JPH06320829A - Thermal printer - Google Patents

Abstract

PURPOSE:To always enable sharp printing by simple operation even when the kind, width and thickness of paper to be used are changed. CONSTITUTION:Support plates 5 are integrally attached to the bearings supporting both ends of a platen roller 2 in a freely rotatable manner and a platen roller fine adjusting mechanism supporting an adjusting plate 6 whose eccentric contact part comes into contact with the lower edge of each of the support plates 5 in a freely revolvable manner by a shaft 33 is provided. When the pressing force of a thermal head 1 to the platen roller 2 is not uniform in its lateral direction, the adjusting plate 6 is revolved to finely adjust the platen roller 2 so that the end part of the platen roller 2 is allowed to approach and separate with respect to the thermal head and the pressing force of the thermal head in the lateral direction is uniformized to obtain sharp printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer which prints on paper by using a thermal head and a platen roller.

[0002]

2. Description of the Related Art Conventionally, in a thermal printer which prints by directly sandwiching a direct thermal paper or a thermal transfer ribbon and paper between a thermal head and a platen roller, a paper narrower than the width of the thermal head is used. When printing, the position where the thermal head is pressed by a cam or the like is changed in the longitudinal direction, so that the pressing force (thermal head pressure) applied to the thermal head is changed between the position with the paper and the position without the paper.

Further, the pressing force needs to be changed according to the type of paper used, the paper width, the thickness, etc., but conventionally, when changing the pressing force, for example, an eccentric cam is directly applied to a pressing leaf spring. , It was done by changing the amount of deflection of the leaf spring. Further, in a thermal printer, printing is generally performed on a thin paper such as a label and on a thick paper called a tag paper. At that time, printing is performed in an optimum state. In order to do so, the position of the heat generating portion of the thermal head is usually slightly different between the two.

Therefore, conventionally, a label printer for label printing and a tag printer for tag paper printing are shipped as separate products with different positions of the above-mentioned heat generating units in advance, or service is provided each time the printer is used. The position of the heat generating part was adjusted according to the type of paper used by man.

[0005]

However, there is a problem in that it is troublesome to apply the pressing force applied to the thermal head by changing the position where the thermal head is pressed in the longitudinal direction by a cam or the like as described above. It was In addition, in order to perform optimal printing according to the type of paper, it is troublesome to prepare two types of printers for thin paper such as labels and thick paper such as tag paper. If a service person adjusts the position of the heat generating part according to the type of paper to be used each time in the field, it not only takes time, but it also takes time before the printer can be used. It was

The present invention has been made in view of the above problems, and it is possible to always perform clear printing by a simple operation even if the type of paper used, the paper width, the paper thickness, etc. are changed. In addition, it is an object of the present invention to prevent the thermal head and the platen roller from directly contacting each other and causing the platen roller to be worn even when printing a narrow paper.

When the paper is changed from a thin paper such as a label to a thick tag paper, or vice versa, the user can easily adjust the position of the heat generating portion of the thermal head to obtain clear printing. It is also intended to do so.
Another object of the present invention is to provide a thermal printer, which has a good assembling property and can easily replace the thermal head in a short time, at a low price.

[0008]

In order to achieve the above object, the present invention presses a direct thermal paper or a thermal transfer ribbon and a paper between a thermal head and a platen roller and presses a heat generating portion of the thermal head. A thermal printer that prints by generating heat is provided with a platen roller fine adjustment mechanism for finely adjusting and moving the end of the platen roller in a direction of approaching and separating from the thermal head.

Further, in the above thermal printer, there is provided a thermal head fine adjustment mechanism for finely adjusting and moving the end portion of the thermal head in the direction of approaching / separating from the platen roller, and further, the pressure applied to the thermal head is switched. It is effective to provide a pressing force switching means. Further, in the above thermal printer, it is preferable to provide a thermal head heat generating portion position adjusting means for moving and adjusting the position of the heat generating portion of the thermal head in the paper transport direction.

