A thermal printer

Abstract

The present invention relates to a thermal printer, comprising a base, a carriage, a printing device and a paper feed roller. The front side of the printing device is connected to the carriage through a support column, and the rear side thereof is connected to the carriage through a deformation structure. When the printing device is subjected to uneven pressure exerted by a recording paper, it can swing with the support column as a fulcrum to make the pressure tend to be uniform, and the deformation structure can produce plastic deformation to maintain the position of the printing device; an elastic member is arranged between the carriage and the base, and when a recording paper is clamped between the printing device and the paper feed roller, the elastic member makes the two closely contact with the recording paper. The present invention enables the printing device to be evenly stressed on the printing paper during the printing process, thereby making the printing clearer.

Description

Technical Field

[0001] The present invention relates to the field of printers, and more particularly, to a thermal printer. Background Art

[0002] Thermal printers are commonly used printing devices. After years of technological upgrades, they have become increasingly mature. However, people's requirements for printing quality are also getting higher and higher, thus posing higher requirements for innovation. To provide better printing quality, the applicant, DIS Global, applied for and published a patent "Photo Printer" with the patent number: 201710598703.2 and a publication date of January 30, 2018. The content is as follows: A photo printer that prints an image or text by applying heat of a given temperature to a paper that senses heat to display colors. It is characterized by including: a substrate that accommodates the paper; a paper feed roller that protrudes from the bottom surface of the substrate and supplies the accommodated paper forward; a paper pressing roller that discharges the paper supplied by the paper feed roller forward; a head that is formed above the paper pressing roller and applies heat to the paper; a swing bracket that has a mounting portion for coupling the head formed on the front side and a coupling portion that is rotatably coupled to the substrate on the rear side for causing the head to swing; and a pressing member that presses the head downward to make it close tightly to the paper entering between the head and the paper pressing roller.

[0003] In the above patent, the rotation axis of the swing bracket is formed behind the rotation axis of the paper pressing roller. Therefore, when the paper enters, according to the pressure situation acting on the head, the head can easily rotate, minimizing the compression of the paper pressing roller. Thus, the paper and the paper pressing roller can be in line contact to the maximum extent, improving the printing quality.

[0004] In the above patent, when the printing paper enters the paper pressing roller and the head, the head swings due to the difference in spring tension on both sides or the uneven left and right thickness of the paper, but it will not maintain its position after swinging. During the printing process, different amounts of heat will also cause different left and right supporting forces, resulting in the head constantly dynamically adjusting its position and causing the printing line to deviate. The specific analysis is as follows: When the head (thermal head) heats the paper (when continuously printing a deep black), as Figure 1 shown, the corresponding area of the printing paper will become hot due to the increase in temperature. When the printing paper is transported forward at this time, its frictional resistance f1 will increase, and then the force for the paper pressing roller to transport the printing paper will increase, and its reaction force f2 will also increase accordingly. Since the outer periphery of the paper pressing roller is a colloid, when the reaction force f2 increases, the circular cross-section of the colloid will deform (as Figure 1As shown, the head of the above patent will descend under the action of the pressing force F of the pressing member, so that the heating unit on the head will deviate from its original position, and the supporting force F1 will move to the position of F2. Only when the force generated by the deformation of the colloid is equal to the supporting force multiplied by the friction coefficient, the deformation of the colloid will stop and the position of the head will stabilize. Eventually, the printing point deviates from the correct printing line position, affecting the printing quality. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a thermal printer, including a base, a carriage, a printing device, and a paper feed roller. The carriage is disposed on the base. The printing device is configured along the width direction of the recording paper. The paper feed roller is disposed opposite to the printing device and rotates while clamping the recording paper therebetween to feed the recording paper out. The front side of the printing device is connected to the carriage through a support column, and the rear side thereof is connected to the carriage through a deformation structure. When the printing device receives uneven pressure exerted by the recording paper, it can swing with the support column as a fulcrum to make the pressure tend to be uniform, and the deformation structure can produce plastic deformation to maintain the position of the printing device; an elastic member is disposed between the carriage and the base, and when the recording paper is clamped between the printing device and the paper feed roller, the elastic member makes the two closely contact with the recording paper.

[0006] Preferably, the printing device includes a swing frame and a thermal head. The front side of the swing frame is connected to the carriage through a support column, and the rear side thereof is connected to the carriage through a deformation structure. The swing frame can swing with the support column as a fulcrum when the thermal head receives uneven pressure exerted by the recording paper to make the pressure tend to be uniform, and the deformation structure can produce plastic deformation to maintain the position of the swing frame.

