the conveying force of the sheet P is obtained by the driving force transmitted to the rotating shaft 4 ′ of the platen roller 4. On the other hand, since the thermal head 3 retracts in the direction of arrow a during non-printing, there is no pressure contact force (f) between the thermal head 3 and the platen roller 4, and the conveyance force of the paper P is due to the conveyance roll 5.

As described above, the transport roll 5 is necessary for transporting the non-printing paper P. However, in the above-mentioned device (a), the transport roll 5 cannot be provided in the vicinity of the pressure contact portion, and the pressure contact point t between the thermal head 3 and the platen roller 4 cannot be provided.
The distance from to the arrangement point t ′ of the transport roll 5 becomes extremely long. Therefore, a large margin is required in the front-back direction of the paper.

Therefore, a printer having the structure shown in FIG. 7 has been proposed as the device (b). In this apparatus, the transport roll 15 is provided in contact with the platen roller 14, and the distance between the contact point t between the thermal head 13 and the platen roller 14 and the disposition position t ′ of the transport roll 15 is short. With this configuration, the margin portion of the paper P is shortened. In addition, the paper feed cassette 12 is provided by the paper feed roller 12.
The paper P is unloaded from the thermal head 13, the paper is conveyed between the thermal head 13 and the platen roller 14, and the ink ribbon 16 wound around the feed roll 17 is sent to the take-up roll 18.
This is the same as the above-mentioned printing device (a). Therefore, the conveyance force of the sheet P is obtained by the rotational force of the platen roller 14 during printing, and the thermal head 13 retracts in the direction of the arrow a during non-printing, so the conveyance force of the sheet P is obtained by the conveyance roll 15.

[0006]

The above-mentioned conventional apparatus has the following problems. That is, the above (a) and (b)
In both devices, the conveyance of the paper P during printing is the rotational driving force of the platen roller 4 (14) based on the pressure contact between the thermal head 3 (13) and the platen roller 4 (14).
Therefore, for example, the pressure contact force (f) between the thermal head 3 (13) and the platen roller 4 (14) is
When (14) is different at both ends in the longitudinal direction, the conveyance force of the sheet P is different at both sides, and the sheet P is attracted to the side having a strong pressure contact force. Therefore, the sheet P is conveyed while being inclined, and there is a problem that the print data cannot be printed at the correct sheet position.

In the case of color printing, the transport roll 5
When the paper P is fed in the reverse direction using (15), for example, when an ink ribbon coated with three colors of yellow (Y), magenta (M), and cyan (C) is used,
Repeat forward feed and reverse feed three times. However, at this time, a rotation deviation occurs and the print position is displaced. For example, the transport roll 5 (15) may come into contact with only one side of the paper P so that the paper P
When the sheet P is conveyed, the sheet P is curved and conveyed in the direction in which the conveyance roll 5 (15) comes into contact. For this reason, the printing accuracy deteriorates, so-called color moire occurs, and the direct processing technique
For example, when the color moire is prevented by the screen angle, the print quality is deteriorated.

Incidentally, in the case of the device (a), in addition to the above problem, a large margin is required before and after the paper as described above,
Even in the case of the device (b), margins are required before and after the paper, though not to the extent of the device (a).

The present invention has been made in view of the above circumstances, and it is possible to accurately and stably feed a sheet, eliminate print misalignment, obtain an image with excellent print quality, and reduce the margin before and after the sheet. An object is to provide a printing device.

[0010]

According to the present invention, the above-mentioned object is achieved by supporting a print head having a large number of printing elements arranged in a line on a platen roller which is rotatable in forward / reverse directions. In a printing device for printing by pressing in a direction orthogonal to a printing element arranged in a line, the platen is located at both end positions of the printing head and extends the pressing contact portion of the printing head. This can be achieved by providing a sheet conveyance assisting device that holds the sheet in cooperation with the roller.

Further, the paper conveyance assisting means is an auxiliary roll to which a driving force is transmitted from a driving gear for driving the platen roller, and the auxiliary roll is extended on the platen roller by extending the press contact portion between the print head and the platen roller. The conveyance of the paper P is assisted by pressing the rollers with a predetermined pressure.

[0012]

According to the present invention, a print head having a large number of printing elements arranged in a line is pressed against a platen roller, a paper and an ink ribbon are conveyed therebetween, and an image according to print data is transferred to the paper. It is a printing device, and by arranging an auxiliary roll that contacts the platen roller on the extension of the pressure contact part between the thermal head and the platen roller, it assists the conveyance of the paper Printing is performed at various positions. That is, in the case of color printing, yellow (Y), magenta (M), cyan (C)
In order to print the three colors, the paper is transported back and forth multiple times.
Since the auxiliary roll is arranged on the extension of the above-mentioned pressure contact portion, the paper feeding force is stable, and it is possible to provide a printing device with excellent printing accuracy without causing rotational deviation.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of the printing apparatus of this embodiment. It should be noted that the configuration of the paper feed cassette that stores the paper P, the configuration of the paper feed roller that carries the paper P out of the paper feed cassette, the configuration of the ink ribbon feed roll, and the configuration of the take-up roll are omitted in FIG. FIG. 2 is a schematic side view of the printing device described above.

