JPH07164713A - Thermal head supporting device - Google Patents

Abstract

PURPOSE:To provide a thermal head supporting device in which an array line of heat generating elements of a thermal head can be easily regulated in parallel with an axial center of a platen at a unit of a head unit. CONSTITUTION:The thermal head supporting device comprises a head unit 16 having a head support 5 detachably coupled at a predetermined play to a head pressing and releasing mechanism for separably displacing to a platen 2 in a direction for regulating parallelism with the platen 2, a thermal head 1 held by the support 5 and opposed to the platen 2, and a pair of right and left connectors 7 having cutouts 11 detachably engaged with concentrically circular parts 3 arranged on an axial center of the platen 2 and position- adjustably mounted at both sides of the head 1. The cutouts 11 of the connectors 7 are engaged with the parts 3 while displacing the support 5 in a range of the play to the mechanism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head supporting device used in a thermal printer.

[0002]

2. Description of the Related Art In a thermal printer, when printing, when a thermal head is pressed against a sheet or an ink ribbon on a platen to insert the sheet or the ink ribbon between the platen and the thermal head, or when the sheet is conveyed. It is necessary to separate the thermal head from the platen. Therefore, various structures have been proposed in which the thermal head is supported so as to be freely separated from and attached to the platen.

For example, in Japanese Unexamined Patent Publication No. 2-139268, a frame supporting a thermal head is urged in a direction away from the platen, a cam presses the frame toward the platen, and the frame is thermally moved depending on a rotational position of the cam. The content of separating from the platen together with the head is described.

Further, in JP-A-2-281984, a head support plate to which a thermal head is fixed is swingably supported by a support shaft, and both sides of the head support plate are biased by independent springs. The thermal head is brought into pressure contact with the platen by rotating the head so that both ends of the spindle are finely moved together with the head support by the long grooves formed in the opposite side plates. It is described that the platen is pressed against the platen with a uniform pressure.

Further, in Japanese Patent Publication No. 55-39465 (Japanese Patent Laid-Open No. 52-119337), a thermal head is fixed to a block via a connecting member, and an assembly of the thermal head, the connecting member and the block is attached to a gimbal joint. The thermal head is pressed against the platen by a spring and the thermal head is brought into pressure contact with the platen, and the rod provided on the block is pulled to pull the thermal head away from the platen.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the invention described in Japanese Patent Publication No. 8, the frame for holding the thermal head is penetrated by the shaft serving as the fulcrum of rotation, so that it is difficult to attach and detach the frame together with the thermal head during assembly or maintenance. Also,
A large number of heat generating elements are arranged in the thermal head along the axial direction of the platen, but it is impossible or extremely difficult to adjust the arrangement line of these heat generating elements to be parallel to the platen.

Also in the invention described in JP-A-2-281984, it is difficult to attach / detach the thermal head together with the head support plate because the support shaft penetrates the side plate and the head support plate. Further, although the pressure contact force of the thermal head with respect to the platen can be made uniform, it is expected that it is very difficult to adjust the arrangement line of the heating elements of the thermal head in parallel with the platen.

In the invention disclosed in Japanese Patent Publication No. 55-39465, since the connecting member is held by the gimbal joint, it is expected that this connecting member will be replaced with the thermal head. Also, with this gimbal joint, it is not possible to adjust the arrangement line of the heating elements of the thermal head in parallel with the platen in the paper transport direction.

Further, the thermal head assembly described in each of the above publications is separated from the printer, and the array line of the heating elements of the thermal head in the assembly unit is arranged in the direction along the sheet conveying direction. It cannot be adjusted parallel to the platen.

[0010]

The invention according to claim 1 is
A head support member removably connected to the platen with a predetermined play in a direction for adjusting the parallelism with the platen to a head pressing / releasing mechanism that is displaceable with respect to the platen, and held by the head support member. A thermal head facing the platen, and a pair of left and right attached to both sides of the thermal head so as to be positionally adjustable, having notches removably fitted to concentric circles arranged on the axis of the platen. A head unit was formed by the locking body.

According to a second aspect of the present invention, in the first aspect of the present invention, a horizontally long ribbon guide roller that bends the path of the ink ribbon that has passed through the platen in the direction of separating the ink ribbon from the paper is provided. Each of the locking bodies is provided with a roller holding portion which is positioned on a straight line parallel to the straight line connecting the centers of the notches formed in the locking body and holds both ends of the ribbon guide roller.

[0012]

According to the present invention, the positions of the locking bodies are adjusted on both sides of the thermal head so that the straight line connecting the centers of the notches of the left and right locking bodies is parallel to the arrangement line of the heating elements of the thermal head. Then, the notch of the locking body is fitted to the concentric circles arranged on the axis of the platen while displacing the head support in the play range with respect to the head pressing / releasing mechanism. It is possible to easily perform the work of aligning the array line of the heating elements with the axis of the platen in units of the head unit.

