JPH0746538Y2 - Thermal head unit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermal head unit for recording a character or an image by heating a heat-sensitive recording paper, a heat-meltable carbon film or the like.

[Prior Art] As a recording method used in a recording unit of a facsimile machine or various printers, there is a thermal recording method in which a thermal recording paper, a heat-meltable carbon film or the like is heated by a thermal head to record characters or 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, a flexible substrate 3 and a head cover 4 are arranged in this order in layers.
Each part is fixed by screwing the head cover 4 to the heat dissipation base 1.

The rear portion of the flexible substrate 3 is coupled to the connector 6 attached to the end portion of the signal cable 5, and the front portion of the flexible substrate 3 contacts the thermal head substrate 2 to connect the signal cable 5 and the thermal head substrate 2. Are connected.

When fixing such a thermal head unit to the device, the L-shaped metal fittings 7 and 8 are screwed to both sides of the heat dissipation base 1, and the device frame is inserted into the holes 7a and 8a formed in the L-shaped metal fittings 7 and 8. The pins 9 and 10 formed on the side were fitted to each other to rotatably support the thermal head unit. Further, L-shaped metal fittings 11 and 12 having guide grooves 11a and 12b are attached to the side of the heat generating portion 2a of the heat dissipation base 1 so as to engage with pins 13 and 14 formed on the apparatus frame side. Was there.

Although not shown, the recording paper is conveyed on the heat generating portion 2a by the platen roller. 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, because of this pressure contact, the heat dissipation base 1 has pins 9 and 10
At the time of rotation starting from, the L-shaped metal fitting 11 and the pin 13, and the L-shaped metal fittings 12 and 14 are engaged with each other, so that the deviation of the recording position can be prevented.

By the way, conventionally, as the material of the heat dissipation base 1, aluminum, iron, stainless steel, etc. have been used, and they have generally been formed by extrusion. Since it is not possible to mold the fine parts with this extrusion process, the L-shaped metal fittings 7,8,11,12
After the heat dissipation base 1 was molded, it had to be fixed by screwing or the like.

For this reason, the conventional thermal head unit has a problem in that it has a large number of parts and requires a large number of assembling steps.

Further, in order to give the heat dissipation base 1 sufficient mechanical strength and heat dissipation effect, for example, a thickness of about 6 mm is required, and the weight of the heat dissipation base 1 itself becomes 400 to 800 g. There was a problem that the thermal head unit was large and heavy.

[Purpose] In view of the above problems, an object of the present invention is to provide a thermal head unit that has a small number of parts, a reduced number of assembly steps, and is small and lightweight.

[Structure] Therefore, in the present invention, while the recording paper is pressed against the platen roller held on the apparatus frame side, images are sequentially recorded along the recording lines on the recording paper conveyed as the platen roller rotates. A thermal head substrate, a heat radiating base plate for mounting the thermal head substrate, and a first supporting member for the heat radiating plate so that the heat radiating base plate swings toward and away from the platen roller. The position of the heat radiating base plate is fixed by engaging the heat radiating base plate mounting portion for swingably mounting to the device frame side with the second supporting member provided on the device frame side with respect to the platen roller. The guide groove for preventing the positional displacement of the thermal head substrate is provided to face the extension line of the recording line of the mounted thermal head substrate. Formed on the heat dissipation base plate, which is necessary for positioning when the thermal head substrate is arranged at a predetermined position on the heat dissipation base plate, and two cut and raised portions each having the guide groove formed therein. The heat dissipation base plate mounting portion, the cut-and-raised parts, and the protrusions are integrally formed with the heat dissipation base plate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of a thermal head unit according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view thereof. In the figure, on one side of the heat dissipation base 15, a heat dissipation base plate mounting portion 15b having a hole 15a formed therein and a cut-and-raised portion 15d having a guide groove 15c are formed. Also, on the other side,
Heat dissipation base plate mounting part 15f with hole 15e and guide groove
A cut-and-raised portion 15h formed with 15g is formed.

Pins 15i to 1 are attached to the top of the heat dissipation base 15
5l is planted and screw holes 15m to 15p are provided on the rear end side in the lateral direction.
Is perforated.

As shown in FIG. 3, the back surface of the heat dissipation base 15 has a so-called rib structure in which a lattice-shaped thick portion 15q and a rectangular-shaped portion 15r thinly formed are formed. ing. Then, for example, the thickness d ₁ of the thick part 15q is 3
The thickness d ₂ of the thin portion 15r is about 1.0 to 1.5 mm.

