JP3302491B2 - Thermal printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer, and more particularly, to a thermal printer which prints a wide print sheet with an ink ribbon interposed therebetween. The present invention relates to a variable thermal printer device.

[0002]

2. Description of the Related Art In a conventional thermal printer, a thermal head is pressed against a platen roller with a constant pressing force.
Printing is performed on a print-receiving sheet sandwiched between a thermal head and a platen roller.

[0003]

However, in the conventional thermal printer device, the thermal head is pressed against the platen roller with a constant pressing force. The pressure of the thermal head against the print head becomes inappropriate, resulting in defective printing or poor feeding of the print-receiving sheet or ink ribbon.

In addition, since the thermal head is constantly pressed against the platen roller with a constant pressing force, there is a disadvantage that the ink ribbon is wasted when there is an unprinted blank portion on the print target sheet. In other words, even if a brake mechanism is provided to suppress the feeding of the ink ribbon, and the ink ribbon is not conveyed only between the blank portions of the print target sheet, the ink ribbon is pressed by the platen roller by the pressing force of the thermal head. Therefore, the rotation of the platen roller causes the ink ribbon to be conveyed together with the print target sheet against the brake mechanism.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a thermal printer capable of printing with an optimal pressing force of a thermal head against a platen roller and saving ink ribbon. I do.

[0006]

In order to achieve the above object, the present invention provides a thermal printer in which a thermal head 24 swingably supported by a support frame 34 is pressed against a platen roller 12 by a pressing mechanism 26. The pressing mechanism 26 is provided on the opposite side of the platen roller 12 with respect to the thermal head 24, and is rotatably supported by the support frame 34;
The tip of the pressing frame 54 and the thermal head 2
4 and a spring member 56 for urging the thermal head 24 toward the platen roller 12 and a rear end forked portion of the pressing frame 54 to form a continuous curved surface.
The cam surface is inscribed in the forked part and rotated.
The pressing frame 54 is swung so that the leading end of the pressing frame 54 is moved close to or away from the platen roller 12.
The thermal head 24 and the platen roller 12
A cam member 58 for adjusting the biasing force of a spring member 56 for biasing the pressing frame and the distal end side of the thermal head.
The swingable arm and the thermal head are
Move the thermal roller so that it moves parallel to the Latin roller.
A vertical operation arm for restricting swinging of the rear end of the pad .

[0007]

According to the present invention, the thermal head 24 is pressed against the platen roller 12 by the spring member 56 provided between the tip of the pressing frame 54 and the thermal head 24. Then, the pressing frame 54 is swung by the cam mechanism 58 that engages with the rear end of the pressing frame 54,
The tip of the pressing frame 54 is moved toward and away from the platen roller 12. Thereby, the thermal head 24
Of the thermal head 24 against the platen roller 12 can be adjusted. That is, as the distal end of the pressing frame 54 moves away from the platen roller 12, the pressing force with which the thermal head 24 presses the platen roller 12 decreases, and the pressing frame 5
As the leading end of the plate 4 approaches the platen roller 12, the pressing force of the thermal head 24 pressing the platen roller 12 increases.

