Patent Description:
<CIT> discloses a printer apparatus of a drop-in type which includes a storage region for a roll of print sheet, a print head, a conveying roller configured to contact the print sheet and rotate to cause the print sheet to be conveyed from the roll to the print head, and a flap having a distal end that contacts an outer circumferential surface of the roll at a point that is lower than a center of the roll while the print sheet is drawn out from the roll for conveyance to the print head.

In a thermal printer, under a state in which a recording sheet is sandwiched between a platen roller and a thermal head, the platen roller is rotated, and thus printing is performed by the thermal head on a print surface of the recording sheet while the recording sheet is conveyed. In the thermal printer, the recording sheet in a form of a roll sheet, which is obtained by winding the recording sheet around a core material, is received in a roll sheet receiving portion formed in a casing. For example, in the related-art thermal printer, a roll sheet is rotatably retained in the roll sheet receiving portion by a support shaft passing through the core material.

Incidentally, in order to reduce environmental loads and improve convenience, for labels such as POS labels on food and various display labels, a so-called linerless label is used as a recording sheet in some cases. The linerless label is a recording sheet without a liner configured to cover a pressure-sensitive adhesive layer formed on a surface opposite to a print surface of the recording sheet. When the recording sheet formed of the linerless label is used as a roll sheet, the pressure-sensitive adhesive layer of the recording sheet located on an outer peripheral side is wound under a state of adhering to the print surface of the recording sheet located on an inner peripheral side. Accordingly, when the linerless label is used as the recording sheet, as compared to a recording sheet without the pressure-sensitive adhesive layer, a larger pulling force is applied to the recording sheet at the time of conveyance of the recording sheet. Thus, it has been difficult to stably retain the roll sheet in the roll sheet receiving portion.

Meanwhile, in the related art, for example, at the time of replacement of the roll sheet, it is required that the support shaft be detached from and inserted into the roll sheet when the roll sheet is removed from and loaded into the roll sheet receiving portion. Accordingly, there has been a problem in that, for example, replacement work of the roll sheet is complicated.

In view of the above, in this technical field, there has been a demand for a thermal printer which allows a roll sheet to be easily removed from and loaded into a roll sheet receiving portion, and is also capable of stably retaining the roll sheet in the roll sheet receiving portion.

According to the present invention, there is provided a thermal printer according to claim <NUM>.

Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:.

Now, with reference to the drawings, an embodiment of the present invention is described. In the embodiment and modification examples described below, corresponding configurations are denoted by the same reference symbols, and description thereof is omitted in some cases. In the following description, expressions such as "parallel", "orthogonal", "center", and "coaxial", which express relative or absolute arrangement, not only represent such arrangement in the strict sense of the word, but also represent a relatively displaced state with an angle or a distance that falls within tolerance or achieves the same function.

<FIG> is a perspective view for illustrating a thermal printer <NUM> in a state in which a cover <NUM> is at a closed position. <FIG> is a perspective view for illustrating the thermal printer <NUM> in a state in which the cover <NUM> is at an open position. As illustrated in <FIG> and <FIG>, the thermal printer <NUM> performs printing on a recording sheet P. The recording sheet P in this embodiment is a so-called linerless label. That is, a front surface of the recording sheet P forms a print surface, and a back surface of the recording sheet P forms a pressure-sensitive adhesive layer. The print surface is covered with a peeling layer (such as a silicon coating). Under a state in which the print surface is directed outward and the pressure-sensitive adhesive layer is directed inward, the recording sheet P is wound around a tubular core material R1 (see <FIG>), thereby forming a roll sheet R. The roll sheet R may have a configuration without the core material R1.

<FIG> is a sectional view taken along the III-III of <FIG>. As illustrated in <FIG>, the thermal printer <NUM> includes a casing <NUM>, a printing unit <NUM>, a positioning mechanism <NUM> (see <FIG>), and a sheet retaining mechanism <NUM>. The thermal printer <NUM> is placed on a placement surface S. In the following description, a direction perpendicular to the placement surface S is referred to as an up-and-down direction (the arrow "UP" indicates an upper side), and two directions orthogonal to the up-and-down direction are referred to as a front-and-rear direction (the arrow "FR" indicates a front side) and a right-and-left direction (the arrow "LH" indicates a left side).

The casing <NUM> is formed into a box shape. Specifically, the casing <NUM> includes a bottom unit <NUM> and the cover <NUM>. The bottom unit <NUM> includes an exterior body <NUM> and a holder <NUM>.

The exterior body <NUM> is formed into a box shape opened upward. The exterior body <NUM> forms a decorative surface (outer surface) of the bottom unit <NUM>. The thermal printer <NUM> is placed on the placement surface S through intermediation of an exterior bottom wall 21a of the exterior body <NUM>. A control board <NUM> is provided inside the exterior body <NUM>. The control board <NUM> is arranged along the exterior bottom wall 21a with a thickness direction of the control board <NUM> matching the up-and-down direction.

The holder <NUM> is provided inside the exterior body <NUM>. The holder <NUM> includes a holder main body 22a and a leg portion 22b. The holder main body 22a is formed into a box shape having a size slightly smaller than that of the exterior body <NUM>. The holder main body 22a defines a roll sheet receiving portion <NUM> and a sheet passage portion <NUM>.