[0007] Preferably, the column section of the support column between the carriage and the swing frame is adjustably located therebetween, so as to change the pre-tightening force between the swing frame and the carriage.

[0008] Preferably, the support column is adjustably disposed on the carriage through a threaded structure.

[0009] Preferably, the support column is located between the carriage and the swing frame, and is a part of one of the two and protrudes toward the other to form the swing fulcrum of the swing frame.

[0010] Preferably, the deformation structure includes a deformation part and a connecting part connecting the carriage and the swing frame. When the swing frame swings, the deformation part can produce plastic deformation to maintain the swinging position of the swing frame.

[0011] Preferably, the deformation structure is provided on the cage, including a connecting portion and a deformation portion formed by hollowing out the cage, and the rear side of the swing frame is fixed to the connecting portion.

[0012] Preferably, when there is no recording paper clamped between the thermal head and the paper pressing roller and the axes of the thermal head and the paper pressing roller are parallel to each other, the thermal head is in the original position; when the recording paper is separated from between the thermal head and the paper pressing roller, under the action of the locking member, the deformation structure can produce plastic deformation so that the thermal head returns to the original position.

[0013] Preferably, the locking member adjusts the gap between the thermal head and the paper pressing roller through a threaded structure.

[0014] Preferably, the locking member keeps a predetermined gap between the thermal head and the paper pressing roller when the thermal head is in the original position.

[0015] Preferably, a pivot portion pivotally connected to the base is provided at the rear end of the cage, and the elastic member applies a force to the cage in the direction of the paper pressing roller to pressurize the printing device so that it is in close contact with the recording paper.

[0016] Preferably, the paper pressing roller is movably provided on the base, and the elastic member applies a force to the paper pressing roller in the direction of the printing device, so that it is in close contact with the recording paper.

[0017] Preferably, the elastic member is a compression spring, a first compression spring mounting portion for mounting the compression spring is provided on the cage, a second mounting portion for mounting the compression spring is provided on the base, and the compression spring is provided between the first compression spring mounting portion and the second mounting portion.

[0018] Preferably, the first compression spring mounting portion is a hollow mounting frame, the second mounting portion is located at the upper end inside the mounting frame, and the second mounting portion passes through the mounting frame to form a mounting space for the compression spring.

[0019] By adopting the above technical solutions, the present invention can achieve the following technical effects:

[0020] 1. In the present invention, through the cooperation of the support column and the deformation structure, the printing device can be adaptively adjusted according to the pressure transmitted by the printing paper, so that the printing pressure distribution is more uniform during the printing process, and thus the printing effect is better;

[0021] 2. At the same time, since the deformation structure produces plastic deformation, when the colloid of the paper pressing roller is locally deformed due to the reaction force, the plastic deformation can keep the printing device in its original position unchanged, so that the heating line on the printing paper of the printing device is stable, thereby improving the printing quality.

[0022] 3. By movably arranging the cage or the paper pressing roller on the base, the printer can better adapt to the printing gaps required by various different pressures of paper transfer within a larger range.

[0023] 4. By adjustably positioning the strut section of the support column between the cage and the printing device, the pre-tightening force between the printing device and the cage is changed, so that the printing device can better adaptively adjust when subjected to uneven forces.

[0024] 5. By arranging a locking member on the printer, when the printing paper disengages from the paper pressing shaft after each printing, the deformation structure can be reset with the support column as the fulcrum.

[0025] 6. By using a compression spring to provide pressure to the cage, the compression spring can provide a highly sensitive elastic force in a very thin printer. Description of the Drawings

[0026] Figure 1 Shows a force diagram of the prior art.

[0027] Figure 2 Shows a perspective view of the first embodiment of the present invention.

[0028] Figure 3 Shows a schematic diagram of the first embodiment of the present invention in a disassembled state.

[0029] Figure 4 Shows a perspective view of the cage of the first embodiment of the present invention.

[0030] Figure 5 Shows Figure 2 A cross-sectional view in the centering direction.

[0031] Figure 6 Shows a model diagram of the movably arranged paper pressing roller of another embodiment.

[0032] Main labels in the drawings: 1. Cage; 2. Swing frame; 3. Printing device; 31. Thermal head; 4. Paper pressing roller; 5. Locking member; 6. Base; 7. Compression spring; 9. Bracket. Detailed Description of the Invention

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention.