A magnesium alloy is used as a material for the heat dissipation base 15, and is processed into such a shape by die casting. Magnesium alloy is lightweight, highly rigid and highly practical, for example, having a specific gravity of 1.74, a specific strength (tensile strength / specific gravity) of 17.0, and a specific proof stress (proof strength / specific gravity) of 11.8.

The thermal head substrate 2 is arranged on the upper surface of the heat dissipation base 15. A heat generating portion 2a is formed on the side of the upper surface of the thermal head substrate 2 in the lateral direction, and a terminal portion 2b for signal input / output is formed on the side of the rear end in the lateral direction. The thermal head substrate 2 also contains an integrated circuit for controlling the heat generating portion 2a.

The thermal head substrate 2 is arranged at a fixed position with its short-side tip portion side being locked by the pins 15j, 15k and its longitudinal side portions being locked by the pins 15i, 15l. That is,
The final positioning and fixing of the thermal head substrate 2 of the heat dissipation base 15 is performed by tightening the mounting screws 16a to 16d, but the positioning before fixing is performed by the pins 15i to 15l. Also, although four pins necessary for positioning are shown in the figure, if there are at least three pins by combining pins 15i, 15j, 15k or pins 15j, 15k, 15l, etc., the thermal head substrate 2 The positioning can be performed with high accuracy and easily.

The flexible substrate 3 is provided on the thermal head substrate 2.
Is provided. The flexible substrate 3 is a flexible printed wiring board, and a terminal portion 3a corresponding to the terminal portion 2b is formed on the lower surface of the front end portion of the flexible printed circuit board, and a flexible printed circuit board is formed on the rear end portion of the flexible substrate 3. A terminal portion 3b connected to the terminal portion 3a in a pattern is formed. Further, holes 3c to 3f through which screws are passed are formed at the central positions of both of them.

The flexible substrate 3 is arranged on the thermal head substrate 2 so that the terminal portion 3a and the terminal portion 2b are in contact with each other.

A head cover 4 is arranged on the flexible substrate 3. The head cover 4 has a hole 4a through which a screw passes.
4d are formed at positions corresponding to the holes 3c to 3f.
The head cover 4 uses these holes 4a to 4d and 3c to 3f and is fixed on the heat dissipation base 15 by mounting screws 16a to 16d. As a result, both the thermal head substrate 2 and the flexible substrate 3 are fixed.

A pressure contact rubber 4e is fixed to the lower surface of the head cover 4. The pressure contact rubber 4e presses the terminal portion 3a from above, so that the terminal portion 3a and the terminal portion 2b are surely brought into contact with each other.

The thermal head unit of the present embodiment has the above configuration,
It is attached to a recording unit such as a facsimile machine. In that case, the heat dissipation base 15 is mounted on the holes 15a and 15e of the heat dissipation base plate mounting portions 15b and 15f by fitting support members such as pins 9 and 10 formed on the device frame side (not shown), respectively, to the device. It is rotatably supported on the frame side.

Further, pins 13 and 14 formed on the device frame side are attached to the guide grooves 15c and 15g of the cut-and-raised portions 15d and 15h so as to engage with each other.

A connector 6 connected to a control device (not shown) is coupled to the terminal portion 3b of the flexible board 3.

With this configuration, although not shown, the recording paper is conveyed on the heat generating portion 2a by the platen roller. At this time, the heat generating part 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 dissipating base 15 rotates with the pins 9 and 10 as starting points, the guide groove 15c and the pin 13 are engaged with each other, and the guide groove 15g and the pin 14 are engaged with each other. Will be done.

Further, the heat generated from the heat generating portion 2a of the thermal head substrate 2 raises the temperature of each portion such as the thermal head substrate 2 itself, the heat radiating base 15 and the head cover 4. However, the heat dissipation base 15 has high thermal conductivity, and the back surface has a rib structure as shown in FIG. 3, and has a large surface area. As a result, a sufficient heat dissipation effect is obtained, and an abnormal temperature rise in each part is prevented.

By the way, when the recording sheet is pressed against the heat generating portion 2a and conveyed, noise such as vibration and stick noise is generated.
This vibration or noise is transmitted to the device frame side via the heat dissipation base 15 and becomes the time of operation emitted from the device. Further, the integrated circuit built in the thermal head substrate 2 is apt to malfunction due to the influence of electric fields and magnetic fields from other circuits in the apparatus, motors, etc., that is, noise.

