Thermal head pressurizing mechanism

Abstract

To take out paper loaded on a loading table and then move the loading table up to a position where the paper can be easily interchanged.SOLUTION: A thermal head pressurizing mechanism is provided with: a platen roller 12 that presses a thermal head 11; a slide unit 13 that slidably holds the thermal head 11 in a pressing direction; a pressurizing spring 14 that generates pressing force in the thermal head 11; a pressing-force adjusting mechanism 15 that adjusts the pressing force to arbitrary pressing force by energizing force generated by extending or contracting a length of the pressurizing spring 14; a supporting part 111 supporting the thermal head 11; a pressurizing unit enclosure 17 held slidably by the slide unit 13 and provided to sandwich the supporting part 111 and the pressing-force adjusting mechanism 15; and a hold unit 18 that fixes the pressurizing unit enclosure 17 in a pressurizing state and releases the state. When the pressurizing state of the pressurizing unit enclosure 17 is released, the thermal head 11, the supporting part 111, the pressurizing spring 14, the pressing-force adjusting mechanism 15 and the pressurizing unit enclosure 17 are moved integrally so as to separate from the platen roller 12.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a thermal head pressure mechanism. [Background technology]

[0002] Thermal printers that print by pressing a thermal head against a platen roller are well known.

[0003] In a thermal printer, it is necessary to press the thermal head against a platen roller, and at the same time release the pressure between the thermal head and the platen roller, move the thermal head along a slide unit in a direction away from the platen roller.

[0004] Patent document 1 describes that during printing, the head drive unit 13 is lowered by using the pressing portion 16c of the pressing lever 16 to press a pre-charge plate 13e, which indirectly presses the thermal head 11 via an elastic member 15, so that the thermal head 11 is brought into close contact with the platen roller 14 with the ink ribbon and printing media sandwiched between them, and that when not printing, the arm portion 13b is lifted by the protrusion portion 16b of the pressing lever 16 to retract the thermal head 11 from the platen roller 14. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-251777 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the printing device described in Patent Document 1, when printing is not in progress, the thermal head 11 is retracted from the platen roller 14 by lifting the arm portion 13b with the protrusion portion 16b of the pressure lever 16, so it was necessary to use a member with sufficient rigidity to withstand this.

[0007] The present invention has been made in consideration of the above problems, and has an object to provide a thermal head pressure mechanism that can release the pressure between the platen roller and the thermal head, and retract the thermal head in a direction away from the platen roller, without using members with appropriate rigidity. [Means for solving the problem]

[0008] In order to achieve the above object, the thermal head pressure mechanism according to the present invention is characterized by: In a printing system that prints by pressing a thermal head against a platen roller, a slide unit that holds the thermal head slidably in a pressing direction; a pressure spring that generates a pressure on the thermal head; a pressure adjustment mechanism that can adjust the pressure to any desired value by expanding or contracting the pressure spring; a pressure unit housing that is slidably held by the slide unit and that is provided so as to sandwich a support portion that supports the thermal head, the pressure spring, and the pressure adjustment mechanism; a hold unit that fixes or releases the pressurizing unit housing in a pressurized state, When the pressurized state of the pressurizing unit housing is released, the thermal head, the support portion, the pressurizing spring, the pressure adjustment mechanism, and the pressurizing unit housing are moved together in a direction away from the platen roller. The point is... Effect of the Invention

[0009] According to the features of the thermal head pressure mechanism of the present invention, the pressure between the platen roller and the thermal head can be released and the thermal head can be retracted in a direction away from the platen roller without using a member having a corresponding rigidity. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic overall view of a conventional printing device; [Diagram 2] 1 is a schematic overall view of a printing apparatus to which a thermal head pressure mechanism according to an embodiment of the present invention is applied; [Diagram 3] 5A to 5C are explanatory diagrams illustrating the operation of a printing device to which a thermal head pressure mechanism according to an embodiment of the present invention is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The same or equivalent parts and components are designated by the same or equivalent reference numerals throughout the drawings. However, it should be noted that the drawings are schematic and may differ from the actual product. In addition, the drawings may include parts with different dimensional relationships and ratios.

[0012] The embodiments described below are merely examples of devices for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the arrangement of each component to that described below. Various modifications can be made to the technical idea of ​​the present invention within the scope of the claims.

[0013] (Printer 1 Configuration) Fig. 1 is an overall schematic diagram of a printing device according to the prior art, with Fig. 1(a) showing a perspective view and Fig. 1(b) showing a side view. The front-rear, up-down, left-right directions shown in Fig. 1(a) will be referred to as front-rear, up-down, left-right directions below. The direction perpendicular to the paper surface of Fig. 1(b) is the left-right direction, and the front direction of the paper surface is the rightward direction. Additionally, the front-rear, up-down, and front-rear directions on the paper surface in Fig. 1(b) are referred to as front-rear, up-down, and front-rear directions. The direction from back to front is the paper transport direction.

