Thermal printer

Abstract

The application discloses a thermal printer, comprising a body and an upper cover capable of rotating between an open position and a closed position, the upper cover comprising an upper support with a bottom opening in a lower part and a print head assembly detachably assembled at the bottom opening, the print head assembly being a pre-assembled integral assembly and comprising a fixing frame, a back plate detachably connected to a lower part of the fixing frame, a thermal sheet fixed to a lower surface of the back plate, and a plurality of springs defined between the fixing frame and the back plate; a plurality of front upper and lower limiting mechanisms and a plurality of rear upper and lower limiting mechanisms are arranged between the lower part of the fixing frame and the back plate, the lower part of the fixing frame comprises a front lower side edge part and a rear lower side edge part separated in front and back, the back plate has a front side edge part and a rear side edge part, the plurality of front upper and lower limiting mechanisms are arranged between the front lower side edge part and the front side edge part and are spaced apart along left and right, and the plurality of rear upper and lower limiting mechanisms are arranged between the rear lower side edge part and the rear side edge part and are spaced apart along left and right.

Description

Technical Field

[0001] This application relates to the field of printer equipment technology, and in particular to a thermal printer. Background Technology

[0002] A thermal printer is a device that prints on thermal paper and is widely used in various printing applications. A typical thermal printer consists of a lower body and a top cover that closes onto the upper body. The body carries a roller that moves the thermal paper, while the top cover houses the printhead assembly with a thermal sheet. During printing, the thermal sheet of the printhead assembly presses against the roller, allowing printing to occur on the thermal paper passing between the two components. To ensure better contact between the thermal sheet and the roller in the printhead assembly and the thermal paper, a spring is typically incorporated into the printhead assembly. This spring applies force to the thermal sheet, maintaining contact between the sheet and the paper.

[0003] Current thermal printers typically use a plug-in method to allow the thermal sheet to be oscillatingly mounted on the top cover. This involves inserting the thermal sheet into a limiting mechanism within the top cover in a specific direction (usually the paper feed direction), and then pressing a spring into the gap between the thermal sheet (or backplate) and the top cover body. However, this mounting method requires the top cover to provide ample space for the thermal sheet insertion, resulting in low space utilization of the top cover. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a thermal printer. By rationally designing the mounting structure and accommodating space for the printhead assembly within the top cover, the space utilization rate of this thermal printer is improved.

[0005] To achieve the above objectives, this application adopts the following technical solution: a thermal printer, comprising a body and a top cover rotatable in an open and closed position, the top cover comprising: an upper support having a receiving space and a printhead assembly detachably mounted in the receiving space; the printhead assembly is a pre-assembled integral assembly and includes a fixing frame, a back plate pivotally supported on the lower part of the fixing frame, a thermal sheet fixed to the lower surface of the back plate, and a plurality of springs, the plurality of springs being constrained between the fixing frame and the back plate; the upper support of the receiving space includes a top wall adjacent to the receiving space from the upper side and the rear side respectively, and a first lateral limiting structure; the rear part of the back plate has a structure adapted to the first lateral limiting structure. The second lateral limiting structure is provided, the receiving space is adapted to accommodate at least a portion of the fixing frame and has a bottom opening and a rear opening, the bottom opening allows the printhead assembly to be inserted upward into the receiving space with the fixing frame in front and the second lateral limiting structure of the back plate on top, the rear opening is configured to allow the second lateral limiting structure of the back plate entering the receiving space to flip backward to move out of the receiving space and form a positioning engagement with the first lateral limiting structure when it moves to the upper position of the first lateral limiting structure; when the printhead assembly is mounted on the upper bracket, the fixing frame is fixed at the top wall, and at least a portion of the thermal sheet is exposed from the bottom opening.

[0006] The thermal printer in this case has a mounting bracket with a size that is adapted to the size of the storage space, which improves the space utilization efficiency of the printer. Moreover, due to the flip-up assembly of the back panel, a lower storage space can be designed under the same conditions. This reduces the space utilization of the top cover to a certain extent, and further reduces the height of the top cover of the thermal printer.

[0007] In some specific embodiments of the above technical solution, the top wall is provided with a plurality of horizontally arranged through holes, the fixing bracket is provided with mounting holes aligned vertically with the plurality of through holes, and the fixing bracket is fixed to the top wall by screws.

[0008] In some specific embodiments of the above technical solutions, the fixing frame is made of metal.