[0034] First Embodiment

[0035] As Figure 2 and Figure 3 shown, a thermal printer includes a base 6, a paper feed roller 61, a holder 1, a printing device 3, and a paper pressing roller 4. The printing device 3 is arranged along the width direction of the recording paper. The printing device 3 is used to provide heat to the thermal printing paper to make the text or pattern appear on the thermal printing paper. Preferably, the printing device 3 includes a resistance heating unit, and the printing device 3 is fixed to the holder 1. Preferably, the printing device 3 further includes a swing frame 2 and a thermal head 31. The front side of the swing frame 2 is connected to the holder 1 through a support column 22, and the rear side is connected to the holder 1 through a deformation structure. The swing frame 2 can swing with the support column 22 as the fulcrum when the thermal head 31 is subjected to uneven pressure exerted by the recording paper, so as to make the pressure tend to be uniform, and the deformation structure can produce plastic deformation to maintain the position of the swing frame 2. A plurality of heating units are provided, and all the heating units are linearly arranged along the width direction of the recording paper to provide heat to the thermal recording paper to print text or patterns on the recording paper. The paper pressing roller 4 is arranged opposite to the printing device 3 and rotates while clamping the recording paper therebetween to feed out the recording paper. The paper pressing roller 4 is rotatably arranged at the front end of the base 6 and rotates around the central axis of the paper pressing roller 4 on the base 6. The outer periphery of the paper pressing roller 4 is a colloid, which can produce elastic deformation under a certain pressure, and the middle is a rigid shaft.

[0036] The rear end of the cage 1 is provided with a pivot portion 17 pivotally connected to the base 6. The pivot portion 17 is fixed to the base 6 and rotates around the base 6. The pivot portion 17 is fixed to the base 6 by bolts, and the cage 1 rotates around the bolts through the pivot portion 17. There are various ways for the cage 1 to rotate around the base 6. For example, a rotating pin shaft is provided on the base 6, and a hole matching the pin shaft is provided on the pivot portion 17 of the cage 1. An elastic member is provided between the cage 1 and the base 6. When a recording paper is clamped between the printing device 3 and the paper pressing roller 4, the elastic member makes both the printing device 3 and the paper pressing roller 4 in close contact with the recording paper. The elastic force provided by the elastic member applies a force to the cage 1 in the direction of the paper pressing roller 4 to press the printing device 3. One of the preferred embodiments of the elastic member in this embodiment is a compression spring 7. The compression spring 7 is installed between the cage 1 and the base 6. The specific structure is as follows: The front end of the cage 1 extends downward to form an installation frame 14, and a first compression spring installation portion 15 is provided on the installation frame 14. A second installation portion 62 for installing the compression spring 7 is provided on the base 6. The second installation portion 62 is located at the upper end inside the installation frame 14. The second installation portion 62 passes through the installation frame 14 to form an installation space for the compression spring 7. The position where the elastic member is provided can be diverse and is not limited to the position in the above solution. For example, it can be provided on the cage 1, etc.

[0037] Relief holes 13 are provided on both sides of the front end of the cage 1. The relief holes 13 are provided to facilitate the installation of the locking member 5 on the swing frame 2. A threaded hole 16 is provided in the middle of the front end of the cage 1, and a support column 22 is installed on the threaded hole 16. At least part of the support column 22 has threads and is used in cooperation with the threaded hole 16. The relative position of the support column 22 with respect to the cage 1 can be adjusted through the threaded structure, that is, if the support column 22 is screwed down more, the bottom of the support column 22 will protrude more from the cage 1.

[0038] Two deformation structures are provided on the rear end of the cage 1. The deformation structures include a connecting portion 12 and a deformation portion 11 formed by hollowing out the cage 1. The rear side of the swing frame 2 is fixed to the connecting portion 12. The cage 1 is made of cold-rolled sheet material, has poor elasticity, and is prone to plastic deformation.

[0039] The front side of the swing frame 2 is connected to the cage 1 through the support column 22, and the rear side is connected to the connecting part 12 of the deformation structure of the cage 1 through the deformation structure. The support column 22 can be adjusted by a threaded structure and abuts against the swing frame 2 to change the distance between the front end of the swing frame 2 and the front end of the cage 1, thereby changing the pre-tightening force of the swing frame 2 relative to the cage 1. When the thermal head 31 is subjected to uneven pressure applied by the recording paper, the swing frame 2 can swing with the support column 22 as the fulcrum to make the pressure tend to be uniform, and the deformation structure can produce plastic deformation to maintain the position of the swing frame 2. The function of the support column 22 is to transmit the pressure generated by the elastic member to the printing device 3, and when the thermal head 31 is subjected to uneven pressure applied by the recording paper, it can swing with the support column 22 as the fulcrum to make the pressure tend to be uniform. Based on the above functions of the support column 22, there are various forms of variation. For example, a support protrusion is provided on the side of the cage 1 facing the swing frame 2; or a support protrusion is provided on the swing frame 2 facing the cage 1 upward, which can also perform the same function.

