JP6422334B2 - Printing unit and thermal printer - Google Patents

Description

  The present invention relates to a printing unit and a thermal printer.

  Conventionally, a thermal printer rotates a platen roller in a state where a recording sheet is sandwiched between a platen roller and a thermal head, thereby heating the printing surface of the recording sheet by a heating element of the thermal head while feeding the recording sheet. Color is printed on the printing surface. This thermal printer is configured such that the recording paper can be easily replaced by detaching the platen roller from the main body frame in which the thermal head is incorporated.

For example, a thermal printer (printing unit) described in Patent Document 1 includes a main body frame, a thermal head, a platen roller, and a platen bearing attached to a roller shaft that protrudes coaxially from both ends of the platen roller. A bearing insertion groove formed in the main body frame in which the platen bearing is detachably inserted, and a lock capable of removing the platen bearing from a lock position where the platen bearing is locked so as not to be removed from the bearing insertion groove. It has a lock lever (lock mechanism) that can move to the release position, and a lever urging member (urging member) that constantly urges the lock lever toward the lock position. The platen bearing is pressed against the inner peripheral end surface of the bearing insertion groove by a lock lever in a locked position, and the position with respect to the main body frame is defined.
According to the thermal printer described in Patent Document 1, the detachable platen roller can be accurately positioned with respect to the main body frame.

JP 2007-331112 A

  Incidentally, in the printing unit, a fitting tolerance is set between the rotation shaft of the lock mechanism and the shaft hole of the main body frame through which the rotation shaft is inserted. For this reason, when an external force is applied to the printing unit, the rotation shaft of the lock mechanism may move within the range of the fitting tolerance (rattle). When the pivot shaft of the lock mechanism moves from a desired position, the holding force acting on the platen roller from the lock mechanism and the acting direction of the holding force become unstable, and the platen roller may be displaced relative to the thermal head. As a result, printing failures such as blurred printing and periodic unevenness (printing unevenness caused by a change in the contact state between the heating element and the recording paper due to periodic vibration) occur.

  Therefore, the present invention provides a printing unit and a thermal printer that can stabilize the position of a platen roller with respect to a thermal head and ensure printing quality.

The printing unit of the present invention includes a main body frame, a platen roller that is detachably attached to the main body frame, a lock position that rotatably holds the platen roller on the main body frame, and the platen roller attached to the main body frame. A main body frame comprising: a lock mechanism supported by the main body frame so as to be rotatable between a lock release position that can be separated from the main body frame; and a thermal head pressed against an outer peripheral surface of the platen roller. In addition, one of the lock mechanisms is provided with a rotation shaft that is inserted into a shaft hole provided in the other member and that rotates the lock mechanism with respect to the main body frame. Urging the lock mechanism toward the lock position, and bringing the pivot shaft into contact with the opening edge of the shaft hole. Comprising a biasing member, characterized in that.
According to the present invention, the urging member urges the lock mechanism toward the lock position, and causes the rotation shaft to abut on a predetermined position at the opening edge of the shaft hole, thereby locking the lock mechanism with respect to the body frame. Can be positioned at a desired position. Thereby, even if an external force is applied to the printing unit, for example, it is possible to suppress the rotation shaft from moving within the range of the fitting tolerance with the shaft hole. Therefore, the holding force acting on the platen roller from the lock mechanism and the acting direction of the holding force can be stabilized, the position of the platen roller with respect to the thermal head can be stabilized, and the print quality can be ensured.

In the above-described printing unit, the shaft hole is a long hole, and the biasing member causes the rotating shaft to abut on a portion located on one end side in the longitudinal direction of the opening edge of the shaft hole. It is desirable.
According to the present invention, it is possible to restrict the rotation shaft from moving in the short direction of the shaft hole by bringing the rotation shaft into contact with a portion located on one end side in the longitudinal direction of the opening edge of the shaft hole. In addition, the rotation shaft can be held at a desired position of the shaft hole. For this reason, the position of the rotation shaft is stabilized in the shaft hole, and rattling of the lock mechanism is suppressed. Therefore, the position of the platen roller with respect to the thermal head can be further stabilized.
Moreover, by making the shaft hole a long hole, the urging direction by the urging member can be stabilized as compared with, for example, the case where the shaft hole is formed in a perfect circle or the like, so that the position of the platen roller relative to the thermal head can be further increased. It is possible to stabilize and suppress variation between products.
In addition, by making the shaft hole a long hole, it becomes easier to manage the size of the shaft hole, so that manufacturing variations can be improved, the life of the mold for forming the shaft hole can be extended, and the manufacturing cost can be reduced. be able to.

In the above-described printing unit, it is preferable that an intersection angle between the longitudinal direction of the shaft hole and the urging direction of the urging member is 45 ° or less.
According to the present invention, since the urging direction of the urging member intersects with the longitudinal direction of the shaft hole at 45 ° or less, half of the component force of the urging force of the urging member is applied to the shaft hole. Can be assigned in the longitudinal direction. As a result, the rotation shaft can be held with a stronger force at a predetermined position in the shaft hole. Therefore, rattling of the locking mechanism can be more reliably suppressed, and the position of the platen roller can be further stabilized.