According to the second aspect of the present invention, by holding both ends of the ribbon guide roller by the roller holding portion of the locking body, it is possible to make the platen and the ribbon guide roller parallel to each other very easily. The paper that has passed through the platen and the ink ribbon can be separated on a ribbon guide roller located on a line perpendicular to the paper transport direction,
Therefore, skew of the paper can be prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 denotes a thermal head, which has a large number of heating elements (not shown) along the axis of the platen 2. At both ends of the platen 2, concentric circle portions (rings) 3 located on the axis of the platen 2 are provided. Further, the back surface of the thermal head 1 is attached by a screw 6 to a plate-shaped head support 5 having a semicircular attachment piece 4. Then, the locking bodies 7 are attached to both sides of the thermal head 1 by screws 8 so that their positions can be adjusted. That is, the left and right locking bodies 7 are formed by the same press die, and the mounting holes are of a size such that the screws 8 are inserted with play in opposition to the screw holes 9 formed on both sides of the thermal head 1. 10, a notch 11 that is detachably fitted to the concentric circles 3 arranged on the platen 2, and a bearing fitting hole 12. A bearing 14, which is a roller holding portion that rotatably holds both ends of the ribbon guide roller 13, is fitted into the bearing fitting hole 12. 15 is a bearing 1
4 is a retaining ring fixed to the end of the ribbon guide roller 13 projecting from 4. Then, the thermal head 1, the head support 5, the locking body 7, and the ribbon guide roller 13
The head unit 16 is formed by the above. In addition,
The locking bodies 7 may be integrally formed on both sides of the head support body 5, but by forming them independently as in this embodiment,
The dimensional accuracy can be improved.

Next, the structure of the head pressing / releasing mechanism 17 for bringing the head unit 16 into and out of contact with the platen 2 will be described with reference to FIG. The head pressing / releasing mechanism 17 includes a center shaft 18 driven by a head lift motor, which will be described later, and a pressing plate 19 fixedly fitted to the center shaft 18. A boss 21 for holding one end of a spring 20 for pressing the head support 5 is formed on both sides of the inner surface of the pressing plate 19, and a circular hole 2 into which a screw 22 is inserted is formed in the central portion.
3 is formed. A screw 24 screwed into the head support 5 is formed at one end of the screw 22, and a flange 25 is formed at the other end. In addition, an annular groove 18a is formed in the center of the center shaft 18 to detachably hold the mounting piece 4. The outer diameter of the bottom of the annular groove 18a is set to be slightly smaller than the semicircular inner diameter of the mounting piece 4, and the width of the annular groove 18a is set to be slightly larger than the plate thickness of the mounting piece 4. Has been. As a result, the head support 5 has a predetermined play in the direction of adjusting the parallelism with the platen 2 and presses the head.
It is connected to the release mechanism 17.

As shown in FIG. 4, a drive gear 26 is fixed to one end of the center shaft 18, and the drive gear 26 includes a stopper gear 27, an idler gear 28,
It is connected to a head lift motor 31 which can rotate in the forward and reverse directions via 29 and a motor gear 30.

In such a structure, the left and right locking bodies 7
The locking bodies 7 are positionally adjusted and attached to both sides of the thermal head 1 so that the straight line connecting the centers of the notches 11 becomes parallel to the arrangement line of the heating elements of the thermal head 1. Then, the head unit 16 is completed by attaching the back surface of the thermal head 1 to the pressing plate 19. The head unit 16 has the mounting piece 4 of the head support 5 fitted into the annular groove 18 a of the center shaft 18,
It is attached to the head pressing / releasing mechanism 17.

Then, as shown in FIG. 4B, the head lift motor 31 is rotated counterclockwise and the center shaft 18 is rotated counterclockwise together with the pressing plate 19, so that the pressing plate 19 is screwed. Since the flange 25 of 22 is pressed to the right, the head unit 16 is separated from the platen 2. In this state, the paper 32 and the ink ribbon 33 can be inserted between the platen 2 and the thermal head 1. Thereafter, as shown in FIG. 4A, when the head lift motor 31 is rotated in the clockwise direction, the center shaft 18 is rotated in the clockwise direction together with the pressing plate 19, so that the spring 20 is compressed and its compression force is increased. Causes the thermal head 1 to move the paper 32 on the platen 2
And the ink ribbon 33 are pressed against each other (see FIG. 3). In this state, by driving the thermal head 1, the ink of the ink ribbon 33 is transferred to the paper 32. That is, printing is performed. In addition, as shown in FIG.
2 is conveyed in the direction of arrow A by a feed roller (not shown), and the ink ribbon 33 is wound in the direction of arrow B by a ribbon reel (not shown), so that the paper 32 and the ink ribbon 33 are separated on the ribbon guide roller 13.