Further, according to the present invention, from a continuous curved surface
Cam surface is inscribed in the forked part of the pressing frame and rotated
And by continuously changing the pressing force of the thermal head 24 against the platen roller 12
If the amount of rotation of the cam member 58 is increased , the operating width of the front end portion of the pressing frame 54 toward and away from the platen roller 12 can be increased, and the thermal head 2
4 can be separated from or contact with the platen roller 12. At this time, the pressing frame 54
And the leading end of the thermal head 24 are swingably connected.
And the swing of the rear end side of the thermal head 24
The vertical operation arm 50 is
It is moved parallel to the Latin roller 12.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a thermal printer according to the present invention. FIG.
FIG. 1 is an overall view of a thermal printer according to the present invention, in which a platen roller 12 is rotatably supported by a casing 10. The timing pulley 12 of the platen roller 12
The timing belt 14 engaging with the first stepping motor 16 is a timing pulley 16
A, the guide roller 18 and the pinch roller 20 are suspended between the feed roller 21 and the timing pulley 21A that rotates the pinch roller 20. The pinch roller 20 is brought into contact with the feed roller 21 by the compression spring 19. And
The print sheet 22 rewound from a paper supply reel (not shown) is sandwiched between the pinch roller 20 and the feed roller 21 and between the platen roller 12 and the thermal head 24. Thereby, the first stepping motor 1
When the sheet 6 is rotated in the direction A in the figure, the rotational force rotates the platen roller 12 and the feed roller 21 via the timing belt 14 to convey the sheet 22 to be printed in the direction a in the figure. When the first stepping motor 16 is rotated in the direction B in the drawing, a so-called back feed, in which the sheet 22 to be printed is conveyed in the direction b in the drawing, is performed.

Above the platen roller 12, a thermal head 24, a pressing mechanism 26 for pressing the thermal head 24 against the platen roller 12, a support frame for supporting a winding reel 30 and a supply reel 32 of an ink ribbon 28, and the like. A head frame 34 (hereinafter, referred to as a head frame) is provided, and a rear end of the head frame 34 is fixed to a head frame shaft 36 rotatably supported by the casing 10.
The rotating shaft 20A of the pinch roller 20 is connected to one end of a swing arm 38 whose center is swingably supported by the casing 10, and has a cam engaging plate 40 at the other end. Are rotatably connected at their lower ends.
A U-shaped cam guide is formed at the upper end portion 40A of the cam engaging plate 40, and the cam guide is engaged with a disk-shaped cam member 42 fitted eccentrically with respect to the head frame shaft 36. Are combined. The relationship between the cam guide and the cam member 42 is such that when the head frame 34 is swung upward with the head frame shaft 36 as a fulcrum shaft and the cam member 42 is rotated by a predetermined amount, the cam engaging plate 40 is pushed down. Is done. Accordingly, the swing arm 38 swings clockwise, so that the pinch roller 20 can be separated from the feed roller 21. Therefore, the head frame 34 (refer to FIG. 3) is swung so that the platen roller 1
2 is released, the pinch roller 20 and the feed roller 21 release the clamping force for clamping the sheet 22 to be printed, and the head frame 34 is swung to bring the thermal head 24 into contact with the platen roller 12. The clamping force returns.

Next, a pressing mechanism 26 for pressing the thermal head 24 against the platen roller 12 will be described with reference to FIGS. Pins 44 are provided on both sides on the tip side of the thermal head 24.
The front ends of a pair of arms 46, 46 are rotatably supported on the head frames 3, 4.
4, a fulcrum pin 48 fixed to both side plates 34A, 34A,
48 is rotatably supported. In addition, thermal head 2
4, an arm 50 bent obliquely downward is provided on the rear upper side.
A rotating shaft 52 having a front end attached thereto (hereinafter referred to as a vertical operation arm) and having a U-shaped rear end supported by both side plates 34A, 34A of the head frame 34.
Is engaged. Thus, when the thermal head 24 is swung about the fulcrum pins 48, 48, the thermal head 24 is maintained horizontal, that is, parallel to the platen roller 12 by the action of the vertical operation arm 50, the arm 46, and the pin 44. Can be. Therefore, the thermal head 24 is fixed to the platen roller 12 by a pair of left and right compression springs described later.
When pressed, the thermal head 24 can be evenly pressed against the platen roller 12 and the pressing position can be kept constant.

