Print head assembly and thermal printer

Abstract

The present application discloses a print head assembly and a thermal printer, the print head assembly comprising: a base; a TPH module that can be detachably attached to the rear of the base and is located below the base; a paper guide bracket that can be detachably attached to the front of the base and is located below the base, with the rear portion of the paper guide bracket overlapping the front portion of the TPH module; a plurality of springs that are arranged between the base and the TPH module and are in a deformed state when the TPH module is attached to the base; a plurality of limiting mechanisms for limiting the maximum range of movement of the TPH module relative to the base in the vertical direction and in the front-back direction; and a locking mechanism for locking the paper guide bracket to the base, the locking mechanism comprising a plurality of barbs provided on the paper guide bracket and a plurality of locking components provided on the base, each barb being configured to engage with a corresponding locking component when the paper guide bracket is attached to the base. The print head assembly of this solution has a simple structure and is more convenient to assemble and disassemble.

Description

Technical Field

[0001] The present application relates to the field of thermal printing technology, and in particular to a print head assembly and a thermal printer. Background Art

[0002] Thermal printers are commonly seen in daily life and are widely used in printing applications such as receipts and labels. In a thermal printer, a thermal head with a heat-generating component presses against a platen roller to print on thermal paper located between the two components.

[0003] In traditional thermal printers, the thermal head is secured to a bracket assembly. This bracket assembly is removable to facilitate printhead maintenance. Common head brackets typically consist of multiple metal or plastic brackets assembled with threaded fasteners, providing sufficient strength and stability to prevent wobble or loosening during printing. However, since threaded fasteners require specialized tools to disassemble and assemble, ease of assembly and disassembly could be improved. Summary of the Invention

[0004] In response to the above technical problems, the purpose of the present application is to provide a print head assembly that is simple to assemble and has a reliable structure, and a thermal printer equipped with the print head assembly.

[0005] According to a first aspect of the present application, a print head assembly is provided, comprising: a base having a top wall, a first side wall and a second side wall separated by the top wall and opposite to each other in front and back, and a third side wall and a fourth side wall separated by the top wall and opposite to each other in left and right; a TPH module comprising a thermal sheet holder and a thermal sheet fixedly mounted on the thermal sheet holder, the TPH module being configured to be attachable to the base along an installation direction and detachable from the base along a detachment direction opposite to the installation direction; wherein the detachment direction is one of a direction from back to front and from front to back, and when the TPH module is attached to the base, it is located at the lower side of the base and is limited in the left and right directions by the base; a paper guide holder which can be detachably attached to the base base and is located on the lower side of the base when attached to the base; when the TPH module and the paper guide bracket are both attached to the base, the paper guide bracket limits the maximum movement range of the TPH module in the front-to-back direction relative to the base; when the paper guide bracket is removed from the base, the TPH module attached to the base is allowed to detach from the base along the detachment direction; a plurality of springs are arranged between the base and the TPH module and are in a deformed state when the TPH module is attached to the base; and a plurality of limiting mechanisms are used to limit the maximum movement range of the TPH module attached to the base in the downward direction and the maximum movement range along the installation direction.

[0006] According to the above solution, by configuring the assembly relationship between the base, TPH module and paper guide bracket and setting a limiting mechanism, the three can be easily assembled using non-threaded fastener installation methods, with a simple structure and more convenient assembly and disassembly.

[0007] In combination with the first aspect, in certain embodiments of the first aspect, the TPH module can be detachably attached to the rear of the base, and the paper guide bracket can be detachably attached to the front of the base; when the TPH module and the paper guide bracket are both attached to the base, the rear of the paper guide bracket overlaps the lower side of the front of the TPH module.

[0008] In combination with the first aspect, in certain embodiments of the first aspect, the print head assembly further includes: a locking mechanism for locking the paper guide bracket with the base, the locking mechanism including a plurality of barbs provided on the paper guide bracket and a plurality of locking components provided on the base, each of the barbs being configured to engage with the corresponding locking component when the paper guide bracket is attached to the base.

[0009] In combination with the first aspect, in certain embodiments of the first aspect, the locking component is a recess or a through hole.