The roll sheet receiving portion <NUM> is located in a rear part of an inside of the holder main body 22a. The roll sheet receiving portion <NUM> allows the roll sheet R to be removed therefrom and loaded thereinto through an upper end opening portion of the holder main body 22a (bottom unit <NUM>). That is, in the thermal printer <NUM>, the roll sheet R can be loaded into and removed from the roll sheet receiving portion <NUM> through the upper end opening portion of the holder main body 22a (so-called drop-in type). The sheet passage portion <NUM> is located in a front part of the inside of the holder main body 22a. In the sheet passage portion <NUM>, a portion of the recording sheet P drawn from the roll sheet receiving portion <NUM> is conveyed toward the front side.

The leg portion 22b extends downward from a holder bottom wall 22c of the holder main body 22a. A plurality of leg portions 22b are provided at intervals in the front-and-rear direction and the right-and-left direction. Lower end portions of the leg portions 22b support the control board <NUM>.

As illustrated in <FIG> and <FIG>, the cover <NUM> opens and closes the upper end opening portion of the bottom unit <NUM>. Specifically, the cover <NUM> includes a cover main body 11a, mounting pieces 11b, guide walls 11c, and a partition wall 11d. The cover main body 11a is formed into a box shape opened downward. In plan view, the cover main body 11a has the same shape as that of the bottom unit <NUM> (exterior body <NUM>). At the closed position, the cover main body 11a is superposed on the bottom unit <NUM> from above, and closes the upper end opening portion of the bottom unit <NUM>. Meanwhile, at the open position, the cover main body 11a is retreated from a space above the bottom unit <NUM>, and opens the upper end opening portion of the bottom unit <NUM>.

When the cover <NUM> (cover main body 11a) is at the closed position, a delivery slot <NUM> is defined between a front wall portion <NUM> of the cover main body 11a and a front wall portion 21d of the exterior body <NUM>. The delivery slot <NUM> allows communication between an inside and an outside of the casing <NUM>, and has a slit shape extending in the right-and-left direction. Through the delivery slot <NUM>, the recording sheet P on which printing is performed by the printing unit <NUM> is delivered toward the front side.

The mounting pieces 11b protrude downward from portions of a rear end portion of a top wall portion 11f of the cover main body 11a, which are located on both sides in the right-and-left direction. The mounting pieces 11b are respectively coupled to a pair of holder side walls 22d of the holder main body 22a opposed to each other in the right-and-left direction. Specifically, the mounting pieces 11b are coupled to upper end portions of the holder side walls 22d so as to be pivotable about an axis along the right-and-left direction. With this configuration, the cover <NUM> pivots relative to the bottom unit <NUM> between the open position and the closed position. The cover <NUM> may be configured to open and close the upper end opening portion of the bottom unit <NUM> through, for example, a sliding operation.

The guide walls 11c protrude downward from portions of the top wall portion 11f located more on the front side than the mounting pieces 11b. The guide walls 11c extend while curving downward as extending toward the front side. The guide walls 11c are opposed to the roll sheet receiving portion <NUM> in the up-and-down direction across the upper end opening portion of the bottom unit <NUM>.

The partition wall 11d extends downward from a portion of the top wall portion 11f located more on the front side than the guide walls 11c. When the cover <NUM> is at the closed position, the partition wall 11d is arranged so as to enter the holder main body 22a from the upper side. The partition wall 11d partitions a space into the roll sheet receiving portion <NUM> and the sheet passage portion <NUM> in the front-and-rear direction.

As illustrated in <FIG>, the printing unit <NUM> includes a platen roller <NUM>, a thermal head <NUM>, a cutter unit <NUM>, and a sheet detection sensor <NUM>. The platen roller <NUM> is a rubber roller extending in the right-and-left direction. The platen roller <NUM> is provided in a front end part of the sheet passage portion <NUM> (part located closer to the delivery slot <NUM>). The platen roller <NUM> stretches between upper front end portions of the holder side walls 22d. The platen roller <NUM> is supported on the holder side walls 22d so as to be rotatable about an axis O1 along the right-and-left direction. When the recording sheet P is conveyed, the platen roller <NUM> is rotated in accordance with a driving force of a driving motor (not shown).

The thermal head <NUM> is provided in a part of an inside of the cover <NUM> located closer to the delivery slot <NUM>. The thermal head <NUM> includes a plurality of heating elements linearly arrayed along the right-and-left direction. The thermal head <NUM> is fixed to a front end portion of the cover <NUM> under a state in which the heating elements are directed downward. The platen roller <NUM> and the thermal head <NUM> are opposed to each other in the up-and-down direction across the delivery slot <NUM> (arranged on one side and another side with respect to the delivery slot <NUM>). When the cover <NUM> is at the closed position, the thermal head <NUM> is held in close contact with the platen roller <NUM>. The recording sheet P is caused to pass through a space between the platen roller <NUM> and the thermal head <NUM> along with rotation of the platen roller <NUM>. A heating pattern of the heating elements of the thermal head <NUM> is controlled based on a signal output from the control board <NUM>. When heat of the heating elements is transferred to the print surface of the recording sheet P, information (such as characters and figures) associated with the heating pattern is printed on the print surface.

