JP4347633B2 - Small thermal printer - Google Patents

Description

  The present invention relates to a small thermal printer, and more particularly to a small thermal printer that can reduce the number of parts and the number of assembling steps and can assure assembly accuracy.

  As an example of a conventional small thermal printer, it has a frame made of a resin material and formed with side plates facing each other, and one side plate has a mounting plate erected upward with a step from this side plate. It has a shape. A motor composed of a stepping motor or the like is screwed to the mounting plate. A drive gear is fixed to the rotation shaft of the motor. Further, each side plate of the frame is formed with a U-shaped groove, and the rotation shaft of the platen roller is rotatably held in the U-shaped groove.

  In addition, a lever member is attached to the outside of each side plate to prevent the rotation shaft inserted into each groove from coming off.

  A platen gear made of a spur gear is attached to one end of the rotating shaft that is pivotally supported by each side plate, and the rotation of the motor is transmitted to the platen roller. It is possible. The platen gear is attached to one end portion of the rotating shaft through a necessary minimum gap formed between the outer surface of one side plate and the end surface of the platen gear facing the outer surface. A lever member for preventing the rotation shaft from coming out of the groove is disposed in the gap, and the end surface of the platen gear and the side surface of the lever member are spaced apart so as not to slide.

  A horizontally long thermal head composed of a line head is disposed on the platen roller. The thermal head is formed with a plurality of heating elements aligned in the longitudinal direction. A torsion coil spring for elastically energizing the thermal head and pressing the thermal head against the platen roller on the rear side opposite to the side on which the heat generating elements of the thermal head are formed. Is arranged. The heating elements of the thermal head can be pressed against the platen roller by the biasing force of the torsion coil spring.

  An intermediate gear at one end of an intermediate gear group composed of a plurality of intermediate gears is engaged with the drive gear of the motor. An intermediate gear at the other end of the intermediate gear group meshes with a platen gear fixed to one end portion of the rotating shaft so that the rotation of the motor is transmitted to the platen roller via the intermediate gear group. It has become.

  The intermediate gear group is located on the rear side of the thermal head on the side opposite to the side on which each heating element is formed, and in the state where the motor is positioned on the inner side of one side plate, on the inner side of the platen gear, Alternatively, they are arranged so as to be flush with the platen gear. Further, a cam member capable of releasing the pressure contact of the thermal head to the platen roller is disposed on the rear side of the thermal head. An operation member capable of operating the cam member is connected to the cam member. The thermal head can be brought into contact with and separated from the platen roller by rotating and operating the operation member.

  According to such a configuration, since the intermediate gear group is not located outside the platen gear, the width dimension of the thermal printer can be reduced.

JP 2003-154714 A (Page 3, FIGS. 1-2)

  However, the conventional small thermal printer as described above has a large number of assembly steps (mainly, the number of steps for assembling the gear portion), and as a result, the assembly accuracy is lowered and the drive accuracy is also affected.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a small thermal printer that can reduce the number of parts and the number of assembling steps and can ensure the assembling accuracy.

  In order to achieve the above-described object, the small thermal printer according to the present invention is characterized in that a reduction gear is formed by at least one reduction gear disposed in a casing, and an output gear including an output shaft and a gear. Further, the output gear is formed to be connected to the platen roller, and the speed reducer is fixed to one side plate of the frame.

  By adopting such a configuration, it is possible to mount the speed reducer simply by directly fixing the box-type speed reducer to one side plate of the frame, so that it is possible to reduce the number of assembly steps for a small thermal printer. As a result, the assembly accuracy can be improved.

  Another feature of the small thermal printer according to the present invention is that a bearing for rotatably supporting the output shaft is formed on the side wall of the casing fixed to the frame of the speed reducer.

  By adopting such a configuration, the assembly accuracy of the platen roller and the output shaft of the speed reducer can be improved, and the operation accuracy of the small thermal printer can be improved.

  Another feature of the small thermal printer according to the present invention is that the reduction gear of the reduction gear is formed integrally with the gear and the rotating shaft, and the reduction gear and the casing are each formed of a resin material. Each of the bearings of the casing that rotatably supports the rotating shaft is coated with a fluorine-based lubricant.

  By adopting such a configuration, the friction coefficient between each shaft and each bearing is reduced, and the amount of wear is reduced. As a result, the lifetime of the small thermal printer can be extended.

  Another feature of the small thermal printer according to the present invention is that a head adjusting mechanism for adjusting the pressure contact position between the thermal head and the platen roller is provided.