In any one of the above thermal printers, engaging members are integrally provided at both ends of the thermal head, and the engaging members are movably fitted in the U-grooves. It is even more effective to provide a pair of head holding members for holding the U.sub.2 and to form a step in the U groove for preventing the engagement member from falling off when the engagement member moves along the U groove.

[0011]

According to the thermal printer configured as described above, when the pressure applied to the platen roller by the thermal head is uneven in the width direction, the platen roller fine adjustment mechanism causes the end of the platen roller to move against the thermal head. If you make a fine adjustment in the approaching / separating direction, the pressure applied by the thermal head can be made uniform in the width direction.
Clear printing is possible.

Since the adjustment by the platen roller fine adjustment mechanism only moves the end portion of the platen roller toward and away from the thermal head, the pressurizing position in the longitudinal direction of the thermal head is changed by a cam or the like. This can be performed by a simple operation as compared with the case of adjusting.

Further, if the thermal head fine adjustment mechanism is provided, the direction in which the end portion of the thermal head is moved toward and away from the platen roller by the fine adjustment mechanism is used even when printing is performed on narrow thick paper. Since it can be finely adjusted and moved, clear printing can be performed on narrow thick paper without directly contacting the thermal head and the platen roller.

Further, by providing a pressing force switching means, the pressing force applied to the thermal head can be easily switched. Therefore, the type of paper used, the width of the paper, the thickness of the paper, the surface condition of the paper, the type of the thermal transfer ribbon are used. Even when things change, you can easily operate it and print clearly on paper.

Further, if the thermal head heat generating portion position adjusting means is provided, even if it is desired to print on both thin paper such as a label and thick tag paper, the corresponding 2
You can easily adjust the position of the heat generating part of the thermal head in the paper transport direction without having to call a service person each time you prepare a different type of printer or change the paper to be printed. It is possible to perform printing at the position of the heat generating portion suitable for.

Further, the engaging members projecting from both ends of the thermal head are movably fitted in the U grooves of the pair of head holding members, and when the engaging members move along the U grooves. If a step is formed in the U groove to prevent the engaging member from coming off, the thermal head can be easily removed by simply moving the engaging member along the U groove of the head holding member. Can be easily replaced, and since the U groove has a step, it is possible to prevent the thermal head from dropping at the time of removal.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a configuration diagram showing a main part of a thermal printer and its periphery showing an embodiment of the present invention, and FIG. 2 is a perspective view showing an assembled state of a thermal head of the thermal printer and each component holding the same. 3 is an exploded perspective view thereof, and FIG. 4 is a left side view of the thermal printer.

As shown in FIG. 1, this thermal printer holds a thermal transfer ribbon 3 and a sheet 4 between a thermal head 1 and a platen roller 2 or only a direct thermal sheet under pressure so that the heat generating portion of the thermal head 1 is heated. Printing is performed by heating 1a. The thermal head 1 is fixed to a head plate 11, and the head plate 1
1 has side plate portions 11 on both sides as clearly shown in FIG. 2 and FIG.
a, 11b, and each side plate portion 11a, 11b thereof
Pins 18, 18, which are engaging members, are integrally provided on the rear end side so as to project outward.

Further, the holding bracket 15 is provided corresponding to the head plate 11, and U-grooves 15a, 15a are respectively formed in the horizontal direction in a pair of side plate portions formed by bending both sides thereof at a substantially right angle. The pins 18, 18 of the head plate 11 are movably fitted in the U grooves 15a to hold the thermal head 1 via the head plate 11.

The pins 18, 18 are connected to the U groove 15
U groove 1 of the pin 18, 18 when moving along a
A step 15b is formed in each U groove 15a to prevent the step 15b from falling off from the 5a. The holding bracket 15 is rotatably supported in the direction of the arrow A by a fulcrum shaft 7 fitted as shown in FIG. 1 into holes 15c, 15c formed in the side plate portions on both sides, respectively. Is fixed to both side plates 40 and 41 shown in FIG.

Further, as shown in FIG. 3, the holding bracket 15 is formed by bending a hook 15f downward at a slight angle at the center of the head plate 11 side, and the hook 1 is formed.
One end of each of the leaf springs 17, 17 is fixed to both sides of 5f by screws at positions symmetrical with respect to the width direction.