A substantially central portion of both side plates 54A of the pressing frame 54 is rotatably supported by the pair of fulcrum pins 48, 48, and a portion between the distal end portion 54A and the thermal head 24 is provided. Has a pair of left and right compression springs 5
A pair of disc-shaped cams are provided with eccentrically fitted cam guides formed on the rear ends 54B of both side plates 54A, 54A. The members 58, 58 are engaged. Each of the cam members 58 is
The peripheral surface becomes a cam surface consisting of a continuous curved surface, and this cam surface
When the cam member 58 rotates by rotating the cam frame 58 in contact with the cam guide , the pressing frame 54 continuously swings with the fulcrum pin 48 as a fulcrum. Approach / separate from

Also, as shown in FIG.
The take-up reel 30 and the supply reel 32 are rotatably supported by a head frame 34, and the ink ribbon 28 rewound from the supply reel 32
It is guided by 0, 60, 60, passes between the thermal head 24 and the platen roller 12, and is connected to the take-up reel 30. Also, the timing pulley 30 of the take-up reel 30
A, the timing belt 62 engaging with the guide roller 6
4. Timing pulley 66 (see FIG. 3) fitted to one end of rotating shaft 52 of pressing mechanism 26 and head frame shaft 3
6 is suspended over a pulley 68 rotatably fitted to the pulley 6. The one-way clutch is incorporated in each of the timing pulley 30A of the take-up reel 30 and the timing pulley 66 of the pressing mechanism 26. And take-up reel 3
The one-way clutch 0 allows the take-up reel 30 to rotate only in the direction in which the ink ribbon 28 is wound, and the one-way clutch in the pressing mechanism 26 rotates only in the direction opposite to the direction in which the take-up reel 30 is wound. The shaft 52 is made rotatable. Further, the timing pulley 7 of the second stepping motor 70 capable of rotating forward and reverse with the pulley 68 of the head frame shaft 36.
0A, the timing belt 72 is suspended. Thereby, when the second stepping motor 70 is rotated in the direction C (clockwise) in the figure, the take-up reel 30 rotates via the timing belts 62 and 72, and the ink ribbon 28 wound around the supply reel 32 is rotated. Take up. At this time, the rotation shaft 52 of the pressing mechanism 26 is not rotated by the one-way clutch. When the second stepping motor 70 is rotated by a predetermined amount in the direction D (counterclockwise) in the figure, only the rotation shaft 52 of the pressing mechanism 26 rotates by a predetermined amount while the rotation of the take-up reel 30 is stopped. As described above, the rotation of the cam member 58 is performed by the second stepping motor 70, and the pressing frame 54 swings in conjunction with the rotation of the cam member 58, and the leading end 54A of the pressing frame 54 It approaches and separates from 12. The supply reel 32 of the ink ribbon 28 has a built-in brake mechanism. By operating the brake mechanism, the feeding of the ink ribbon 28 is stopped.

While the sheet 22 to be printed is being conveyed, a paper thickness sensor 74 for detecting the thickness of the sheet 22 to be printed, a sheet sensor 76 for detecting the presence or absence of the sheet 22 to be printed, A ribbon sensor 78 for detecting the presence or absence is provided. The print sheet 22 printed by the thermal head 24 and the platen roller 12
Is cut at a predetermined position by a cutting section 80 composed of a rotary cutter 80A and a contact member 80B with which the rotary cutter 80A comes into contact.

Next, the operation of the thermal printer according to the present invention having the above-described structure will be described. First, the head frame 34 is swung upward to separate the thermal head 24 from the platen roller 12 and to separate the pinch roller 20 from the feed roller 21. Then, the leading end of the print-receiving sheet 22 is pulled out from the paper supply reel, and set between the pinch roller 20 and the feed roller 21 and between the thermal head 24 and the platen roller 12. Further, the leading end of the ink ribbon 28 is pulled out from the supply reel 32, and is connected to the take-up reel 30 through the space between the thermal head 24 and the platen roller 12.

