JP2002086769A - Line thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a line thermal printer in which a contact pressure between a line thermal head 30 and a platen 21 is easily maintained to be uniform even if a head frame 28 is deformed. SOLUTION: In the line thermal printer 1, a pressing force of an elastic member 39 is made to act to the line thermal head 30 from a head arm 24 directly without being passed through the head frame 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing section of a line thermal printer.

[0002]

2. Description of the Related Art In a line thermal printer, a line thermal head is arranged so as to face a platen, and a thermal paper or a thermal ink ribbon and a paper are passed between them to perform printing. In this case, the state of the contact pressure of the line thermal head against the platen greatly affects the quality of printing. However, since the line thermal head is rigid and long in the axial direction of the platen, it is necessary to maintain the parallelism with respect to the platen axis as accurately as possible. It is required that the contact pressure be uniform in the direction (main scanning direction). For this reason, in a printing mechanism that uses a line thermal head, a spring is arranged on the left and right in the main scanning direction between the head frame on which the line thermal head is mounted and the head arm that supports it, and the line thermal head is placed on the platen. To maintain an appropriate contact pressure and a uniform contact pressure on the sheet by the reaction force.

The balance pressure adjusting mechanism disclosed in Japanese Patent Application Laid-Open No. Hei 5-169689 has a head fixing bracket mounted on a head frame mounted on a main body frame side so as to be swingable at a central portion in a longitudinal direction, and the left and right sides of the fixing bracket are connected to a head. A structure pressed by a pressure spring is disclosed. The line thermal head is fixed to a head fixing bracket. It is characterized in that it has a pressing force adjusting means for the head pressure spring and a pressing force display means.

In the thermal printer disclosed in Japanese Patent Application Laid-Open No. 6-143736, a head frame is mounted between a lower chassis and an upper chassis so as to be swingable in the vertical and horizontal directions.
It discloses a structure in which two spring members are arranged between an upper chassis and a head frame at an interval in the main scanning direction. The line thermal head is fixed to the head frame. As a structure for swinging the head frame in the left-right direction, a structure in which a protrusion provided at the center of the rear portion of the head frame is fitted into a concave groove provided in the upper chassis. The pressing device disclosed in Japanese Patent No. 2995420 discloses a structure in which two springs are arranged at intervals in a main scanning direction between a head support to which a line thermal head is fixed and a pressing plate on a main body case side. I have. It is characterized in that the line thermal head is easily attached to and detached from the body frame.

As described above, the conventional mechanism comprises a spring between a head fixing member or a head frame or a head support (hereinafter referred to as a head frame) to which the line thermal head is mounted and a member (head arm) on the main body frame side. The line thermal head is pressed toward the platen via a head frame. However, the head frame is softer in material than the substrate of the line thermal head, and is easily lifted up relatively frequently for ribbon saving in which only the paper is sent without performing printing. In addition, deformation due to a change in temperature is likely to occur. Although this deformation is very slight, it has a great effect on the contact pressure between the line thermal head and the platen. The head frame is often rotated so as to be lifted by the head arm on the body frame side when paper is set in the printer, but such a structure also easily causes deformation of the head frame.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a line thermal printer which can easily maintain a uniform contact pressure between a line thermal head and a platen even when a head frame is deformed.

[0007]

A platen is rotatably provided on a main body frame, a head arm is attached, and a head frame is arranged between the platen and the head arm to hold a line thermal head. Then, an elastic member such as a compression spring is disposed between the head arm and the line thermal head to urge the line thermal head toward the platen. That is, the pressing force of the elastic member is applied directly to the line thermal head from the head arm without passing through the head frame. The line thermal head maintains a contact pressure between the line thermal head and the sheet by the reaction force.

The elastic member sometimes exerts a pressing force on the line thermal head via a pressing member attached to the head arm. The pressing member has, for example, a pin shape and is attached to the head arm so as to be able to reciprocate along an axis in a direction from the head arm to the platen. The pressing member is provided at least two times in the main scanning direction of the line thermal head.
It is preferable to provide a location.