In the printing unit, it is preferable that the biasing member is interposed between the main body frame and the lock mechanism.
According to the present invention, since the urging member is attached in the printing unit, the printing unit can be assembled to the housing with the urging member attached. This makes it easier to assemble the printing unit to the housing and reduce the manufacturing cost compared to a configuration in which the biasing member is interposed between the housing and the lock mechanism.

A thermal printer according to the present invention includes the above-described printing unit.
According to the present invention, since the printing unit is provided, a thermal printer that can stabilize the position of the platen roller with respect to the thermal head and ensure printing quality can be obtained.

  According to the present invention, the urging member urges the lock mechanism toward the lock position, and causes the rotation shaft to abut on a predetermined position at the opening edge of the shaft hole, thereby locking the lock mechanism with respect to the main body frame. Can be positioned at a desired position. Thereby, even if an external force is applied to the printing unit, for example, it is possible to suppress the rotation shaft from moving within the range of the fitting tolerance with the shaft hole. Therefore, the holding force acting on the platen roller from the lock mechanism and the acting direction of the holding force can be stabilized, the position of the platen roller with respect to the thermal head can be stabilized, and the print quality can be ensured.

It is a perspective view of a thermal printer when a paper cover is in a closed position. It is a perspective view of a thermal printer when a paper cover is in an open position. It is the perspective view seen from the back of a printing unit. It is the perspective view seen from the front of the printing unit. FIG. 6 is a perspective view of the printing unit as viewed from the rear with the platen roller removed. FIG. 5 is a perspective view of the printing unit as viewed from the rear in a state where a platen roller and a thermal head are removed. It is sectional drawing in the VII-VII line of FIG. It is explanatory drawing of the locking mechanism in a locked position. It is explanatory drawing of the lock mechanism in a lock release position. It is operation | movement explanatory drawing of a printing unit. It is a side view which shows the other structure of a shaft hole. It is a side view which shows the other structure of a shaft hole.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Thermal printer)
FIG. 1 is a perspective view of the thermal printer when the paper cover is in the closed position. FIG. 2 is a perspective view of the thermal printer when the paper cover is in the open position. The thermal printer is used in a state where it is placed on the installation surface. In the figure, the arrow UP is defined as upward, the arrow FR is defined as front, and the arrow LH is defined as left.

  As shown in FIG. 1, the thermal printer 1 is configured to be able to print a recording paper P. The recording paper P is thermal paper that changes color when heat is applied, and is suitably used for printing various labels, receipts, tickets, and the like. As shown in FIG. 2, the recording paper P is set in the thermal printer 1 in the state of the roll paper R wound so as to have the hollow hole 5, and printing is performed on the portion pulled out from the roll paper R. Is called.

  The thermal printer 1 includes a casing 3 having an opening 3 a, a paper cover 20 that is rotatably supported by the casing 3 and opens and closes the opening 3 a of the casing 3, and a printing unit 30.

  The casing 3 is formed of a plastic such as polycarbonate or a metal material, and a front portion thereof is formed in a substantially rectangular parallelepiped shape having an upper wall 10, while a rear portion thereof is formed in a box shape that opens upward. On the inner surface of the casing 3, ribs (not shown) and the like are formed, and the casing 3 is reinforced. An operation unit 14 for performing various operations of the thermal printer 1 is disposed on the upper wall 10 of the casing 3. The operation unit 14 is provided with various function switches 15 such as a power switch and a FEED switch, and a power lamp for informing ON / OFF information of the power switch adjacent to the function switch 15 and an error of the thermal printer 1. Various lamps 16 such as an ERROR lamp for notification are arranged. An open button 18 for the paper cover 20 is provided between the upper wall 10 and the side wall 12 of the casing 3. Further, a first cutting blade 26 for cutting the recording paper P is formed at the rear edge of the upper wall 10 of the casing 3.

  At the rear of the casing 3, a roll paper storage unit 21 in which the roll paper R is stored through the opening 3 a is defined. The roll paper storage unit 21 includes a guide plate 22 that holds the roll paper R, and holds the roll paper R between the guide plate 22 and the inner surface of the paper cover 20. The guide plate 22 is arcuate in a cross-sectional view as viewed from the left and right directions, holds the roll paper in a state where the outer peripheral surface of the roll paper R is in contact with the inner peripheral surface thereof, and also records the recording paper P drawn from the roll paper R. Is guided to the printing unit 30.