Then, as shown in FIG. 2, the hook 15f of the holding bracket 15 is correspondingly inserted into the hole 11c formed in the center of the head plate 11, and the tip ends of the left and right leaf springs 17, 17 are inserted. When the upper surface of the holding bracket 15 is pushed down by the cam 16 for pressing the thermal head as shown in FIG. 1, each leaf spring 1
In FIG. 7, the left side is bent and the head plate 11 is pushed down, whereby the thermal head 1 is brought into pressure contact with the platen roller 2 with a predetermined pressing force.

As shown in FIG. 4, the cam 16 is fixed to substantially the center of the support shaft 27, and both ends of the support shaft 27 are supported by the side plates 40 and 41 on both sides via bearings, respectively. A pressure release lever 28 is fixed to one end side (right side in the figure) of the pressure release lever 28. Further, as shown in FIG. 1, both ends of the holding bracket 15 are pulled and urged upward by springs 30 and 30 (see also FIGS. 2 and 3), and the pressure release lever 28 is moved from the position shown in the figure to the timepiece. When it is rotated in the rotating direction, the pushing down by the cam 16 is released, so that it is rotated in the direction away from the platen roller 2 by the urging force of the spring 30.

As shown in FIG. 4, both ends of the platen roller 2 are rotatably supported by the left and right side plates 8 and 9 via bearings 31 and 31, respectively, and the cored bars inside the bearings 31 and 31 respectively. Collars 19 and 19 are rotatably fitted in the portion, and an E-ring is attached to the outer side of the collars to regulate lateral displacement.

FIG. 5 is a front view for explaining a platen roller fine adjustment mechanism for finely adjusting and moving the end of the platen roller in the direction of approaching and separating from the thermal head. Bearings 31, 3 for supporting both ends of the platen roller 2
1 is integrally fixed to the upper portions of the supporting plates 5 and 5 provided on both sides corresponding to each other, and the parallel surface portion of the bearing 31 formed on the back side in FIG. The same applies to the side) and is vertically movably fitted in a U-shaped guide groove 9a.

Below the bearing 31 of the support plate 5, 2
The individual long holes 5a, 5a are formed, and the pin 3 is formed in each long hole.
By inserting 2 and 32 and fixing one end thereof to the side plate 9, the support plate 5 can be moved up and down in the direction of arrow B without being laterally shaken.

Below the supporting plate 5, an adjusting plate 6 is provided on the shaft 3.
3 rotatably supports the eccentric abutment portion 6a formed on the upper edge of the adjusting plate 6 to abut on the lower edge portion of the support plate 5, and forms a V-shaped groove 6b in the arc-shaped portion of the lower edge. A plurality of steps are formed at intervals, and the claw portion of the lock leaf spring 22 is engaged with the V-shaped groove 6b so that the position of the adjusting plate 6 in the turning direction can be freely selected and fixed.

Generally, when the thermal head is assembled, when the thermal head is replaced, when it is transported or when it is dropped, the pressure applied to the paper and the platen roller by the thermal head is wide. In some cases, the positions may not be uniform in each direction (left and right in FIG. 4). This is a non-uniformity that cannot be illustrated, but if this happens, the printing state on either the left or right side of the thermal head will be faint, and clear printing cannot be performed.

However, in the thermal printer according to this embodiment, either one of both ends of the platen roller 2 can be selectively moved up and down to approach and separate from the thermal head 1 as described with reference to FIG. Therefore, clear printing can be performed even in the above case. For example, when the printing state on the right end side in FIG. 4 is slightly faded, the lower edge portion of the support plate 5 is rotated by rotating the adjustment plate 6 on the right end side in the clockwise direction from the position shown in FIG. Since the portion of the eccentric contact portion 6a where the amount of eccentricity increases becomes abutted, the support plate 5 ascends along with the bearing 31 along the guide groove 9a.

Therefore, the right end side of the platen roller 2 in FIG. 4 is pushed up and comes into strong pressure contact with the thermal head 1 and becomes parallel to the thermal head 1, so that the thermal head 1 is pressed over the entire width direction. Becomes uniform, and clear printing can be performed without blurring over the entire area.