<FIG> is a perspective view for illustrating the cutter unit <NUM>. As illustrated in <FIG> and <FIG>, the cutter unit <NUM> includes a fixed blade <NUM> and a movable blade <NUM>. The fixed blade <NUM> is arranged in a part of an inside of the bottom unit <NUM> located between the platen roller <NUM> and the delivery slot <NUM>. The fixed blade <NUM> is formed into a plate-like shape extending in the right-and-left direction. The fixed blade <NUM> is arranged under a state in which a blade edge 47a of the fixed blade <NUM> is directed upward. The movable blade <NUM> is arranged in a part of the inside of the cover <NUM> located between the thermal head <NUM> and the delivery slot <NUM>. The movable blade <NUM> is formed into a plate-like shape extending in the right-and-left direction. The movable blade <NUM> is configured to be movable up and down under a state in which a blade edge 48a of the movable blade <NUM> is directed downward. When the movable blade <NUM> is moved downward, the movable blade <NUM> climbs over the fixed blade <NUM> from the front side, and thus the cutter unit <NUM> cuts the recording sheet P between the blade edges 47a and 48a.

As illustrated in <FIG>, the blade edge 48a of the movable blade <NUM> is formed into a V shape extending in a direction (upward direction) of retreating from the blade edge 47a of the fixed blade <NUM> as extending from each end portion in the right-and-left direction toward a center portion of the blade edge 48a. In the center portion of the blade edge 48a of the movable blade <NUM> in the right-and-left direction, a recessed portion 48b is formed to be recessed from the blade edge 48a. A bottom of the recessed portion 48b is configured so as to be prevented from coming into contact with the recording sheet P when the cutter unit <NUM> cuts the recording sheet P. With this configuration, when the cutter unit <NUM> cuts the recording sheet P, an uncut portion is left at a portion of the recording sheet P opposed to the recessed portion 48b (so-called partial cutting). In this embodiment, description is made of a configuration in which one recessed portion 48b is formed, and thus one uncut portion is left (one portion is uncut), but the present invention is not limited to this configuration. For example, a plurality of recessed portions 48b may be formed, and thus a plurality of uncut portions may be left (a plurality of portions are uncut). Further, the recessed portion 48b is not an essential component.

As illustrated in <FIG>, the sheet detection sensor <NUM> is provided in a part of the inside of the cover <NUM> located more on the front side than the movable blade <NUM>. The sheet detection sensor <NUM> is, for example, a reflective photosensor. The sheet detection sensor <NUM> detects whether or not a portion of the recording sheet P has passed through the cutter unit <NUM>. That is, the sheet detection sensor <NUM> detects whether or not there is a portion of the recording sheet P located more on the front side (downstream side) than an uncut portion left after the recording sheet P is cut by the cutter unit <NUM>.

<FIG> is a plan view for illustrating an interior of the bottom unit <NUM>. <FIG> is a perspective sectional view taken along the line VI-VI of <FIG>. As illustrated in <FIG> and <FIG>, the positioning mechanism <NUM> positions the roll sheet R in the right-and-left direction in the roll sheet receiving portion <NUM>. The positioning mechanism <NUM> includes a pair of guide walls <NUM>, a pinion <NUM>, and racks <NUM>.

The guide walls <NUM> are provided in the roll sheet receiving portion <NUM> (in the holder <NUM>) so as to be opposed to each other in the right-and-left direction. The guide walls <NUM> each include a protruding portion 51a (see <FIG>) protruding downward. The protruding portion 51a protrudes below the holder bottom wall 22c through a through-hole <NUM> formed in the holder bottom wall 22c. The through-hole <NUM> is formed into a slit shape extending in the right-and-left direction. The guide walls <NUM> are configured so as to be movable in a direction of coming close to or separating away from each other (right-and-left direction) under a state in which the protruding portions 51a are guided in the through-holes <NUM>.

The pinion <NUM> is provided on the holder bottom wall 22c so as to be directed downward. Specifically, the pinion <NUM> is provided on a portion of the holder bottom wall 22c, which defines the roll sheet receiving portion <NUM>, and corresponds to a center portion in the front-and-rear direction and the right-and-left direction. The pinion <NUM> is supported on the holder bottom wall 22c so as to be rotatable about an axis along the up-and-down direction.

The racks <NUM> are respectively coupled to the pair of guide walls <NUM> through intermediation of the protruding portions 51a. The racks <NUM> extend below the holder bottom wall 22c in the right-and-left direction toward the guide walls <NUM> opposed to each other. One of the racks <NUM> extending from one of the guide walls <NUM> meshes with the pinion <NUM> from one side in the front-and-rear direction (for example, the front side). Another one of the racks <NUM> extending from another one of the guide walls <NUM> meshes with the pinion <NUM> from another side in the front-and-rear direction (for example, the rear side). Accordingly, in the positioning mechanism <NUM>, the pinion <NUM> is rotated by a linear driving force applied to one of the racks <NUM>, and thus a rotational driving force of the pinion <NUM> is transmitted to another one of the racks <NUM>. In this manner, the racks <NUM> are moved in the right-and-left direction so as to come close to or separate away from each other, and thus the pair of guide walls <NUM> are moved synchronously.