A line thermal head is often supported on a head frame movably in a direction toward a platen. One mode of the movement is that the line thermal head is supported by the head frame at a substantially central position in the main scanning direction, and the left and right ends can swing up and down. of course,
A structure that can swing without a special fulcrum may be used. The line thermal head is supported on a head frame by a screw member and is detachable. If one end of the screw member is projected to the upper surface side of the head arm to form a manual operation unit, the attachment / detachment work is easy.

When the pressing members are arranged at at least two places in the main scanning direction of the line thermal head, an adjusting member for adjusting the pressing force of the elastic member on the line thermal head may be provided on one of the pressing members. When there is a change in the thickness of the paper in the width direction or when printing is performed using one side of the printable width such as receipt printing, contact at the printing location can be changed by changing one pressing force in the main scanning direction. By making the pressure uniform, the quality of printing can be improved. The head arm, together with the line thermal head,
A configuration in which the line thermal head is movable between a first position not in contact with the platen and a second position in which the line thermal head is in contact with the platen, and when the head arm is in the first position, the line thermal head is not pressed by the elastic member. May be.

[00011]

FIG. 1 shows a line thermal printer 1 embodying the present invention, in which a front cover 3 and upper and right side wall covers 4 are opened with respect to a main body frame 2. FIG. 2 shows a state where the covers 3 and 4 are omitted and the paper 5 and the thermal ribbon 6 are loaded. The main body frame 2 includes a machine box 7, a bottom wall 8, and a rear wall 9 that form a left side wall. The machine box 7 has a main wall 10 that is arranged inwardly from the left side wall. The main wall 10 has a roll support shaft 11, a tension roller 12, a paper feed unit 13, a printing unit 14 (upper body frame 15, lower body frame 16), a rewinding side tape shaft 17 and a winding side tape shaft 18 from the rear. Are attached to the main wall 10 in a cantilever manner.

The paper roll 1 is supported by the roll support shaft 11.
8 (FIG. 2) can be easily detached manually. The tension roller 12 is made of a synthetic resin sponge, and has a friction between the paper 5 and is soft. When the tension of the paper is increased, the cross-sectional shape of the roller 12 is distorted to absorb the excessive tension and prevent the paper from being damaged. I do. Although not shown in detail, the paper feed unit 13 includes a feed roller, a guide roller, and a pinch roller that is disposed opposite to the feed roller and the guide roller in the vertical direction. Send to 14. A mechanism for rotating the feed roller and its control mechanism are housed inside the machine box 7. The left end of the pinch roller can be moved up and down by the hinge structure on the main wall 10 side.

The printing section 14 is composed of an upper body frame 15 and a lower body frame 16 which are vertically opposed to each other (FIG. 3).
A platen 21 is disposed on the lower main body frame 16.
The upper body frame 15 has left and right frame walls 22 and 23 in parallel, between which a head arm 24 (FIG. 5) is attached so as to be rotatable in the vertical direction. This vertical rotation is performed by rotating an operation lever 25 provided on the right frame wall 23. The state rotated forward in FIG. 3 is the printing position (second position), and the state rotated upward in FIG. 4 is the retracted position (first position).

The head arm 24 has support pins 26 and 27 which are long in the main scanning direction (horizontal direction) and are slidable in the platen direction (vertical direction) at intervals on the left and right, respectively. The frame 28 is fixed.
The left and right support pins 26 and 27 have stopper rings 2 at the top.
9 is secured. A line thermal head 30 is arranged on the lower surface side of the head frame 28, and is fixed to a lower end of a mounting pin 31 penetrating through a central portion of the head frame 24.

That is, the mounting pin 31 is enlarged at the upper end to form a manual operation section 32, and has a male screw 33 with a reduced diameter at the lower end. It is screwed into a female screw 34 formed at the center of the thermal head 33. At this time, the depth of the female screw 34 is larger than the length of the male screw 33 in the head frame 2.
8 is formed shallower than the thickness of the line thermal head 30.
When it is screwed and fixed to the female screw 34, a slight gap is generated between the lower surface of the head frame 28 and the upper surface of the line thermal head 30. This gap is 0.5mm
This is the clearance when the line thermal head 30 is tilted right and left. Reference numeral 35 denotes a stopper ring.

