JPH0646681Y2 - Thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to the structure of a thermal head used in a printer device such as a facsimile or a word processor.

[Conventional technology]

Conventionally, a thermal head 20 used for a printer or the like in a facsimile or a word processor is described in, for example, Japanese Utility Model Laid-Open No. 63-92751, and is constructed as shown in FIG.

That is, on the upper surface of the heat dissipation plate 21 made of aluminum or the like, the head substrate 22 made of ceramic or the like and the connection circuit board 23 having the mounting substrate 24 are arranged side by side, and on the upper surface of the head substrate 22,
A heating resistor 25 is formed, and this heating resistor 25 is connected to a drive circuit 26 such as a highly integrated driver circuit including a chip carrier IC, a shift register, etc., which is also provided on the head substrate 22.

Then, as a means for electrically connecting the connection circuit board 23 with the connector 27 to the external circuit for driving the thermal head 20 and the connection terminal electrode 28 in the drive circuit 26, a connection circuit board is provided. A cover body configured to cover the drive circuit 26 on the upper surface of the connection circuit board 23 while overlapping the edge portion 23a of 23 with the connection terminal electrode 28.
29 is arranged such that the lower surface 29a of the cover body 29 is in close contact with the connection circuit board 23, and the cover body 29 is connected to the connection circuit board.
The heat sink 21 with the screw 33 that penetrates the place of the close contact with 23
Screwed to the bottom of the cover 29 to connect the circuit board
In a portion where 23 and the connection terminal electrode 28 overlap, a fitting insertion groove 30 extending along the edge portion 23a of the connection circuit board 23 is formed,
The elastic cord body 31 fitted in the insertion groove 30 is pressed against the upper surface of the connection circuit board 23 by screwing the cover body 33 to the heat dissipation plate 21, and the elastic force of the elastic cord body 31 causes the connection. Circuit board
The edge portion 23a of 23 is connected to the connection terminal electrode 2 on the head substrate 22.
I am trying to connect to 8.

Reference numeral 32 is a platen roller for pressing a thermal paper (not shown) against the heating resistor 25.

[Problems to be solved by the device]

However, this conventional thermal head has the following problems because it has a configuration in which the fitting groove 30 having a square or semicircular cross section is simply formed on the lower surface of the cover body 29.

． That is, first, since the cross-sectional shape of the fitting insertion groove 30 is only square or semicircular, when the cover body 29 is attached to the heat dissipation plate 21, the elastic string body 31 is inserted into the fitting insertion groove when the cover body 29 is turned downward. You're out of thirty, so
Since the cover body 29 must be assembled while holding the elastic cord body 31 so as not to come out from the inside of the fitting insertion groove 30 provided on the lower surface of the cover body 29, it takes much labor for assembling the thermal head, which increases the cost. Invite.

In this case, in order to prevent the elastic cord body 31 from coming off from the inside of the fitting insertion groove 30, as shown in FIG.
The cross-sectional shape of the elastic cord 31 is substantially square, and the width dimension (a) and the depth dimension (a) of the elastic cord 31 are slightly smaller than the diameter (d) of the elastic cord 31 having a circular cross section. It is conceivable that it may be forced into the fitting groove 30 by force against its elastic deformation.
Since the diameter (d) of the elastic cord body 31 has a considerably large variation, it is necessary to completely eliminate the elastic cord body 31 coming out of the fitting groove 30 as described above. You cannot do it.

． In addition, as described in Japanese Utility Model Laid-Open No. 60-141256, the lower surface of the cover body 29 is formed without leaving a gap between the portion of the cover body through which the screw penetrates and the connection circuit board. The part of the heat sink 21 through which the fastening screw 33 penetrates is closely attached to the upper surface of the connection circuit board 23 because the screw 33
In the state in which the cover is completely screwed in, the lower surface of the cover body 29 is brought into close contact with the connecting circuit board 23 to prevent the circuit from being broken due to an excessive pressing force by the elastic cord body 23. This is to prevent the cover body 29 from coming into contact with the platen roller 32 by allowing the body 29 to be held in a predetermined posture, but conventionally, this object could not be sufficiently achieved.