The sheet retaining mechanism <NUM> includes a flap unit <NUM>, a near-end sensor (sensor) <NUM>, a first guide roller <NUM>, and a second guide roller <NUM>. The flap unit <NUM> partitions the inside of the holder main body 22a in the front-and-rear direction into the roll sheet receiving portion <NUM> and the sheet passage portion <NUM>, and presses the roll sheet R in a direction of separating away from the delivery slot <NUM> (rearward direction). In this embodiment, a part of the inside of the holder main body 22a located more on the rear side than the partition wall lid and the flap unit <NUM> forms the roll sheet receiving portion <NUM>, and a part of the inside of the holder main body 22a located more on the front side than the partition wall lid and the flap unit <NUM> forms the sheet passage portion <NUM>.

As illustrated in <FIG>, <FIG>, and <FIG>, the flap unit <NUM> includes a flap 61a, an urging member 61b, and a flap roller 61c. The flap 61a extends upward in a cantilevered manner from a portion of the holder bottom wall 22c located more on the front side than the pinion <NUM> and more on the rear side than the partition wall lid. The flap 61a is supported on the holder bottom wall 22c at a lower end portion of the flap 61a so as to be pivotable about an axis (first axis) O2 along the right-and-left direction. A length of the flap 61a is set so as to prevent the flap 61a from interfering with the first guide roller <NUM> in an entire pivoting range of the flap 61a.

A curved surface <NUM> is formed on a surface (rear surface) of a distal end portion of the flap 61a, which is directed in a clockwise direction about the axis O2 as shown in <FIG>. The curved surface <NUM> is formed into an arc shape protruding in a counterclockwise direction (toward the front side or sheet passage portion) about the axis <NUM>. The curved surface <NUM> retains an outer peripheral surface of the roll sheet R when, for example, the roll sheet R has a small diameter.

The urging member 61b is, for example, a torsion spring. The urging member 61b is interposed between the flap 61a and the holder bottom wall 22c. The urging member 61b urges the flap 61a toward the rear side (in the clockwise direction). The flap roller 61c is provided at a portion of the distal end portion of the flap 61a, which is located more on the distal end side than the curved surface <NUM>, so as to be rotatable about an axis (second axis) O3 along the right-and-left direction. The flap roller 61c includes large-diameter portions <NUM> and small-diameter portions <NUM> arranged alternately and continuously in the right-and-left direction. The flap roller 61c can be brought into contact with the recording sheet P at the large-diameter portions <NUM>.

The near-end sensor <NUM> is provided on the holder bottom wall 22c at a vicinity of a proximal end portion of the flap unit <NUM> (flap 61a). In the clockwise direction about the axis <NUM>, the near-end sensor <NUM> detects a near end of the roll sheet R based on a pivot angle θ of the flap unit <NUM> with respect to the holder bottom wall 22c. The near end refers to a state in which a remaining amount of the roll sheet R has reached an amount (outer diameter) recommended to replace the roll sheet R.

The near-end sensor <NUM> includes a lever 62a that is pivotable in the front-and-rear direction. The lever 62a is connected to the flap 61a. When the lever 62a pivots in the front-and-rear direction along with pivoting of the flap 61a, the near-end sensor <NUM> is switched between an ON state and an OFF state.

When the pivot angle θ of the flap 61a with respect to the holder bottom wall 22c is smaller than a predetermined angle, the near-end sensor <NUM> keeps the OFF state (the lever 62a does not perform an ON operation). Meanwhile, when the flap 61a pivots so that the pivot angle θ of the flap 61a reaches the predetermined angle, the near-end sensor <NUM> is brought into the ON state. In this embodiment, the predetermined angle is, for example, about <NUM>° with respect to the holder bottom wall 22c. At the predetermined angle, a distal end portion of the flap unit <NUM> is most distant from the delivery slot <NUM>.

When the lever 62a performs the ON operation, the near-end sensor <NUM> outputs an ON signal to the control board <NUM>. When the control board <NUM> receives the ON signal from the near-end sensor <NUM>, the control board <NUM> causes an informing unit (such as a light source and/or a sound source) provided in the casing <NUM> to recommend a user to replace the roll sheet R. When the lever 62a reaches a rearmost end position (ON position), the flap 61a is restrained from further pivoting in the clockwise direction (toward the rear side). Meanwhile, when the lever 62a reaches a foremost end position (OFF position), the flap 61a is restrained from further pivoting in the counterclockwise direction. That is, the lever 62a of the near-end sensor <NUM> also functions as a stopper configured to limit the pivoting range of the flap 61a. However, a stopper separate from the near-end sensor <NUM> may be provided for the flap 61a.

The first guide roller <NUM> leads, toward the printing unit <NUM>, the recording sheet P to be drawn from the roll sheet R. The first guide roller <NUM> is a driven roller that is rotated by, for example, friction generated between the recording sheet P and the first guide roller <NUM> along with conveyance of the recording sheet P. The first guide roller <NUM> is supported on a lower end portion of the partition wall lid so as to be rotatable about an axis (third axis) O4 along the right-and-left direction. That is, the first guide roller <NUM> is caused to enter and retreat from the holder main body 22a along with an opening and closing operation of the cover <NUM>. The axis O4 of the first guide roller <NUM> is located more on the front side and the upper side (downstream side in a conveying direction of the recording sheet P) than the axis O2 of the flap unit <NUM>. The axis O4 of the first guide roller <NUM> is located more on the rear side and the lower side (upstream side in the conveying direction of the recording sheet P) than the axis O1 of the platen roller <NUM>. In the illustrated example, an outer diameter of the first guide roller <NUM> is equal to an outer diameter of the platen roller <NUM>.