Further, between the head arm 24 and the line thermal head 30, left and right pressing pins 35, 36 are further provided.
Are arranged to press the line thermal head 30 toward the platen during the printing operation. That is, the pressing pins 35 and 36 are slidably inserted into the left and right portions of the head arm 24 with respect to the platen in the up-down direction. Locking ring 3 fixed at the bottom
A compression spring 39 as a male member is disposed between 8, 8 and the lower surface of the head arm 24. The lower ends of the pressing pins 35 and 36 can be in direct contact with the line thermal head 30 through holes provided at corresponding locations of the head arm 28. FIG. 5 shows a state in which the head arm 24 is rotated upward. Since the head frame 28 is hanging from the head arm 24, the lower ends of the pressing pins 35 and 36 are attached to the line thermal head 30. Not in contact.

FIG. 6 shows a line thermal headset 20.
Is in the printing position, the line thermal head 30 is moved from the head arm 24 moved downward to the compression spring 3.
9 and is pressed against the platen. Then, the line thermal head 30 maintains the contact pressure against the paper 5 by the reaction force. At this time, the compression spring 3
The elasticity of 9 presses the pressing pins 35 and 36, and the tips press the line thermal head 30 directly. Code 40
Is an adjusting screw which is tapped and screwed into the head arm 24 and whose lower end is in contact with the pressing plate 41. The pressing plate 41 includes the right support pin 27 and the pressing pin 36.
These are used as guides so as to be slidable, and are constantly urged upward by a compression spring 39. Adjustment screw 4
When screwing 0, platen 21 and line thermal head 3
The interval to 0 becomes smaller on the right side. Further, the contact pressure on this side can be increased. Turning the adjusting screw 40 in the opposite direction to raise the pressing plate 41 can lower the contact pressure.

The pinch roller of the paper feed unit 13 is lifted upward, and the operation lever 25 of the printing unit 14 is rotated to form a gap between the headset 20 and the platen 21 (FIG. 4). Is set around the tension roller 12 and the paper feed unit 13 and the print unit 14 as shown in FIG. In addition, the heat-sensitive ribbon 6 of the roll mounted on the rewinding-side tape shaft 17 is passed through the space between the line thermal head 30 and the platen 21 in the printing unit 14 and attached to the opposite winding-side tape shaft 18.

When the line thermal head set 20 is lifted by the operation lever 25 (FIG. 4), the line thermal head 30 is hung by the head arm 24 via the mounting pin 31 (FIG. 5). The lower ends of 35 and 36 are separated from the line thermal head 30. The head frame 28 also has left and right support pins 2.
6 and 27, the initial thermal gap between the line thermal head 30 and the lower surface of the head frame 28 is 0.5 mm. Then, the pinch roller is lowered and locked, and the head set 20 is lowered by the operation lever 25 to set the print position.

Then, the head arm 24 is brought into contact with the paper 5 with the line thermal head 30 sandwiching the thermal ribbon 6, and the head frame 28 engages the bent portions on both sides with the guide member on the lower main body frame 16 side and further moves. Is positioned at a position slightly lower than the position where the movement stops. For this reason, the pressing pins 35 and 36 move downward via the compression spring 39 and the stopper ring 38, and the leading ends thereof come into contact with the line thermal head 30 to press both ends of the line thermal head 30. That is, the line thermal head 30 is directly urged with the head arm 24 as a reference without going through the head frame 28, and the reaction force is the contact pressure with the paper 4. Therefore, the contact pressure of the line thermal head 30 is not affected by the head frame 2 that is likely to be deformed, and a stable contact pressure can be maintained.

The width of the paper 5 is narrow, and the arrangement of the paper is
When it is deviated from the printable width of 4 (the length of the printable area of the line thermal head 30), the adjusting screw 40 is operated so that the contact pressure at the paper portion becomes uniform. The adjusting screw 40 connects the line thermal head 30 to the head frame 28.
It can also be used in the case of initial setting to arrange parallel to the lower surface.
Although the line thermal head 30 may be inclined by the adjusting screw 40, the inclination is extremely small, so that it is sufficient to provide a clearance for slidably attaching the mounting pin 31 to the head arm 24. . However, a slight change in the position at both ends of the line thermal head 30 causes a large change in the contact pressure.
In FIG. 5, the position of the locking ring 38 for receiving the compression spring 39 is adjusted by the adjustment screw 40 on the left pressing pin 35.
The position that is higher than the right pressing pin 36 provided with is a size adjustment for using the compression spring 39 of the same size.