[0009] In some specific embodiments of the above technical solution, the second lateral limiting structure includes a left limiting part and a right limiting part, and the first lateral limiting structure includes a left limiting protrusion and a right limiting protrusion; when the printhead assembly is assembled in the receiving space, the left limiting part and the right limiting part respectively cooperate with the left limiting protrusion and the right limiting protrusion.

[0010] In some specific embodiments of the above technical solution, a plurality of front upper and lower limiting mechanisms and a plurality of rear upper and lower limiting mechanisms are provided between the lower part of the fixing frame and the back plate. The lower part of the fixing frame includes a front lower side and a rear lower side separated from each other. The back plate has a front side and a rear side. The plurality of front upper and lower limiting mechanisms are arranged between the front lower side and the front side and are spaced apart from each other on the left and right. The plurality of rear upper and lower limiting mechanisms are arranged between the rear lower side and the rear side and are spaced apart from each other on the left and right. In some specific embodiments of the above technical solution, each of the front upper and lower limiting mechanisms includes a front support part arranged on the front lower side and a front hook arranged on the front side. Each of the rear upper and lower limiting mechanisms includes a rear support part arranged on the rear lower side and a rear hook arranged on the rear side. The openings of all the front hooks and all the rear hooks are simultaneously arranged to the left or simultaneously arranged to the right. Each of the front support parts is located in the opening of the corresponding front hook, and each of the rear support parts is located in the opening of the corresponding rear hook. The printer assembly in this case has no additional third parts or fasteners between the mounting bracket, backplate and thermal sheet, resulting in lower cost and easier assembly.

[0011] In some specific embodiments of the above technical solutions, both the front hook and the rear hook are inverted L-shapes.

[0012] In some specific embodiments of the above technical solutions, the opening of each of the front hooks has a first height measured in the vertical direction, and the opening of each of the rear hooks has a second height measured in the vertical direction; the second height is set to be less than the first height, so that when the rear hook and the rear support are in contact in the vertical direction, there is a gap between the front hook and the front support in the vertical direction.

[0013] In some specific embodiments of the above technical solutions, the difference between the second height and the first height is set such that the back plate can swing back and forth relative to the fixing frame with the plurality of rear hooks as fulcrums within a range not greater than a threshold angle.

[0014] In some specific embodiments of the above technical solutions, the back plate is provided with a left limiting part and a right limiting part at its rear, and the upper bracket is provided with a left limiting groove and a right limiting groove near the bottom opening; when the printhead assembly is assembled at the bottom opening, the left limiting part and the right limiting part are respectively located in the left limiting groove and the right limiting groove.

[0015] In some specific embodiments of the above technical solutions, the printhead assembly is configured to be inserted into the bottom opening with the left and right limiting portions facing downwards and the fixing frame in front, and is allowed to rotate after the left and right limiting portions have completely passed through the bottom opening.

[0016] In some specific embodiments of the above technical solutions, the upper support has a top wall located directly above the bottom opening, and the printhead assembly is configured to be allowed to rotate after the left and right limiting parts have completely passed through the bottom opening and the fixing frame touches the top wall, so as to rotate the left and right limiting parts into the corresponding left and right limiting slots.

[0017] In some specific embodiments of the above technical solution, the upper bracket is provided with a plurality of front positioning notches and a plurality of rear positioning notches on the front and rear edges of the bottom opening, respectively; when the printhead assembly is assembled at the bottom opening, each of the front upper and lower limiting mechanisms is located in the corresponding front positioning notch, and each of the rear upper and lower limiting mechanisms is located in the corresponding rear positioning notch.

[0018] In some specific embodiments of the above technical solutions, the cross-section of the fixing frame along the vertical direction is an inverted U-shape, and the spring is housed inside the fixing frame. In this case, the spring can be wrapped inside the fixing frame and the back plate, making it less likely to fall out during a drop, thus providing excellent drop resistance for the thermal printer.

[0019] Other beneficial effects of this application will be further explained in conjunction with the accompanying drawings in the specific embodiments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a thermal printer provided in an embodiment of this application;

[0021] Figure 2 for Figure 1 The diagram shown illustrates the structure of a thermal printer in some embodiments where the top cover is in the open position.

[0022] Figure 3 for Figure 1 The diagram shows an exploded view of a thermal printer in some embodiments.

[0023] Figure 4 A bottom view of the top cover provided in some embodiments of this application;

[0024] Figure 5 for Figure 4The diagram shown illustrates the top cover in some embodiments when the printhead assembly is not attached.