[0010] In combination with the first aspect, in certain embodiments of the first aspect, the multiple locking components are respectively arranged at at least two positions at the intersection of the first side wall and the top wall, the intersection of the third side wall and the top wall, and the intersection of the fourth side wall and the top wall.

[0011] The multiple locking components are respectively arranged at at least two positions of the intersection of the first side wall and the top wall, the intersection of the third side wall and the top wall, and the intersection of the fourth side wall and the top wall.

[0012] In combination with the first aspect, in certain embodiments of the first aspect, the front portion of the thermal film holder has a front side wall extending upward, and the multiple limiting mechanisms include a first limiting mechanism, and the first limiting mechanism includes at least one socket or at least one first tongue provided on the front side wall and at least one first tongue or at least one socket provided on the top wall.

[0013] In combination with the first aspect, in certain embodiments of the first aspect, the top wall is provided with at least one first plug tongue extending toward the first side wall, and the front side wall provides at least one socket adapted to the position of each of the plug tongues; when the TPH module is connected to the base, each of the first plug tongues is inserted into the corresponding socket.

[0014] In combination with the first aspect, in certain embodiments of the first aspect, the multiple limiting mechanisms include a second limiting mechanism and a third limiting mechanism, the second limiting mechanism includes a first stop wall provided on the third side wall and extending toward the fourth side wall and with its upper portion suspended, and a second plug tongue extending upward and backward from a portion of the left side edge of the thermal film holder, the third limiting mechanism includes a second stop wall provided on the fourth side wall and extending toward the third side wall and with its upper portion suspended, and a third plug tongue extending upward and backward from a portion of the right side edge of the thermal film holder; when the TPH module is connected to the base, the second plug tongue extends into the upper side of the first stop wall, and the third plug tongue extends into the upper side of the second stop wall.

[0015] In combination with the first aspect, in certain embodiments of the first aspect, the multiple limiting mechanisms include a fourth limiting mechanism and a fifth limiting mechanism, the fourth limiting mechanism includes a first notch provided by the bottom of the third side wall and a first protrusion provided by the left side of the paper guide bracket; the fifth limiting mechanism includes a second notch provided by the bottom of the fourth side wall and a second protrusion provided by the right side of the paper guide bracket; when the TPH module is connected to the base, the first protrusion is located at the first notch, and the second protrusion is located at the second notch.

[0016] In combination with the first aspect, in certain embodiments of the first aspect, the print head assembly further includes: a restraint mechanism for preventing the paper guide bracket from moving in a front-to-rear direction relative to the base when the paper guide bracket is attached to the base.

[0017] In combination with the first aspect, in certain embodiments of the first aspect, the restraint mechanism includes a first protrusion located at the lower end of the third side wall, a third protrusion located at the lower end of the fourth side wall, a first gap provided by the left side of the paper guide bracket, and a second gap provided by the right side of the paper guide bracket; when the paper guide bracket is attached to the base, the first protrusion is confined in the first gap, and the third protrusion is confined in the second gap. In combination with the first aspect, in certain embodiments of the first aspect, the left side of the paper guide bracket is provided with a first protrusion and a second protrusion arranged front to back, the first gap is defined by the first protrusion and the second protrusion, the right side of the paper guide bracket is further provided with a third protrusion and a fourth protrusion arranged front to back, the second gap is defined by the third protrusion and the fourth protrusion; after the base, the TPH module, and the paper guide bracket are assembled, the second protrusion is located in the first notch and in front of the first protrusion, and the fourth protrusion is located in the second notch and in front of the second protrusion.

[0018] In combination with the first aspect, in certain embodiments of the first aspect, a plurality of spring mounting seats are provided on the top wall, and each of the springs is mounted on a corresponding spring mounting seat.

[0019] In a second aspect of the present application, a thermal printer is provided, comprising the print head assembly of the first aspect.