That is, when the cover body 29 is fastened to the heat dissipation plate 21 with the screw 33, first, the elastic cord body fitted in the fitting insertion groove 30.
As shown in FIG. 8, 31 contacts the upper surface of the edge portion 23a of the connecting circuit board 23, and then, from this state, the elastic cord body 31 is deformed against its elasticity. In that case, in the elastic cord body 31, a portion of the elastic cord body 31 that is in contact with the edge portion 23a of the connecting circuit board 23 is the ninth portion.
As indicated by the reference numerals 31a and 31b in the figure, it is deformed so as to protrude from the fitting insertion groove 30 toward both sides thereof.

In some cases, one of the protrusion deforming portions 31a and 31b may be sandwiched between the protrusion 29a of the cover body 29 and the connecting circuit board 23, and then the protrusion deforming one of the protrusions may be deformed. Since the cover body 29 is lifted by the amount of sandwiching 31a, the cover body 29 is
However, not only will it come into contact with the platen roller 32, but also the connection circuit board 29 will be excessively pressed too much, causing a disconnection in the printed wiring at the edge 23a of the connection circuit board 23. There was a risk that

． Further, one of the protruding deformation portions 31 in the elastic cord pulling
When a is not sandwiched between the lower surface 29a of the cover body 29 and the connection circuit board 23, the lower surface 29a of the cover body 29 is
However, since it comes into direct contact with the edge portion 23a of the connection circuit board 23 and strongly presses the edge portion 23a against the edge corner portion of the head substrate 21, the connection circuit board 23 There is also a possibility that the printed wiring in the above may be broken at the edge portion of the head substrate 21.

The present invention aims to provide a thermal head that solves these problems.

[Means for Solving the Problems]

In order to achieve this technical problem, the present invention forms a heat generating resistor 4 and a drive circuit 5 for the heat generating resistor 4 on a head substrate 3 mounted on the upper surface of a heat dissipation plate 2, and also connects the heat generating resistor 4 to the drive circuit 5. Connection terminal electrode 9 is formed, and a circuit board 6 for connection to an external circuit is provided on a portion of the upper surface of the heat dissipation plate 2 opposite to the heating resistor 4 with the drive circuit 5 interposed therebetween. The connection circuit board 6 is mounted so that an edge portion of the connection circuit board 6 is superposed on the connection terminal electrode 9 of the head substrate 3, and further, the drive circuit 5 is configured to be covered on the upper surface of the connection circuit board 6. The cover body 11 is arranged such that the lower surface 11a of the cover body 11 is in close contact with the connecting circuit board 6 over an appropriate range, and the cover body 11 is
The cover body 11 is screwed to the heat dissipation plate 2 with a screw 15 penetrating a portion of the cover body 11 that is closely attached to the connection circuit board 6, and is connected to the connection circuit board 6 on the lower surface 11a of the cover body 11. At the portion corresponding to the overlapping portion with the terminal electrode 9,
A fitting section groove 13 is provided, and the connecting circuit board 6 is pressed against the connecting terminal electrode 9 by screwing the cover body 11 to the heat dissipation plate 2 in the fitting section groove 13. Elastic cord 10
In the thermal head 1 in which the above is fitted, a gap of an appropriate size b is formed between the connection circuit board 6 and a portion of the lower surface 11a of the cover body 11 that overlaps with the head substrate 3 in plan view. Is formed on the raised bottom surface 11a ', and the fitting groove is formed on the raised bottom surface 11a'.
13 is a bottom surface of the cover body 11 where the fitting insertion groove 13 is raised.
The depth dimension f from the lower surface 11a of the cover body 11 in the fitting groove 13 is smaller than the diameter d1 of the elastic cord body 10 by being formed so as to be appropriately separated from the stepped portion 11a ″ with respect to a ′. The size of the cover member in the fitting groove 13
The depth from the raised bottom surface 11a ′ of 11 is the elastic string 10
Set to a size larger than the radius of the
The cross-section of the fitting insertion groove 13 has a lateral width c at the entrance that is smaller than the diameter d1 of the elastic cord body 13, and a lateral width e at the back of the entrance that is greater than the lateral width c at the entrance. The configuration is such that it is formed into a deeply spread shape.