[0025] Figure 6 Exploded schematic diagram of the printhead assembly provided in some embodiments of this application;

[0026] Figure 7 A top view of the mounting bracket provided in some embodiments of this application;

[0027] Figure 8 for Figure 7 The diagram shows a bottom view of the mounting bracket in some embodiments;

[0028] Figure 9 This is a schematic diagram of the structure of the backplate provided in some embodiments of this application;

[0029] Figure 10 Assembly diagrams of the mounting bracket and backplate provided in some embodiments of this application;

[0030] Figure 11 for Figure 10 The diagram shows the structure of the printhead assembly after the fixing plate and back plate are assembled.

[0031] Figure 12 The upper support provided in the embodiments of this application is a structural schematic diagram in some embodiments;

[0032] Figure 13 for Figure 12 The diagram shows the upper support structure from another perspective;

[0033] Figure 14 for Figure 13 A cross-sectional view of the upper support along the AA direction in some embodiments;

[0034] Figure 15 for Figure 11 The printhead assembly shown is assembled in Figure 12 The diagram shows the structure of the upper support.

[0035] Figure 16 A cross-sectional schematic diagram of the thermal printer provided in some embodiments of this application. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0037] This application provides a printhead assembly and a thermal printer. The thermal printer provided in this application may include, but is not limited to, the product type with a side-opening top cover as described in the illustrations and text; this application does not specifically limit this type. For ease of description, the following uses a side-opening thermal printer as an example to illustrate the technical solution of this application.

[0038] In this article, directional terms such as "up," "down," "left," "right," "front," and "back" are defined relative to the orientation of the structure as shown in the attached diagram. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and can change accordingly depending on the orientation of the structure.

[0039] Please see Figure 1 and Figure 2 The illustration shows a thermal printer 100 according to an embodiment of this application. The thermal printer 100 includes a top cover 10 and a body 20. The right end of the top cover 10 is rotatably connected to the body 20 via a pivot (not shown), and the top cover 10 is rotatable relative to the body 20 about a longitudinal axis X extending front to back. The top cover 10 has a closed position that is closed on the upper part of the body 20 (see reference). Figure 1 ) and the opening position that opens laterally from the upper part of the fuselage 10 (see Figure 2 ).

[0040] See Figure 3 In some implementations of this application, the upper cover 10 includes an upper housing 1, an upper support 2, a control motherboard 3, and a printhead assembly 4. The body 20 includes a lower housing 5, a lower support 6, a roller module 7, and a rechargeable battery pack 8.

[0041] The roller module 7 includes a roller 71, a motor 72, and a reduction gear set 73. The motor 72 is powered by a rechargeable battery pack 8. The rotation of the motor 72 drives the reduction gear set 73 to rotate, which in turn transmits the power to the roller 71. During printing, the thermal paper is propelled forward by the rotating roller 71. The roller module 7 and the rechargeable battery pack 8 are supported by a lower bracket 6, which is housed within the lower housing 5 (see reference). Figure 2 ).

[0042] See Figure 4 and Figure 5 The upper bracket 2 is housed within the upper housing 1, and the control motherboard 3 is located between the upper bracket 2 and the upper housing 1. The front of the upper bracket 2 provides a receiving space 21 for accommodating the printhead assembly 4. The printhead assembly 4 is mounted as an integral component in this receiving space 21, and the thermal pad 43 of the printhead assembly 4 (see below) protrudes from the receiving space 21. Exemplarily, the printhead assembly 4 can be mounted to the upper bracket 2 by screws.

[0043] See Figure 6 The printhead assembly 4 includes a mounting bracket 41, a back plate 42, a thermal sheet 43, and a plurality of springs 44. The back plate 42 is detachably mounted to the lower part of the mounting bracket 41. The thermal sheet 43 is fixed to the lower surface of the back plate 42. Exemplarily, the thermal sheet 43 can be fixed to the lower surface of the back plate 42 by means of adhesive or screws.

[0044] See Figure 7 and Figure 8 In some implementations of this application, the fixing frame 41 is an elongated member extending in the left-right direction. The fixing frame 41 is typically a rigid member made of metal.

