Thermal printer and portable terminal

A thermal printer includes a platen roller, a thermal head, a head support plate, a frame including a platen roller support portion, a turn support portion configured to support the head support plate, and an urging member configured to urge the head support plate in a direction in which the thermal head approaches the platen roller. The thermal head is fixed to an opposed surface of the head support plate, which is in a first region located on one side with respect to the turn support portion, and is opposed to the platen roller in the first direction. The urging member is interposed between the opposed surface of the head support plate in a second region, which is located on another side with respect to the turn support portion and an urging member support portion of the frame.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2016-098106 filed on May 16, 2016, the entire content of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermal printer and a portable terminal.

2. Description of the Related Art

Hitherto, a thermal printer has been known as a printer configured to perform printing on a recording sheet (heat-sensitive paper). The thermal printer includes a thermal head, a platen roller, and a frame. The thermal head includes a heating element. The platen roller is configured to feed the recording paper by nipping the recording paper with the thermal head. The frame is configured to support the platen roller and the thermal head. In the thermal printer, the heating element of the thermal head is caused to generate heat as appropriate during a course of feeding the recording paper through rotation of the platen roller, thereby being capable of printing various information on the recording paper.

The above-mentioned thermal head is supported on the frame so as to be turnable under a state of being fixed to a head support plate. An urging member configured to urge the thermal head against the platen roller is interposed between the frame and the head support plate. With this, the thermal head is pressed against an outer peripheral surface of the platen roller.

Incidentally, particularly for a thermal printer which is to be mounted to a portable terminal such as a card payment terminal, downsizing in a thickness direction, that is, in a direction in which the thermal head approaches and separates from the platen roller has been demanded. In order to downsize the thermal printer in the thickness direction, it is conceivable to reduce a space for a head back surface region, that is, a region between a back surface of the head support plate and the frame.

However, for a related-art thermal printer, there is a limit in downsizing the thermal printer in the thickness direction while securely pressing the thermal head against the platen roller. Therefore, for the thermal printer of this type, downsizing in the thickness direction has been demanded.

SUMMARY OF THE INVENTION

According to one embodiment of the present invention, there is provided a thermal printer, including a platen roller, a thermal head arranged so as to oppose to the platen roller, a head support plate configured to hold and fix the thermal head, a frame including a roller support portion configured to support the platen roller so as to be rotatable about a first direction, a turn support portion configured to support the head support plate so as to be turnable about the first direction, and an urging member configured to urge the head support plate in a direction in which the thermal head approaches the platen roller about the first direction. The head support plate extends in a second direction intersecting the first direction. The thermal head is fixed to an opposed surface of the head support plate, which is in a first region located on one side in the second direction with respect to the turn support portion, and is opposed to the platen roller in the first direction. The urging member is interposed between the opposed surface of the head support plate in a second region, which is located on another side in the second direction with respect to the turn support portion and an urging member support portion of the frame, which is opposed to the opposed surface in a third direction intersecting the second direction as viewed from the first direction.

In the above-mentioned thermal printer according to the one embodiment of the present invention, wherein the head support plate is bent in a direction which an urged portion side of the head support plate separates from the urging member support portion in the third direction.

In the above-mentioned thermal printer according to the one embodiment of the present invention, wherein the urging member comprises a cylindrical coil spring having an axial direction in the third direction.

In the above-mentioned thermal printer according to the one embodiment of the present invention, herein the turn support portion comprises a shaft that extends in the first direction and is supported on the frame, and wherein the head support plate is turnably supported on the frame through intermediation of the turn support portion.

In the above-mentioned thermal printer according to the one embodiment of the present invention, wherein the turn support portion is integrally formed with the frame and protrudes toward the head support plate from a portion of the frame, which is located on a side opposite to the urging member support portion in the third direction with respect to the head support plate.

In the above-mentioned thermal printer according to the one embodiment of the present invention, wherein the head support plate and the frame have a regulation portion configured to regulate movement of the head support plate in the second direction with respect to the frame.

According to one embodiment of the present invention, there is provided a portable terminal, including the above-mentioned thermal printer, and a casing to which the thermal printer is mounted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, embodiments of the present invention are described with reference to the accompanying drawings.FIG. 1is a perspective view of a portable terminal1. As illustrated inFIG. 1, the portable terminal1is, for example, a payment terminal which is portable by a user. The portable terminal1includes a casing11, an input display portion12, and a thermal printer13.