  By adopting such a configuration, even when the outer diameter of the platen roller is reduced, a stable pressure contact force between the platen roller and the thermal head can be secured, and high quality printing and printer Miniaturization can be achieved at the same time.

  Another feature of the small thermal printer according to the present invention is that a manual paper feeding mechanism is provided.

  By adopting such a configuration, paper feeding can be performed without providing an automatic paper feeding mechanism, so that the size of the printer can be reduced.

  Another feature of the small thermal printer according to the present invention is that power is supplied from a device that outputs print data.

  By adopting such a configuration, it is not necessary to provide an internal power supply in the printer itself, and the size and weight can be reduced.

  According to the present invention, it is possible to reduce the number of parts and the number of assembling steps of a small thermal printer and improve the assembling accuracy.

  Further, the assembly accuracy of the platen roller and the output shaft of the speed reducer can be improved, and the operation accuracy of the small thermal printer can be improved.

  Further, the friction coefficient between each shaft of the reduction gear and each bearing is reduced, and the amount of wear is reduced. As a result, the lifetime of the small thermal printer can be extended.

  In addition, a stable pressure contact force between the platen roller and the thermal head can be secured, and both high-quality printing and downsizing of the printer can be achieved.

  Further, since the paper can be fed without an automatic paper feeding mechanism, the printer can be miniaturized.

  Further, it is not necessary to provide an internal power supply in the printer itself, and the size and weight can be reduced.

  Hereinafter, embodiments of a small thermal printer of the present invention will be described with reference to the drawings.

  1 is a perspective view from above showing a small thermal printer according to an embodiment of the present invention, FIG. 2 is a perspective view from below of FIG. 1, and FIG. 3 is a schematic perspective view showing an embodiment of the main part of FIG. 4, FIG. 4 is a longitudinal sectional view of FIG. 1, FIG. 5 is a schematic perspective view showing only the reduction gear of FIG. 1, FIG. 6 is a perspective view showing an embodiment of the reduction gear of FIG. 8 is an enlarged perspective view showing only the platen roller bearing, FIG. 8 is an enlarged perspective view showing only the head mounting plate of FIG. 1, and FIG. 9 is an enlarged perspective view showing only the head adjustment shaft of FIG.

  As shown in FIGS. 1 and 2, a small thermal printer 1 according to the present embodiment is formed at a lower portion of one side wall 2e in the longitudinal direction, and a paper feed port 2a for feeding printing paper (not shown), A substantially rectangular printer main body 2 having a paper discharge port 2b formed on the upper surface 2f on the side wall (not shown) side facing the side wall 2e formed with the paper feed port 2a and for discharging the printing paper. Have. Further, a concave portion 2c for accommodating a paper holder 18 to be described later is formed on the lower surface of the lower wall 2g of the printer main body 2, and one side adjacent to the side wall 2e on which the paper feed port 2a is formed. On the side wall 2h, an opening 2d is formed at an arbitrary position for supplying electric power to a motor 7 and a control board 17 which will be described later and in which a connection terminal 19 for inputting print data is disposed.

  As shown in FIGS. 3 and 4, the printer main body 2 mainly includes a platen roller 4, a head mounting plate 5, a thermal head 16, and a speed reducer 8 formed in a substantially rectangular parallelepiped box shape. And the frame 3 that supports the head mounting plate 5 movably and supports the rotation shafts 4a, 4b of the platen roller 4 so as to be rotatable with the speed reduction device 8, and the platen roller 4 via the speed reduction device 8. A motor 7 having a drive shaft 7a for rotating the motor 7 and a control board 17 for controlling the drive of the motor 7 are disposed.

  The concave portion 2c of the lower wall 2g accommodates a plurality of printing sheets fed from the sheet feeding port 2a, and a cylindrical sheet holder 18 that conveys the printing sheets to the platen roller 4 side. The paper discharge port 2b is disposed so as to be rotatable downward about a horizontal support shaft 18a supported by the printer main body 2.

  Further, on the far side of the paper holder 18 of the printer body 2 in the paper conveyance direction, as shown in FIG. 4, the paper conveyance that guides the printing paper 22 conveyed from the paper holder 18 to the platen roller 4. A sheet guide portion 2i inclined in a curved shape in the direction from the bottom to the top is formed.

  As shown in FIGS. 1, 2, and 4, the paper holder 18 is formed with a paper feed port 18 a having a wide open top on the side facing the paper feed port 2 a of the printer body 2. An opening 18c that is widened in the longitudinal direction is formed in the lower wall 18b of the holder 18.