It is preferred that the first guide roller <NUM> be designed in consideration of impact absorbing performance against, for example, contact of the roll sheet R. As such a configuration, it is preferred that, similarly to the platen roller <NUM>, an outer surface of the first guide roller <NUM> be made of, among elastically deformable materials such as a rubber material, a material softer than a material for the second guide roller <NUM>.

The second guide roller <NUM> is provided in the sheet passage portion <NUM> between the platen roller <NUM> and the first guide roller <NUM>. The second guide roller <NUM> is a driven roller that is rotated by, for example, friction generated between the recording sheet P and the second guide roller <NUM> along with conveyance of the recording sheet P. The second guide roller <NUM> is supported on the holder side walls 22d so as to be rotatable about an axis (fourth axis) O5 along the right-and-left direction. The axis O5 of the second guide roller <NUM> is arranged more on the front side and the lower side (downstream side in the conveying direction of the recording sheet P) than the axis O4 of the first guide roller <NUM>. The axis O5 of the second guide roller <NUM> is located more on the rear side and the lower side (upstream side in the conveying direction of the recording sheet P) than the axis O1 of the platen roller <NUM>. In the illustrated example, the second guide roller <NUM> has a diameter smaller than the diameter of the first guide roller <NUM>.

It is preferred that the second guide roller <NUM> be designed in consideration of, for example, cost reduction and peelability from the pressure-sensitive adhesive layer. As such a configuration, an outer surface of the second guide roller <NUM> may be made of, among elastically deformable materials such as a resin material, a material harder than the material for the first guide roller <NUM>. The first guide roller <NUM> and the second guide roller <NUM> may be rotated independently of each other in accordance with, for example, the driving force of the driving motor (not shown).

A space in the sheet passage portion <NUM> between the first guide roller <NUM> and the second guide roller <NUM> forms a sheet passing path through which the recording sheet P passes between the roll sheet receiving portion <NUM> and the printing unit <NUM>. When the recording sheet P passes through the sheet passing path, the recording sheet P is brought into contact with the first guide roller <NUM> or the second guide roller <NUM>, and thus is restrained from moving in a thickness direction (up-and-down direction) of the recording sheet P. With this configuration, an entry angle of the recording sheet P into the printing unit <NUM> is limited within a predetermined angle range.

Next, operations of the above-mentioned thermal printer <NUM> are described. First, a method of setting the roll sheet R is described. As illustrated in <FIG>, after the cover <NUM> is set to the open position, the roll sheet R is loaded into the roll sheet receiving portion <NUM>. Then, the roll sheet R falls into the roll sheet receiving portion <NUM> while the outer peripheral surface of the roll sheet R is brought into slide contact with a holder rear wall of the holder main body 22a and the flap 61a. Thus, the flap 61a pivots counterclockwise against an urging force of the urging member 61b. That is, the roll sheet R is caused to enter the roll sheet receiving portion <NUM> so as to expand the roll sheet receiving portion <NUM> toward the front side. Pivoting of the flap 61a in the counterclockwise direction is restrained when the lever 62a reaches the foremost end position. Thus, under a state in which the roll sheet R is supported by the holder rear wall and the flap 61a, the roll sheet R is received in the roll sheet receiving portion <NUM>. In this case, the urging force of the urging member 61b is applied to the roll sheet R through the flap 61a, and thus the roll sheet R is retained in the roll sheet receiving portion <NUM> under a state in which the roll sheet R is pressed toward the rear side. In the illustrated example, the roll sheet R is spaced above the holder bottom wall 22c, but the outer peripheral surface of the roll sheet R may be held in contact with the holder bottom wall 22c in accordance with an outer diameter of the roll sheet R. When the lever 62a is moved to the foremost end position, the near-end sensor <NUM> is brought into the OFF state.

After the roll sheet R is loaded, a leading edge portion of the recording sheet P is guided to the delivery slot <NUM> along the second guide roller <NUM> and the platen roller <NUM>. Under this state, the cover <NUM> is moved to the closed position. Then, a root portion (boundary portion with the roll sheet R) of the recording sheet P drawn from the roll sheet R is pressed downward by the first guide roller <NUM>, and the leading edge portion is sandwiched between the platen roller <NUM> and the thermal head <NUM>. Thus, the roll sheet R is set in the roll sheet receiving portion <NUM> under a state in which a center axis of the roll sheet R matches the right-and-left direction.

Next, a method of positioning the roll sheet R is described. After the roll sheet R is set in the roll sheet receiving portion <NUM>, the guide walls <NUM> are moved in conformity with a sheet width of the roll sheet R. Specifically, under a state in which at least one of the guide walls <NUM> is grasped, the at least one of the guide walls <NUM> is pressed in the right-and-left direction toward an end surface of the roll sheet R. Then, a pressing force applied to one of the guide walls <NUM> is also applied to another one of the guide walls <NUM> through the pinion <NUM>, and thus the guide walls <NUM> are moved synchronously in a direction of coming close to or separating away from each other. At a point in time when the guide walls <NUM> are brought close to or brought into abutment against the end surfaces of the roll sheet R, the guide walls <NUM> are stopped. In this manner, a center of the roll sheet R in the right-and-left direction is positioned near a center of the roll sheet receiving portion <NUM> in the right-and-left direction. In this embodiment, the guide walls <NUM> merely position the roll sheet R in the right-and-left direction, and do not support rotation of the roll sheet R.

