JP2762045B2 - Thermal head unit - 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 head unit in which a thermal head substrate having a heating section is fixed on a heat radiating base.

[0002]

2. Description of the Related Art As a recording system in a recording unit of a facsimile apparatus or various printers, there is a thermal recording system in which a thermal recording paper, a heat-fusible carbon film, or the like is heated by a thermal head to record characters and images.

FIG. 4 shows a conventional example of a thermal head unit used in such an apparatus. A thermal head substrate 2 having a heat generating portion 2a is provided on a heat radiating base 1.
And the flexible printed circuit board 3 and the head cover 4 are disposed one on top of the other, and the head cover 4 is screwed to the heat radiation base 1 to fix each part.

The rear part of the flexible printed board 3
The signal cable 5 is connected to a connector 6 attached to an end of the signal cable 5, and a front portion of the flexible printed circuit board 3 contacts the thermal head substrate 2, and the signal cable 5 and the thermal head substrate 2 are connected.

When such a thermal head unit is fixed to an apparatus, L-shaped metal fittings 7 are provided on both sides of the heat radiation base 1.
8 is fixed by screws or the like, holes 7a, 8b are formed in the L-shaped metal fittings 7, 8, and pins 9, 10 formed on the apparatus frame side are fitted into the holes 7a, 8b. The head unit was rotatably supported.

On the side of the heat generating portion 2a of the heat radiating base 1, L-shaped fittings 11 and 12 are fixed, and notches 11a and 12a are formed in the L-shaped fittings 11 and 12, respectively. The shaft 12a of the platen roller 13 for conveying the recording paper is engaged with the shaft 12a.

On the other hand, when recording an image, a recording paper (not shown) is conveyed by the platen roller 13 over the heat generating portion 2a. At this time, the heat generating portion 2a is pressed against the recording paper, whereby the recording paper is heated and an image is recorded. Also, when the heat radiation base 1 rotates starting from the pins 9 and 10 due to this pressure contact, the L-shaped fittings 11 and 12 and the shaft 14 are engaged with each other so that the recording position is prevented from being shifted. Become.

[0008]

Heretofore, conventionally, aluminum, iron, stainless steel and the like have been used as a material of the heat radiation base 1 and generally formed by extrusion. In this extrusion process, since a fine portion cannot be formed, the L-shaped metal fittings 7, 8, 11, and 12 had to be fixed by screws or the like after forming the heat radiation base 1.

For this reason, the conventional thermal head unit has a problem that the number of parts is large and the number of assembly steps is increased.

In order to provide the heat radiation base 1 with sufficient mechanical strength and heat radiation effect, for example, a thickness of 6 mm is required.
mm, the weight of the radiation base 1 itself is 40
There was a problem that the thermal head unit was large and heavy, weighing 0 to 800 grams.

On the other hand, Japanese Patent Application Laid-Open No. 62-284754 (hereinafter referred to as "conventional example") has proposed a method for making the thermal head thinner and for simplifying the position adjustment between the heat generating portion and the platen roller.

In general, it is desirable that the heat-generating portion is pressed against the platen roller to some extent evenly from the relation with the recording density and the like, but a thin metal plate is used as the base member as in the above-mentioned conventional example. In some cases, its strength is weakened,
The metal substrate is freely deformed by the pressure contact with the platen roller, and it is difficult to suppress the contact pressure between the platen roller and the heat generating portion within a predetermined range.

In the above conventional example, a U-shaped bent portion is formed on the metal substrate. Due to the presence of the bent portion, the metal substrate near the bent portion has a certain degree of flatness with respect to the longitudinal direction. Or, it seems that the strength has been improved.

However, in the above-mentioned conventional example, since the heat-generating portion and the U-shaped bent portion are formed at positions separated from each other on the metal substrate, the vicinity of the heat-generating portion which is essential for flatness or strength is required. The metal substrate is still freely deformed, and as a result, it is difficult to keep the contact pressure between the platen roller and the heat generating portion within a predetermined range. Further, since the heat generating portion and the U-shaped bent portion are formed at positions separated from each other, the above-described deformation may cause a positional relationship between the platen roller and the heat generating portion to be shifted.

The present invention has been made in view of such circumstances, and has as its object to provide a small and lightweight thermal head unit which can reduce the number of parts and the number of assembling steps. In addition, by using a sheet-shaped thin heat dissipation base, the flatness or strength near the heat generating part is secured,
It is another object of the present invention to provide a thermal head capable of accurately positioning a platen roller and a heating section.