  The paper cover 20 is made of plastic such as polycarbonate. The paper cover 20 is supported at the rear end thereof so as to be rotatable with respect to the casing 3 by a hinge shaft (not shown). Further, the paper cover 20 is configured such that the front end can be locked to a body frame 31 (see FIG. 3) of the printing unit 30 described later by a platen roller 51 described later attached to the front end. By pressing the open button 18 of the casing 3, the paper cover 20 is unlocked from the casing 3 that houses the main body frame 31, and is opened and closed from the closed position (see FIG. 1) to the open position (see FIG. 2). It is configured to be possible. Further, as shown in FIG. 1, in the closed position of the paper cover 20, there is a gap along the width direction of the recording paper P between the front edge of the paper cover 20 and the rear edge of the upper wall 10 of the casing 3. Is provided. This gap constitutes a discharge port 19 through which the printed recording paper P is discharged. Further, a second cutting blade 27 (see FIG. 2) for cutting the recording paper P is formed on the front edge of the paper cover 20. The recording paper P sent out from the discharge port 19 is cut by being pulled down while being in contact with the first cutting blade 26 or the second cutting blade 27 described above.

(Printing unit)
FIG. 3 is a perspective view seen from the rear of the printing unit. FIG. 4 is a perspective view seen from the front of the printing unit. FIG. 5 is a perspective view of the printing unit as viewed from the rear with the platen roller removed. FIG. 6 is a perspective view seen from the rear of the printing unit in a state where the platen roller and the thermal head are removed.
As shown in FIG. 3, the printing unit 30 includes a main body frame 31, a thermal head 41, a platen roller 51, and a lock mechanism 60.

(Body frame)
The main body frame 31 is formed by bending a plate material such as metal, and has a U-shape that is open upward when viewed from the front-rear direction. Specifically, the main body frame 31 includes a bottom portion 32 extending in the left-right direction and a pair of side wall portions 33 (a left side wall portion 33A and a right side wall portion 33B) erected upward from both sides in the left and right direction of the bottom portion 32. And a support portion 34 disposed on the upper surface of the bottom portion 32. The main body frame 31 is fixed on a base member (not shown) having a bottom 32 disposed in the casing 3.

As shown in FIG. 5, a roller insertion groove 35 that is cut downward is formed at the upper edge of each side wall 33. The platen roller 51 is detachably inserted into the roller insertion groove 35 along the vertical direction (see FIG. 3).
As shown in FIGS. 3 and 4, a motor 58 is attached to the right side wall 33 </ b> B. The motor 58 is attached to the right side wall portion 33B from the inside, and its output shaft 58a penetrates the right side wall portion 33B and protrudes outward from the main body frame 31.

  As shown in FIG. 6, the support portion 34 is a member having a rectangular shape in a plan view, and is formed so that both left and right end portions protrude upward. A head pressing plate 34 a is fixed to the upper portion of the support portion 34. The head pressing plate 34 a is a plate-like member whose longitudinal direction is the left-right direction, and is disposed between the pair of side wall portions 33.

As shown in FIG. 3, a first shaft 36 extending in the left-right direction is disposed in the lower rear portion of the main body frame 31. Both ends of the first shaft 36 are fixed to the pair of side wall portions 33, respectively.
In the main body frame 31, a second shaft 37 (corresponding to a “rotating shaft” in the claims) that extends along the left-right direction is disposed at a portion that is located obliquely forward and upward with respect to the first shaft 36. . Similar to the first shaft 36, both ends of the second shaft 37 are fixed to the pair of side wall portions 33.

(Thermal head)
7 is a cross-sectional view taken along line VII-VII in FIG.
As shown in FIGS. 5 and 7, the thermal head 41 prints on the recording paper P and is pressed against the outer peripheral surface of the platen roller 51. The thermal head 41 is formed in a rectangular shape when viewed from the front-rear direction. The thermal head 41 is arranged on the inner side of the upper wall 10 of the casing 3 so as to be exposed in the opening 3a, and is arranged in a state where the longitudinal direction thereof coincides with the width direction of the recording paper P. (See FIG. 2). On the head surface 41a of the thermal head 41, a large number of heating elements 42 arranged in a line parallel to the left-right direction are arranged. The head surface 41 a faces the printing surface of the recording paper P, and the recording paper P can be held between the outer peripheral surface of the platen roller 51. The heating elements 42 of the thermal head 41 are controlled to generate heat based on signals from a control unit (not shown). The thermal head 41 prints various characters and figures on the printing surface of the recording paper P by controlling the heat generation of the heating element 42.

The thermal head 41 is affixed and fixed to a head support 45 supported by the main body frame 31. The head support 45 is a plate-like member whose longitudinal direction is the left-right direction, and is disposed between the pair of side wall portions 33, and the thermal head 41 is attached and fixed to the rear surface. The head support body 45 is disposed behind the head pressing plate 34 a, and the lower part is rotatably supported by the second shaft 37.
Further, as shown in FIGS. 6 and 7, an elastic member that urges the head support 45 and the head pressing plate 34a between the head support 45 and the head pressing plate 34a in a direction in which they are separated from each other. 46 is interposed. In other words, the elastic member 46 is configured to always press the head support 45 toward the rear. A plurality of elastic members 46 (five in this embodiment) are arranged at intervals in the left-right direction.