[0045] The mounting bracket 41 has an inverted U-shaped cross-section along its vertical direction. The mounting bracket 41 includes a front sidewall 411, a rear sidewall 412, and a top wall 413 that separates the front and rear sidewalls 411 and 412. The top wall 413 of the mounting bracket 41 has several threaded mounting holes 4131, allowing the mounting bracket 41 to be fixed to the upper bracket 2 by screws inserted into the mounting holes 4131. In other embodiments, self-tapping screws can also be used to attach the mounting bracket to the upper bracket, in which case the mounting holes do not need to be threaded. The front sidewall 411 has a lower front side portion 41111, where multiple front support portions 4112 and multiple front limiting portions 4113 protruding forward relative to the front sidewall 411 are provided. Multiple front support portions 4112 are spaced apart in the left-right direction, and the front edges of the multiple front support portions 4112 are located on the first reference plane 91; multiple front limiting portions 4113 are spaced apart in the left-right direction, and the front edges of the multiple front limiting portions 4113 are located on the second reference plane 92.

[0046] The number of front limiting portions 4113 is the same as the number of front support portions 4112, and each front limiting portion 4113 is adjacent to a front support portion 4112. Each front support portion 4112 has a width dimension W1 measured in the front-rear direction, and each front limiting portion 4113 has a width dimension W2 measured in the front-rear direction, wherein W2 is set to be less than W1.

[0047] The rear sidewall 412 has a rear lower side edge 4121, and a plurality of rear support portions 4122 and a plurality of rear limiting portions 4123 protruding rearward relative to the rear sidewall 412 are provided at the rear lower side edge 4121. The plurality of rear support portions 4122 are spaced apart in the left-right direction, and the rear edges of the plurality of rear support portions 4122 are located on the third reference plane 93; the plurality of rear limiting portions 4123 are spaced apart in the left-right direction, and the rear edges of the plurality of rear limiting portions 4123 are located on the fourth reference plane 94.

[0048] The number of rear limiting portions 4123 is the same as the number of rear support portions 4122, and each rear limiting portion 4123 is adjacent to a rear support portion 4122. Each rear support portion 4122 has a width dimension W3 measured in the front-rear direction, and each rear limiting portion 4123 has a width dimension W4 measured in the front-rear direction; wherein, W4 is set to be less than W3.

[0049] Multiple front support portions 4112 and multiple rear support portions 4122 constitute the support structure provided at the lower part of the fixing frame 41. When the back plate 42 is attached to the lower part of the fixing frame 41, the front and rear portions of the back plate 42 will be supported on the support structure.

[0050] The upper surface of part of the top wall 413 is recessed downward to form multiple protrusions 4132, and the upper end of the spring 43 can be attached to these protrusions 4132.

[0051] The first datum plane 91, the second datum plane 92, the third datum plane 93, and the third datum plane 94 are all vertical planes parallel to each other; among them, the first datum plane 91 and the third datum plane 93 have a longitudinal distance D1 (this longitudinal distance is the distance measured along the front-back direction, the same below), and the second datum plane 92 and the fourth datum plane 94 have a longitudinal distance D2.

[0052] See Figure 9 In some implementations of this application, the back plate 42 is an elongated member extending in the left-right direction. The back plate 42 is typically a metal component with excellent thermal conductivity. The back plate 42 is sheet-like and has a front side portion 421 and a rear side portion 422 that are opposite each other.

[0053] A plurality of front hooks 423 are provided at the front side edge 421, protruding upward relative to the upper surface 420 of the back plate 42. Each front hook 423 is inverted L-shaped. The plurality of front hooks 423 are spaced apart in the left-right direction and are all located on the fifth reference plane 95. The openings of the plurality of front hooks 423 are all uniformly set to the right. The opening of each front hook 423 has a height dimension H1 measured in the vertical direction.

[0054] A plurality of rear hooks 424 are provided at the rear side edge 422, protruding upward relative to the upper surface 420 of the back plate 42. Each rear hook 424 is also inverted L-shaped. The plurality of rear hooks 424 are spaced apart in the left-right direction and are all located on the sixth reference plane 96. The openings of the plurality of rear hooks 424 are all uniformly oriented to the right. The opening of each rear hook 424 has a height dimension H2 measured in the up-down direction. Wherein, H1 is set to be greater than H2. In addition, in some embodiments, the opening height dimension of the middle rear hook 424 is set to be greater than the opening height dimension of the rear hooks 424 on the left and right sides.

[0055] The fifth datum plane 95 and the sixth datum plane 96 are also vertical planes and parallel to each other, with a longitudinal distance D3 between them. The value of D3 is in the range of D1≥D3≥D2.