The casing11includes a casing main body15and a printer cover16. The casing main body15is formed into a box shape having a rectangular shape in plan view. In a distal end portion of the casing main body15, there is formed a recording paper receiving portion17configured to receive recording paper P (heat-sensitive paper). The recording paper P is received, under a state of being wound into a roll, in the recording paper receiving portion17. The printer cover16is turnably connected to the casing main body15through intermediation of a hinge portion (not shown). The printer cover16is configured to open and close the recording paper receiving portion17. In the casing11, there is formed a discharge port18, which is configured to discharge the recording paper P to the outside, between an opening edge of the recording paper receiving portion17and a distal edge of the printer cover16. The input display portion12is arranged on a front surface of the casing11. The input display portion12is, for example, a touch panel. The input display portion12is configured to display various information on a screen and enable operation to the information displayed on the screen.

The thermal printer13is mounted at a position adjacent to the discharge port18in the casing11. The thermal printer13is configured to print information with respect to the recording paper P, which is fed from the recording paper receiving portion17, and to discharge the recording paper P through the discharge port18.

FIG. 2is a perspective view of the thermal printer13.FIG. 3is an exploded perspective view of the thermal printer13. As illustrated inFIG. 2andFIG. 3, the thermal printer13includes a head unit22and a platen roller23. The head unit22includes a thermal head21. In the example illustrated inFIG. 1, the head unit22is assembled to the casing main body15. The platen roller23is assembled to the printer cover16and is rotatably supported on the printer cover16. The printer cover16has a shaft in the lower part ofFIG. 1, and is opened by left-front side ofFIG. 1. At that time, the platen roller23moves with the printer cover16. Thereby, the platen roller23and the thermal head21(the part of head unit22) are removed, and the recording paper becomes in a free state. Conversely, when the printer cover16is closed, the platen roller23follows with the printer cover16. At that time, the platen roller23is located at the position contact with the thermal head21. In this way, the head unit22and the platen roller23are combined so as to be separable along with opening and closing of the printer cover16. When the printer cover16takes a closed position, the head unit22and the platen roller23are opposed to each other across the above-mentioned discharge port18. In the following description, an axial direction of the platen roller23is described as an X direction (first direction), and two directions orthogonal to the X direction are described as a Y direction (third direction) and a Z direction (second direction). Further, in the following description, in each of the X direction, the Y direction, and the Z direction, a direction indicated by the arrow in the drawings is described as a plus direction, and a direction opposite to the arrow is described as a minus direction.

As illustrated inFIG. 3, a frame31of the head unit22is formed into a U-shape which is opened in a plus Z direction in front view from the Y direction. Specifically, the frame31includes a base portion32, a first side plate portion33, and a second side plate portion34. The base portion32extends in the X direction. The first side plate portion33and the second side plate portion34are connected to both end portions of the base portion32in the X direction. The base portion32includes a guide wall35and a back surface plate36(seeFIG. 4). The guide wall35is located in a plus Y direction of the base portion32. The back surface plate36is located in a minus Y direction with respect to the guide wall35. A surface of the guide wall35which is oriented in the plus Y direction constructs a paper passage surface which is configured to guide the recording paper P in the plus Z direction. The paper passage surface is a curved surface which protrudes in the minus Y direction.

FIG. 4is a sectional view taken along the line IV-IV ofFIG. 2. As illustrated inFIG. 4, the back surface plate36is arranged so that a center portion thereof in the X direction is opposed to the guide wall35at an interval in the Y direction. Meanwhile, both end portions of the back surface plate36in the X direction are connected to the guide wall35.

As illustrated inFIG. 3, first, the second side plate portion34is connected to an end portion of the base portion32, which includes the guide wall35and the back surface plate36, in a plus X direction. A portion of the second side plate portion34which protrudes in the plus Z direction with respect to the base portion32constructs a second shaft support portion37. At an end edge of the second shaft support portion37in the plus Z direction, there is formed a second roller receiving groove38which is recessed in the minus Z direction. At a portion of an inner peripheral edge of the second roller receiving groove38which is located in the plus Y direction, there is formed a second hook portion39which protrudes in the minus Y direction.

The first side plate portion33is connected to the end portion of the base portion32in a minus X direction. A portion of the first side plate portion33which protrudes in the plus Z direction with respect to the base portion32constructs a first shaft support portion41. At an end edge of the first shaft support portion41in the plus Z direction, there is formed a first roller receiving groove (roller support portion)42which is recessed in the minus Z direction. At a portion of an inner peripheral edge of the first roller receiving groove42which is located in the plus Y direction, there is formed a first hook portion43which protrudes in the minus Y direction. A portion of the first side plate portion33which protrudes in the minus Z direction with respect to the base portion32constructs a motor support portion44.