  As shown in FIG. 5, a stopper 45 a for restricting the rotation range of the head support 45 is formed at the upper end of the head support 45. The stopper 45 a extends outward in the left-right direction of the head support 45 and faces the inside of the recess 33 a formed at the upper portion of the side wall 33 of the main body frame 31. The stopper 45a is configured to move in the recess 33a as the head support 45 rotates, and to be able to contact both front and rear end surfaces of the recess 33a. The stopper 45a regulates the amount of rotation of the head support 45 by contacting the end surface of the recess 33a.

(Platen roller)
As shown in FIGS. 3 and 7, the platen roller 51 is pressed against the thermal head 41, and rotates with the recording paper P sandwiched between the thermal head 41, thereby feeding out the recording paper P. The platen roller 51 includes a roller shaft 52, a roller main body 53 externally mounted on the roller shaft 52, and a pair of bearings 54 attached to both ends of the roller shaft 52. The roller shaft 52 is formed slightly longer than the separation distance between the pair of side wall portions 33 of the main body frame 31. The roller body 53 is formed of rubber or the like, for example, and is uniformly disposed along the axial direction (left-right direction) of the roller shaft 52 over the entire portion excluding both ends of the roller shaft 52.

  As shown in FIG. 2, the platen roller 51 is rotatably attached to the front edge of the paper cover 20 via a platen frame 55 and is detachably attached to the main body frame 31 as the paper cover 20 is opened and closed. Yes. As shown in FIG. 3, the platen roller 51 has a pair of bearings 54 mounted on both ends thereof in the roller insertion groove 35 of the main body frame 31 (see FIG. 5) when the paper cover 20 is in the closed position (see FIG. 1). ) Is inserted. The platen roller 51 is provided so that the roller main body 53 comes into contact with the thermal head 41 in a state where the recording paper P pulled out from the roll paper R is sandwiched between the platen roller 51 and the roller insertion groove 35. ing.

  A driven gear 56 is fixed to one end (right end) of the platen roller 51 in the axial direction. The driven gear 56 meshes with a gear transmission mechanism 57 attached to the main body frame 31 when the platen roller 51 is held by the pair of side wall portions 33. The gear transmission mechanism 57 is connected to the output shaft 58 a of the motor 58 and transmits the rotational driving force from the motor 58 to the driven gear 56. As a result, the platen roller 51 rotates while being held by the pair of side wall portions 33 and can feed the recording paper P.

(Lock mechanism)
FIG. 8 is an explanatory diagram of the lock mechanism in the lock position, and is a cross-sectional view taken along line VIII-VIII in FIG. 3. FIG. 9 is an explanatory diagram of the locking mechanism in the unlocked position, and is a cross-sectional view of a portion corresponding to the line VIII-VIII in FIG.
As shown in FIGS. 3 and 8, the lock mechanism 60 is rotatably supported by the second shaft 37 and holds the platen roller 51 inserted into the roller insertion groove 35. In the present embodiment, the lock mechanism 60 includes a lock position (position shown in FIG. 8) that rotatably holds the platen roller 51 on the main body frame 31, and an unlock position where the platen roller 51 can be detached from the main body frame 31. (Position shown in FIG. 9). The lock mechanism 60 includes a pair of lock arms 62 that respectively hold the bearings 54 of the platen roller 51, and a connecting plate 66 that connects the pair of lock arms 62. Since the pair of lock arms 62 are formed in the same shape, only one of the lock arms 62 will be described in the following description. In the following description of the configuration of the lock mechanism 60, a state where the lock mechanism 60 is in the locked position (the state shown in FIG. 8) will be described unless otherwise specified.

  As shown in FIG. 4, the connecting plate 66 has a plate shape extending in the left-right direction with the front-rear direction as the thickness direction, and is located in front of the head pressing plate 34 a between the pair of side wall portions 33 of the main body frame 31. Has been placed. The connecting plate 66 has a lever abutting portion 67 at the lower end portion on the left side. The lower surface of the lever abutting portion 67 extends in the front-rear and left-right directions, and a second operation piece 93 of a release lever 90 described later comes into contact therewith.

  As shown in FIG. 8, the pair of lock arms 62 is a flat plate-like member, and protrudes from the both ends in the left-right direction of the connecting plate 66 toward the rear. The lock arm 62 includes a base portion 63 disposed below the roller insertion groove 35 when viewed from the left-right direction, and a holding portion 64 extending upward from the rear upper end of the base portion 63.