[0040] Assume that the force provided by the elastic member (compression spring 7) to the printing device 3 is F, and the deformation force of the deformation structure is F1; the rubber roller of the paper pressing roller will deform during printing. Assume that the supporting force on the side with light density is F2, and the supporting force on the side with dark density is F2'. The pressure difference between the two sides is △F = F2' - F2. To achieve a better printing effect, preferably, F > F1 > △F. When F > F1, the force of the spring can cause certain deformation between the printing device 3 and the cage 1, so that the forces of the left and right springs act evenly on the printing device 3, reducing the uneven left and right pressures caused by spring and part errors. F1 > △F can prevent the problem that the change in the pressure difference caused by the different deformations on both sides of the rubber roller causes the change in the position of the heating unit of the printing device 3, resulting in the deviation of the heating position and affecting the printing quality, thereby ensuring the printing quality.

[0041] During the printing process of the printer, when the force values of the left and right springs are different or the left and right thicknesses of the printing paper are different, because F > F1, the printing device 3 will swing left and right adaptively to make the contact force between the printing device 3 and the recording paper uniform, and the deformation structure can keep the position of the swung printing device 3 unchanged. As Figure 1 shown, when the adjusted printer continues to print, if a deep black color needs to be printed on the left side, the printing device 3 continuously heats a local area of the recording paper. The corresponding place on the printing paper will become hot due to the increase in temperature. When the printing paper is transported forward at this time, its friction coefficient will increase, so its frictional resistance f1 will increase, and then the force for the paper pressing roller 4 to transport the printing paper will increase, and its reaction force f2 will also increase accordingly. Since the outer circumference of the paper pressing roller 4 is a colloid, when the reaction force f2 increases, it will cause the cross-section of the circular colloid to deform (as Figure 1As shown in the figure, at this time, since F1 > △F, the deformation structure remains unchanged, so the printing device 3 remains in its original position. At this time, the position of the heating unit of the printing device 3 remains unchanged, ensuring that the axis printed by the original printing device 3 does not change or shift, thus guaranteeing high-quality printing. This solves the problem in the prior art that the position change of the printing device 3 causes the offset of the printing points, thereby affecting the printing quality.

[0042] As Figure 5 shown, when there is no recording paper clamped between the printing device 3 and the paper pressing roller 4 and the printing line of the printing device 3 is parallel to the axis of the paper pressing roller 4, the swing frame 2 is in its original position; when the printer is in the printing process, the swing frame 2 swings due to the uneven force transmitted from the recording paper, and under the action of the deformation structure, while maintaining its position, when the recording paper disengages from between the printing device 3 and the paper pressing roller 4, the holding frame 1 will rotate towards the paper pressing roller 4 under the action of the elastic member, so that the swing frame 2 also rotates and approaches the paper pressing roller 4. Finally, under the action of the locking member 5, one end of the swing frame 2 will first abut against the base 6, and the other end, under the pressure provided by the elastic member, the deformation structure deforms, causing the other end to continue to move downwards. Finally, the locking members 5 on both sides of the swing frame 2 will abut against the supporting portion 63 of the base 6, so that the swing frame 2 returns to its original position. The locking member 5 keeps a predetermined gap between the printing device 3 and the paper pressing roller 4 when the printing device 3 is in its original position. The locking member 5 can be a screw. The screw passes through the relief hole 13 of the holding frame 1 and is then tightened and fixed on the swing frame 2. The bottom of the screw abuts against the supporting portion 63 of the base 6. By adjusting the screw, the gap size between the printing device 3 and the paper pressing roller 4 when the printing device 3 is in its original position can be adjusted. The locking member 5 can have various structures. It can also be a protrusion with a certain length extending upwards from the supporting portion 63 of the base 6, or a protrusion with the same function provided downward on the swing frame 2.

[0043] Second Embodiment

[0044] In the second embodiment, the cage 1 is fixed on the base 6, the paper pressing roller 4 is arranged at the front end of the bracket 9, the rear end of the bracket 9 is movably arranged on the base 6, and the elastic member applies a force to the bracket 9 in the direction of the printing device 3, so that the paper pressing roller 4 is in close contact with the recording paper. In the second embodiment, in order to enable the paper pressing roller 4 to be movably connected to the base 6, there are various ways. It is also possible to directly provide an installation groove on the base 6, and the two ends of the paper pressing roller 4 are provided with movable parts that cooperate with the installation groove, and the elastic member is arranged below the paper pressing roller 4, so that the generated pressure makes the paper pressing roller 4 approach the printing device 3. Compared with the first embodiment, the installation part of the compression spring 7 is cancelled on the cage 1, and the rest is the same as the first embodiment, so it will not be repeated here.