[0056] A lateral limiting structure 427 is also provided at the rear of the back plate 42. This lateral limiting member can effectively prevent the back plate 42 from moving arbitrarily in the lateral direction (i.e., the left-right direction) after the printhead assembly 4 is assembled into the receiving space 21. In some implementations of this application, the lateral limiting structure 427 includes a left limiting portion 425 and a right limiting portion 426 that are far apart from each other in the left-right direction. The left limiting portion 425 and the right limiting portion 426 protrude rearward relative to the rear side portion 422. In some embodiments of this application, the left limiting portion 425 extends rearward and then to the left from a portion of the rear side portion 422 and forms an L-shaped structure; similarly, the right limiting portion 426 extends rearward and then to the right from a portion of the rear side portion 422 and forms an L-shaped structure.

[0057] When assembling the printhead assembly 4, the thermal sheet 43 is fixed to the lower surface of the back plate 42; multiple springs 44 are respectively attached to the corresponding protrusions 4132 on the inner side of the mounting bracket 41, and then the back plate 42 is inserted into the lower part of the mounting bracket 41 from left to right. See [link to documentation]. Figure 10 Conversely, the backplate 42 can also be pulled off the bracket 41 from right to left to detach it from the lower part of the bracket 41.

[0058] In the printhead assembly 4 of this application, since there are no additional third parts or fasteners between the mounting bracket 41, back plate 42, thermal sheet 43, and spring 44, the manufacturing cost is low and assembly is easy. Traditional thermal printers typically place the back plate with the thermal sheet onto the top cover, and then press the spring from the front (i.e., the side away from the rotation center of the back plate) between the back plate and the top cover body (or mounting bracket). With this installation method, the spring is prone to popping out from the gap between the back plate and the front of the top cover body (or mounting bracket) when dropped, resulting in poor drop resistance. The mounting bracket 41 structure provided in some embodiments of this application effectively protects multiple springs 44; that is, multiple springs 44 can be enclosed within the mounting bracket 41 and back plate 42. Even if the printhead assembly 4 is dropped from a height, the springs 44 will not fall out from inside the mounting bracket 41, resulting in excellent drop resistance for the printhead assembly 4.

[0059] like Figure 11As shown, after the printhead assembly 4 is assembled, each front hook 423 and each rear hook 424 will be supported at the corresponding front support 4112 and the corresponding rear support 4122, respectively. Each front limiting part 4113 is located behind the corresponding front hook 423, and each rear limiting part 4123 is located in front of the corresponding rear hook 424. At this time, since the opening heights of the front hooks 423 and the rear hooks 424 are inconsistent, when each rear hook 424 contacts the corresponding rear support 4122 in the vertical direction, there is a gap between each front hook 423 and the corresponding front support 4112 in the vertical direction. This gap allows the back plate 42 to swing back and forth relative to the mounting frame 41. In some embodiments, the difference in opening height between the front hooks 423 and the rear hooks 424 is set to allow the back plate 42 to swing back and forth relative to the mounting frame 41 with the multiple rear hooks 424 as fulcrums within a range not exceeding a threshold angle.

[0060] In the printhead assembly 4 of this application, after the multiple front support portions 4112 and multiple front hooks 423 are joined, multiple front upper and lower limiting structures 45 arranged in the left and right direction can be formed at the front of the back plate 42 and the front of the fixing frame 41, which can effectively suppress the deformation of the front of the back plate 42 in the upper and lower direction; similarly, after the multiple rear support portions 4122 and multiple rear hooks 424 are joined, multiple rear upper and lower limiting structures 46 arranged in the left and right direction can also be formed at the rear of the back plate 42 and the rear of the fixing frame 41, which can effectively suppress the deformation of the rear of the back plate 42 in the upper and lower direction; therefore, the printhead assembly 4 of this application is particularly suitable for thermal sheets with a long shaft length.

[0061] When the printhead assembly 4 is in operation, it achieves an adaptive structure. With the top cover 10 in the closed position, the rear hook 424 contacts the corresponding rear support 4122, and a gap remains between the front hook 424 and the front support 4112. The back plate 42, carrying the thermal sheet 43, rotates using the multiple rear hooks 424 as fulcrums, automatically adapting to the actual position of the rubber roller 71 for normal operation. The rubber roller 71 supports the thermal sheet 43 from below, and the thermal sheet 43 undergoes adaptive deformation under the pressure of multiple springs 44, conforming to the rubber roller 71. Among the multiple rear hooks 424, the outermost rear hook 424, with its smaller opening height, will contact the corresponding rear support 4122 first, leaving a gap between the middle rear hook 424 and its corresponding rear support 4122. Under the pressure of the springs 44, the back plate 42 and the thermal sheet 43 deform upwards in the middle, automatically adapting to the rubber roller 71 deforming downwards in the middle under the pressure of the printhead assembly 4. When the top cover 10 is in the open position, each front hook 423 contacts the corresponding front support 4112, which can effectively prevent the heat-sensitive sheet 43 from being excessively deformed and damaged under the pressure of the spring 43.