[0022]

According to the present invention, the pressing force acting as a reaction force acting between the platen and the head arm via the line thermal head is stabilized, and uniform and clear printing can be always obtained. Since the line thermal head is supported at the center and both ends can be elastically displaced, the line thermal head flexibly responds even to paper with changing thickness or paper with wavy, uniform and beautiful printing Can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall perspective view showing a cover opened.

FIG. 2 is a perspective view showing a state where a cover is removed.

FIG. 3 is a perspective view (printing position) showing a printing section taken out.

FIG. 4 is a perspective view showing a print section taken out (retreat position).

FIG. 5 is a front view schematically showing the line thermal headset (retreat position).

FIG. 6 is a front view schematically showing the line thermal headset (print position).

FIG. 7 is a front view schematically showing a mounted state of a sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Line thermal printer 2 Main body frame 3 Front cover 4 Top / right side wall cover 5 Paper 6 Thermal ribbon 7 Machine box 8 Bottom wall 9 Rear wall 10 Main wall 11 Roll support shaft 12 Tension roller 13 Paper feed section 14 Printing section 15 Upper main body frame 16 Lower body frame 17 Rewind-side tape shaft 18 Rewind-side tape shaft 19 Paper roll 20 Line thermal headset 21 Platen 22 Left frame wall 23 Right frame wall 24 Head arm 25 Operating lever 26 Support pin (left) 27 Support pin (right) ) 28 Head frame 29 Stopper ring 30 Line thermal head 31 Mounting pin 32 Manual operation unit 33 Male screw 34 Female screw 35 Left pressing pin 36 Right pressing pin 37 Stopper ring 38 Locking ring 39 Compression spring 40 Adjusting screw 41 Push Board

Continued on the front page (72) Inventor Masahiko Ueda 6-1-12 Honcho, Tanashi-shi, Tokyo F-term (reference) in Citizen Watch Co., Ltd. Tanashi Works 2C065 AA01 AB01 AB03 CC05 CC10 CC17 CC18 CC24 DA03 DA04 DA17 DA23

Claims (10)

[Claims] 1. A main body frame, a platen rotatably provided on the main body frame, a head arm attached to the main body frame, a head frame holding a line thermal head, and a platen via at least the line thermal head. And an elastic member for biasing the line thermal head toward the platen by applying a pressing force as a reaction force between the head frame and the head arm. A line thermal printer characterized in that it acts on the line thermal head directly from the head arm without any intervention of the printer. 2. The apparatus according to claim 1, wherein the pressing force of the elastic member acts on the line thermal head via a head pressing member attached to the head arm so as to reciprocate along an axis in a direction from the head arm to the platen. The line thermal printer according to claim 1. 3. The line thermal printer according to claim 2, wherein at least two head pressing members are provided in a main scanning direction of the line thermal head. 4. The line thermal printer according to claim 2, wherein the head pressing member has a substantially pin shape. 5. The line thermal printer according to claim 1, wherein the elastic member is a compression coil spring. 6. The line according to claim 1, wherein the line thermal head is supported movably in a direction toward a platen with respect to a head frame. Thermal printer. 7. The line thermal printer according to claim 6, wherein the line thermal head is supported by a head frame at a substantially central position in the main scanning direction. 8. The line according to claim 7, wherein the line thermal head is supported on a head frame by a screw member having one end protruding toward the upper surface of the head arm and serving as a manual operation unit. Thermal printer. 9. An apparatus according to claim 1, wherein an adjusting member for adjusting a pressing force of said elastic member on said line thermal head is provided on at least one end side of said line thermal head in the main scanning direction. The line thermal printer according to any one of the above. 10. The head arm is movable between a first position where the line thermal head does not contact the platen and a second position where the line thermal head contacts the platen. When the head arm is at the first position, 11. The line thermal printer according to claim 1, wherein the elastic member is configured to release a pressing force applied to the line thermal head.