FIG. 7 is a front view and a side view showing a thermal head fine adjustment mechanism for finely adjusting and moving the end of the thermal head toward and away from the platen roller. The thermal head fine adjustment mechanism finely moves the thermal head 1 toward and away from the platen roller 2 via the head plate 11 by rotating the head adjustment lever 26 shown in FIG. 7A. It is what makes me.

The head adjusting lever 26 is rotatably attached to the front side plate 9 by a shaft 23.
The shaft 23 is a shaft having a D-shaped cross-section formed by forming a flat surface on a part of its outer periphery, and a hole of a head adjusting lever 26 having a D-shaped hole corresponding to the shape is fitted therein. There is. As shown in FIG. 7B, the shaft 23 projects inside the side plate 9 (on the left side in the figure), and is rotatably supported by a bearing 25 fitted in that portion and fixed to the side plate 9. The eccentric plate 10 is attached to the left side of the bearing 25 of the shaft 23 in the figure by inserting a D-shaped hole formed corresponding to the shaft 23 and fixing it integrally with a screw 24. Note that FIG.
7B, for convenience of explanation, the position of the head adjusting lever 26 is illustrated in a state of being rotated with respect to FIG. 7A.

Then, on the right end side of the shaft 23 in the figure, the disc spring 3
4 is inserted and an E ring 35 is attached to the outer side thereof, and the head adjusting lever 26 is always pressed and urged toward the side plate 9.
Further, a protrusion 26a is formed on the tip end side of the head adjusting lever 26, and engaging holes 9b to 9d are formed at intervals on the side plate 9 side so as to correspond to the protrusion 26a, as shown in FIG. 7A. Then, the head adjusting lever 26 can be fixedly held at each rotating position by selectively inserting the protrusions 26a into the engaging holes, and the position of the eccentric plate 10 that rotates integrally with the head adjusting lever 26. I can change.

The eccentric plate 10 has a pin 12 (see FIGS. 2 and 3) having a screw hole 12a, which will be described later, integrally fixed to the head plate 11 as shown in FIG. The thermal head 1 is pushed up via the pin 12 and the head plate 11 according to the amount of eccentricity that varies depending on the rotation position of the platen roller 2.
Away from.

By the way, when the narrow thick paper 4 is set close to one end portion of the platen roller 2 as shown in FIG. 6, the thermal head 1 normally operates as shown in FIG. Not only does the thermal head pressure become non-uniform because the edge 4a of 4 is a fulcrum, but the left side of the sheet of paper 4 does not contact the thermal head 1 and the right side of the sheet 4 directly contacts the platen roller 2. It may happen.

In such a state, the platen roller 2 is adjusted by the platen roller fine adjustment mechanism as described with reference to FIG.
Even if the right end side is adjusted downward in FIG. 6, the thermal head 1 is still tilted with the edge 4a as a fulcrum, and the left side of the sheet 4 has a weak pressure although there is a degree of difference. It is impossible to avoid the state where the right side of the thermal head 1 is still in contact with the platen roller 2 as it is.

However, since this thermal printer is provided with the thermal head fine adjustment mechanism as described in FIGS. 7A and 7B, in such a case, the head adjustment lever 26 is moved to the position shown in FIG. If the projection 26a is rotated clockwise in (a) to be inserted into the engagement hole 9c or 9d and fixed, the eccentric plate 10 contacts the pin 12 and forcibly pushes it up. 1 is head plate 1
1 (0 <δ2 <δ1) or 9 (0 <δ1 <δ2) because it rises via 1 and separates from the platen roller 2.

Next, by rotating the adjusting plate 6 of the platen roller fine adjusting mechanism of FIG. 5, the right end side of the platen roller 2 in FIG. 8 or 9 is vertically moved and adjusted to the optimum position. For example, the paper 4 held between the thermal head 1 and the platen roller 2 can be pressed with a uniform head pressure over the entire width direction, and the platen roller 2 on the right end side of the thermal head 1 can be pressed. Contact can be avoided.