Next, the head frame 34 is swung until it is locked to the platen roller 12, so that the thermal head 24 is brought into contact with the platen roller 12 and the pinch rollers 20A, 20B are returned to the holding force. Next, when the head frame 34 is locked, the paper thickness sensor 74
Detects the thickness of the print-receiving sheet 22, and the detection result is output to the second stepping motor 70. Then, based on the detection result, the second stepping motor 70
Rotate a predetermined amount in the direction (counterclockwise). The rotational force of the second stepping motor 70 is controlled by the timing belts 62 and 7.
2, the rotation shaft 52 of the pressing mechanism 26 is rotated by a predetermined amount. At this time, the take-up reel 30 does not rotate due to the one-way clutch. When the rotation shaft 52 of the pressing mechanism 26 rotates by a predetermined amount, the eccentric cam member 58 causes the pressing frame 54 to swing. For example, as shown in FIG. 2, when the sheet thickness of the print-receiving sheet 22 is small, the rear end portion 54B
The cam member 58 is rotated by a predetermined amount so that the roller swings upward, and the distance between the pressing frame 54 and the platen roller 12 is reduced. That is, the rear end portion 54B of the pressing frame 54
Cam member 58 engaged in the forked cam guide
By swinging upward by the action of (1), the distal end portion 54A of the pressing frame 54 swings downward, and the distance between the pressing frame 54 and the platen roller 12 is reduced. As a result, the urging force of the compression spring 56 for urging the thermal head 24 against the platen roller 12 is increased, so that the pressing force of the thermal head 24 against the platen roller 12 is small even when the sheet 22 to be printed is thin. It does not become too much. Therefore, printing failure and feeding failure of the printing target sheet 22 and the ink ribbon 28 do not occur.

Further, as shown in FIG.
2 is thick, the rear end 5 of the pressing frame 54
The cam member 58 is rotated by a predetermined amount so as to swing 4B downward. As a result, the distal end portion 54A of the pressing frame 54 swings upward, the distance between the pressing frame 54 and the platen roller 12 increases, and the urging force of the compression spring 56 is weakened. Even if the thickness is large, the pressing force of the thermal head 24 against the platen roller 12 does not become too large. At this time, the cam member
The pressing force of the thermal head 24 is continuously
It can be changed continuously,
Driving is easily performed. Furthermore, when the paper thickness changes
Thermal head 24 keeps parallel to platen roller 12
The thermal head 24 can be moved while
The position where the roller 12 is pressed can be kept constant, and the printing quality can be improved.
Can be kept good.

Next, when the pressing force of the thermal head 24 against the platen roller 12 is appropriately adjusted, the first stepping motor 16 rotates in the direction A to
2 and the second stepping motor 70 rotates in the C direction to transport the ink ribbon 28. Then, printing on the print-receiving sheet 22 by the thermal head is started. In this printing operation, the printing target sheet 22
There is a blank area that does not require printing on the thermal head 2
When the printing operation of No. 4 is stopped, the printing operation stop information of the thermal head 24 is output to the second stepping motor 70 and the brake mechanism of the supply reel 32 of the ink ribbon 28. Then, while the rotation of the supply reel 32 stops,
The second stepping motor 70 switches the rotation direction from the C direction to the D direction based on the print operation stop information,
The rotation of the take-up reel 30 also stops. Further, the second stepping motor 70 rotates a predetermined amount in the direction D, and the pressing mechanism 2
6 by rotating the cam member 58 of FIG. 6 to separate the distal end portion 54A of the pressing frame 54 from the platen roller 12,
The thermal head 24 is slightly separated from the platen roller 12. Thus, the print-receiving sheet 22 is nipped and conveyed by the pinch roller 20 and the feed roller 21, but the ink ribbon 28 is not conveyed. Also, the print-receiving sheet 22
Is transferred from the space portion to the printing portion, and based on the printing operation information of the thermal head 24, the second stepping motor 70, the take-up reel 30, the supply reel 32, and the pressing mechanism 26 The operation is performed in the reverse step, and the thermal head 24 contacts the platen roller 12 and the pressing force of the thermal head 24 is reduced.
And the ink ribbon is transported and printing is performed again. Therefore, the ink ribbon 28 is conveyed only when printing is performed on the print-receiving sheet 22, so that the ink ribbon 28 can be saved.