The platen roller23nips the recording paper P with the thermal head21to convey the recording paper P toward the discharge port18. Specifically, the platen roller23includes a platen shaft51and a roller main body52. The platen shaft51extends in the X direction. At both end portions of the platen shaft51in the X direction, there are mounted a first bearing53and a second bearing54, respectively. The bearings53and54are retained in the above-mentioned roller receiving grooves38and42, respectively. With this, the platen roller23is supported on the shaft support portions37and41(frame31) so as to be rotatable about an axis extending in the X direction and so as to be removable from the frame31. The roller support portions of the shaft support portions37and41, which are configured to rotatably support the platen roller23, are not limited to the roller receiving grooves38and42. At a portion of the platen shaft51which is located in the minus X direction with respect to the first platen shaft53, there is arranged a driven gear56. Under a state in which the platen roller23is retained in the roller receiving grooves38and42, the driven gear56is positioned in the minus X direction from the first shaft support portion41.

The roller main body52is made of, for example, rubber. The roller main body52is externally mounted to a portion of the platen shaft51other than the both end portions of the platen shaft51in the X direction. An outer peripheral surface of the roller main body52is held in contact with the above-mentioned thermal head21.

At a portion of the above-mentioned frame31which is located in the plus X direction with respect to the motor support portion44, there is arranged a motor61. The motor61is arranged under a state in which a rotary shaft (not shown) thereof protrudes in the minus X direction. The motor61is connected to the controller through intermediation of a flexible board45or the like.

Between the motor61and the motor support portion44in the X direction, there is arranged a first speed reduction mechanism62configured to reduce power of the motor61. The first speed reduction mechanism62is, for example, a planetary gear mechanism. The first speed reduction mechanism62has an output gear63which protrudes in the minus X direction. The output gear63protrudes through a through hole44a,which is formed in the motor support portion44, in the minus X direction with respect to the motor support portion44.

At a portion which is located in the minus X direction with respect to the above-mentioned first side plate portion33, there is arranged a second speed reduction mechanism65. The second speed reduction mechanism65is a gear train mechanism including a two-step gear. The second speed reduction mechanism65provides connection between the output gear63of the first speed reduction mechanism62and a driven gear56of the platen roller23. As illustrated inFIG. 2, the second speed reduction mechanism65is covered with a gear cover66from the minus X direction.

As illustrated inFIG. 3, the thermal head21has a plate-like shape having a thickness direction in the Y direction and extending in the X direction. On an end surface of the thermal head21in the plus Y direction, a plurality of heating elements21aare arrayed in the X direction at intervals. The thermal head21is connected to a controller (not shown) or the like through intermediation of the flexible board45. A driver IC (not shown) mounted to the thermal head21controls heat generation of the heating elements21ain accordance with a signal from the controller so that the thermal head21performs printing with respect to the recording paper P.

As illustrated inFIG. 4, the thermal head21is fixed to a head support plate46which is arranged on the frame31in the minus Y direction with respect to the roller receiving grooves38and42. The head support plate46has a plate-like shape having a thickness direction in the Y direction. The head support plate46is supported from the minus Y direction by a support protrusion (turn support portion)72which protrudes in the plus Y direction from an end portion of the above-mentioned back surface plate36in the plus Z direction. With this, the head support plate46is turnable at the support protrusion72as a support point with respect to the frame31about an axis which extends in the X direction.

The head support plate46includes an urging portion (second region)75and a head mounting portion (first region)76. The urging portion75is located in the minus Z direction with respect to the support protrusion72. The head mounting portion76is located in the plus Z direction with respect to the support protrusion72. The urging portion75is arranged in a gap of the above-mentioned base portion32which is formed between the guide wall35and the back surface plate36.

The head mounting portion76extends in the plus Z direction from an end edge of the urging portion75in the plus Z direction. In the example ofFIG. 4, a length of the above-mentioned urging portion75in the Z direction is larger than a length of the head mounting portion76in the Z direction. The head mounting portion76has a bent portion81which is bent so as to cause the head mounting portion76to protrude in the plus Y direction. The bent portion81linearly extends over an entire region of the head support plate46in the X direction. Thus, under a state in which the platen roller23is mounted, a portion of the head mounting portion76which is located in the minus Z direction from the bent portion81(hereinafter referred to as “minus Z direction plate portion76a”) is linearly connected to the urging portion75. Meanwhile, a portion of the head mounting portion76which is located in the plus Z direction from the bent portion81(hereinafter referred to as “plus Z direction plate portion76b”) is inclined so as to extend in the minus Y direction toward the plus Z direction.