However, the heat dissipation base 15 is made of a magnesium alloy having a close-packed hexagonal crystal structure. Such a material has a good vibration damping characteristic and a high shielding effect against an electric field and a magnetic field. Therefore, the vibrations and noise are difficult to be transmitted to the device frame side, and the noise generated from the device is reduced. Further, the heat dissipation base 15 is the thermal head substrate 2.
Although it has a function of shielding an electric field and a magnetic field, since the magnesium alloy has a high effect, malfunction due to noise can be prevented.

As described above, according to the present invention, the heat dissipating base 15 includes the heat dissipating base plate mounting portions 15b and 15f for rotatably supporting the thermal head unit and the cut-and-raised parts for preventing the recording position from being displaced during the rotation. The parts 15d and 15h are integrally formed by die casting. As a result, the number of parts is small and the number of assembling steps can be reduced as compared with the conventional case in which each part is composed of individual parts.

In addition, the back surface of the heat dissipation base 15 is a grid-like thick part
A so-called rib structure is formed by forming 15g and a thin portion 15r. As a result, the mechanical strength can be increased with a small amount of material, and the thermal head unit can be made compact and lightweight.

In addition, the manufacturing cost will be reduced due to the reduction of the assembly man-hours and materials. Further, the rib structure as described above increases the surface area, so that the heat radiation effect is enhanced.

Furthermore, since a magnesium alloy having a high vibration damping characteristic and a high shielding effect is used as the material, generation of noise such as stick noise during recording operation is reduced.

In this embodiment, the material of the heat dissipation base 15 is the most practical magnesium alloy as a light alloy, but aluminum (specific gravity: 2.7, specific strength: 10.9, specific proof strength: 9.
4), steel (specific gravity: 7.87, specific strength: 8.0, specific proof stress: 5.5), stainless steel (specific strength: 15.2, specific proof strength: 13.3), etc. Naturally, the effect is obtained.

[Effect] As described above, according to the present invention, since the heat dissipation base plate mounting portion, the cut-and-raised portion, and the protrusions for positioning three points are integrally formed on the heat dissipation base plate, The accuracy of the mounting position of the thermal head substrate with respect to the platen roller is improved, the positional deviation at the time of recording is eliminated, a good recorded image can be obtained, and the positional deviation due to aging can be prevented. Further, the thermal head substrate can be easily and accurately arranged at a predetermined position on the heat dissipation base plate, and the accuracy of the mounting position of the thermal head substrate with respect to the platen roller is also improved in this respect. Furthermore, there is an advantage that the number of parts and the number of assembling steps are reduced to enhance the economic effect.

[Brief description of 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 exploded perspective view thereof, FIG. 3 is a perspective view showing a back surface of a heat dissipation base, and FIG. 4 is a conventional thermal head. It is an appearance perspective view showing an example of a unit. 1,15 …… Heat dissipation base, 2 …… Thermal head substrate, 2a…
… Heating part, 2b, 3a, 3b …… Terminal part, 3 …… Flexible substrate, 4 …… Head cover, 5 …… Signal cable, 6 ……
Connector, 9,10,13,14 …… Pin, 15a, 15e …… Hole, 15b, 1
5f: Heat dissipation base plate mounting part, 15d, 15h: Cut and raised part, 15c, 1
5g …… Guide groove.

Claims (1)

[Scope of utility model registration request] 1. A thermal head substrate for sequentially recording an image along a recording line on a recording paper conveyed with the rotation of the platen roller while pressing the recording paper against a platen roller held on the apparatus frame side. A heat dissipating base plate for mounting the thermal head substrate, and the heat dissipating plate via a first supporting member so that the heat dissipating base plate swings in a direction of approaching and separating from the platen roller. Side of the thermal head substrate relative to the platen roller by fixing the position of the heat radiating base plate by engaging the heat radiating base plate mounting portion for swingably mounting to the side and the second supporting member provided on the apparatus frame side. Of the guide groove for preventing the positional deviation of the guide line and the guide groove provided on the extended line of the recording line of the mounted thermal head substrate. Two cut-and-raised parts each having a groove, and at least 3 formed on the heat dissipation base plate necessary for positioning when disposing the thermal head substrate at a predetermined position on the heat dissipation base plate. A thermal head unit, comprising: a point projection portion; and the heat dissipation base plate mounting portion, the cut-and-raised portion, and the projection portion formed integrally with the heat dissipation base plate.