[0020] Other advantages of the present application will be described in detail in the subsequent detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A structural diagram of a thermal print head provided in one embodiment of the present application;

[0022] Figure 2 A structural diagram of a print head assembly provided in one embodiment of the present application;

[0023] Figure 3 A disassembled diagram of a print head assembly provided in one embodiment of the present application;

[0024] Figure 4 A structural diagram of the lower portion of the base provided in one embodiment of the present application;

[0025] Figure 5 A structural diagram of the upper portion of a TPH module provided in one embodiment of the present application;

[0026] Figure 6 for Figure 5 The structural diagram of the lower part of the TPH module;

[0027] Figure 7 for Figure 5 The disassembly diagram of the TPH module;

[0028] Figure 8 A structural diagram of the upper portion of a paper guide bracket provided in one embodiment of the present application;

[0029] Figure 9 for Figure 8 A structural diagram of the upper portion of the paper guide bracket from another perspective;

[0030] Figure 10 for Figure 8 Structural diagram of the lower part of the paper guide bracket;

[0031] Figure 11 for Figure 6 The TPH module in Figure 4 Schematic diagram of base assembly direction in FIG;

[0032] Figure 12 for Figure 6 The TPH module in Figure 4 A schematic cross-sectional view of the base at the position of the first tongue and the socket after assembly is completed;

[0033] Figure 13 for Figure 6 The TPH module in Figure 4 A schematic cross-sectional view of the base at the position of the second tongue and the first retaining wall after assembly is completed;

[0034] Figure 14 for Figure 6 The TPH module in Figure 4 Schematic diagram of the structure of the left part of the base after assembly;

[0035] Figure 15 for Figure 6 The TPH module in Figure 4 Schematic diagram of the structure of the right part of the base after assembly;

[0036] Figure 16 for Figure 8 The paper guide bracket and Figure 14 Schematic diagram of the base and TPH module assembly direction;

[0037] Figure 17 This is a schematic structural diagram of the left side of a print head assembly according to one embodiment of the present application;

[0038] Figure 18 for Figure 8 The paper guide bracket and Figure 14 Another schematic diagram of the base and TPH module assembly direction;

[0039] Figure 19 This is a schematic structural diagram of the right side of a print head assembly according to one embodiment of the present application. DETAILED DESCRIPTION

[0040] The technical solution of the present application is clearly described above with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present application, not all of them. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0041] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0042] It should be noted that the directional words such as "down", "up", "back", "front", "left", and "right" described in the embodiments of the present application are described based on the angles shown in the accompanying drawings and should not be understood as limitations on the embodiments of the present application.

[0043] The terms "a" and "an" used in the above description are intended to indicate at least one of the specified elements. In addition, as used herein, the term "include" means including but not limited to, and the term "comprising" means including but not limited to. The term "based on" means at least partially based on.

[0044] refer to Figure 1 , Figure 1 The present application provides a thermal printing device 400 for a thermal printer. The function of the printing device 400 is to heat the print head and contact it with the front of a thermal label, causing the heat-responsive material (e.g., thermal paper) to react and thereby print. The thermal printing device 400 is provided with a print head assembly 100 that pivots about a pivot 200. The print head assembly 100 can be locked to the base (not shown) of the thermal printing device 400 via an operable locking block 300. The base of the thermal device 400 is equipped with a rotatable rubber roller and a drive assembly that drives the rubber roller to rotate. When the print head assembly 100 is locked to the base, the print head of the print head assembly 100 abuts against the rubber roller. The rubber roller on the base contacts the back of the printing paper and feeds the printing paper, while the print head prints on the front of the printing paper.

[0045] See also Figure 2 and Figure 3 , which shows the components of a printhead assembly 100. The printhead assembly 100 mainly includes a base 1, a TPH module 2, a paper guide 3, and a pair of springs 4. The base 1 is located on the upper side, the paper guide 3 is located on the lower side, and the TPH module 2 is located between the base 1 and the paper guide 3. These components engage with each other through their own concave and convex parts and a hook mechanism to form a solid module.

[0046] In this example, the positional relationship described is set with reference to the movement direction of the printing paper of the thermal printing device 400 in operation; wherein, the printing paper moves in the front-to-back direction, and the width direction of the print head is the left-to-right direction.

[0047] See also Figure 4 The base 1 shown is a single, integrated component. The base 1 has a square, box-like structure. It includes a top wall 11, a first side wall 12 and a second side wall 13 separated by the top wall 11 and opposing each other in the front-to-back direction, and a third side wall 14 and a fourth side wall 15 separated by the top wall 11 and opposing each other in the left-to-right direction.