FIGS. 10 to 14 are views for explaining the pressing force switching means for switching the pressing force applied to the thermal head. As shown in FIGS. 10 and 11, the pressing force switching means is a pressing force switching member 13 formed of, for example, a thin metal plate between the upper surface of the holding bracket 15 to which the leaf spring 17 is attached and the cam 16 for pushing it down. 11 is inserted as shown in FIG. 11, or it is pulled out by sliding it toward the front side of the drawing as shown in FIG. 10 (FIGS. 12 and 13).
(See also
The pressing force for pressing 1 is changed so that the pressure applied to the platen roller 2 of the thermal head 1 integrated with the head plate 11 is switched.

The pressing force switching member 13 is shown in FIGS.
As shown in Fig. 12, one end of a flat plate formed in a T shape is bent to form an operating portion 13a, and elongated holes 13b and 13c are formed in parallel on the right side in FIG. Stepped screws 14 and 14 (see also FIG. 14) are fitted into and fixed to the upper surface of the holding bracket 15 so that the whole can be moved along the long holes 13b and 13c.

Further, the pressurizing force switching member 13 is formed with an abutting portion 13d which abuts against the cam 16 and has a predetermined width W, and the pressurizing force switching member 13 is provided with stepped screws 14 and 14 long. When the holes 13b and 13c are moved to positions near the right end in FIG. 12, the lower surface of the cam 16 rotated to a position closest to the pressing force switching member 13 causes the contact portion 13 to move.
It is arranged so that it is located away from d.

Further, when the pressing force switching member 13 is moved to the vicinity of the opposite end, as shown in FIG. 13, the lower surface of the cam 16 is positioned on the contact portion 13d. Then, as shown in FIG. 14, a spherical projection 13 is formed on the lower surface side of the pressing force switching member 13 so that the pressing force switching member 13 is positioned at the positions shown in FIGS. 12 and 13.
e is provided in a protruding manner, and correspondingly, engagement holes 15d and 15e are formed in the upper surface of the holding bracket 15.

Since the pressing force switching member 13 is formed in this manner, the cam 1 is moved to the position shown in FIG.
1 by rotating the pressure release lever 28.
As shown in 0, when the cam 16 is rotated to the position shown in the figure where the pressing force is applied, the cam 16 does not contact the pressing force switching member 13 and directly pushes down the upper surface of the holding bracket 15.

Therefore, the holding bracket 15 is pushed down to the inclination angle θ1 formed by the upper surface with respect to the horizontal line passing through the fulcrum shaft 7 serving as the rotation fulcrum and inclined, and the biasing force of the leaf spring 17 corresponding to the inclination angle θ1. The thermal head 1 moves to the platen roller 2 via the head plate 11 by the pressing force of
Is pressurized to.

When the pressurizing force switching member 13 is set to the position shown in FIG. 13 and the cam 16 is also rotated to the position where the pressurizing force is applied as shown in FIG.
6 presses down the upper surface of the holding bracket 15 via the pressing force switching member 13.

Therefore, this time, the inclination angle of the holding bracket 15 becomes an inclination angle θ2 (θ1 <θ2) inclining more by the plate thickness of the pressurizing force switching member 13, and the leaf spring corresponds to the increase of the inclination angle. The thermal head 1 is strongly pressed against the platen roller 2 by the pressing force strengthened by the increase in the deflection amount of 13.

As described above, the pressurizing force switching means according to this embodiment merely inserts or pulls out the pressurizing force switching member 13 formed of a thin plate between the cam 16 and the upper surface of the holding bracket 15. It is possible to change the inclination angle of the holding bracket 15 and change the pressure applied to the platen roller 2 of the thermal head 1 by a simple mechanism of.
Therefore, it is effective in reducing the number of parts and improving the assemblability.

By the way, in a thermal printer, printing is generally performed on a thin label sheet or the like, and on a thick sheet called a tag sheet, since printing is performed in an optimum state for them, It is necessary to make the position of the heat generating portion of the thermal head slightly different between them.