In both figures, the platen roller 20 is constructed by disposing a silicon type rubber material on a peripheral surface 20b on a metal rotating shaft 20a. The hardness of this rubber material is, for example, about 70 degrees. A platen gear 21 is fixed to one end of the rotary shaft 20a of the platen roller 20, and a drive gear 19 meshes with the platen gear 21.
The rotational force of a motor (not shown) is transmitted to the drive gear 19, and the platen gear 21, that is, the platen roller 20 is rotated in the arrow direction by rotating the drive gear 19 in the arrow direction.

On the platen roller 20 described above,
A thermal head 22 is provided. The thermal head 22 is configured by forming a large number of printing elements “L” in a line shape in parallel with the arrangement direction of the platen roller 20.
It is configured to be rotatable around a and 22b in the arrow a direction or the arrow b direction. The rotation in the arrow a direction or the arrow b direction is performed by a pressure contact release mechanism (not shown) and the biasing mechanism 39 shown in FIG. 2, and when printing on the paper P, a predetermined biasing force (pressing force ( F)) rotates the thermal head 22 in the direction of arrow b.

Platen roller 20 and thermal head 22
The ink ribbon 24 and the paper P are conveyed in between, and during the printing process, the ink ribbon 24 and the paper P are brought into pressure contact directly below the printing elements "L" arranged in a line. As described above, the ink ribbon 24 is sent from the feed roll (not shown) to the take-up roll (in the direction of arrow c), and the paper P is carried out from the paper feed cassette (not shown) by the paper feed roller. Is.

On the other hand, an auxiliary roll shaft 26 having both ends rotatably attached to the frame 25 is provided on the extension line of the printing element "L" indicated by the dotted line, and the auxiliary roll shaft 2 is provided.
6 is an auxiliary roll gear 27 fixed to the auxiliary roll shaft 26.
It is configured to rotate by. That is, the auxiliary roll gear 27 meshes with the platen gear 21 provided on the platen roller 20, and the rotational driving force of the motor is transmitted to the auxiliary roll gear 27 via the platen gear 21. Further, the auxiliary roll shaft 26 is provided with a pair of auxiliary rolls 28a and 28b on the left and right sides.
The position where b and the platen roller 20 contact each other is on the extension line L ′ of the above-mentioned line-shaped printing element “L”. Therefore, the auxiliary rolls 28a and 28b are located on the extension line of the printing element "L" arranged in a line, and the paper P is conveyed in the arrow d or d'direction on the extension line of the printing element "L". Is.

The transporting operation and the printing operation of the paper P in the printing apparatus having the above configuration will be described. First, in the non-printing state, the thermal head 22 is rotating in the direction of arrow a, and the thermal head 22 and the platen roller 20 are in the non-contact state. In this state, drive the paper feed roller (not shown),
The ink ribbon 24 wound around the feed roll is driven while the paper P is unloaded from the paper feed cassette and the take-up roll is driven.
In the direction of arrow c. After that, the paper P is printed by the printing element "L".
On the extension line L'of.

In this state, the print processing state is entered. That is, for example, an urging mechanism (not shown) is driven to rotate the thermal head 22 in the direction of arrow b to apply a predetermined pressure contact force (F) between the thermal head 22 and the platen roller 20. Then, by rotating the platen roller 20, the paper P is conveyed in the direction of arrow d and the ink ribbon 24 is moved in the direction of arrow c. During this time, the print elements of the thermal head 22 generate heat based on the print data,
The ink of the ink ribbon 24 is printed at a predetermined position on the paper P. Further, since the transport rolls 28a and 28b are positioned on the extension line L'of the above-mentioned printing element "L", the transport process of the paper P in the arrow d direction is assisted during the printing process, and the paper P is deviated. Prevent it from being sent.

After that, when the trailing edge of the paper P reaches just below the printing element "L" (on the extension line L'of the printing element "L"), the paper P is moved in the direction of the arrow d'opposite to the direction of the arrow d. Then, the paper P is fed in the reverse direction (reverse feed) until the leading edge of the paper P reaches directly below the printing element “L”. This reverse feeding is performed by the transport rolls 28a and 28b, and the auxiliary rolls 28a and 28b are positioned on the extension line L'of the printing element "L" as described above, so that the sheet P may be transported with deviation. Absent.