[0014] 1(a) and (b), a printing device 100 according to the prior art is comprised of a thermal head 101, a platen roller 102 that presses against the thermal head 101, a slide unit 103 that holds the thermal head 101 so that it can slide in the pressing direction, a pressure spring 104 that generates a pressure on the thermal head 101, a pressure adjustment mechanism 105 that adjusts the pressure to an arbitrary value by a biasing force generated by expanding or contracting the length of the pressure spring 104, and a retraction cam 106 that retracts the thermal head 101 in a direction away from the platen roller 102. Note that a description of a retraction cam support structure that supports the retraction cam 106 and a cam drive structure that drives the retraction cam 106 will be omitted here.

[0015] In the printing device 100, which is the conventional technology, when releasing the pressure between the thermal head 101 and the platen roller 102, the retraction cam 106 is rotated in the direction of arrow Y1, and the components that are integral with the thermal head 101 are pushed upward by the retraction cam 106, thereby releasing the pressure between the thermal head 101 and the platen roller 102 and at the same time moving the thermal head 101 along the slide unit 103 in a direction away from the platen roller 102.

[0016] As described above, in the conventional printing apparatus 100, in order to release the pressure between the thermal head 101 and the platen roller 102, the retraction cam 106 is used to retract the thermal head 101 in a direction away from the platen roller 102.

[0017] Therefore, it is necessary to use the retraction cam 106 to move the thermal head 101 against the pressure, and in this state, a load far exceeding the pressure required for printing is applied to all components that receive the biasing force of the pressure spring 104.

[0018] To ensure the rigidity needed to withstand this load, it was necessary to increase the thickness of the components and the shaft diameter, which resulted in an increase in the size of the printing device. Also, it was necessary to use a pressure spring that allows for the extra deflection required to retract the thermal head 101, and the spring would be large in both outer diameter and length.

[0019] Fig. 2 is an overall schematic diagram of a printing device 1 to which a thermal head pressure mechanism according to an embodiment of the present invention is applied, with Fig. 2(a) showing a perspective view and Fig. 2(b) showing a side view. The front-rear, up-down, left-right directions shown in Fig. 2(a) will be referred to as front-rear, up-down, left-right directions below. The direction perpendicular to the paper surface of Fig. 2(b) is the left-right direction, and the front direction of the paper surface is the rightward direction. Additionally, the front-rear, up-down, and front-rear directions on the paper surface in Fig. 2(b) are referred to as front-rear, up-down, and front-up-down directions. The direction from back to front is the paper transport direction.

[0020] 2(a) and (b), the printing apparatus 1 according to the embodiment of the present invention includes a thermal head 11, a platen roller 12 that presses against the thermal head 11, a slide unit 13 that holds the thermal head 11 slidably in the pressing direction, a pressure spring 14 that generates a pressure on the thermal head 11, a pressure adjustment mechanism 15 that adjusts the pressure to an arbitrary value by a biasing force generated by expanding and contracting the length of the pressure spring 14, a support part 111 that is disposed below the pressure spring 14 and supports the thermal head 11, a pressure unit housing 17 that is slidably held by the slide unit 13 and is provided so as to sandwich the support part 111, the pressure spring 14, and the pressure adjustment mechanism 15, and a hold unit 18 that fixes and releases the pressure unit housing 17 in a pressurized state. A plate-shaped member 112 that slides and moves on the slide unit 13 together with the thermal head 111 is provided as a part of the support member 111 near an alignment mechanism 22 described later (see FIG. 2).

[0021] The support portion 111 formed integrally with the thermal head 11, the pressure adjustment mechanism 15, and the pressure unit housing 17 are each slidably held on the shaft of the slide unit 13.

[0022] In the pressurized state, the pressurizing unit housing 17 is fixed by being held by the hold unit 18 (toggle clamp), and the upper position of the pressurizing spring 14 is fixed via the pressure adjustment mechanism 15. At that time, the thermal head 11 comes into contact with the platen roller 12, and at the same time, the lower part 17b of the pressurizing unit housing 17 and the lower part of the plate-like member 112 formed integrally with the thermal head 11 separate, and the load of the pressurizing spring 14 is transmitted to the thermal head 11.

[0023] In the pressure release state, at the same time as the hold unit 18 is released, the pressure unit housing 17 and the pressure adjustment mechanism 15 move upward as a unit by the reaction force of the pressure spring 14 to a position where the lower part of the plate-like member 112 formed integrally with the thermal head 11 comes into contact with the lower part 17b of the pressure unit housing 17. In this state, the load of the pressure spring 14 is received by the inner upper and lower surfaces of the pressure unit housing 17, so the thermal head 11, the pressure adjustment mechanism 15, and the pressure unit housing 17 can move without load.