[0048] A downwardly protruding tongue 51 is provided in the middle of the top wall 11, and the first tongue 51 extends toward the front side where the first side wall 12 is located. A pair of spring mounting seats 41 and 42 are also provided on the lower surface of the top wall 11 and are spaced apart from each other.

[0049] The left end portion 121 of the first side wall 12 and the left end portion 131 of the second side wall 13 protrude leftward relative to the third side wall 14 on the left side and are both provided with shaft holes 122 and 132 for the pivot shaft 200 to penetrate.

[0050] A first through hole 81 and a second through hole 82 spaced apart from each other are provided at the junction of the first side wall 12 and the top wall 11 .

[0051] A third through hole 83 is provided at the intersection of the third side wall 14 and the top wall 11. The bottom of the third side wall 14 has a first convex wall 71 and a second convex wall 72 arranged in a front-to-rear arrangement, with a first notch 73 formed between the first and second convex walls 71 and 72. The rear edge of the second convex wall 72 extends toward the right side of the fourth side wall 15 to form a first retaining wall 61. The upper portion of the first retaining wall 61 is suspended, i.e., it is a certain distance from the top wall 11.

[0052] A fourth through hole 84 is provided at the intersection of the fourth side wall 15 and the top wall 11. The bottom of the fourth side wall 15 has a third and fourth raised walls 74 and 75 arranged in a front-to-rear manner, with a second notch 76 formed between the third and fourth raised walls 74 and 75. The rear edge of the fourth raised wall 75 extends toward the left side of the third side wall 14 to form a second retaining wall 62, the upper portion of which is also suspended in the air.

[0053] The first through hole 81, the second through hole 82, the third through hole 83, the fourth through hole 84, the first notch 73 and the second notch 76 are all distributed in the front half of the base 1; while the spring mounting seats 41 and 42, the first retaining wall 61 and the second retaining wall 62 are all distributed in the back half of the base 1.

[0054] See also Figure 5-7The illustrated TPH module 2 comprises a thermal sheet holder 21, a thermal sheet 22 fixedly mounted on the thermal sheet holder 21, and a front paper guide 23 fixedly mounted on the thermal sheet holder 21, forming an integrated component. The thermal sheet holder 21 is made of a material with excellent thermal conductivity, such as metal. The front portion of the thermal sheet holder 21 has an upwardly extending front sidewall 212. A socket 52 is provided in the middle of the front sidewall 212. This socket 52 is configured to accommodate the insertion of a first insertion tongue 51. Furthermore, in this example, the vertical diameter of the socket 52 is greater than the vertical height of the first insertion tongue 51. A pair of spring mounting seats 43 and 44 are also spaced apart on the upper surface of the thermal sheet holder 21. The rear portion of the thermal sheet holder 21 has an upwardly extending folded edge 213. A portion of the left side of the thermal sheet holder 21 extends upward and rearward to form a second insertion tongue 63, and a portion of the right side extends upward and rearward to form a third insertion tongue 64. A first protrusion 713 protruding to the left is provided on the left side of the thermal sheet holder 21 near the front side wall 212, and a second protrusion 714 protruding to the right is provided on the right side of the thermal sheet holder 21 near the front side wall 212. The front paperboard guide 23 has several bosses 231 and an upwardly extending folded edge 232 at the rear. The rear portion of the thermal sheet holder 21 has several mounting holes 211 adapted to accommodate these bosses 231. The bosses 231 of the front paperboard guide 23 are inserted into the corresponding mounting holes 211, and the folded edge 232 is hidden behind the folded edge 213. The front paperboard guide 23 is fixedly connected to the thermal sheet holder 21. The thermal sheet 22 can be secured to the bottom surface of the thermal sheet holder 21 by screws or glue and is located on the front side of the front paperboard guide 23.

[0055] The TPH module 2 is an integrated component that can be detachably assembled on the lower side of the rear half of the base 1; the two can be assembled together without the need for threaded fasteners for assembly.

[0056] See also Figure 8-10 The illustrated paper guide 3 is a single, integrated component. It includes a body 31, which is provided with a pair of upwardly extending first and second barbs 85 and 86 near its front edge. A third barb 87 is provided on the left side of the body 31, and a fourth barb 88 is provided on the right side. The left side of the body 31 is further provided with a first protrusion 77 and a second protrusion 78 arranged in a front-to-back relationship, with a first gap 79 between them. The right side of the body 31 is further provided with a third protrusion 710 and a fourth protrusion 711 arranged in a front-to-back relationship, with a second gap 712 between them.