In this embodiment, the ink ribbon 24 is sequentially coated with three colors of inks of yellow (Y), magenta (M) and cyan (C), and the paper P is transferred to transfer the inks of the respective colors. Are moved at least three times in the forward direction (arrow d direction) and the reverse direction (arrow d'direction). During this reciprocating movement, since the auxiliary rolls 28a and 28b are positioned on the extension of the printing element "L", the paper P can be fed accurately and stably, and printing can be performed at a correct position even by a plurality of reciprocating operations. It can be performed.

That is, the auxiliary rolls 28a and 28b are driven through the auxiliary roll gear 27, and the auxiliary roll 28
The a and 28b are integrally rotated by the auxiliary roll shaft 26, and the driving force at both ends of the paper P and the conveying speed are extremely stable. Therefore, there is no positional deviation of the paper P, the printing position accuracy is extremely stable, and it is possible to obtain an image of high printing quality without color moire.

Next, another embodiment of the present invention will be described. FIG. 3 is a schematic configuration diagram of a printing apparatus according to another embodiment. The same members as those in the above-described embodiment are designated by the same reference numerals, and the structural description will be omitted. The configuration different from the above-described embodiment is that an auxiliary roll mechanism such as an auxiliary roll shaft (26) and auxiliary rolls (28a, 28b) is provided on the thermal head. That is, in the above-described embodiment, the auxiliary roll mechanism such as the auxiliary roll shaft (26) is rotatably attached to the frame (25) in the above-described auxiliary roll mechanism, but in the present embodiment, the auxiliary roll mechanism is mounted on the thermal head 29. This is a configuration in which a mechanism is provided. Further, FIG. 4 shows a sectional structure of the auxiliary roll mechanism.

In the present embodiment, the reason why such a structure is adopted will be briefly described. In the above-mentioned embodiment, the ink ribbon (2
When it is necessary to move the thermal head (22) largely, for example, when the removal work of 4) is necessary, the auxiliary roll mechanism such as the auxiliary roll shaft (26) becomes an obstacle to the work.
In such a case, if the work of removing the auxiliary roll mechanism is performed, the left and right balance of the auxiliary rolls 28a and 28b becomes unstable. Therefore, even in such a case, the maintenance can be easily performed without removing the auxiliary roll mechanism.

Specifically, a bearing base 30 having a vertically elongated long hole 30 'is provided on the thermal head 29, and an auxiliary roll shaft 31 is inserted through the long hole 30' of the bearing base 30. The auxiliary roll shaft 31 is arranged so as to be located immediately above the printing element "L" and its extension line L '. An auxiliary roll gear 32 is fixed to the tip of the auxiliary roll shaft 31 and meshes with the platen gear 21 of the platen roller 20. Further, auxiliary rolls 33a and 33b are fixedly mounted on the auxiliary roll shaft 31 and are located on the above-mentioned L '.

A pair of spring receivers 34, 34 are provided on the thermal head 29. The spring receivers 34, 34 are provided.
Rod-shaped crimp springs 35, 35 are provided in the groove with their centers in contact with each other. Further, one ends of the pressure springs 35, 35 are in contact with bearings 36, 36 provided on the auxiliary roll shaft 31, and the other ends are in contact with the upper surface of the thermal head 29. Therefore, the auxiliary roll shaft 31 (auxiliary rolls 33a and 33b) is always urged downward by the pressure springs 35 and 35. On the other hand, the thermal head 29 is also configured to apply the above-mentioned biasing force (pressure contact force) in the arrow b direction by the biasing mechanism 39 shown in FIG. Therefore, even when the thermal head 29 slightly moves in the direction of arrow a and is in the non-printing state, the auxiliary roll shaft 31 receives the urging force of the pressure bonding spring 35 and moves below the elongated hole 30 ′, and the auxiliary roll 33.
a and 33b are brought into pressure contact with the platen roller 20 at a predetermined pressure. Further, when the thermal head 29 moves in the direction of the arrow b and is in a printing state, the auxiliary roll shaft 31 receives the urging force of the pressure bonding spring 35, but the auxiliary rolls 33a and 33b contact the platen roller 20. 31 is a long hole 30
Move above ´. Even in this state, the auxiliary roll 33
The a and 33b are in contact with the platen roller 20 as described above, and are in contact with each other with a predetermined pressure.