[0062] See Figure 12-14In some implementations of this application, the upper support 2 is a single component, and the receiving space 21 is defined by the upper support 2. The receiving space 21 has a bottom opening 211 located at the lower part of the upper support 2 and a rear opening 212 located at the rear part of the upper support 2. The upper support 2 includes a top wall 24 located at the upper part, which is vertically aligned with the bottom opening 211 and defines the upper boundary of the receiving space 21. The top wall 24 has a plurality of horizontally arranged through holes 25, which are vertically aligned with a plurality of mounting holes 4131 on the fixing bracket 41. The fixing bracket 41 is fixed to the top wall 24 by screws that pass through both the through holes 25 and the mounting holes 4131. The upper support 2 also includes a bottom wall 28, the front side 281 of which defines the rear boundary of the bottom opening 211. The upper support 2 also includes a lateral limiting structure 210, which is adjacent to the rear opening 212 of the receiving space 21 from the rear. The upper support 2 includes a front wall 29. The front wall 29 defines the front boundary of the receiving space 21, and the bottom end 291 of the front wall 29 defines the front boundary of the bottom opening 211. A plurality of front receiving notches 26 are provided at the bottom end 291 of the front wall 29, and a plurality of rear receiving notches 27 are provided at the front side 281 of the bottom wall 28.

[0063] The lateral limiting structure 210 includes a left limiting protrusion 22 and a right limiting protrusion 23 that protrude upward relative to the front side 281 of the bottom wall 28. The lateral limiting structure 210 on the upper bracket 2 and the lateral limiting structure 427 on the back plate 42 are configured to cooperate with each other.

[0064] The bottom opening 211 of the receiving space 21 is configured to allow the printhead assembly 4 to be inserted upward into the receiving space 21 with the mounting bracket 41 in front, the back plate 42 behind, and the lateral limiting structure 427 of the back plate 42 on top. The rear opening 212 is configured to allow the lateral limiting structure 427 of the back plate 42 entering the receiving space 1 to flip backward when it moves upward to the position above the lateral limiting structure 210, and to form a positioning engagement with the lateral limiting structure 210 after the lateral limiting structure 427 passes over the lateral limiting structure 210; after this backward flipping step is completed, it enables the lateral limiting structure 427 to be removed from the receiving space 21 through the rear opening 212, and the lateral limiting structure 424 to form a positioning engagement with the lateral limiting structure 210 in the left-right direction after passing over the lateral limiting structure 210.

[0065] In some embodiments, the timing of the rearward flipping of the lateral limiting structure 427 can be set so that the fixing frame 41 just contacts the top wall 24, at which point the lateral limiting structure 427 has moved above the lateral limiting structure 210. In some embodiments, after the lateral limiting structure 427 has finished flipping backward, the rear edge of the back plate 42 will be located above the front edge 281 of the bottom wall 28.

[0066] When the printhead assembly 4 is installed on the upper bracket 2, it is inserted into the receiving space 21 through the bottom opening 211 with the left limiting part 425 and the right limiting part 426 of the back plate 42 on top and the fixing frame 41 in front. After the left limiting part 425 and the right limiting part 426 pass through the rear opening of the receiving space 21 and the fixing frame 41 contacts the top wall 24 directly above the receiving space, the back plate 42 is rotated backward so that the left limiting part 425 and the right limiting part 426 pass over the left limiting protrusion 22 and the right limiting protrusion 23 from the top and respectively engage with the left limiting protrusion 22 and the right limiting protrusion 23 of the upper bracket 2. Multiple front upper and lower limiting structures 46, which are formed by the engagement of multiple front support parts 4112 and multiple front hooks 423, and multiple rear upper and lower limiting structures 47, which are formed by the engagement of multiple rear support parts 4122 and multiple rear hooks 424, enter the front receiving notch 26 and the rear receiving notch 27 respectively, and the thermal sheet 43 is exposed to the outside; finally, by using screws to pass through the through hole 25 and lock the mounting hole 4131, the fixing bracket 41 can be fixed on the upper bracket 2.