[0057] The paper guide bracket 3 can be detachably assembled on the lower side of the front half of the base 1 , and before assembly, the rear portion of the paper guide bracket 3 overlaps the lower side of the front portion of the bracket body 21 of the TPH module 2 .

[0058] like Figure 11 As shown, when the TPH module 2 is assembled on the base 1 from bottom to top and from front to back, the two ends of the pair of springs 4 will be supported on the spring mounting seats 41, 42, 43 and 44 respectively, and the TPH module 2 presses the pair of springs 4 upward and pushes it in from front to back.

[0059] like Figure 12 As shown, the first inserting tongue 51 is inserted into the socket 52. Since the diameter of the socket 52 in the vertical direction is greater than the height of the first inserting tongue 51 in the vertical direction, the TPH module 2 can be supported on the first inserting tongue 51 by a certain range of swinging in the left-right direction and the vertical direction. The first inserting tongue 51 and the socket 52 form a limiting mechanism 5. The limiting mechanism 5 can constrain the front of the TPH module 2. Specifically, under the action of the limiting mechanism 5, the maximum upward and backward movement of the front of the TPH module 2 relative to the base 1 are both limited.

[0060] like Figure 13 As shown, the second tongue 63 will be inserted into the upper side of the first retaining wall 61 and spaced apart from the first retaining wall 61 in the front-to-rear direction; these second tongues 63 and the first retaining wall 61 will constitute another limiting mechanism 6, which can constrain the left rear portion of the TPH module 2. Specifically, under the action of the limiting mechanism 6, the maximum downward and rearward movement of the left rear portion of the TPH module 2 relative to the base 1 are restricted.

[0061] Similarly, the third tongue 64 will also be inserted into the second retaining wall 62 and will be spaced apart from the second retaining wall 62 in the front-to-rear direction. In this way, the third tongue 64 and the second retaining wall 62 will form another limiting mechanism (not shown in the figure), which can constrain the right rear portion of the TPH module 2; under the action of this limiting mechanism, the maximum downward and rearward movement of the rear portion of the TPH module 2 relative to the base 1 are restricted.

[0062] like Figure 14 As shown, the first protrusion 713 is located in the first notch 73 and is clearance-matched with the first convex wall 71 and the second convex wall 72 in the front-to-back direction. These protrusions and the notch constitute a limiting mechanism 7. The limiting mechanism 7 can constrain the left side of the TPH module 2. Specifically, under the action of the limiting mechanism 7, the maximum upward and backward movement of the left side of the TPH module 2 relative to the base 1 is limited.

[0063] like Figure 15As shown, the second protrusion 714 is located in the second notch 76 and is clearance-matched with the third protruding wall 74 in the front-to-back direction. These protrusions and notches constitute a limiting mechanism 70; the limiting mechanism 70 can constrain the right side of the TPH module 2. Specifically, under the action of the limiting mechanism 70, the maximum upward and backward movement of the right side of the TPH module 2 relative to the base 1 is limited.

[0064] Thus, the TPH module 2 will be swingably mounted on the lower side of the base 1. When the TPH module 2 abuts against the rubber roller of the printer (not shown in the figure), a pair of springs 4 will be compressed, and the TPH module 2 will adaptively tilt, thereby being in full alignment with the rubber roller along the axial direction. In this solution, the first retaining wall 61 and the second retaining wall 62 will be used to limit the ends of the movable stroke of the TPH module 2 in the up and down directions. When detached from the rubber roller, the second tongue 63 and the first retaining wall 61, and the third tongue 64 and the second retaining wall 62 abut against each other under the action of the springs; and when the TPH module 2 abuts against the rubber roller, the rubber roller pushes the TPH module 2 in the direction of the compression spring 2, and the second tongue 63 and the first retaining wall 61, and the third tongue 64 and the second retaining wall 62 are spaced apart. And by virtue of the action of the above-mentioned multiple limiting mechanisms, the maximum movement range of the TPH module 2 relative to the base in the up and down directions and in the front and back directions is limited.