In the printing apparatus having the above-mentioned structure, the feeding operation and the printing operation of the paper P will be described below. This process is similar to that of the above-described embodiment. First, in the non-printing state, the paper feed roller (not shown) is driven to carry out the paper P from the paper feed cassette, and the winding roll is driven to feed the paper P. The ink ribbon 24 wound around the roll is sent in the direction of arrow c.
After that, when the paper P reaches the extension line L'of the print element "L", the print data supplied from, for example, a computer is supplied to the print elements arranged in a line, and the print processing state is entered. . That is, the biasing mechanism 39 is driven,
By rotating the thermal head 29 in the direction of arrow b, applying a predetermined pressure contact force (F) between the thermal head 29 and the platen roller 20, and rotating the platen roller 20,
The paper P is conveyed in the direction of arrow d, and the ink ribbon 2
4 is moved in the direction of arrow c. During this time, the print element of the thermal head 29 is heated based on the print data, and the ink of the ink ribbon 24 is printed at a predetermined position on the paper P.
Further, since the transport rolls 33a and 33b are positioned on the extension line L'of the above-mentioned printing element "L", the transport process of the paper P in the arrow d direction is assisted during the printing process, and the paper P is deviated. Prevent it from being sent.

After that, when the printing process for one of the three colors of yellow (Y), magenta (M), and cyan (C) is completed, the printing process for the next color is performed, so the auxiliary roll 33
a and 33b are driven in reverse rotation (conveyed in the direction of arrow d '),
For example, the paper P is fed in the reverse direction until the leading edge of the paper P reaches directly below the printing element "L". Also in this case, the auxiliary roll 33a,
Since 33b is located on the extension line L'of the printing element "L",
The paper P will not be biased and conveyed.

After that, the paper P is moved twice more in the forward direction (direction of arrow d) and in the reverse direction (direction of arrow d '), and three colors of yellow (Y), magenta (M) and cyan (C) are selected. The ink is printed on the paper P at a predetermined position. Even when driven in this manner, the auxiliary rolls 33a and 33b are integrally movable by the auxiliary roll shaft 31, the driving force at both ends of the paper P and the transport speed are constant, and the paper P is not displaced. The printing position accuracy is also extremely stable, and an image with excellent printing quality can be obtained. Further, since the auxiliary rolls 33a and 33b are provided integrally with the thermal head 29, the thermal head 29 is used as the fulcrum 2 at the time of maintenance such as replacement of the ink ribbon 24.
Maintenance can be easily performed by rotating and retracting largely around 2a and 22b.

In the above-described embodiment, the auxiliary roll mechanism has a structure in which the tips of the pressure springs 35, 35 are brought into contact with the auxiliary roll shaft 31 to apply a biasing force to the auxiliary rolls 33a, 33b. It is not limited to, for example, FIG.
The bearing base 38 having the structure shown in FIG. 2 may be attached to the upper surface of the thermal head 29, the biasing force of the biasing member 40 can be adjusted by the screw 42, and the auxiliary roll shaft 31 may be held by the pressing member 41. .

In another embodiment, the crimp spring 35
Is not limited to a rod shape, and may be a spring having another shape such as a leaf spring. Further, in the above-described two embodiments, the auxiliary rolls 28a, 28b (33a, 33b) are configured to rotate by the driving force transmitted via the auxiliary roll gear 27 (32), but the auxiliary roll gears 27 (32). It is also possible to use a driven roll that is driven by the platen roller 20 without providing (1).

[0032]

As described above in detail, according to the present invention, the paper can be fed accurately and stably, and printing can be performed at the correct position, so that an image having excellent printing quality can be obtained. be able to.

Further, even in the case of color printing, the printing position accuracy is excellent and the color moire processing is not required, and from this point also an image of high printing quality can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a printing apparatus according to an embodiment.

FIG. 2 is a schematic side view of a printing apparatus according to an embodiment.

FIG. 3 is a schematic configuration diagram of a printer according to another embodiment.

FIG. 4 is a configuration diagram of an auxiliary roll mechanism of a printing apparatus according to another embodiment.

FIG. 5 is a diagram showing a modification of the auxiliary roll mechanism of the printing apparatus of another embodiment.

FIG. 6 is a schematic configuration diagram of a conventional printing device.

FIG. 7 is a schematic configuration diagram of a conventional printing device.

[Explanation of symbols]

 19 drive gear 20 platen roller 20a rotary shaft 21 platen gear 22, 29 thermal head 22a, 22b support shaft 24 ink ribbon 25 frame 26, 31 auxiliary roll shaft 27, 32 auxiliary roll gear 28a, 28b, 33a, 33b auxiliary roll 30 bearing holder 30 ′ Long hole 31 Auxiliary roll shaft 34 Spring receiver 35 Crimping spring 36 Bearing 39, 40 Biasing member 41 Holding member 42 Screw

Claims (1)

[Claims] 1. A print head comprising a large number of printing elements arranged in a line and being orthogonal to the printing elements arranged in a line and supported by a platen roller which is rotatable in forward / reverse directions. In a printing apparatus that presses a sheet of paper conveyed in a direction to perform printing, the sheet is nipped in cooperation with the platen roller at both end positions of the print head and extension of the press contact portion of the print head. A printing apparatus comprising a sheet conveyance assisting means.