[0016]

According to the present invention, there is provided a thermal head unit in which a thermal head substrate having a heat generating portion is fixed on a heat radiating base, and a bent portion formed by bending one long side of the heat radiating base. And the long side on which the bent portion is formed on both short sides of the heat radiating base, and formed by processing, and engages with the engaged member to position the heat generating portion and the platen roller. The thermal head substrate is fixed to the long side where the bent portion is formed.

Further, the positioning means is formed by bending both short sides of the heat radiation base, and is engaged with a shaft of the platen roller.

Further, a projection for engaging with the thermal head substrate and guiding the fixed position is formed integrally with the heat radiating base.

[0019]

Therefore, since the heat radiation base is bent and the support mechanism for the apparatus frame and the displacement prevention mechanism are integrally formed, the number of parts can be reduced, and the size and weight can be reduced. Further, the flatness or strength in the vicinity of the heat generating portion can be ensured, and accurate positioning between the platen roller and the heat generating portion can be performed.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a perspective view of a thermal head unit according to one embodiment of the present invention.

In FIG. 1, the heat radiation base 15 is formed of a sheet metal having a thickness of about 0.8 to 1.2 mm, and is formed on one side of the long side to increase strength against bending in the long side direction. A bent portion 15a is formed by bending an edge portion, and a step 15b is formed by bending a central portion.

A cut-and-raised portion 15d formed with a hole 15c and a cut-and-raised portion 15f formed with a cut-out portion 15e are formed at one short edge of the short side, and the other edge is formed at the other edge. Is hole 1
A cut-and-raised portion 15h in which 5g is drilled and a cut-and-raised portion 15j in which a cutout 15i is formed are formed.

A step 15b is formed on the heat radiating base 15, and the thermal head substrate 2 is provided with pins 15k to 15n mounted on the heat radiating base 15 at a high position on the upper surface thereof.
And fixed by bonding or the like.
The flexible printed circuit board 3 is similarly fixed to a lower position on the upper surface via a bake plate 16 for insulation. In this embodiment, the thickness of the thermal head substrate 2 is about 0.6 mm, the total thickness of the flexible printed circuit board 3 and the bake plate 16 is about 1 mm, and the step 15b is about 0.4 mm. Thereby, the thermal head substrate 2
And the height of the upper surface of the flexible printed circuit board 3 is equal.

On one side of the upper surface of the thermal head substrate 2, a heating portion 2a corresponding to an image recording line is formed, and at the other end, a terminal portion 2b for signal input is formed. . Although not shown, the thermal head substrate 2 contains an integrated circuit for controlling the heating section 2a.

A terminal 3a for connecting to the terminal 2b is formed at one end of the flexible printed circuit board 3, and a terminal 3b for connecting to the connector 6 is formed at the other end. . The terminal portion 3a and the terminal portion 2b are located at the same height due to the step 15b, and both are connected by soldering.

The thermal head unit of this embodiment is mounted on a recording unit such as a facsimile machine with the above configuration. In that case, the heat radiation base 15 is provided with the cut and raised portions 15d,
By fitting pins 9 and 10 formed on the apparatus frame (not shown) into the holes 15c and 15g of 15h, the apparatus is rotatably supported on the apparatus frame. In addition, cut and raised part 1
The shafts 14 of the platen roller 13 are attached to the notches 15e and 15i of 5f and 15j, respectively. Further, a connector 6 connected to a control device (not shown) is connected to the terminal 3b of the flexible printed circuit board 3.

In this configuration, a recording sheet (not shown) is conveyed by the platen roller 13 over the heating section 2a. At this time, the heat generating portion 2a is pressed against the recording paper, whereby the recording paper is heated and an image is recorded.

In this recording operation, when the heat radiating base 15 rotates about the pins 9 and 10, the notch 15
e, 15i and the platen roller 14 are engaged with each other, thereby preventing the recording position from shifting.

The temperature of the thermal head substrate 2 itself rises due to the heat generated by the heat generating portion 2a. However, since the heat is radiated from the heat radiation base 15, an abnormal temperature rise is prevented.

As described above, in this embodiment, the heat radiation base 15 is formed of sheet metal, and the terminal 2b of the thermal head substrate 2 and the terminal 3b of the flexible printed board 3 are connected by soldering. Heat dissipation base 1
5 fixed to the upper surface.

As a result, the weight of the entire thermal unit can be reduced without reducing the strength as compared with the conventional thermal unit, and the thickness and thickness are reduced because the head cover 4 as shown in FIG. 4 is not used. Is formed. The inventors made a trial production of a thermal unit for A4 size recording, and as a result, have confirmed that the thermal unit can be formed with a weight of about 100 g and the depth can be reduced by about 10 to 15 mm as compared with the conventional case. .