Subsequently, a method of performing printing on the recording sheet P is described. Under a state in which the recording sheet P is sandwiched between the platen roller <NUM> and the thermal head <NUM>, along with rotation of the platen roller <NUM>, the recording sheet P is conveyed toward the delivery slot <NUM>. At this time, the heating elements of the thermal head <NUM> generate heat as appropriate, and thus various kinds of information is printed on the recording sheet P. After passing through a space between the fixed blade <NUM> and the movable blade <NUM>, the recording sheet P on which printing is performed by the thermal head <NUM> is delivered to an outside of the thermal printer <NUM> through the delivery slot <NUM>.

After printing on the recording sheet P is finished, the recording sheet P is cut. Specifically, the movable blade <NUM> is moved downward so that the movable blade <NUM> climbs over the fixed blade <NUM> from the front side. Thus, the recording sheet P is sandwiched between the blade edge 47a of the fixed blade <NUM> and the blade edge 48a of the movable blade <NUM>. In this manner, the recording sheet P is cut. In this embodiment, a bottom of the recessed portion 48b of the movable blade <NUM> is configured to be prevented from coming into contact with the blade edge 47a of the fixed blade <NUM>. With this configuration, a printed portion of the recording sheet P is continuous with the roll sheet R through intermediation of the uncut portion left on the recording sheet P. After cutting by the cutter unit <NUM>, the uncut portion left on the recording sheet P is torn, thereby being capable of taking out a piece of the recording sheet P for which printing is finished.

In this embodiment, a linerless label is used as the recording sheet P. Accordingly, the piece of the recording sheet P taken out of the thermal printer <NUM> can be bonded to various kinds of products through intermediation of the pressure-sensitive adhesive layer as it is.

Subsequently, operations of the sheet retaining mechanism <NUM> are described. When a printing operation is continuously performed on the recording sheet P to be drawn from the roll sheet R, the outer diameter of the roll sheet R gradually decreases. That is, along with continuous use, the roll sheet R is brought into a state of having a middle diameter as illustrated in <FIG> and <FIG>, and then is brought into a state of having a small diameter as illustrated in <FIG> and <FIG>.

Under a state in which the roll sheet R has the middle diameter as illustrated in <FIG>, at the time of stoppage of conveyance, the roll sheet R is pressed toward the rear side by the flap 61a. In this case, under a state in which the roll sheet R is held in contact with the flap 61a, the holder bottom wall 22c, and the holder rear wall, the roll sheet R is retained in a rear part of the roll sheet receiving portion <NUM>. Further, under a state in which the portion of the recording sheet P drawn from the roll sheet R is guided along the flap roller 61c, the first guide roller <NUM>, and the second guide roller <NUM>, the drawn portion is led to the printing unit <NUM>. When conveyance is stopped under a state in which the roll sheet R has the middle diameter, the roll sheet R restrains the flap 61a from pivoting in the clockwise direction. With this configuration, the pivot angle θ of the flap 61a is regulated within a range smaller than the predetermined angle. That is, under a state in which the roll sheet R has the middle diameter, the near-end sensor <NUM> keeps the OFF state.

Meanwhile, under a state in which the roll sheet R has the middle diameter as illustrated in <FIG>, when the printing operation is started, the roll sheet R is moved toward the delivery slot <NUM> in accordance with a pulling force applied to the roll sheet R by rotation of the platen roller <NUM>. Specifically, by the pulling force applied to the roll sheet R, the flap 61a pivots in the counterclockwise direction (that is, towards the front side or sheet passage portion <NUM>), and the roll sheet R is moved on the rear surface of the flap 61a from the proximal end portion toward the distal end portion of the flap 61a. After that, the roll sheet R is brought into contact with the first guide roller <NUM>, thereby being restrained from moving to the front side. In this manner, under a state in which the roll sheet R is pressed by the flap 61a toward the rear side while being held in contact with the first guide roller <NUM>, printing is performed on the recording sheet P. That is, the recording sheet P is drawn by rotation of the platen roller <NUM>, and thus the roll sheet R is rotated under a state of being held in contact with the first guide roller <NUM> and the flap 61a.

Under a state in which the roll sheet R has the small diameter as illustrated in <FIG>, at the time of stoppage of conveyance, the roll sheet R is pressed by the flap 61a toward the rear side. In this case, under a state in which the roll sheet R is held in contact with the curved surface <NUM>, the roll sheet R is retained at a distance from the holder bottom wall 22c and the holder rear wall. Thus, the roll sheet R can be restrained from slipping upward away from the flap 61a. Further, under a state in which the portion of the recording sheet P drawn from the roll sheet R is guided along the flap roller 61c, the first guide roller <NUM>, and the second guide roller <NUM>, the drawn portion is led to the printing unit <NUM>.