[0067] like Figure 15 As shown, when the printhead assembly 4 is assembled in the receiving space 21, the lateral limiting structure 427 and the lateral limiting structure 210 cooperate with each other, that is, the left limiting part 425 and the right limiting part 425 abut against the left limiting protrusion 22 and the right limiting protrusion 23 respectively. The left limiting part 425 is restricted to move to the left by the left limiting protrusion 22, and the right limiting part 426 is restricted to move to the right by the right limiting protrusion 23, thereby preventing the back plate 42 from moving in the left and right directions relative to the upper support 2.

[0068] Compared to the traditional installation method of inserting the thermal head from the bottom, in this embodiment, the upper bracket 2 is designed with the bottom opening size based on the area to be exposed of the thermal sheet 43, and the specifications of the fixing frame 41 are adaptively set according to the size of the receiving space 21. Therefore, the upper bracket 2 does not need to provide space for the back plate 42 and the thermal sheet 43 to move back and forth, improving the space utilization efficiency of the printer. At the same time, if the structure of the receiving space 21 is not suitable for the printhead assembly 4 to flip (i.e., the printhead assembly 4 is installed by inserting it entirely into the receiving space 21 from the top of the upper bracket 2 in the traditional way), the overall height of the receiving space must be increased due to the restriction of the overall height of the printhead assembly 4 and the obstruction of the lateral limiting structure 210, so that the printhead assembly 4 can be inserted entirely into the receiving space 21 from between the lateral limiting structure 215 and the top wall 24. This reduces the space utilization rate of the upper cover 10 to some extent.

[0069] After the printhead assembly 4 is installed on the upper bracket 2, the back plate 42 and the thermal sheet 43 extend at least partially from the rear opening 212 of the receiving space 21 and are supported above the bottom wall 28 of the upper bracket 2 (see [reference]). Figure 15The control motherboard 3 is mounted adjacent to the rear side of the receiving space 21 and covers the portion of the back plate 42 and the thermal sheet 43 that extends out of the receiving space 21 and is supported above the bottom wall 28 of the upper bracket 2 from top to bottom, thereby making full use of the space.

[0070] Furthermore, traditional bolts used to secure the printhead typically mate with the plastic body of the housing, meaning the mounting holes that mate with the threads are usually located on the plastic part. During printer use, frequent opening and closing of the cover causes the thermal pad to constantly switch between detaching from and contacting the rollers, resulting in continuous stress changes between the printhead and the housing. When these stress changes are reflected in the bolts used to secure the printhead, the bolts tend to loosen and continuously wear down the mounting holes. Because plastic has relatively low wear resistance and structural strength, the mounting holes often become damaged after prolonged use, leading to a failure to secure the printhead and reduced print quality. At the same time, since the mounting holes are located on the plastic body of the housing, they cannot be replaced individually, resulting in high maintenance costs. In this embodiment, the mounting holes are located on the mounting bracket 41; when the mounting holes are damaged, only the mounting bracket 41 needs to be replaced. Moreover, the metal mounting bracket 41 is much stronger than plastic parts, making it less prone to damage to the mounting holes.

[0071] See Figure 16 When the upper cover 10 is in the closed position, covering the upper part of the machine body 20, the heat-sensitive sheet 43 contacts the rubber roller 711. The front hook 423 is supported above the front support part 4112, and the front upper and lower limiting structure 45 formed by the two serves to limit the upper and lower parts of the front of the fixed plate 41 and the front of the back plate 42; the front limiting part 4113 is located on the rear side of the front hanging structure 423, which can effectively limit the distance of forward movement of the back plate 42 relative to the fixed frame 41. The rear hook 424 is supported above the rear support part 4122, and the rear upper and lower limiting structure 46 formed by the two serves to limit the upper and lower parts of the rear of the fixed plate 41 and the rear of the back plate 42; the rear limiting part 4123 is located on the front side of the rear hanging structure 424, which can effectively limit the distance of backward movement of the back plate 42 relative to the fixed frame 41. The left limiting protrusion 22 and the right limiting protrusion 23 limit the left limiting part 425 and the right limiting part 426; this not only effectively restricts the movement of the back plate 42 relative to the fixing frame 41 in multiple directions, but also effectively suppresses the deformation of the heat-sensitive sheet 43.

[0072] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made without departing from the spirit and scope of this application. The scope of protection claimed by this application is defined by the appended claims, specification, and their equivalents.