[0024] In the retreated state, the entire unit, which is movable without load in the pressure-released state, is moved further upward and fixed in the moved position.

[0025] The support part 111 formed integrally with the thermal head 11 is provided with a holder 20 that is rotatably held with the main scanning direction (front-rear direction) of the thermal head 11 as a rotation axis (axis perpendicular to the pressing direction) of the thermal head 11. Two rolling bearings 21 are disposed adjacent to each other on the rotatable holder 20.

[0026] An alignment mechanism 22 is provided that automatically adjusts the pressure balance in the main scanning direction (front-rear direction) when pressing the thermal head 11 against the platen roller 12. The alignment mechanism 22 desirably uses a rolling bearing 21 with extremely low sliding resistance. However, the rolling bearing 21 causes runout of the inner and outer ring shafts in the gap between the inner and outer rings.

[0027] Therefore, a configuration is adopted in which two rolling bearings 21 are arranged adjacent to each other. With this configuration, the runout of the inner and outer rings of one rolling bearing 21 is held by the adjacent other rolling bearing 21, so that the runout of the alignment mechanism 22 can be dramatically improved.

[0028] FIG. 3 is an explanatory diagram illustrating the operation of a printing device 1 to which a thermal head pressure mechanism according to an embodiment of the present invention is applied, with FIG. 3(a) showing the pressure release state and FIG. 3(b) showing the retracted state.

[0029] 3(a), in the pressure release state, as soon as the hold unit 18 is released, the pressure unit housing 17 and the pressure adjustment mechanism 15 move upward together by the reaction force of the pressure spring 14 to a position where the lower part of the plate-like member 112 formed integrally with the thermal head 11 comes into contact with the lower part 17b of the pressure unit housing 17. In this state, the load of the pressure spring 14 is received by the inner upper and lower surfaces of the pressure unit housing 17, so that the thermal head 11, the pressure adjustment mechanism 15, and the pressure unit housing 17 can move without load.

[0030] 3(b), in the retracted state, the entire unit including the pressure unit housing 17, which is movable without load in the pressure release state, is moved further upward and fixed in the moved position. This allows the thermal head 11 to be retracted from the platen roller 12.

[0031] (Additional Note) This application discloses the following inventions.

[0032] (Appendix 1) In a printing system that prints by pressing a thermal head against a platen roller, a slide unit that holds the thermal head slidably in a pressing direction; a pressure spring that generates a pressure on the thermal head; a pressure adjustment mechanism that can adjust the pressure to any desired value by expanding or contracting the pressure spring; a pressure unit housing that is slidably held by the slide unit and that is provided so as to sandwich a support portion that supports the thermal head, the pressure spring, and the pressure adjustment mechanism; a hold unit that fixes or releases the pressurizing unit housing in a pressurized state, When the pressurized state of the pressurizing unit housing is released, the thermal head, the support portion, the pressurizing spring, the pressure adjustment mechanism, and the pressurizing unit housing are moved together in a direction away from the platen roller. A thermal head pressure mechanism comprising:

[0033] As a result, when the pressure is released, the pressure unit housing receives the entire load of the pressure spring, and the thermal head, pressure spring, pressure adjustment mechanism, and pressure unit housing can move together in a direction away from the platen roller without load. This eliminates unnecessary pressure spring force and eliminates the need for the pressure spring to tolerate excessive deflection, making it possible to miniaturize the device. [Explanation of symbols]

[0034] 1 Printing device 11 Thermal head 12 Platen roller 13 Slide unit 14 Pressure spring 15 Pressure adjustment mechanism 17 Pressurizing unit housing 18 Hold Unit 20 Holding part 21 Rolling bearings 22 Alignment mechanism

Claims

[Claim 1] In a printing system that prints by pressing a thermal head against a platen roller, a slide unit that holds the thermal head slidably in a pressing direction; a pressure spring that generates a pressure on the thermal head; a pressure adjustment mechanism that can adjust the pressure to any desired value by expanding or contracting the pressure spring; a pressure unit housing that is slidably held by the slide unit and that is provided so as to sandwich a support portion that supports the thermal head, the pressure spring, and the pressure adjustment mechanism; a hold unit that fixes or releases the pressurizing unit housing in a pressurized state, When the pressurized state of the pressurizing unit housing is released, the thermal head, the support portion, the pressurizing spring, the pressure adjustment mechanism, and the pressurizing unit housing are moved together in a direction away from the platen roller. A thermal head pressure mechanism comprising:

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