[0065] like Figure 16-17 As shown, when the paper guide bracket 3 is assembled on the base 1 from bottom to top, the rear part of the paper guide bracket 3 overlaps the front lower side of the TPH module 2; the first convex wall 71 is located in the first gap 79, the second protrusion 78 is located at the first notch 73 and is located in front of the first protrusion 713, and the first convex wall 71 and the first gap 79 constitute a constraint mechanism 701, which can enable the left side of the paper guide bracket 3 to form a rearward and forward position limit on the base 1.

[0066] like Figure 18-19 As shown, when the paper guide bracket 3 is assembled on the base 1 from bottom to top, the third protrusion 74 is located in the second gap 712, the fourth protrusion 711 is located at the second notch 76 and is located in front of the second protrusion 714, and the fourth protrusion 74 and the second gap 712 constitute a constraint mechanism 702, which can enable the right side of the paper guide bracket 3 to form a backward and forward position limit for the base 1 respectively.

[0067] Continue as Figure 16-19 As shown, the first barb 85, the second barb 86, the third barb 87 and the fourth barb 88 are respectively engaged with the first through hole 81, the second through hole 82, the third through hole 83 and the fourth through hole 84, and these barbs and through holes can constitute a locking mechanism, which enables the paper guide bracket 3 to be locked on the base 1, thereby indirectly locking the TPH module 2 and the base 1 together.

[0068] In this example, after the paper guide bracket 3 and the base 1 are locked together, the second protrusion 78 and the first notch 73, as well as the fourth protrusion 711 and the second notch 76, collectively define a pair of "spaces" on the left and right sides, respectively accommodating the first and second protrusions 713, 714. The first and second protrusions 713, 714 of the TPH module 2 are positioned within these "spaces" and engage with the clearances of the surrounding walls. This allows the first and second protrusions 713, 714 to be positioned front and rear without interfering with the swinging motion of the TPH module 2. This prevents the first and second protrusions 713, 714 from dislodging from the front and prevents the ends of the TPH module 2 from excessively shifting in the left and right directions, which could cause deflection in the printed image.

[0069] As can be seen from the above description, after the base 1, TPH module 2, and paper guide 3 are assembled, the TPH module 2 retains a certain amount of play in the front-to-back direction. This allows for adaptive vertical deflection of the rubber roller when the TPH module 2 initially presses against the rubber roller. Subsequently, when the thermal printer begins printing, the rubber roller conveys the paper forward, and the TPH module 2, driven by the paper, moves backward until the first and second protrusions 713, 714 contact the second and fourth protrusions 72, 75 on their respective sides, thereby positioning the TPH module 2 in the front-to-back direction.

[0070] The print head assembly 100 of this case has low manufacturing cost and is safe and reliable in structure after assembly. When parts on the print head need to be repaired or replaced, the base 1, TPH module 2 and paper guide bracket 3 can also be easily disassembled, and the maintenance cost is low.

[0071] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above embodiments. The above embodiments and descriptions are only for illustrative purposes. Various changes and improvements may be made to the present application without departing from the spirit and scope of the present application. The scope of protection claimed in the present application is defined by the appended claims, the description and their equivalents.