The bent portion81may be formed in the urging portion75. That is, it is only necessary that the bent portion81be bent in a direction in which the urging portion75separates from the guide wall35in the Y direction as compared to a case where the entire head support plate46is formed linearly. However, the entire head support plate46may be formed linearly.

The above-mentioned thermal head21is fixed to an end surface of the plus Z direction plate portion76bof the head mounting portion76in the plus Y direction, that is, to a surface opposed to the platen roller23. The thermal head21is held in press-contact with an outer peripheral surface of the platen roller23. As illustrated inFIG. 3, at both end portions of the plus Z direction plate portion76bof the head mounting portion76in the X direction, there are formed engagement pieces (regulation portions)78which protrude in both directions in the X direction. The engagement pieces78are individually received in engagement recess portions (regulation portions)79formed in the side plate portions33and34. Movement of the engagement pieces78in the Z direction is regulated in the engagement recess portions79. With this, movement of the thermal head21in the Z direction with respect to the frame31is regulated. It is only necessary that the engagement pieces78and the engagement recess portions79be configured to regulate movement of the head support plate46in the Z direction with respect to the frame31within a predetermined range.

As illustrated inFIG. 4, urging members85are interposed between an end portion of the urging portion75in the minus Z direction and the frame31. The urging members85are cylindrical coil springs each having an axial direction in the Y direction. End portions of the urging members85in the minus Y direction are held in abutment against an end surface of the urging portion75in the plus Y direction at the end portion of the urging portion75in the minus Z direction. Meanwhile, end portions of the urging members85in the plus Y direction are held in abutment against an urging member support portion87, which is formed in the above-mentioned guide wall35, from the minus Y direction. With this, the urging members85urge the urging portion75and the urging member support portion87in a direction of separating the urging portion75and the urging member support portion87from each other in the Y direction. That is, the urging members85urge the head support plate46in a direction in which the thermal head21is pressed against the platen roller23. Not limited to the cylindrical coil springs, there may be used conical coil springs, leaf springs, or the like as the urging member85.

In the illustrated example, the urging member support portion87is a bottom surface of a recess portion which is recessed in the plus Y direction with respect to an end surface of the guide wall35in the minus Y direction. However, as long as the urging members85can be supported, the configuration of the urging member support portion87can be changed as appropriate.

The urging members85of a first embodiment of the present invention are arranged at two locations in the X direction at intervals. At a position between the guide wall35and the back surface plate36of the base portion32and between the urging members85adjacent to each other in the X direction, the above-mentioned flexible board45is drawn in the Z direction. However, the number, layout, and the like of the urging members85can be changed as appropriate.

Next, an operation method of the above-mentioned portable terminal1is described. In the following description, it is assumed that a leading edge of the recording paper P is nipped between the platen roller23and the thermal head21. In the portable terminal1, printing with respect to the recording paper P is started through operation to the input display portion12. Specifically, a signal is output from the controller to the motor61through, for example, the flexible board45, with the result that the motor61rotates. The power of the motor61is reduced by the first speed reduction mechanism62and the second speed reduction mechanism65and thereafter is transmitted to the driven gear56. With this, the platen roller23is rotated. Then, the recording paper P nipped between the outer peripheral surface of the platen roller23and the thermal head21is delivered toward the discharge port18.

When the signal is output from the controller to the thermal head21through the flexible board45during the course of delivering the recording paper P through rotation of the platen roller23, the heating elements21aof the thermal head21generate heat as appropriate. With this, various information is printed with respect to the recording paper P. Then, the recording paper P discharged through the discharge port18is cut and used as, for example, a receipt.

Next, an action of the thermal printer13according to the first embodiment is described. In the following, a closing operation of the printer cover16is described as an example of an operation of the head support plate46.FIG. 5andFIG. 6are explanatory views for illustrating a mounting and removing operation for the platen roller23, and are sectional views corresponding toFIG. 4. As illustrated inFIG. 5andFIG. 6, during the closing operation of the printer cover16, a roller main body52of the platen roller23presses the head support plate46in the minus Y direction through intermediation of the thermal head21. Then, as illustrated inFIG. 6, the head support plate46turns, with the contact portion to the support protrusion72as a support point, in a direction against the urging force of the urging members85, that is, in a direction in which the head mounting portion76moves in the minus Y direction. With this action, bearings53and54of the platen roller23enter the roller receiving grooves38and42.