The radiation base 15 has a bent portion 15a.
And the step 15b, sufficient strength can be obtained against bending in the long side direction.

Further, the cut-and-raised portions 15d and 15h for supporting the thermal head unit and the cut-and-raised portions 15f and 15j for preventing the recording position from being displaced are provided on the heat radiation base 15.
It is integrated with. In the case of sheet metal processing, such a relatively complicated shape can be easily processed with high accuracy. As a result, the number of parts is reduced, the material and the number of assembly steps are reduced, and as a result, the manufacturing cost is reduced as compared with the related art in which each part is configured by individual parts.

Further, since the heat radiation base 15 is made of metal and has a shielding effect against static electricity and the like, an effect of preventing noise mixed into the integrated circuit in the thermal head substrate 2 can be obtained.

FIG. 2 is an external perspective view of a thermal head unit according to another embodiment of the present invention, and FIG. 3 is an exploded perspective view thereof. In the figure, the same reference numerals as those in FIG. 1 indicate the same parts or portions, and a head cover 4 is newly provided. In addition, the step 15b of the heat radiation base 15 formed in FIG. 1 is eliminated.

The head cover 4 fixes the thermal head substrate 2 and the flexible printed circuit board 3 on the heat radiation base 15. The head cover 4 has screw holes 4a to 4d for passing screws (not shown). As well as
A press contact rubber 4e is fixed along the lower surface. In the same manner as described above, screw holes 3c to 3f are formed in the flexible printed circuit board 3, and screw holes 15o to 15r for fixing the screws are formed in the heat radiation base 15.

The terminal 3a of the flexible printed circuit board 3 is formed on the lower surface. And the radiation base 1
First, the thermal head substrate 2 is disposed on the upper surface of
Next, the flexible printed circuit board 3 is arranged so that the terminal portion 3a contacts the upper surface of the heat generating portion 2a.
Further, the head cover 4 is disposed so as to press the contact surface from the pressure contact rubber 4e, and these are fixed to the heat radiation base 15 by screws.

As described above, in this embodiment, the thermal head substrate 2 and the flexible printed circuit board 3 are fixed on the heat radiating base 15 by the head cover 4. Can be formed in the same manner as in the above embodiment, so that the number of parts and the number of assembling steps can be reduced, and a small and lightweight thermal head unit can be obtained.

[0040]

As described above, according to the present invention,
Since the heat radiation base is bent to integrally form the support mechanism for the apparatus frame and the displacement prevention mechanism, the number of parts can be reduced, and the size and weight can be reduced. In addition, the flatness or strength in the vicinity of the heat generating portion is ensured, and the effect that the platen roller and the heat generating portion can be accurately positioned can be obtained.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a thermal head unit according to an embodiment of the present invention.

FIG. 2 is an external perspective view of a thermal head unit according to another embodiment of the present invention.

FIG. 3 is an exploded perspective view of the thermal head unit.

FIG. 4 is an external perspective view showing a conventional example of a thermal head unit.

[Explanation of symbols]

 1, 15 Heat radiation base 2 Thermal head substrate 2a Heating portion 2b, 3a, 3b Terminal portion 3 Flexible printed circuit board 4 Head cover 4e Press-contact rubber 6 Connector 7, 8, 11, 12 L-shaped metal fittings 7a, 8b, 15c, 15g Hole 9, 10, 15k, 15l, 15m, 15n Pin 11a, 12a, 15e, 15i Notch 13 Platen roller 14 Shaft 15a Bend 15b Step 15d, 15f, 15h, 15j Cut-up

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) B41J 2/32 B41J 2/335 B41J 25/34

Claims (3)

(57) [Claims] 1. A thermal head unit having a thermal head substrate having a heat generating portion fixed on a heat radiating base, wherein: a bent portion formed by bending one long side of the heat radiating base; Positioning means that is formed by processing the long side on which the bent portion is formed on both side sides and engages with the engaged member to position the heat generating portion and the platen roller. A thermal head unit, wherein the thermal head substrate is fixed to a long side on which the bent portion is formed. 2. The thermal head unit according to claim 1, wherein said positioning means is formed by bending both short sides of said heat radiation base and engages with a shaft of said platen roller. 3. The thermal head unit according to claim 1, wherein a projection for engaging with the thermal head substrate and guiding a fixed position is formed integrally with the heat radiation base.