Claims

1. A print head assembly, characterized in that: include: The base comprises a top wall, a first side wall and a second side wall separated by the top wall and facing each other front to back, and a third side wall and a fourth side wall separated by the top wall and facing each other left to right; A TPH module includes a thermal sheet holder and a thermal sheet fixedly mounted on the thermal sheet holder, wherein the front portion of the thermal sheet holder has an upwardly extending front sidewall. The TPH module is configured to be attachable to the base along an installation direction and detachable from the base along a detachment direction opposite to the installation direction; wherein the detachment direction is one of a back-to-front direction and a front-to-back direction. When attached to the base, the TPH module is located below the base and is limited in the left-right direction by the base. a paper guide bracket detachably attached to the base and located on the lower side of the base when attached to the base; when the TPH module and the paper guide bracket are both attached to the base, the paper guide bracket limits the maximum range of movement of the TPH module in the front-to-back direction relative to the base; when the paper guide bracket is detached from the base, the TPH module attached to the base is allowed to detach from the base along the detachment direction; a plurality of springs disposed between the base and the TPH module and in a deformed state when the TPH module is attached to the base; as well as Multiple limiting mechanisms are used to limit the maximum downward movement range and the maximum movement range along the installation direction of the TPH module attached to the base. The multiple limiting mechanisms include a first limiting mechanism, a second limiting mechanism, and a third limiting mechanism. The first limiting mechanism includes at least one socket or at least one first plug tongue provided on the front side wall and at least one first plug tongue or at least one socket provided on the top wall. The second limiting mechanism includes a first stop wall provided on the third side wall and extending toward the fourth side wall and with its upper portion suspended, and a second plug tongue extending upward and rearward from a portion of the left side of the thermal film holder. The third limiting mechanism includes a second stop wall provided on the fourth side wall and extending toward the third side wall and with its upper portion suspended, and a third plug tongue extending upward and rearward from a portion of the right side of the thermal film holder. When the TPH module is attached to the base, the second plug tongue extends into the upper side of the first stop wall, and the third plug tongue extends into the upper side of the second stop wall.

2. The print head assembly according to claim 1, wherein: The TPH module can be detachably attached to the rear of the base, and the paper guide bracket can be detachably attached to the front of the base; when the TPH module and the paper guide bracket are both attached to the base, the rear of the paper guide bracket overlaps the lower side of the front of the TPH module.

3. The print head assembly according to claim 1, wherein: It also includes a locking mechanism for locking the paper guide bracket with the base, the locking mechanism including a plurality of barbs provided on the paper guide bracket and a plurality of locking components provided on the base, each of the barbs being configured to engage with a corresponding locking component when the paper guide bracket is attached to the base.

4. The print head assembly according to claim 3, wherein: The locking component is a recess or a through hole.

5. The print head assembly according to claim 4, wherein: The multiple locking components are respectively arranged at at least two positions of the intersection of the first side wall and the top wall, the intersection of the third side wall and the top wall, and the intersection of the fourth side wall and the top wall.

6. The print head assembly according to claim 1, wherein: The top wall is provided with at least one first plug tongue extending toward the first side wall, and the front side wall provides at least one socket adapted to the position of each of the plug tongues; when the TPH module is connected to the base, each of the first plug tongues is inserted into the corresponding socket.

7. The print head assembly according to claim 1, wherein: The multiple limiting mechanisms include a fourth limiting mechanism and a fifth limiting mechanism, the fourth limiting mechanism includes a first notch provided by the bottom of the third side wall and a first protrusion provided by the left side of the paper guide bracket; the fifth limiting mechanism includes a second notch provided by the bottom of the fourth side wall and a second protrusion provided by the right side of the paper guide bracket; when the TPH module is connected to the base, the first protrusion is located at the first notch, and the second protrusion is located at the second notch.

8. The print head assembly according to claim 7, wherein: Also includes: The restraint mechanism is used to prevent the paper guide bracket from moving in the front-rear direction relative to the base when the paper guide bracket is attached to the base.

9. The print head assembly according to claim 8, wherein: The restraint mechanism includes a first convex wall located at the lower end of the third side wall, a third convex wall located at the lower end of the fourth side wall, a first gap provided by the left side of the paper guide bracket, and a second gap provided by the right side of the paper guide bracket; when the paper guide bracket is attached to the base, the first convex wall is confined in the first gap, and the third convex wall is confined in the second gap.

10. The print head assembly according to claim 9, wherein: The left side of the paper guide bracket is provided with a first protrusion and a second protrusion arranged front to back, and the first gap is defined by the first protrusion and the second protrusion. The right side of the paper guide bracket is also provided with a third protrusion and a fourth protrusion arranged front to back, and the second gap is defined by the third protrusion and the fourth protrusion. When the TPH module and the paper guide bracket are both mounted on the base, the second protrusion is located in the first notch and in front of the first protrusion, and the fourth protrusion is located in the second notch and in front of the second protrusion.

11. The print head assembly according to claim 1, wherein: A plurality of spring mounting seats are provided on the top wall, and each of the springs is mounted on the corresponding spring mounting seat.

12. A thermal printer comprising the print head assembly according to any one of claims 1 to 11.

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