In a case in which conveyance is stopped under a state in which the roll sheet R has the small diameter, when the pivot angle θ of the flap 61a reaches the predetermined angle, the ON operation is performed on the near-end sensor <NUM> by the lever 62a. When the near-end sensor <NUM> is brought into the ON state, the near-end sensor <NUM> outputs the ON signal to the control board <NUM>. When the control board <NUM> receives the ON signal from the near-end sensor <NUM>, the control board <NUM> causes the informing unit (such as a light source and/or a sound source) provided in the casing <NUM> to recommend a user to replace the roll sheet R.

Under a state in which the roll sheet R has the small diameter as illustrated in <FIG>, when the printing operation is started, the roll sheet R is moved toward the delivery slot <NUM> in accordance with the pulling force applied to the roll sheet R by rotation of the platen roller <NUM>. Specifically, by the pulling force applied to the roll sheet R, the flap 61a pivots in the counterclockwise direction. After that, the roll sheet R is brought into contact with both the first guide roller <NUM> and the second guide roller <NUM>, thereby being restrained from moving to the front side. In this manner, under a state in which the roll sheet R is pressed by the flap 61a toward the rear side while being held in contact with the first guide roller <NUM> and the second guide roller <NUM>, printing is performed on the recording sheet P. That is, the recording sheet P is drawn by rotation of the platen roller <NUM>, and thus the roll sheet R is rotated under a state of being held in contact with the first guide roller <NUM>, the second guide roller <NUM>, and the flap 61a.

As described above, in this embodiment, there is adopted the configuration in which, in a space of the casing <NUM> between the printing unit <NUM> and the roll sheet receiving portion <NUM>, there are provided the flap 61a pivotable about the axis O2, and the urging member 61b configured to urge the flap 61a about the axis O2 in a direction of separating away from the delivery slot <NUM>. With this configuration, the roll sheet R is always pressed by the flap 61a in a direction of separating away from the delivery slot <NUM>, and thus a position of the roll sheet R (in the front-and-rear direction or the up-and-down direction) in the roll sheet receiving portion <NUM> is likely to be stable. Accordingly, even in a case in which a large pulling force is required for conveyance of the recording sheet P as in a case of conveyance of a linerless label, the recording sheet P can be stably conveyed without being affected by the outer diameter of the roll sheet R. In addition, in this embodiment, it is not required that the roll sheet R be retained at the core material R1 of the roll sheet R. Thus, the roll sheet R can be easily removed from and loaded into the roll sheet receiving portion <NUM>, and the configuration can be simplified.

In this embodiment, there is adopted the configuration in which the flap roller 61c is provided at the distal end portion of the flap 61a so as to be rotatable about the axis O3. With this configuration, a frictional force applied between the distal end portion of the flap unit <NUM> and the recording sheet P is reduced, thereby being capable of smoothly conveying the recording sheet P.

In this embodiment, there is adopted the configuration in which the recording sheet P is led to the printing unit <NUM> through a space between the first guide roller <NUM> and the second guide roller <NUM>. With this configuration, the first guide roller <NUM> and the second guide roller <NUM> can limit a movement range of the recording sheet P to be drawn from the roll sheet R. Thus, irrespective of the position of the roll sheet R in the roll sheet receiving portion <NUM>, the recording sheet P is led to the printing unit <NUM> within the predetermined angle range. Accordingly, the recording sheet P can be stably fed toward the printing unit <NUM>.

In this embodiment, there is adopted the configuration in which the first guide roller <NUM> is made of the material softer than the material for the second guide roller <NUM>. With this configuration, an impact applied to the first guide roller <NUM> when the roll sheet R is brought into contact with the first guide roller <NUM> is likely to be relieved. Accordingly, for example, generation of noise accompanied with movement of the roll sheet R in the roll sheet receiving portion <NUM> can be suppressed.

In this embodiment, there is adopted the configuration in which the near-end sensor <NUM> includes the lever 62a that is connected to the flap 61a, and is pivotable between the ON position and the OFF position along with pivoting of the flap 61a. With this configuration, the lever 62a of the near-end sensor <NUM> pivots in synchronization with the flap 61a, and thus the near-end sensor <NUM> is switched between the ON state and the OFF state in accordance with the pivot angle of the flap 61a. Accordingly, as compared to a case in which a mechanism configured to operate the lever 62a is provided separately from the flap unit <NUM>, the configuration can be simplified.

In this embodiment, there is provided the positioning mechanism <NUM> configured to position the roll sheet R in the roll sheet receiving portion <NUM> in the right-and-left direction (first direction) along the center axis of the roll sheet R. The positioning mechanism <NUM> includes the guide walls <NUM> that are configured so as to be movable in the right-and-left direction, and are brought into abutment against the roll sheet R from both sides in the right-and-left direction. With this configuration, the guide walls <NUM> are brought into abutment against the roll sheet R, and thus can restrain the roll sheet R from moving in the roll sheet receiving portion <NUM> in the right-and-left direction. Thus, the guide walls <NUM> are moved in conformity with the sheet width of the roll sheet R, thereby being capable of suppressing movement of the roll sheet R in the roll sheet receiving portion <NUM> in the right-and-left direction irrespective of the sheet width of the roll sheet R. As a result, for example, printing misregistration, and generation of noise accompanied with movement of the roll sheet R in the roll sheet receiving portion <NUM> can be suppressed.