[Function and effect of device]

With this configuration, the lateral width dimension of the inlet portion of the fitting insertion groove is smaller than the diameter of the elastic cord body, and the fitting insertion groove has a cross-sectional shape that widens inward, so that the bottom surface of the cover body is When the elastic cord is fitted into the fitting groove, when the elastic cord passes through the inlet of the fitting groove, once the elastic cord is closed against the elasticity, the elastic cord is inserted into the inlet. After passing, after this, it will be restored to the original diameter, therefore, even if there is a large variation in the diameter of the elastic cord body, it will not fall into the fitting insertion groove. Can be fitted.

Therefore, according to the present invention, the elastic cord body fitted in the fitting insertion groove of the cover body is kept fitted in the fitting insertion groove even if there is a large variation in the diameter dimension. Therefore, the number of steps required for assembling the thermal head can be reduced, and the cost can be reduced.

Also, the fitting groove formed on the raised bottom surface of the cover body is appropriately spaced from the stepped portion with respect to the raised bottom surface, so that when the cover body is fastened to the heat dissipation plate with a screw, an elastic cord is used. Even if the body is crushed and deformed and sticks out to both sides of the fitting insertion groove, both protruding and deforming portions of the elastic cord body from the fitting insertion groove are absorbed in the gap between the raised bottom surface of the cover body and the connection circuit board. Therefore, it is possible to reliably prevent the disconnection of the circuit due to the elastic string body pressing the connecting circuit board excessively, and to fasten the cover body to the heat dissipation plate in a state of being in close contact with the connecting circuit board. Therefore, it is possible to reliably prevent the problem that the cover body comes into contact with the platen roller.

Further, since at least a portion of the lower surface of the cover body that overlaps the head substrate in plan view is formed on the raised bottom surface, the lower surface of the cover body does not directly contact the connecting circuit board on the head substrate. Since it is not present, the disconnection of the circuit due to the connection circuit board being strongly pressed against the edge portion of the head board can be reliably prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings (FIGS. 1 to 4).

In this figure, reference numeral 1 indicates a line-type thermal head, which is provided with a heat dissipation plate 2 made of aluminum or the like having a large heat transfer coefficient. A head substrate 3 made of an electrical insulator is mounted, a heating resistor 4 is formed on the upper surface of the head substrate 3 in a straight line, and a drive circuit 5 which is a highly integrated circuit such as a chip carrier IC is provided. There is.

Reference numeral 6 represents the drive circuit 5 on the upper surface of the heat dissipation plate 2.
Is a circuit board for connection arranged at a site opposite to the heat generating resistor 4 with the heat generating resistor 4 interposed therebetween, and the circuit board 6 for connection is mounted on the upper surface of the heat dissipation plate 2 via a mounting substrate 8 made of an electric insulator. In addition, the connector 7 is provided so as to be connected to an external circuit. A circuit pattern is printed on the lower surface of the connecting circuit board 6, and the edge portion 6a at one end of the connecting circuit board 6 is appropriately spaced so as to extend rearward from the drive circuit 5 on the upper surface of the head substrate 3. After being superposed on the upper surfaces of the plurality of pattern-printed connection terminal electrodes 9, the superposed portions are pressed by an elastic cord body 10 for pressure welding, which will be described later.
And the drive circuit 5 on the head substrate 3 are electrically connected.

Reference numeral 11 denotes a cover body made of an appropriate material such as synthetic resin or FRP so as to cover the drive circuit 5 and the connection circuit board 6, and the cover body 11 has a lower surface 11a. Are arranged on the upper surface of the connecting circuit board 6 so as to be in close contact with each other over an appropriate range, and the cover body 11 is radiated to the heat radiating plate by a plurality of screws 15 penetrating the contact portion of the connecting circuit board 6. Conclude to 2.

The cover body 11 includes a connection circuit board 6 and a connector 7.
A recess 14 is provided to cover the connection solder with.

The bottom surface 11a of the cover body 11 has a raised bottom surface that is appropriately spaced from the upper surface of the connection circuit board 6 at a portion overlapping the head substrate 3 in a plan view.
11a 'is formed, and a fitting insertion groove 13 is formed in a portion of the raised bottom surface 11a' corresponding to the overlapping portion of the connection circuit board 6 and the connection terminal electrode 8, and the fitting insertion groove 13 is raised. Bottom 11
It is formed so as to be separated from the stepped portion 11a ″ of a ′ by an appropriate dimension L, and the fitting groove 13 is made of rubber or soft synthetic resin and has a diameter d1.
The elastic cord body 10 having a circular cross section is fitted.