In this embodiment, the cam member 58 of the pressing mechanism 26 is rotated by the driving force of the second stepping motor 70. However, the cam member 58 is manually separated from the driving force transmitting mechanism of the second stepping motor 70. May be rotated. Further, the thermal head 2 is pressed by the pressing mechanism 26.
4 is adjusted based on the thickness of the sheet 22 to be printed, but is not limited to this. For example, the pressing force of the thermal head 24 may be adjusted appropriately based on the transport speed of the sheet 22 to be printed. It may be adjusted to obtain pressure.

[0020]

As described above, according to the thermal printer of the present invention, the thermal head presses the platen roller by the spring member provided between the tip of the plate and the thermal head. The leading end of the plate is continuously moved toward and away from the platen roller by the cam mechanism that engages the rear end of the plate, the biasing force of the spring member is changed, and the tip of the thermal head is pressed. Thick frame
Arm and the thermal head
Since the vertical movement arm that regulates the swing of the end side is provided ,
Check the pressing position of the thermal head against the platen roller.
The pressing force of the thermal head can be adjusted while keeping it constant . Thus, for example, even if the sheet thickness of the sheet to be printed changes, the pressing force of the thermal head against the platen roller can be adjusted according to the sheet thickness, thereby preventing printing failure or feeding failure of the sheet to be printed or the ink ribbon. it can.

The thermal head can be separated from the platen roller or brought into contact with the platen roller by increasing the operating width of the leading end of the plate-like body toward and away from the platen roller. In this way, if there is a blank area on the sheet to be printed that does not require printing during printing, the thermal head is separated from the platen roller, and only the sheet to be printed is transported by, for example, a feed roller, and the ink ribbon is not transported. As a result, the ink ribbon can be saved.

[Brief description of the drawings]

FIG. 1 is an overall view of a thermal printer according to the present invention.

FIG. 2 is an explanatory view for explaining the structure of the pressing mechanism of the thermal printer device of the present invention and the operation of the pressing mechanism when the sheet thickness of the print-receiving sheet is small.

FIG. 3 is a front view illustrating a pressing mechanism of the thermal printer according to the present invention.

FIG. 4 is an explanatory diagram for explaining an operation of a pressing mechanism when a sheet to be printed is thick;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Casing 12 ... Platen roller 16, 70 ... 1st and 2nd stepping motor 19, 56 ... Compression spring (spring member) 20 ... Pinch roller 21 ... Feed roller 22 ... Printed sheet 24 ... Thermal head 26 ... Pressing mechanism DESCRIPTION OF REFERENCE NUMERALS 30: Ink ribbon take-up reel 32: Ink ribbon supply reel 34: Head frame (support frame) 36: Head frame shaft 38: Swing arm 40: Cam engaging plates 42, 58 ... Cam member 44: Pin 46 arm 48 ... A fulcrum pin 50... A vertical operation arm 52... A rotating shaft 54... A pressing frame 54 </ b> A.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 25/312 B41J 2/32 B41J 25/316

Claims (1)

(57) [Claims] 1. A thermal printer device in which a thermal head supported swingably by a support frame is pressed against a platen roller by a pressing mechanism, wherein the pressing mechanism is opposite to the platen roller with respect to the thermal head. And a spring member rotatably supported by the support frame and provided between the distal end of the press frame and the thermal head to bias the thermal head toward the platen roller. , Which engages the rear forked portion of the pressing frame and has a continuous curved surface.
The distal end portion of the pressing frame to oscillate the press frame as close-spaced with respect to the platen roller by rotating by inscribing the beam surface bifurcated portion, with the thermal head to the platen roller side A cam member for adjusting the biasing force of the biasing spring member, the pressing frame and the thermal head.
Arm that connects the tip of the
The plate moves parallel to the platen roller.
Vertical movement arm that regulates the swing of the rear end of the thermal head.
Thermal printer apparatus characterized by comprising a beam and,.