In this embodiment, there is adopted the configuration in which, in the center portion of the blade edge 48a of the movable blade <NUM> in the right-and-left direction, the recessed portion 48b is formed to be recessed from the blade edge 48a. With this configuration, the recording sheet P is cut so as to be prevented from coming into contact with the bottom of the recessed portion 48b, and thus an uncut portion is left at the portion of the recording sheet P opposed to the recessed portion 48b. Accordingly, even when a linerless label is used as the recording sheet P, the cut piece of the recording sheet P can be prevented from adhering to an unexpected place. In particular, in this embodiment, the positioning mechanism <NUM> is provided as described above. Thus, the center of the roll sheet R in the right-and-left direction is positioned near the center of the roll sheet receiving portion <NUM> in the right-and-left direction. As a result, irrespective of the sheet width of the roll sheet R, an uncut portion can be left near the center of the recording sheet P in the right-and-left direction.

The technical scope of the present invention is not limited to the above-mentioned embodiment, and various modifications may be made thereto without departing from the scope of the present invention as defined by the appended claims. In the above-mentioned embodiment, description is made of the thermal printer <NUM> of the drop-in type (loading type) as an example, but the present invention is not limited to this configuration. The thermal printer <NUM> may be of an axial support type in which the roll sheet R is supported at the core material R1 so as to be rotatable. In the above-mentioned embodiment, description is made of the case in which a linerless label is used as the recording sheet P, but the present invention is not limited to this configuration. In the above-mentioned embodiment, description is made of the configuration in which the delivery slot <NUM> is opened toward the front side, but the present invention is not limited to this configuration. The delivery slot <NUM> may be formed to be directed in an optional direction. In the above-mentioned embodiment, description is made of the configuration in which the platen roller <NUM> and the fixed blade <NUM> are provided on the bottom unit <NUM> side, whereas the thermal head <NUM> and the movable blade <NUM> are provided on the cover <NUM> side. However, the present invention is not limited to this configuration. The platen roller <NUM> and the fixed blade <NUM> may be provided on the cover <NUM> side, whereas the thermal head <NUM> and the movable blade <NUM> may be provided on the bottom unit <NUM> side. As another example, the entire printing unit <NUM> may be provided on any one of the bottom unit <NUM> and the cover <NUM>. Further, the cutter unit <NUM> is not an essential component.

In the above-mentioned embodiment, description is made of the configuration in which the flap unit <NUM> is provided on the bottom unit <NUM> side, but the present invention is not limited to this configuration. The flap unit <NUM> may be provided on the cover <NUM> side so as to be pivotable. In the above-mentioned embodiment, description is made of the configuration in which the flap unit <NUM> pivots about the axis O2 along (for example, parallel to) the center axis of the roll sheet R, but the present invention is not limited to this configuration. The flap unit <NUM> may pivot about an axis along the up-and-down direction. In the above-mentioned embodiment, description is made of the configuration in which the flap roller 61c is provided at the distal end portion of the flap 61a, but the flap roller 61c may be provided at a portion other than the distal end portion of the flap 61a. In this case, a plurality of flap rollers 61c may be provided. However, the flap roller 61c is not an essential component.

In the above-mentioned embodiment, description is made of the configuration in which the sheet retaining mechanism <NUM> includes the first guide roller <NUM> and the second guide roller <NUM>, but the present invention is not limited to this configuration. The sheet retaining mechanism <NUM> may include only any one of the first guide roller <NUM> and the second guide roller <NUM>, or may include three or more rollers.

Claim 1:
A thermal printer (<NUM>), comprising:
a casing (<NUM>) including:
a roll sheet receiving portion (<NUM>) that allows a roll sheet (R), which is obtained by winding a recording sheet (P), to be loaded into the roll sheet receiving portion (<NUM>); and
a delivery slot (<NUM>) through which a portion of the recording sheet (P) drawn from the roll sheet (R) is delivered to an outside of the thermal printer (<NUM>);
a printing unit (<NUM>) including:
a thermal head (<NUM>) provided in a space of the casing (<NUM>) between the roll sheet receiving portion (<NUM>) and the delivery slot (<NUM>), and configured to perform printing on the recording sheet (P); and
a platen roller (<NUM>) configured to convey the recording sheet (P) toward the delivery slot (<NUM>) while sandwiching the recording sheet (P) between the thermal head (<NUM>) and the platen roller (<NUM>);
a flap (61a) provided on a portion of the casing (<NUM>) between the printing unit (<NUM>) and the roll sheet receiving portion (<NUM>) so as to be pivotable about a first axis (O2), and configured to press the roll sheet (R) in a direction of separating away from the delivery slot (<NUM>) through abutment against an outer peripheral surface of the roll sheet (R); and
an urging member (61b) configured to urge the flap (61a) about the first axis (O2) in the direction of separating away from the delivery slot (<NUM>), characterized in that the thermal printer (<NUM>) further comprises:
a flap roller (61c) provided at a distal end portion of the flap (61a), and configured so as to be rotatable about a second axis (O3) along a center axis of the roll sheet (R), and allowed to be brought into abutment against the recording sheet (P).