In this case, the cover body in the fitting insertion groove 13
By making the depth dimension f of the 11 from the lower surface 11a, that is, the depth dimension f from the lower surface 11a of the cover body 11 to the bottom surface 13a of the fitting groove 13 smaller than the diameter d1 of the elastic cord body 10, The elastic cord body 10 is formed by fastening the cover body 11 to the heat sink 2.
Is elastically deformed, and further, the depth dimension (fb) from the raised bottom surface 11a 'in the fitting insertion groove 13 is set to the elastic cord 1
The dimension is set to be larger than the radius (d1 / 2) of 0, and the cross section of the fitting insertion groove 13 is such that the lateral width dimension c at the entrance of the fitting insertion groove 13 is larger than the diameter d1 of the elastic cord body 10. It is formed in a trapezoidal shape that is small and widens so that the lateral width dimension e of the bottom portion of the fitting insertion groove 13 is larger than the lateral width dimension c of the inlet portion.

Therefore, a pair of left and right holding projections 16 are formed in the opening of the fitting insertion groove 13 with respect to the lower surface of the cover body 11, and a pair of left and right engaging cavities 17 are formed in the bottom of the fitting insertion groove 13. It will be in the specified form.

The lower surface 11a of the cover body 11 in the fitting groove 13
The depth dimension f from is approximately 2 / of the diameter d1 of the elastic cord 10.
It is preferable to set it to about 3 to 3/5.

In this configuration, the fitting insertion groove 13 on the lower surface of the cover body 11
When the elastic cord 10 is fitted into the inside, the elastic cord 10
When passing through the portions of both holding projections 16 at the entrance of the fitting insertion groove 13, once passes through the holding projections 16 in a state where the diameter is narrowed against its elasticity, and after this, ,
The elastic cord 10 will be restored to its original diameter.
Even if there is a large variation in its diameter, the elastic insertion cord 13 does not come out of the insertion insertion groove 13 and a part of the elastic cord 13 covers the insertion insertion groove 13. It can be securely fitted in the state of protruding from the lower surface of the body 11.

Then, the elastic cord body 10 in which the cover body 11 is fitted in the fitting insertion groove 13 on the lower surface thereof is brought into contact with the overlapping portion of the edge portion 6a of the connection circuit board 6 and the connection terminal electrode 9. After mounting, the cover body 11 is fastened to the heat dissipation plate 2 with the screw 15 so that the edge portion of the connection circuit board 6 is secured.
6a is elastically pressed by the elastic cord body 10 against the connecting terminal electrodes 9 on the head substrate 3, so that the circuit substrate 6 is electrically connected to the head substrate 3. be able to.

At the time of fastening the cover body 11, the elastic cord body 10 has a fitting insertion groove 13 as shown in FIG.
Although it will be deformed so as to protrude from both sides of the elastic string body 10, both elastically deformable portions 10a and 10b protrude from the insertion groove 13 of the elastic cord body 10.
Is absorbed in the gap between the raised bottom surface 11a ′ of the cover body 11 and the connection circuit board 6, so that the cover 11 is
Under the state in which the lower surface is tightly attached to the connection circuit board 6 and is fastened to the head substrate 3, the elastic circuit string 10 presses the connection circuit board 6 against the connection terminal electrodes 9 with an appropriate pressing force. You will be able to do it.

Therefore, the cover body 11 can be surely prevented from coming into contact with the platen roller 32, and the circuit in the connection circuit board 6 and the connection terminal electrode 9 may be disconnected due to the excessive pressing force of the elastic cord body 10. It can be reliably prevented. Further, since the lower surface 11a of the cover body 11 does not directly contact the edge portion 6a of the connection circuit board 6, the circuit on the connection circuit board 6 is formed of the cover body 11 and the head board 3. It is also possible to reliably prevent the wire from being broken by being pinched by the edge portion.