  The opening 18c has a manual sheet feeding mechanism in which a sheet conveyance pad 21 made of a thin rubber sheet is disposed by adhering both ends in the sheet conveyance direction to the upper surface of the lower wall 18b of the holder 18. ing. The sheet feeding mechanism moves the sheet conveying pad 21 to the downstream side in the sheet conveying direction while pressing the upstream side of the sheet conveying pad 21 in the sheet conveying direction from below with a finger, so that the sheet conveying pad 21 is elastically deformed and the sheet is conveyed. The lowest printing paper among the plurality of printing papers fed to the holder 18 can be brought into close contact with the paper carrying pad 21 and carried to the platen roller 4 side.

  Further, as shown in FIG. 4, a sheet separating plate 20 that is inclined from the upper side to the lower side in the sheet conveying direction is arranged on the upper surface inside the sheet holder 18 on the downstream side in the sheet conveying direction in the sheet holder 18. The printing paper 22 conveyed by the paper conveyance pad 21 is separated from the overlapping printing paper 22 by the frictional force with the paper separating plate 20, and only the lowest printing paper 22 is removed from the printing paper 22 It is conveyed to the platen roller 4. The paper transport pad 21 that has been pressed by the finger and moved to the downstream side in the paper transport direction is temporarily bent by its elastic force, but when it is released, it returns to its original shape by its elastic return force. .

  As shown in FIG. 3, the frame 3 has two bottom walls 3c, 3c extending in parallel in a substantially rectangular shape, and both bottoms 3c are formed at both ends in the longitudinal direction. Side walls 3a and 3b erected so as to connect the wall 3c, and an inclined plate 3d erected so as to be positioned above the bottom wall 3c on one side of the outside of the bottom wall 3c; Are integrally formed with each other.

  Each of the side walls 3a and 3b is formed with a circular hole 3e that is fitted to the head mounting plate 5 and in which a head adjustment shaft 6 for adjusting the position of the head mounting plate 5 is adjustable. Further, the side wall 3a is fitted into a notch (which may be an opening) 3f through which the one rotation shaft 4a of the platen roller 4 is inserted, a drive shaft 7a of the motor 7, and a tip of the drive shaft 7a. The motor gear 7b is inserted therethrough and an opening (not shown) for fixing the motor 7 is formed. The side wall 3b supports the other rotating shaft 4b of the platen roller 4 to be rotatable. An opening 3g for fitting the platen roller bearing 14 is formed. Further, the bottom wall 3c is formed with an opening 3h through which the printing paper conveyed from the paper holder 18 and conveyed by the paper guiding portion 2i of the printer main body 2 is inserted.

  As shown in FIG. 5, the speed reducer 8 includes a casing 9 formed by dividing into an upper casing 9 a and a lower casing 9 b made of a resin material such as polybutylene terephthalate (PBT). Inside, a first reduction gear 10 that meshes with the motor gear 7b of the motor 7, an output gear 11 that is formed to be engaged with or integrally connected to the rotary shaft 4a of the platen roller 4, and the first reduction gear. A second reduction gear 12 that meshes with the gear 10 and the output gear 11 is housed.

  The first reduction gear 10, the second reduction gear 12, and the output gear 11 are made of a resin material such as polyacetal (POM). The output gear 11 includes an output shaft 11a, a rotary shaft 11b, and a gear 11c formed integrally or by fitting, and the first reduction gear 10 and the second reduction gear 12 are formed as shown in FIG. In addition, the rotary shafts 10a, 10b, 12a, 12b, the large gears 10c, 12c, and the small gears 10d, 12d are formed integrally or by fitting.

  In one side wall 9c of the lower casing 9b, a bearing 9e that rotatably supports the output shaft 11a of the output gear 11, an insertion hole 9f through which the motor gear 7b of the motor 7 is inserted, and the first reduction gear 10 and bearings 9g and 9h that rotatably support one of the rotary shafts 10b and 12a of the second reduction gear 12, respectively.

  A bearing that rotatably supports the other rotary shafts 10a, 11b, and 12b of the first reduction gear 10, the output gear 11, and the second reduction gear 12 on the other side wall 9d of the lower casing 9b. 9i, 9j, 9k are formed.

  Further, a fluorine-based lubricant 13 is applied to the sliding portions of the bearings 9g, 9h, 9i, 9k.

  The opposing surfaces of the speed reduction device 8 and the side wall 3a of the frame 3 are respectively fitted with irregularities, or fixed by screwing, crimping, welding or the like.