Therefore, in the thermal printer according to this embodiment, the thermal head 1a shown in FIGS. 15A and 15B is used to adjust the position of the heat generating portion 1a of the thermal head 1 in the paper transport direction (left-right direction in the figure). An L-shaped sheet metal member 21 which is a head heating unit position adjusting means is provided.

When the paper 4 to be printed is a thick paper such as a tag, as shown in FIG. 15A, a head unit composed of the thermal head 1 and the head plate 11 to which the thermal head 1 is integrally fixed, In the drawings of the side plate portions 11a and 11b (inner side of the drawing) formed on both sides of the head plate 11, the left end edges of the collars 19 and 19 which are rotatably attached to both ends of the core metal 2a of the platen roller 2, respectively. The heat generating portion 1a of the thermal head 1 is positioned on the platen roller 2 by being brought into contact with the respective outer peripheral surfaces.

When the paper 4 to be printed is a thin paper such as a label, the side plates 11a and 11b on both sides of the head plate 11 have the shape shown in FIG. 16 as shown in FIG. 15 (b). The sheet metal member 21 is attached by tightening the screws passing through the hole 21a into the screw holes 12a of the pin 12 shown in FIG.
The left end surface of the thermal head 1 is brought into contact with the outer peripheral surfaces of the collars 19, 19 attached to the platen roller 2 as shown in FIG. Is shifted rearward (to the right in the figure) by the plate thickness of the sheet metal member 21 for positioning.

In this thermal printer, when the thermal head 1 is detached in a unit state when it is replaced, the pressure release lever 28 is first rotated clockwise from the position shown in FIG. The pressure applied to the platen roller 2 of the thermal head 1 is released. Then, the holding bracket 15 is rotated about the fulcrum shaft 7 in the clockwise direction by the urging force of the spring 30, as shown in FIG.

In this state, the head plate 11 integrated with the thermal head 1 has the hook 15f of the holding bracket 15 inserted into the hole 11c formed at the center in the front, as described with reference to FIG. The pins 18 and 18 projecting from the
The hook 1 is held by being engaged with the grooves 15a, 15a.
Since 5f is slightly inclined downward, when the head unit in which the thermal head 1 is integrally fixed to the head plate 11 is pulled out in the direction of arrow C in FIG. 18, it is attached to the leaf spring 17 and the platen roller 2. It can be easily removed without being disturbed.

The U-grooves 15a, 15a on both sides are provided with a step 15b for preventing the pins 18, 18 from falling out of the U-groove 15a when the pins 18, 18 move along the groove. , When the head unit is pulled out from the holding bracket 15, the pin 18 abuts against the step 15b and its movement is temporarily stopped. Therefore, if the pin 18 is pulled out diagonally forward and pulled out, the head unit is mistakenly pulled from the holding bracket 15. It can be removed without dropping it.

[0055]

As described above, according to the present invention, the platen roller fine adjustment mechanism is used when uniform printing cannot be performed because the pressure applied to the platen roller by the thermal head is uneven in the width direction. Therefore, it is possible to make it uniform by just performing a simple fine adjustment such that the end of the platen roller is moved closer to or away from the thermal head, and clear printing can be performed.

Further, if a thermal head fine adjustment mechanism is provided, even when printing is performed on narrow thick paper, the mechanism finely moves the end portion of the thermal head toward and away from the platen roller. Since it can be adjusted and moved, clear printing can be performed without directly contacting the thermal head and the platen roller.

Further, by providing the pressing force switching means, the pressing force applied to the thermal head can be easily switched, so that the type of paper used, the paper width, the paper thickness, the surface condition of the paper, and the special surface are used. Even when the supply is used or the type of thermal transfer ribbon is changed, clear printing can be performed on the paper by switching the pressing force according to the paper with a simple operation.

Further, if the thermal head heat generating portion position adjusting means is provided, even if it is desired to print on both thin paper such as a label and thick tag paper, the corresponding 2
The user himself / herself simply moved and adjusted the position of the heat-generating part of the thermal head in the paper transport direction without having to call a service person every time he or she prepared a different type of printer or changed the paper to be printed, and adjusted it to each paper. Printing can be performed in the optimum condition.