A shaft hole 81 is formed at the center of the base 63 in the vertical direction. The shaft hole 81 is formed in an oval shape whose longitudinal direction is a direction orthogonal to a straight line L passing through the central axis Q2 of the platen roller 51 and the central axis Q1 of the second shaft 37 when viewed from the left-right direction.
The second shaft 37 is inserted into the shaft hole 81. The lock mechanism 60 rotates around the second shaft 37 by the shaft hole 81 and the second shaft 37. The lock mechanism 60 is configured to be slidable with respect to the second shaft 37 within the range of the shaft hole 81. At this time, in the lock mechanism 60, the second shaft 37 abuts on the front end edge in the shaft hole 81 at the lock position (the state shown in FIG. 8), and abuts on the rear end edge in the shaft hole 81 at the lock release position ( The state shown in FIG.

  A third shaft 68 is attached to the lower portion of the base 63. The third shaft 68 is disposed along the left-right direction in front of the first shaft 36, and both end portions are fixed to the pair of base portions 63, respectively. The central axis Q3 of the third shaft 68 is disposed on the straight line L when viewed from the left-right direction.

  The holding portion 64 extends from the region opposite to the thermal head 41 side across the platen roller 51 in the front-rear direction, through the upper portion of the platen roller 51 toward the thermal head 41 side (see FIG. 7). ). The front end surface 64a of the holding portion 64 (portion connected to the upper end surface of the base portion 63) extends obliquely rearward toward the upper side, and then extends while curving toward the front side. A curved portion of the front end surface 64a is formed in an arc shape along the outer peripheral surface of the bearing 54 of the platen roller 51 when viewed from the left-right direction. The lock mechanism 60 holds the bearing 54 in the roller insertion groove 35 by sandwiching the bearing 54 between the inner peripheral edge of the roller insertion groove 35 by the curved portion of the front end surface 64 a contacting the bearing 54.

  The tip end portion 64b of the holding portion 64 (the front end of the front end face 64a) is formed so as to be positioned closer to the thermal head 41 (front side) than the straight line L when viewed from the left-right direction. The distal end portion 64 b is formed such that the closest distance to the upper end surface of the base portion 63 is larger than the outer diameter of the bearing 54.

Further, the distal end portion 64b has a distance from the central axis Q1 of the second shaft 37 in the state where the locking mechanism 60 is in the locked position, from the longest distance between the central axis Q1 of the second shaft 37 and the outer peripheral surface of the bearing 54. It is formed to be shorter. Thereby, the rotation of the lock arm 62 around the second shaft 37 (center axis Q1) is restricted by the front end portion 64b coming into contact with the bearing 54 from the front.
Further, the distal end portion 64b is located at a distance from the central axis Q1 of the second shaft 37 when the second shaft 37 is in contact with the rear end edge of the shaft hole 81 (the state shown in FIG. 9). It is formed so as to be larger than the longest distance between the central axis Q1 of the shaft and the outer peripheral surface of the bearing 54. Accordingly, the lock arm 62 can rotate around the second shaft 37 (center axis Q1) without the tip end portion 64b coming into contact with the bearing 54.

  As shown in FIG. 3, a pair of urging members 70 are interposed between the first shaft 36 and the third shaft 68. The pair of urging members 70 are extended in the front-rear direction along the inner side surfaces of the pair of base portions 63, respectively. As shown in FIG. 8, the urging member 70 is a coil spring, for example, and urges the first shaft 36 and the third shaft 68 in a direction in which they approach each other. Thereby, the urging member 70 urges the lock mechanism 60 toward the lock position (the direction in which the holding portion 64 is directed forward around the second shaft 37). The urging direction of the urging member 70 is set to be orthogonal to the straight line L when viewed from the left-right direction. That is, the urging direction of the urging member 70 coincides with the longitudinal direction of the shaft hole 81 described above.

As shown in FIG. 4, a release lever 90 that releases the mounted state of the platen roller 51 and the main body frame 31 in conjunction with the operation of the open button 18 is provided on the left side wall portion 33 </ b> A of the main body frame 31. The release lever 90 is supported between the left side wall portion 33A and the support portion 34, and is attached so as to be rotatable about the left-right direction. The release lever 90 includes a shaft portion 91 extending in the left-right direction, a first operation piece 92 extending rearward from the shaft portion 91 outside the left side wall portion 33A, and a shaft portion 91 inside the left side wall portion 33A. A second operation piece 93 extending forward is integrally formed. The first operation piece 92 is configured to be linked to the open button 18 from below and to be pushed down as the open button 18 is pressed. The second operation piece 93 is linked to the lever abutting portion 67 of the lock mechanism 60 from below, and is configured to be pushed up when the open button 18 is pressed.
The release lever 90 rotates clockwise as viewed from the left as the open button 18 is pressed, and pushes up the lever abutting portion 67 of the lock mechanism 60 via the second operation piece 93. As a result, the lock mechanism 60 moves toward the unlock position (see FIG. 9).