Then, as the bearings53and54of the platen roller23goes over top portions of the hook portions39and43, the head support plate46turns, with the contact portion to the support protrusion72as a support point, in a direction of restoring the urging members85, that is, in the direction in which the head mounting portion76moves in the plus Y direction. With this action, the platen roller23is assembled to the head unit22under a state in which the thermal head21is pressed by the restoring force of the head support plate46. Thus, the above-mentioned printing operation can be performed under a state in which the recording paper P is reliably sandwiched between the platen roller23and the thermal head21. At the time of an opening operation of the printer cover16, an operation which is reverse to the above-mentioned operation is performed.

As described above, in the first embodiment, the urging members85are interposed between the end surface of the urging portion75in the plus Y direction which is located at the head support plate46in the minus Z direction with respect to the support protrusion72and the urging member support portion87of the frame31which is opposed to the end surface of the urging portion75in the plus Y direction. According to this configuration, the urging members85are arranged in the plus Y direction of the head support plate46, thereby being capable of reducing the head back surface region, that is, the region in the minus Y direction with respect to the head support plate46as compared to the related-art configuration in which the urging members85are arranged in the minus Y direction of the head support plate46. With this, the thermal printer13can be downsized in the Y direction.

In the first embodiment, the head support plate46is bent in the minus Y direction, thereby being capable of increasing a space for arranging the urging members85which is formed between the urging member support portion87and the head support plate46as compared to the case where the head support plate46linearly extends. As a result, the urging members85having a large urging force can be arranged between the urging member support portion87and the head support plate46. In this case, even when the number of urging members85is reduced, a stable urging force can be exerted on the head support plate46. Therefore, the flexible board45can be drawn between the urging members85which are adjacent in the X direction, which may result in improvement in space efficiency in the frame31. Further, the space for arranging the urging members85is secured between the urging member support portion87and the head support plate46, thereby being capable of using the cylindrical coil springs as the urging members85. With this, for example, as compared to the case where conical coil springs are used, more stable load (urging force) can be exerted on the head support plate46.

In the first embodiment, the head support plate46is directly supported so as to be turnable by the support protrusion72integrally formed with the frame31, thereby being capable of reducing the number of parts as compared to the case where a member configured to support turning of the head support plate46is provided separately from the frame31. In the first embodiment, the engagement pieces78and the engagement recess portions79which are configured to regulate the movement of the head support plate46in the Z direction with respect to the frame31are provided, thereby being capable of preventing drop of the head support plate46from the frame31and enabling a stable operation of the head support plate46.

The portable terminal1of the first embodiment includes the above-mentioned thermal printer13, thereby being capable of providing the portable terminal1having a small size.

Next, a second embodiment of the present invention is described.FIG. 7is a sectional view of a thermal printer100according to the second embodiment. The second embodiment is different from the above-mentioned embodiment in that a head support plate101is turnably supported on the frame31through intermediation of a shaft (turn support portion)102. In the following description, components which are the same as those of the above-mentioned embodiment are denoted by the same reference symbols, and description thereof is omitted. In the thermal printer100illustrated inFIG. 7, shaft support pieces110are formed on both end portions of the head support plate101in the X direction. The shaft support pieces110protrude in the minus Y direction from a boundary portion of the head support plate101between the urging portion75and the head mounting portion76. The shaft support pieces110are formed at equivalent positions in the Z direction. Each shaft support piece110has a through hole110awhich penetrates through the shaft support piece110in the X direction.

The shaft102is formed into a bar-like shape which extends in the X direction. The shaft102is inserted into the through hole110aof each shaft support piece110. Both end portions of the shaft102in the X direction are supported on the above-mentioned shaft support portions37and41of the frame31.

In the second embodiment, the actions and effects which are similar to those of the above-mentioned embodiment can be achieved. Further, the urging force of the urging member85can be stably exerted on the head support plate101, thereby being capable of allowing the head support plate101to stably turn about the shaft102.

Note that, the technical scope of the present invention is not limited to the above-mentioned embodiments, but various modifications may be made without departing from the gist of the present invention.

In the above-mentioned embodiments, description is made of the case where the payment terminal is used as one example of the portable terminal1. However, not limited to this configuration, the configuration of the present invention may be applied to various types of portable terminals.

Besides the above, the components in the above-mentioned embodiments may be replaced by well-known components as appropriate without departing from the gist of the present invention. The above-mentioned modified examples may be combined with each other as appropriate.