Claims

1. A thermal printer, comprising a body and a top cover rotatable in an open and closed position, characterized in that, The upper cover includes: an upper support having a receiving space and a printhead assembly detachably mounted in the receiving space; the printhead assembly is a pre-assembled integral assembly and includes a mounting frame, a back plate pivotally supported at the lower part of the mounting frame, a thermal sheet fixed to the lower surface of the back plate, and a plurality of springs, the plurality of springs being constrained between the mounting frame and the back plate; the upper support includes a top wall adjacent to the receiving space from the upper side and the rear side respectively, and a first lateral limiting structure; the rear part of the back plate has a second lateral limiting structure adapted to the first lateral limiting structure; the receiving space is adapted to accommodate at least part of the... The mounting bracket has a bottom opening and a rear opening. The bottom opening allows the printhead assembly to be inserted upward into the receiving space with the mounting bracket in front and the second lateral limiting structure of the back plate on top. The rear opening is configured to allow the second lateral limiting structure of the back plate, which enters the receiving space, to flip backward when it moves to the upper position of the first lateral limiting structure, so as to move out of the receiving space and form a positioning engagement with the first lateral limiting structure. When the printhead assembly is mounted on the upper bracket, the mounting bracket is fixed to the top wall, and at least part of the thermal pad is exposed from the bottom opening.

2. The thermal printer according to claim 1, characterized in that, The top wall has multiple horizontally arranged through holes, and the fixing bracket has mounting holes aligned vertically with the multiple through holes. The fixing bracket is fixed to the top wall by screws.

3. The thermal printer according to claim 2, characterized in that, The mounting bracket is made of metal.

4. The thermal printer according to claim 1, characterized in that, The second lateral limiting structure includes a left limiting part and a right limiting part, and the first lateral limiting structure includes a left limiting protrusion and a right limiting protrusion; when the printhead assembly is assembled in the receiving space, the left limiting part and the right limiting part respectively cooperate with the left limiting protrusion and the right limiting protrusion.

5. The thermal printer according to claim 1, characterized in that, The lower part of the fixing frame and the back plate are provided with a plurality of front upper and lower limiting mechanisms and a plurality of rear upper and lower limiting mechanisms. The lower part of the fixing frame includes a front lower side and a rear lower side that are separated front and rear. The back plate has a front side and a rear side. The plurality of front upper and lower limiting mechanisms are arranged between the front lower side and the front side and are spaced apart from each other on the left and right. The plurality of rear upper and lower limiting mechanisms are arranged between the rear lower side and the rear side and are spaced apart from each other on the left and right.

6. The thermal printer according to claim 5, characterized in that, Each of the aforementioned front upper and lower limiting mechanisms includes a front support portion arranged on the front lower side and a front hook arranged on the front side. Each of the aforementioned rear upper and lower limiting mechanisms includes a rear support portion arranged on the rear lower side and a rear hook arranged on the rear side. The openings of all the aforementioned front hooks and all the aforementioned rear hooks are simultaneously arranged to the left or simultaneously arranged to the right. Each of the aforementioned front support portions is located within the opening of the corresponding front hook, and each of the aforementioned rear support portions is located within the opening of the corresponding rear hook.

7. The thermal printer according to claim 6, characterized in that, Both the front hook and the rear hook are inverted L-shapes.

8. The thermal printer according to claim 7, characterized in that, Each of the front hooks has an opening with a first height measured in the vertical direction, and each of the rear hooks has an opening with a second height measured in the vertical direction; the second height is set to be less than the first height, so that when the rear hook and the rear support are in contact in the vertical direction, there is a gap between the front hook and the front support in the vertical direction.

9. The thermal printer according to claim 8, characterized in that, The difference between the second height and the first height is set such that the back plate can swing back and forth relative to the fixing frame with the rear hook as the fulcrum within a range not greater than a threshold angle.

10. The thermal printer according to claim 5, characterized in that, The upper support has multiple front positioning notches and multiple rear positioning notches on the front and rear edges of the accommodating space, respectively; when the printhead assembly is assembled in the accommodating space, each of the front upper and lower limiting mechanisms is located in the corresponding front positioning notch, and each of the rear upper and lower limiting mechanisms is located in the corresponding rear positioning notch.

11. The thermal printer according to claim 1, characterized in that, The fixed frame has an inverted U-shaped cross-section along the vertical direction, and the spring is housed inside the fixed frame.

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