By the way, the thermal head 1 is attached to the platen 2
When the head unit 16 is assembled, the notches 11 of the locking body 7 are fitted to the concentric circles 3 arranged on the axis of the platen 2 when the head unit 16 is assembled.
The locking bodies 7 are positionally adjusted and attached to both sides of the thermal head 1 so that the straight line connecting the centers of the notches 11 becomes parallel to the arrangement line of the heating elements of the thermal head 1, and the annular groove 18a and the attachment piece are attached. Head play due to play between 4 and
By fitting the notches 11 of the locking body 7 into the concentric circles 3 arranged on the axis of the platen 2 while displacing the head support 5 with respect to the release mechanism 17, the thermal head 1
It is possible to easily perform the work of aligning the array line of the heating elements in parallel with the axis of the platen 2 in units of the head unit 16.

When the paper 32 and the ink ribbon 33 are separated on the ribbon guide roller 13, the paper 32 is separated.
May be pulled by the adhesive force of the ink ribbon 33. In this case, if the axis of the ribbon guide roller 13 is not parallel to the platen 2, in other words, if the ribbon guide roller 13 is inclined with respect to a straight line perpendicular to the conveyance direction of the paper 32, the paper 32 is skewed. However, according to the present invention, the bearing 14 that holds both ends of the ribbon guide roller 13 is located on a straight line parallel to the straight line connecting the centers of the notches 11 formed in the left and right locking bodies 7, and the locking body 7 is provided. The platen 2 and the ribbon guide roller 13 can be made parallel to each other very easily because they are provided in each of the above. As a result, the paper 32 and the ink ribbon 3 that have passed through the platen 2
3 can be separated from each other on the ribbon guide roller 13 which is perpendicular to the conveyance direction of the paper 32. Therefore, the paper 32
Skew can be prevented.

[0021]

According to the first aspect of the present invention, the head pressing / releasing mechanism which is displaceably contactable and separable with respect to the platen is detachably connected with a predetermined play in the direction for adjusting the parallelism with the platen. A head support, a thermal head held by the head support, and notches that are detachably fitted to concentric circles arranged on the axis of the platen so that the positions can be adjusted on both sides of the thermal head. Since the head unit was formed with the pair of left and right locking bodies attached, both sides of the thermal head should be aligned so that the straight line connecting the centers of the cutouts of the left and right locking bodies is parallel to the array line of the heating elements of the thermal head. Concentric circles where notches of the locking body are arranged on the axis of the platen while displacing the locking body on the By fitting them, it is possible to easily perform the work of aligning the array line of the heating elements of the thermal head with the axis of the platen in units of the head unit, which facilitates the assembly work and maintenance. You can

According to the second aspect of the invention, as described above, the ribbon guide roller for separating the ink ribbon from the sheet is provided, and the ribbon guide roller is arranged on a straight line parallel to the straight line connecting the centers of the notches formed in the left and right locking bodies. Since the roller holding portions for positioning and holding both ends of the ribbon guide roller are provided for each of the locking bodies, by holding both ends of the ribbon guide roller by the roller holding portions of the locking body, the platen and the ribbon guide roller are Can be parallelized very easily, which allows
The paper that has passed through the platen and the ink ribbon can be separated on the ribbon guide roller that is located on a line that is perpendicular to the paper transport direction, and therefore, skew of the paper can be prevented.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a head unit.

FIG. 2 is an exploded perspective view showing a relationship between a head unit and a head pressing / releasing mechanism.

FIG. 3 is a side view showing a path of a sheet and an ink ribbon.

FIG. 4 is a side view showing the operation of the head pressing / releasing mechanism.

[Explanation of symbols]

 1 Thermal Head 2 Platen 3 Concentric Circles 5 Head Support 7 Locking Body 11 Notch 13 Ribbon Guide Roller 14 Roller Holding Section 16 Head Unit 17 Head Pressing / Release Mechanism 32 Paper 33 Ink Ribbon

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location B41J 17/30 B 25/304 35/04 A B41J 25/30 U (72) Inventor Hisao Suzuki Shizuoka 570 Ohito, Ohito-cho, Takata-gun, Tokyo Inside the Ohito plant of Tokyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A head support member removably connected to a platen pressing / releasing mechanism that is movable in and out of contact with a platen in a direction for adjusting the parallelism with the platen, with a predetermined play, and the head supporter. A thermal head that is held by the body and faces the platen, and a notch that is detachably fitted to concentric circles arranged on the axis of the platen, and is mounted on both sides of the thermal head so as to be positionally adjustable. A thermal head supporting device, characterized in that a head unit is formed by a pair of left and right locking bodies. 2. A straight line connecting the centers of the notches formed in the left and right locking bodies, provided with a horizontally long ribbon guide roller that bends the path of the ink ribbon that has passed through the platen in the direction of separating from the paper. 2. The thermal head support device according to claim 1, wherein a roller holding portion for holding both ends of the ribbon guide roller is provided on each straight line parallel to the thermal head support device.