Next, the operation of the printing unit 30 described above will be described.
First, the closing operation of the paper cover 20 will be described. In addition, in the open position of the paper cover 20, the lock mechanism 60 shall be in the lock position mentioned above.
As shown in FIGS. 1 and 2, after the roll paper R is put into the roll paper storage unit 21, the paper cover 20 is closed. Then, first, the bearing 54 of the platen roller 51 comes into contact with the holding portion 64 of the lock arm 62 from above, and the outer peripheral surface of the roller body 53 comes into contact with the thermal head 41.

  When the paper cover 20 is pushed further in the closing direction, the bearing 54 of the platen roller 51 pushes the lock mechanism 60 toward the unlocking position (the direction against the urging force of the urging member 70) via the holding portion 64. To do. Further, the platen roller 51 resists the urging force of the elastic member 46 around the second shaft 37 by the outer peripheral surface of the roller body 53 pressing the head support 45 via the thermal head 41. Rotate in the direction. As a result, the bearings 54 enter the roller insertion grooves 35 of the main body frame 31 separately while pushing the gap in the front-rear direction between the holding portion 64 and the thermal head 41.

Thereafter, when the bearing 54 gets over the tip end portion 64 b of the holding portion 64, the lock mechanism 60 is rotated toward the lock position by the restoring force of the urging member 70. Thereby, the bearing 54 is held between the front end surface 64a of the holding portion 64 and the inner peripheral edge of the roller insertion groove 35, the platen roller 51 is rotatably held by the main body frame 31, and the paper cover 20 is closed. It becomes. In this state, the driven gear 56 of the platen roller 51 meshes with the gear transmission mechanism 57 attached to the main body frame 31.
Thus, the closing operation of the paper cover 20 is completed.

FIG. 10 is an operation explanatory view of the printing unit, and is a side sectional view mainly showing the left side wall portion 33A of the main body frame 31, the bearing 54 of the platen roller 51, and the lock mechanism 60.
Here, as shown in FIG. 10, the lock mechanism 60 is urged toward the lock position by the urging member 70 as described above. Specifically, in the lock mechanism 60, the curved portion of the front end surface 64 a of the holding portion 64 is in contact with the bearing 54 of the platen roller 51 at the lock position. For this reason, in the lock mechanism 60, a first torque T1 is generated around the contact portion between the front end surface 64a of the holding portion 64 and the bearing 54 in the lock position (the direction in which the base portion 63 is directed rearward). The curved portion of the front end surface 64 a of the holding portion 64 is formed along the outer peripheral surface of the bearing 54. For this reason, the rotation center of the first torque T1 substantially coincides with the center axis Q2 of the bearing 54 (platen roller 51).

  Thereby, the lock mechanism 60 maintains the contact state in which the front end edge of the shaft hole 81 is in contact with the second shaft 37 from the front at the lock position. That is, the contact state between the second shaft 37 and the shaft hole 81 is held by the biasing force F (first torque T1) of the biasing member 70, so that the lock mechanism 60 is pivoted with respect to the second shaft 37. The movement within the range of the hole 81 can be suppressed.

  Further, when the lock mechanism 60 is in the locked position (a contact state between the second shaft 37 and the front end portion of the opening edge of the shaft hole 81), the lock mechanism 60 is subjected to the first force F of the bias member 70 due to the biasing force F. A second torque T2 is generated around the central axis Q1 of the two shaft 37 toward the lock position. Due to the second torque T2, the holding portion 64 of the lock mechanism 60 is urged forward to hold the bearing 54 of the platen roller 51, and the thermal head 41 (see FIG. 7) around the outer peripheral surface of the platen roller 51. ).

In this embodiment, the longitudinal direction of the shaft hole 81 coincides with the direction orthogonal to the straight line L from the left-right direction. That is, the longitudinal direction of the shaft hole 81 is centered on the central axis Q2 of the platen roller 51 when viewed from the left-right direction, and coincides with the tangential direction of the virtual circle passing through the central axis Q1 of the second shaft 37.
On the other hand, in the urging member 70, the urging force F acts on the third shaft 68, and the urging direction is a straight line connecting the central axis Q2 of the platen roller 51 and the central axis Q3 of the third shaft 68 as viewed from the left-right direction ( It coincides with the direction orthogonal to the straight line L). For this reason, the urging force F of the urging member 70 is all the first torque T1, and acts between the second shaft 37 and the shaft hole 81 at the contact portion between the second shaft 37 and the shaft hole 81. This is the pressing force. Moreover, since the shaft hole 81 is a long hole, the second shaft 37 is restricted from moving in the short direction of the shaft hole 81 in the shaft hole 81, and the position of the second shaft 37 is stabilized in the shaft hole 81. .

  Further, the urging direction of the urging member 70 coincides with a direction orthogonal to a straight line (straight line L) connecting the central axis Q1 of the second shaft 37 and the central axis Q3 of the third shaft 68 when viewed from the left-right direction. Yes. For this reason, all of the urging force F of the urging member 70 becomes the second torque T <b> 2 and becomes a pressing force acting between the holding portion 64 and the bearing 54 of the platen roller 51. Therefore, the urging force F of the urging member 70 can be efficiently applied to the positioning of the second shaft 37 with respect to the shaft hole 81 and the holding of the platen roller 51 by the holding portion 64.

