JP3242359B2 - Cover device in thermal print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal print head used as a printing means for a facsimile or a printer, and more particularly to a cover device for a surface of the thermal print head.

[0002]

2. Description of the Related Art Recent thermal print heads are disclosed in, for example,
As described in Japanese Patent Publication No. 258309, a head substrate provided with a heating resistor on the upper surface of a heat radiating plate and a circuit board provided with a connector for external connection are parallel to each other.
In addition to the above arrangement, a cover made of synthetic resin is provided on the upper surface side of the circuit board, and the upper surface of the circuit board and the respective driving ICs in the head substrate are covered with the cover body. It is configured to be mounted so as to cover a part of it.

[0003] In this case, when the synthetic resin cover body is formed, the reinforcing ribs and the like are integrally formed on the back surface of the cover body when forming the cover body. The part is warped downwardly convex so that the part becomes higher than the middle part, and therefore, when this cover body is mounted on the upper surface side of the circuit board, the upper surface of the head substrate The printing paper and / or the transfer ribbon paper pressed by the platen roller against the heating resistor portion is partially strong at one end or both end portions of both ends of the cover body along the longitudinal direction. This may cause a problem that the printing paper and / or the transfer ribbon paper may be torn or wrinkled due to the tendency to contact. There was.

[0004] It is a technical object of the present invention to provide a cover made of a synthetic resin which does not cause such a problem.

[0005]

In order to achieve this technical object, the present invention provides a head substrate having a heat-generating resistor provided on the upper surface of a metal heat sink and a connector for connection to the outside. And a circuit board provided in parallel with each other, and a cover body made of synthetic resin is mounted on the upper surface side of the circuit board.In the thermal print head, the cover body is in a state before being mounted on the circuit board. In this case, the central portion along the longitudinal direction of the cover body is deformed so as to be upwardly convex so as to be higher than both end portions .
The length of the circuit board on the lower surface at both ends in the longitudinal direction
Removably engages with the engagement parts provided at both ends in the hand direction
The present invention is characterized in that an engaging piece is provided . Is the thing.

[0006]

As described above, the cover body made of synthetic resin is upwardly projected so that the center portion along the longitudinal direction of the cover body before mounting on the circuit board is higher than both end portions. In a state where the cover body is mounted on the circuit board, a printing paper and / or a paper sheet pressed against a portion of the heating resistor on the upper surface of the head substrate by a platen roller in a state where the cover body is mounted on the circuit board. It is possible to eliminate the tendency that the transfer ribbon paper comes into strong contact with both end portions of the cover body as in the related art. Rather, the printing paper and / or the transfer ribbon paper are formed of the cover body. Of these, it is possible to make strong contact with the central portion in the longitudinal direction or to make contact almost equally over the entire length in the longitudinal direction of the cover body.

Therefore, according to the present invention, when a cover made of synthetic resin is mounted on the upper surface side of the circuit board, the cover may cause tearing of the printing paper and / or transfer ribbon paper, This has the effect of reliably reducing generation of wrinkles. Moreover, the longitudinal length of the cover body
The lower surface of both ends in the direction, in the longitudinal direction of the circuit board
It is detachably engaged with the engaging portions provided at both ends.
By integrally providing the engaging pieces described above, it is possible to easily attach the cover body to the circuit board and remove the cover body .

According to the third aspect of the present invention, it is possible to reliably prevent the cover body from being shifted in the direction perpendicular to the longitudinal direction, and also to have the height of the projection piece. Due to the increase or decrease of the dimensions, the cover body is made to be substantially parallel to the circuit board in a state where the cover body is mounted, or to a form in which the center portion in the longitudinal direction of the cover body is higher than both end portions. Can be arbitrarily set, and when the central portion in the longitudinal direction is higher than both end portions, the height of the central portion can be set arbitrarily.

[0009] Further, with the configuration as described in claim 4, the lifting of the cover body can be prevented.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. In these drawings, reference numeral 1 denotes a heat radiating plate made of metal such as aluminum, and a ceramic head substrate 2 is provided on one side of a groove 1a extending in the longitudinal direction on the upper surface of the heat radiating plate 1.
On the other side, the circuit boards 3 are respectively fixed with an adhesive or the like.

A heating resistor 4 is formed on the upper surface of the head substrate 2 so as to extend linearly in the longitudinal direction, and a plurality of driving ICs 5 for the heating resistor 4 are arranged in a line in the longitudinal direction. They are mounted side by side. Each drive IC 5 is covered with a coat 6 made of synthetic resin. On the other hand, the circuit board 3 is provided with a connector 7 for connection to the outside,
Various wiring patterns (not shown) extending from the head substrate 2 toward the respective driving ICs 5 are formed.

The head substrate 2 and the circuit substrate 3
Between each of the driving ICs 5 on the head substrate 2,
Lead terminals 8 for electrically connecting various wiring patterns on the circuit board 3 are mounted. And
Reference numeral 9 denotes a cover body provided on the upper surface of the circuit board 3 so as to cover the upper surface of the circuit board 3 and a part of each of the driving ICs 5. The cover body 9 is made of heat-resistant synthetic resin. It is manufactured by molding with a metal mold, and the cover body 9 is formed in a form in which it is warped upwardly convex so that a central portion along the longitudinal direction is higher than both end portions. After the molding, the whole is bent while being heated, so that the central portion along the longitudinal direction is warped upwardly convex so that the central portion is higher than both end portions.