  As shown in FIG. 3, the rotary shaft 4 a is fitted to the output shaft 11 a of the output gear 11 of the reduction gear 8, and the rotary shaft 4 b is connected to the side wall 3 b of the frame 3. The platen roller bearing 14 fitted in the opening 3g is rotatably supported and arranged from the outside.

  As shown in FIG. 7, the platen roller bearing 14 has a cylindrical shape formed with a bearing portion 14b that fits into the opening 3g of the side wall 3b and rotatably supports the rotating shaft 4b of the platen roller 4. A sliding portion 14a and a disc-shaped retaining portion 14c that prevents the sliding portion 14a from falling off are integrally formed. The bearing portion 14b is formed eccentric with respect to the sliding portion 14a, and the platen roller bearing 14 is mounted on the outer surface of the retaining portion 14c by a tool (not shown) such as a flat-blade screwdriver. A groove 14d that can be rotated is formed. Then, by rotating the platen roller bearing 14, the contact state between the platen roller 4 and a thermal head 16, which will be described later, can be adjusted. After adjusting the platen roller 4 to an arbitrary position, a screw or the like is used. The platen roller bearing 14 is fixed.

  As shown in FIG. 8, substantially semicircular side plates 5b and 5c are integrally formed on both ends of the head mounting plate 5 in the longitudinal direction of a substantially rectangular thermal head mounting surface 5a as viewed from the front. The side plates 5b and 5c are formed with holes 5d and 5e for fitting the head adjustment shaft 6, respectively. As shown in FIG. 3, the head mounting plate 5 is disposed between the platen roller 4 and the inclined plate 3d of the frame 3, and the side walls 3a and 3b of the frame 3 are inserted into the holes 5d and 5e. The head adjustment shafts 6 are respectively fitted from the outside. Further, the head adjusting shaft 6 is fixed to the side walls 3a and 3b by screws (not shown) or the like.

  As shown in FIG. 9, the head adjusting shaft 6 includes sliding portions 6 b that slide with the circular holes 3 e of the side walls 3 a and 3 b of the frame 3, and holes of the side plates 5 b and 5 c of the head mounting plate 5. A fitting portion 6a for fitting with 5d and 5e, respectively, and a retaining portion 6c for retaining the head adjusting shaft 6 are integrally formed. The fitting portion 6a is formed eccentrically with respect to the sliding portion 6b, and the head adjusting shaft is formed on the outer surface 6d of the retaining portion 6c by a tool (not shown) such as a flathead screwdriver. A groove 6e is formed so that 6 can rotate. Then, by rotating the head adjusting shaft 6, the contact between the thermal head 16 attached to the head attaching plate 5 and the platen roller 4 can be adjusted. After adjusting the head 16 to an arbitrary position, the head adjusting shaft 6 is fixed with a screw or the like. By adjusting the platen roller bearing 14 and the head adjustment shaft 6, the contact between the platen roller 4 and the heating element 16 a of the thermal head 16 can be brought into the most suitable state. In the present embodiment, the head adjustment shaft 6 and the platen roller bearing 14 constitute a head adjustment mechanism.

  As shown in FIGS. 3 and 4, the thermal head 16 is a line thermal head having a substantially rectangular shape when viewed from the front, and a plurality of heating elements 16a are aligned in the longitudinal direction. The plate 5 is disposed on the thermal head mounting surface 5a facing the platen roller 4 (note that the plurality of heating elements 16a are shown as one region in FIGS. 3 and 4).

  Between the head mounting plate 5 and the inclined plate 3d, a projection (not shown) or the like is formed on the head mounting plate 5 and a coil spring 15 is disposed, and the head mounting plate 5 is elastic. Is energized.

  A stepping motor or the like is used as the motor 7. The motor 7 is fixed by inserting the motor gear 7 b through the insertion hole 8 f of the reduction gear 8 and fitting into the opening of the side wall 3 a of the frame 3. Yes.

  The control board 17 is disposed above the paper holder 18 and connected to the motor 7. Further, the control board 17 is supplied with electric power to the motor 7 and the control board 17 and outputs print data to the control board 17 by an external device (not shown) and a cable (not shown). A connection terminal 19 to be connected is disposed at the position of the opening 2d of the printer main body 2.

  Next, the operation of the small thermal printer according to this embodiment having the above-described configuration will be described.

  The connection terminal of the small thermal printer 1 in which the contact state between the platen roller 4 and the heating element 16a of the thermal head 16 is adjusted in advance by a head adjusting mechanism including the head adjusting shaft 6 and the platen roller bearing 14. 19 is connected to an external device (not shown) such as a mobile phone or a PDA by a cable (not shown).