[0045] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A thermal printer, comprising a base (6), a holder (1), a printing device (3) and a paper feed roller (4). The holder (1) is provided on the base (6). The printing device (3) is arranged along the width direction of the recording paper. The paper feed roller (4) is arranged opposite to the printing device (3), and rotates while clamping the recording paper therebetween to feed out the recording paper. It is characterized in that: The front side of the printing device (3) is connected to the holder (1) through a support column (22), and the rear side thereof is connected to the holder (1) through a deformation structure. When the printing device (3) receives uneven pressure applied by the recording paper, it can swing with the support column (22) as a fulcrum to make the pressure tend to be uniform, and the deformation structure can produce plastic deformation to maintain the position of the printing device (3). An elastic member is provided between the holder (1) and the base (6). When the recording paper is clamped between the printing device (3) and the paper feed roller (4), the elastic member makes the two closely contact with the recording paper. The paper feed roller (4) is movably arranged on the base (6), and the elastic member applies a force to the paper feed roller (4) in the direction towards the printing device (3), so that it closely contacts with the recording paper.

2. A thermal printer according to claim 1, It is characterized in that, The printing device (3) includes a swing frame (2) and a thermal head (31). The front side of the swing frame (2) is connected to the holder (1) through a support column (22), and the rear side thereof is connected to the holder (1) through a deformation structure. The swing frame (2) can swing with the support column (22) as a fulcrum when the thermal head (31) receives uneven pressure applied by the recording paper to make the pressure tend to be uniform, and the deformation structure can produce plastic deformation to maintain the position of the swing frame (2).

3. A thermal printer according to claim 2, It is characterized in that, The pillar section of the support column (22) between the holder (1) and the swing frame 2 is adjustably located therebetween, so as to change the pre-tightening force between the swing frame (2) and the holder (1).

4. A thermal printer according to claim 3, It is characterized in that, The support column (22) is adjustably arranged on the holder (1) through a threaded structure.

5. A thermal printer according to claim 2, It is characterized in that, The support column (22) is located between the holder (1) and the swing frame (2), and is a part of one of the two and protrudes towards the other to form the swing fulcrum of the swing frame (2).

6. A thermal printer according to claim 2, It is characterized in that, The deformation structure includes a deformation part and a connecting part connecting the holder (1) and the swing frame (2). When the swing frame (2) swings, the deformation part can produce plastic deformation to maintain the swing position of the swing frame (2).

7. A thermal printer according to claim 6, It is characterized in that, The deformation structure is arranged on the cage (1), and includes a connecting part and a deformation part formed by hollowing out the cage (1). The rear side of the swing frame (2) is fixed to the connecting part.

8. A thermal printer according to claim 2, wherein, when there is no recording paper clamped between the thermal head (31) and the paper pressing roller (4) and the axes of the thermal head (31) and the paper pressing roller (4) are parallel to each other, the thermal head (31) is in the original position; when the recording paper is separated from between the thermal head (31) and the paper pressing roller (4), under the action of the locking member (5), the deformation structure can generate plastic deformation so that the thermal head (31) returns to the original position.

9. A thermal printer according to claim 8, wherein, the locking member (5) adjusts the gap between the thermal head (31) and the paper pressing roller (4) through a threaded structure.

10. A thermal printer according to claim 9, wherein, the locking member (5) keeps a predetermined gap between the thermal head (31) and the paper pressing roller (4) when the thermal head (31) is in the original position.

11. A thermal printer according to claim 1, wherein, a pivot joint part (17) pivotally connected to the base (6) is arranged at the rear end of the cage (1), and the elastic member applies a force to the cage (1) in the direction of the paper pressing roller (4) to press the printing device (3) so that it is in close contact with the recording paper.

12. A thermal printer according to any one of claims 1 to 11, wherein, the elastic member is a compression spring (7). A first compression spring mounting part (15) for mounting the compression spring (7) is arranged on the cage (1), and a second mounting part (62) for mounting the compression spring (7) is arranged on the base (6). The compression spring (7) is arranged between the first compression spring mounting part (15) and the second mounting part (62).

13. A thermal printer according to claim 12, wherein, the first compression spring mounting part (15) is a hollow mounting frame (14), the second mounting part (62) is located at the upper end inside the mounting frame (14), and the second mounting part (62) passes through the mounting frame (14) to form a mounting space for the compression spring (7).

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