The fitting groove 13 is not limited to the depth of the form in which the holding projections 16 and 16 are provided on both the left and right sides of the opening with respect to the lower surface of the cover body 11, and as shown in FIG. body
By providing the holding projection 18 only on one side of the opening with respect to the lower surface of 11, the lateral width c at the entrance is smaller than the diameter d ₁ of the elastic cord body 10 and at the back of the fitting groove 13 at the entrance. The lateral width dimension e may be formed to be wider than the lateral width dimension c of the inlet portion so as to be widened, and the projection portion 19 may be provided on the bottom surface 13a of the fitting insertion groove 13 (note that When the protrusion 19 is provided in this manner, the tip of the protrusion 19 becomes a substantial bottom surface of the fitting groove 13.).

[Brief description of drawings]

1 to 5 show an embodiment of the present invention, FIG. 1 is a plan view of a thermal head, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is an enlarged fitting groove. A sectional view, FIG. 4 is an explanatory view of a pressed state, FIG. 5 is an enlarged sectional view showing a second embodiment of a fitting groove, FIGS. 6 to 9 show a conventional example, and FIG. 6 is a thermal head. FIG. 7 is an enlarged sectional view showing a sectional shape of a conventional fitting insertion groove, and FIGS. 8 and 9 are enlarged views showing an operation of a conventional elastic cord body. 1 ... Thermal head, 2 ... Heat sink, 3 ... Head board, 5 ... Drive circuit, 6 ... Connection circuit board, 8 ... Mounting board, 6a, ... Edge of connection circuit board, 9 ... Connection terminal electrode, 10 ... Elastic cord body, 11 ... Cover body, 11a ...
… Bottom of cover, 11a ′ …… Bottom of cover, 13
...... Fit groove.

Claims (1)

[Scope of utility model registration request] 1. A head substrate 3 mounted on the upper surface of a heat dissipation plate 2.
And a driving circuit 5 for the heating resistor 4 and the heating resistor 4.
And forming a connection terminal electrode 9 to the drive circuit 5, and at a portion of the upper surface of the heat dissipation plate 2 opposite to the heating resistor 4 with the drive circuit 5 interposed therebetween. The circuit board 6 for connection to an external circuit is mounted so that the edge portion of the circuit board 6 for connection is overlapped with the terminal electrode 9 for connection on the head substrate 3, and further mounted on the upper surface of the circuit board 6 for connection. The cover body 11 configured to cover the drive circuit 5 is arranged such that the lower surface 11a of the cover body 11 is in close contact with the connecting circuit board 6 over an appropriate range, and the cover body 11 is covered with the cover body 11. The lower surface 11a of the cover body 11 is screwed to the heat dissipation plate 2 with a screw 15 penetrating a portion of the body 11 that is in close contact with the connection circuit board 6, and the connection circuit board 6 and the connection terminal electrode on the lower surface 11a of the cover body 11. In the part corresponding to the overlapping part with 9. A fitting section groove 13 is provided, and the connecting circuit board 6 is pressed against the connecting terminal electrode 9 by screwing the cover body 11 to the heat dissipation plate 2 in the fitting section groove 13. In the thermal head 1 having the elastic cord body 10 fitted therein, at least a portion of the lower surface 11a of the cover body 11 that overlaps with the head substrate 3 in a plan view is appropriately dimensioned between the connecting circuit board 6. It is formed on the raised bottom surface 11a 'where the gap b is formed, and the fitting insertion groove is formed on the raised bottom surface 11a'.
13 is a bottom surface of the cover body 11 where the fitting insertion groove 13 is raised.
The depth dimension f from the lower surface 11a of the cover body 11 in the fitting groove 13 is smaller than the diameter d1 of the elastic cord body 10 by being formed so as to be appropriately separated from the stepped portion 11a ″ with respect to a ′. The size of the cover member in the fitting groove 13
The depth from the raised bottom surface 11a ′ of 11 is the elastic string 10
Set to a size larger than the radius of the
The cross-section of the fitting groove 13 has a lateral width dimension c at the inlet portion smaller than the diameter d1 of the elastic cord body 13, and a lateral width dimension e deeper than the inlet portion greater than the lateral width dimension c at the inlet portion. The thermal head is characterized by being formed in a wide shape.