Next, the opening operation of the paper cover 20 will be described.
First, when the open button 18 is pressed, the release lever 90 is rotated in conjunction therewith. As a result, the lock mechanism 60 is pressed toward the unlock position (the direction against the urging force of the urging member 70) via the second operation piece 93. Specifically, the lock mechanism 60 slides so that the rear end edge of the shaft hole 81 approaches the second shaft 37 by rotating around the contact portion between the front end surface 64 a of the holding portion 64 and the bearing 54. . As a result, the lock mechanism 60 is pushed upward, the tip end portion 64b of the holding portion 64 is separated from the outer peripheral surface of the bearing 54, and the rotation of the lock mechanism 60 around the second shaft 37 is allowed.
When the open button 18 is further pressed in this state, the lock mechanism 60 rotates around the second shaft 37, whereby the holding portion 64 is retracted to the unlock position where the bearing 54 can be detached from the roller insertion groove 35. When the paper cover 20 is pulled up in this state, the bearing 54 of the platen roller 51 is detached from the roller insertion groove 35. As a result, the platen roller 51 is removed from the main body frame 31, and the paper cover 20 is in the open position.
Thus, the closing operation of the paper cover 20 is completed.

By the way, when an external force is applied to the thermal printer 1 (printing unit 30), the lock mechanism 60 at the lock position moves upward with respect to the main body frame 31 (the rear end edge of the shaft hole 81 approaches the second shaft 37). The holding portion 64 may move away from the outer peripheral surface of the bearing 54.
Even in this case, the lock mechanism 60 moves downward (in the direction in which the front end edge of the shaft hole 81 approaches the second shaft 37) with respect to the main body frame 31 by the restoring force of the urging member 70, and promptly locks the lock position. Will return to. Thereby, the contact state in which the front end edge of the shaft hole 81 is in contact with the second shaft 37 from the front is maintained at the locked position. In particular, in the present embodiment, since the longitudinal direction of the shaft hole 81 coincides with the urging direction of the urging member 70, the urging force F of the urging member 70 is effectively assigned to the longitudinal direction of the shaft hole 81. be able to. Thereby, the second shaft 37 can be held with a stronger force at a predetermined position in the shaft hole 81. Therefore, rattling of the lock mechanism 60 can be more reliably suppressed, and the position of the platen roller 51 can be further stabilized.

Thus, in the present embodiment, the main body frame 31 has the second shaft 37 that is inserted into the shaft hole 81 provided in the lock mechanism 60 and that rotates the lock mechanism 60 with respect to the main body frame 31. Is provided. In addition, a biasing member 70 that biases the lock mechanism 60 toward the lock position and abuts the second shaft 37 and the opening edge of the shaft hole 81 is provided.
According to this configuration, the urging member 70 urges the lock mechanism 60 toward the lock position and brings the second shaft 37 into contact with a predetermined position at the opening edge of the shaft hole 81, thereby causing the main body frame 31. In contrast, the lock mechanism 60 can be positioned at a desired position. Thereby, even if an external force acts on the printing unit 30, for example, the second shaft 37 can be prevented from moving within the range of the shaft hole 81. Therefore, the holding force acting on the platen roller 51 from the lock mechanism 60 and the acting direction of the holding force can be stabilized, the position of the platen roller 51 with respect to the thermal head 41 can be stabilized, and the print quality can be ensured.

In the present embodiment, since the second shaft 37 is brought into contact with a predetermined portion of the opening edge of the shaft hole 81, the holding accuracy of the platen roller 51 by the lock mechanism 60 is determined between the second shaft 37 and the shaft hole 81. It depends on the accuracy of the contact surface with the predetermined portion at the opening edge. For this reason, when managing the roundness of the shaft hole and the concentricity of the shaft hole and the rotating shaft at the time of manufacture, in order to guarantee the holding accuracy of the platen roller by the lock mechanism, as in the conventional printing unit Compared to the above, manufacturing variations can be easily suppressed, and the die used for manufacturing the lock mechanism 60 having the shaft hole 81 can be easily managed, and thus the manufacturing cost can be reduced.
Further, by making the shaft hole 81 a long hole, the size control of the shaft hole 81 is facilitated, so that manufacturing variations can be improved, the life of the mold for molding the shaft hole 81 can be increased, and the manufacturing cost can be reduced. Reduction can be achieved.

Further, in the present embodiment, the shaft hole 81 is a long hole, and the biasing member 70 causes the second shaft 37 to abut on the portion of the opening edge of the shaft hole 81 that is located on one end side in the longitudinal direction. ing.
According to this configuration, the second shaft 37 moves in the short direction of the shaft hole 81 by bringing the second shaft 37 into contact with the portion of the opening edge of the shaft hole 81 located on one end side in the longitudinal direction. The second shaft 37 can be held at a desired position of the shaft hole 81 after restricting the operation. For this reason, the position of the second shaft 37 is stabilized in the shaft hole 81, and rattling of the lock mechanism 60 is suppressed. Therefore, the position of the platen roller 51 with respect to the thermal head 41 can be further stabilized.