  Then, a plurality of printing papers 22 are inserted from the paper feed port 2a of the printer body 2 or the paper feed port 18a of the paper holder 18 rotated downward, and the paper transport pad 21 is pressed from below to above with a finger. While moving from the upstream side to the downstream side in the paper transport direction. Then, the paper transport pad 21 is moved to the downstream side together with the printing paper 22 by bonding the lowest printing paper 22 by a frictional force. Note that the printing paper 22 used in the present embodiment is a thermal recording paper. The lowest printing sheet 22 moved by the sheet conveying pad 21 comes into contact with the sheet separating plate 20, and only one printing sheet 22 is surely secured by the frictional force and inclination of the sheet separating plate 20. Guided to the inclined portion 18 a of the paper holder 18. Further, the leading end of the printing paper 22 guided to the inclined portion 18 a is held between the platen roller 4 and the heating element 16 a of the thermal head 16 by the paper guiding portion 2 i of the printer body 2.

  After the leading end of the printing paper 22 is sandwiched between the platen roller 4 and the heating element 16a of the thermal head 16, the control board 17 outputs the printing data from the external device, so that the control board 17 The driving of the roller 4 and the heat generation of each heating element 16a of the thermal head 16 are controlled, printing is performed on the printing paper 22, and the printing paper 22 printed from the paper discharge port 2b of the printer body 2 is discharged. Is done.

  As described above, since the small thermal printer 1 according to the present invention performs the conveyance of the printing paper 22 by moving the paper conveyance pad 21 with a finger, it does not require a conventional paper feeding and conveyance mechanism, Further, since the battery is not provided, power is supplied from an external device (not shown) that outputs print data by a connection cable (not shown) connected to the connection terminal 19. The number of points and assembly man-hours can be greatly reduced, and the printer can be miniaturized.

  Further, even when an error occurs in dimensional accuracy during the assembly of the printer and the contact between the platen roller 4 and the heating element 16a of the thermal head 16 is not stable, the head adjustment mechanism including the head adjustment shaft 6 and the platen roller bearing 14 allows the platen roller to The contact between the roller 4 and the heating element 16a of the thermal head 16 can be adjusted and stabilized.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible as needed.

The perspective view from the top which showed the embodiment of the small thermal printer concerning the present invention FIG. 1 is a perspective view from below. The schematic perspective view which showed embodiment of the principal part of FIG. 1 is a longitudinal sectional view of FIG. 1 is a schematic perspective view showing only the speed reducer of FIG. The perspective view which showed embodiment of the reduction gear of FIG. Enlarged perspective view showing only the platen roller bearing of FIG. Enlarged perspective view showing only the head mounting plate of FIG. Enlarged perspective view showing only the head adjustment shaft of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Small thermal printer 2 Printer main body 3 Frame 4 Platen roller 5 Head mounting plate 6 Head adjustment shaft 7 Motor 8 Reduction device 9 Casing 10 First reduction gear
11 Output gear
12 Second reduction gear
13 Lubricant
14 Platen roller bearing 15 Coil spring 16 Thermal head 17 Control board 18 Paper holder 19 Connection terminal
20 Paper separator
21 Paper transport pad 22 Printing paper

Claims (6)

A thermal head, a platen roller that can be pressed against the thermal head, a motor having a drive shaft that rotationally drives the platen roller, a frame in which two side walls opposed to the bottom wall are integrally formed, In a small thermal printer provided with a speed reducer that transmits the rotation of the drive shaft of the motor to the platen roller,
The reduction gear is formed by at least one reduction gear disposed in a casing, an output gear including an output shaft and a gear, and the output gear is formed in connection with the platen roller, The reduction device is fixed to one side wall of the frame. The small thermal printer according to claim 1, wherein a bearing that rotatably supports the output shaft is formed on a side wall of the casing that is fixed to the frame of the speed reducer. The reduction gear of the reduction gear includes a gear and a rotary shaft that are integrally formed, the reduction gear and the casing are each formed of a resin material, and the casing that rotatably supports the rotary shaft of the reduction gear. The small thermal printer according to claim 1, wherein a fluorine-based lubricant is applied to each of the bearings. The small thermal printer according to any one of claims 1 to 3, further comprising a head adjustment mechanism for adjusting a pressure contact position between the thermal head and the platen roller. The small thermal printer according to any one of claims 1 to 4, wherein a manual paper feeding mechanism is provided. 6. The small thermal printer according to claim 1, wherein the power is supplied from a device that outputs print data.