The lower surface of both ends in the longitudinal direction of the cover body 9 is detachably engaged with notch engaging portions 3a and 3b provided at both ends in the longitudinal direction of the circuit board 3. Stop pieces 9a, 9b are integrally provided, and the locking pieces 9a, 9b are engaged with the notch engaging portions 3a, 3b of the circuit board 3, whereby the cover body 9 is formed. And is detachably attached to the circuit board 3.

In this case, the dimension L1 between the locking pieces 9a and 9b in the cover body 9 is determined by the circuit board 3
By slightly reducing the dimension L0 between the notch engaging portions 3a and 3b in the above, the cover body 9 is straightened so as to reduce or eliminate upward convex warpage deformation against its elasticity. Meanwhile, the both locking pieces 9a and 9b are configured to engage with both the notch engaging portions 3a and 3b of the circuit board 3.

When the cover 9 is attached to the circuit board 3, the lower surface of the cover 9 fits into the through hole 3 c formed in the circuit board 3 and contacts the upper surface of the heat sink 1. One or two protruding pieces 9c are provided integrally with each other. Furthermore, the lower surface of the cover body 9
One or two sub-engaging portions which are detachably engaged with the lower surface of the head substrate 2 when the cover body 9 is mounted on the circuit board 3 in the middle portion in the longitudinal direction. A piece 9d is provided integrally.

In this configuration, when the cover body 9 is mounted on the circuit board 3, first, as shown in FIG. By pressing the entire body 9 downward as shown by an arrow A in FIG. 4 while correcting the upward deformation of the body 9 against its elasticity so as to reduce or eliminate the upward deformation, the two members can be engaged with each other. The stop pieces 9a and 9b are engaged with the notch engaging portions 3a and 3b of the circuit board 3.

With such mounting, the cover 9
But, as in the prior art, it can be eliminated to become a form that it warped downward convex shape so say that higher than the central portion in the longitudinal direction both end portions of the along, the cover body 9 The upper surface is in a form substantially parallel to the circuit board 3 when mounted on the circuit board 3 or in a form in which the central portion in the longitudinal direction of the cover body 9 is higher than both end portions. The head substrate 2
The printing paper and / or the transfer ribbon paper pressed by the platen roller against the portion of the heating resistor 4 in
The cover body 9 can be made to contact substantially equally over the entire length in the longitudinal direction, or the cover body 9 can be brought into strong contact with a central portion of the cover body 9 in the longitudinal direction.

Further, when the cover 9 is mounted, a projection 9 integrally provided on the lower surface of the cover 9 is provided.
By fitting c into the through hole 3c formed in the circuit board 3 and abutting on the upper surface of the heat sink 1, the cover body 9 is surely prevented from moving in a direction perpendicular to the longitudinal direction. In addition to the above, by increasing or decreasing the height of the projecting piece 9c, the cover 9 may be made substantially parallel to the circuit board 3 with the cover 9 attached, or the cover 9 In the case where the central portion in the longitudinal direction is higher than both end portions, the height of the central portion can be arbitrarily set when the central portion in the longitudinal direction is higher than both end portions. It can be set arbitrarily.

Further, in a state where the cover 9 is mounted, the sub-engaging piece 9d integrally provided on the lower surface of the cover 9 is engaged with the lower surface of the head substrate 2 to thereby form the cover 9 Can be prevented from rising.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a cross-sectional view showing a state where a cover body is attached to the thermal print head.

FIG. 5 is a perspective view of an assembled state showing the embodiment of the present invention.

FIG. 6 is a sectional view taken along line VI-VI of FIG.

FIG. 7 is a sectional view taken along line VII-VII of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat sink 2 Head board 3 Circuit board 3a, 3b Engagement part 3c Through hole 4 Heating resistor 5 Driving IC 6 Resin coat 7 Connector 8 Lead terminal 9 Cover body 9a, 9b Engagement piece 9c Projection piece 9d Sub-engagement Piece

Claims (4)

(57) [Claims] 1. A head substrate having a heating resistor provided on an upper surface thereof, and a circuit board having a connector for connection to the outside are provided on an upper surface of a metal heat radiating plate in parallel with each other. On the side, in a thermal print head comprising a synthetic resin cover body attached, the cover body, in a state before mounting to a circuit board,
To form the warp in an upward convex shape as part of the central along its longitudinal direction is higher than the portion at both ends, this
The circuit board is provided on the lower surface of both ends in the longitudinal direction of the cover body.
Attach to the engaging portions provided at both ends in the longitudinal direction of the plate.
A cover device for a thermal print head, wherein an engagement piece adapted to be removably engaged is provided . 2. The cover according to claim 1, wherein
To both engagement portions of the circuit board on both engagement pieces of the body
Engagement with the cover body reduces warpage of the cover body.
A cover device for a thermal print head, wherein the cover device is engaged after straightening . 3. The cover according to claim 1, wherein the cover is provided with a projection that fits into a through hole formed in the circuit board and contacts the upper surface of the heat sink. Cover device in a thermal printhead. 4. The method according to claim 1, wherein :
A cover device for a thermal print head , wherein a sub-engaging piece that engages with a lower surface of a head substrate is provided at a middle portion of the cover body in a longitudinal direction . "