  In addition, since the shaft hole 81 is a long hole, the urging direction by the urging member 70 can be stabilized as compared with, for example, the case where the shaft hole 81 is formed in a perfect circle or the like. The position of 51 can be made more stable, and variations between products can be suppressed.

  The urging member 70 is interposed between the main body frame 31 (first shaft 36) and the lock mechanism 60 (third shaft 68). According to this configuration, since the urging member 70 is attached in the printing unit 30, the printing unit 30 can be assembled to the casing 3 with the urging member 70 attached. Thereby, compared to the configuration in which the urging member 70 is interposed between the casing 3 and the lock mechanism 60, the printing unit 30 can be easily assembled to the casing 3, and the manufacturing cost can be reduced.

  Since the thermal printer 1 of the present embodiment includes the printing unit 30, the position of the platen roller 51 with respect to the thermal head 41 can be stabilized and the printing quality can be ensured.

The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, in the above embodiment, the lock mechanism 60 is rotatable by the shaft hole 81 formed in the lock mechanism 60 and the second shaft 37 (rotation shaft) provided in the main body frame 31. . However, the present invention is not limited to this, and the lock mechanism may be rotatable by a rotation shaft provided in the lock mechanism and a shaft hole formed in the main body frame.

  Moreover, in the said embodiment, although the longitudinal direction of the shaft hole 81 and the urging | biasing direction of the urging | biasing member 70 corresponded (parallel), the crossing angle of both may be 45 degrees or less. In this case, more than half of the urging force of the urging member 70 can be assigned in the longitudinal direction of the shaft hole 81. Thereby, the second shaft 37 can be held with a stronger force at a predetermined position in the shaft hole 81. Therefore, rattling of the lock mechanism 60 can be more reliably suppressed, and the position of the platen roller 51 can be further stabilized.

  Moreover, in the said embodiment, although the shaft hole 81 was formed in the ellipse shape, it is not limited to this. For example, as shown in FIG. 11, the shaft hole 181 may be elliptical. In this case, it is desirable to set the radius of curvature at both ends in the longitudinal direction of the shaft hole 181 to be smaller than the radius of the second shaft 37. The second shaft 37 and the opening edge of the shaft hole 181 are brought into contact with each other at a portion located on one end side of the shaft hole 181 in the longitudinal direction. Shaking with the shaft hole 181 can be further suppressed. Moreover, as shown in FIG. 12, the shaft hole 281 may be circular. Even in this case, the second shaft 37 can be positioned at a desired position of the shaft hole 281 by the urging member 70, and the second shaft 37 can be prevented from moving within the range of the fitting tolerance with the shaft hole 281. Moreover, the shape of the shaft hole and the rotation shaft (second shaft) is not limited to the above shape, and may be any shape as long as they are in contact with each other at a predetermined location.

  In addition, it is possible to appropriately replace the components in the above-described embodiments with known components without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Thermal printer 30 ... Printing unit 31 ... Main body frame 37 ... 2nd shaft (rotating shaft) 41 ... Thermal head 51 ... Platen roller 60 ... Lock mechanism 70 ... Energizing member 81,181,281 ... Shaft hole

Claims (4)

Body frame,
A platen roller detachably attached to the main body frame;
A lock mechanism supported by the main body frame so as to be rotatable between a lock position for rotatably holding the platen roller on the main body frame and an unlock position where the platen roller can be detached from the main body frame. When,
A thermal head pressed against the outer peripheral surface of the platen roller;
In the printing unit with
One of the main body frame and the lock mechanism is inserted into a shaft hole provided in the other member, and the rotation mechanism rotates the lock mechanism relative to the main body frame. A shaft is provided,
A biasing member that biases the lock mechanism toward the lock position and abuts the rotating shaft and the opening edge of the shaft hole,
The shaft hole is a long hole,
The biasing member biases the lock mechanism in the same direction as the longitudinal direction of the shaft hole,
The pivot axis is
When the locking mechanism is in the locked position, the biasing force of the biasing member makes contact with a portion located on one end side in the longitudinal direction of the opening edge of the shaft hole,
When the lock mechanism is in the unlock position, it moves to the other end side in the longitudinal direction of the opening edge of the shaft hole.
A printing unit characterized by that. The crossing angle between the longitudinal direction of the shaft hole and the biasing direction of the biasing member is 45 ° or less.
The printing unit according to claim 1 . The biasing member is interposed between the main body frame and the lock mechanism,
The printing unit according to claim 1 , wherein the printing unit is a printing unit. The printing unit according to claim 1 is provided.
A thermal printer characterized by that.

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