Further, the engaging members projecting from both ends of the thermal head are movably fitted into the U grooves of the pair of head holding members, and when the engaging members move along the U grooves. If a step for preventing the engaging member from falling is formed in the U groove, the thermal head can be easily removed and replaced in a short time only by moving the engaging member along the U groove of the head holding member. Therefore, serviceability is improved. Further, since the U groove has a step, it is possible to prevent the thermal head from being accidentally dropped when the thermal head is removed.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a main part and its periphery of a thermal printer showing an embodiment of the present invention.

FIG. 2 is a perspective view showing the assembled state of the thermal head of the thermal printer and each component holding the same.

FIG. 3 is an exploded perspective view of the same.

FIG. 4 is a left side view of the thermal printer of FIG.

FIG. 5 is a front view for explaining a platen roller fine adjustment mechanism for finely adjusting and moving the end portion of the platen roller in a direction of approaching and separating from the thermal head.

FIG. 6 is a diagram showing a state in which the thermal head 1 is tilted when a narrow cardboard is set close to one end of a platen roller.

FIG. 7 is a diagram showing a front surface and a side surface of a thermal head fine adjustment mechanism for finely adjusting and moving an end portion of the thermal head toward and away from the platen roller.

8 is a diagram showing a state in which the position of the thermal head is adjusted by a thermal head fine adjustment mechanism from the state shown in FIG.

FIG. 9 is a diagram showing a state in which the position of the thermal head has been moved and adjusted more than in FIG. 8;

FIG. 10 is a front view showing a state in which a pressing force switching member is removed from between a top surface of a holding bracket and a cam.

FIG. 11 is a front view showing a state in which a pressing force switching member is likewise inserted between the upper surface of the holding bracket and the cam.

12 is a perspective view showing a positional relationship between the cam and the pressing force switching member in the state of FIG.

13 is a perspective view showing the positional relationship between the cam and the pressing force switching member in the state of FIG.

FIG. 14 is a cross-sectional view for explaining the positioning and holding structure of the pressing force switching member with respect to the holding bracket.

FIG. 15 is a schematic diagram for comparing and explaining the thermal head heat generating portion position adjusting means when not used and when used.

FIG. 16 is a perspective view showing a sheet metal member as an example of the thermal head heat generating portion position adjusting means.

FIG. 17 is a front view showing a state in which the pressure applied to the thermal head is released when the thermal head is detached as a unit.

FIG. 18 is a front view showing a state in which the thermal head is removed in a unit state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 thermal head 1a heat generating part 2 platen roller 3 thermal transfer ribbon 4 paper 6 adjusting plate (platen roller fine adjustment mechanism) 10 eccentric plate 11 head plate 13 pressing force switching member 15 head holding member 15a U groove 15b step 18 pin (engaging member ) 21 sheet metal member (thermal head heating section position adjusting means) 26 head adjusting lever

Claims (5)

[Claims] 1. A thermal printer in which direct thermal paper or a thermal transfer ribbon and paper are sandwiched by pressure between a thermal head and a platen roller to heat a heat generating portion of the thermal head to perform printing, and an end of the platen roller is provided. A thermal printer, comprising: a platen roller fine adjustment mechanism for finely adjusting and moving the unit toward and away from the thermal head. 2. The thermal printer according to claim 1, further comprising a thermal head fine adjustment mechanism for finely adjusting and moving the end portion of the thermal head in a direction of moving toward and away from the platen roller. Thermal printer. 3. The thermal printer according to claim 1 or 2, further comprising a pressing force switching means for switching a pressing force applied to the thermal head. 4. The thermal printer according to claim 1, further comprising a thermal head heat generating portion position adjusting means for moving and adjusting the position of the heat generating portion of the thermal head in the sheet conveying direction. Characteristic thermal printer. 5. The thermal printer according to claim 1, wherein engaging members are integrally projected at both ends of the thermal head, and the engaging members are U-shaped. A pair of head holding members that movably fit in and hold the thermal head are provided, and a step for preventing the engaging member from falling off when the engaging member moves along the U groove. A thermal printer characterized by being formed in the U groove.