JP2547470B2 - Print head - Google Patents

Description

TECHNICAL FIELD The present invention relates to a print head such as a thermal print head or an LED print head.

(B) Prior Art FIG. 5 is an exploded perspective view showing a general liner type thermal print head.

In this thermal print head, a head substrate (ceramic substrate) 2 is attached to the upper surface of a heat dissipation plate 4, and a flexible substrate 51 provided on the upper surface of an auxiliary plate 5 is attached to the ceramic substrate 2.
In addition to being superposed on the electrode portion (connection terminal portion), the flexible substrate (including the auxiliary plate) 51 and the ceramic substrate 2 are pressed and fixed to the heat dissipation plate 4 by screws 61 from above by the pressing cover 6. A common electrode 21, a heating resistor element array 22, and a drive IC 25 are provided on the ceramic substrate 2. Applying voltage to the common electrode 21
Information is printed by selecting the heating resistance element of No. 2 and causing it to generate heat.

This print head has a problem associated with heat generation, that is, due to the difference in coefficient of thermal expansion between the heat dissipation plate 4 and the ceramic substrate 2, the ceramic substrate 2 having a very small thermal expansion is pulled by the heat dissipation plate 4 having a large thermal expansion. A plurality of curved or serial head substrates 2 are opened (heating resistor element array 22
There is a problem that printing efficiency deteriorates and the common electrode section
There was a problem that a voltage drop (voltage drop due to resistance) occurred at the center of the length of 21 and the print quality deteriorated.

Therefore, the applicant of the present application has previously proposed a thermal print head as shown in FIG. This print head
The ceramic base substrate 1 is adhered via the adhesive 41 applied to the central portion of the upper surface of the heat dissipation plate 4.
A plurality of head substrates (ceramic substrates) 2 and 2 are attached to the upper surface of the. Then, the electrode portion of the head substrate 2 is overlapped with the flexible substrate 51 provided on the upper surface of the auxiliary plate 5, and the head substrate 2 and the flexible substrate 51 are pressed and fixed by the pressing cover. In this pudding head, the ceramic substrate 2 and the base substrate 1 are adhered over the entire surface, and the base substrate 1
The heat radiating plate 4 and the heat radiating plate 4 are bonded at a part of the center. Therefore, even when the heat dissipation plate 4 is thermally expanded (thermally expanded), since the tensile force of the heat dissipation plate 4 acting on the base substrate 1 is small, this tensile force is adhered and fixed between the base substrate 1 and the head substrate 2. It is absorbed by force. Therefore, the head substrate 2 is not affected by the tensile force due to the thermal expansion of the heat dissipation plate 4, and the thermal expansion of the heat dissipation plate 4 causes the head substrate 2 to bend (bend in a concave shape) or to open a plurality of head substrates 2 and 2. Therefore, the deterioration of the print quality such as the occurrence of a white print portion is eliminated.

However, even in the above print head proposed by the applicant of the present application, the problem of the voltage drop of the common electrode still remains.

(C) Problem to be Solved by the Invention As a technique for suppressing the voltage drop of the print head, the techniques shown in FIGS. 6, 7, and 8 are known.

In the technique shown in FIG. 6, the flexible substrate (the substrate having the copper foil 72 on the film 71) 7 is superposed on the common electrode 21 of the head substrate 2 provided on the upper surface of the heat dissipation plate 4, and the metal plate 8 is provided from above. Pressure contact and screw the metal plate 8 to the heat dissipation plate 4.
81 is fixed and the flexible substrate 7 and the common electrode 21 are pressed and fixed. In addition, the technique shown in FIG. 7 is applied to the long flexible substrate 7 with respect to the common electrode 21 of the head substrate 2.
One end of the flexible board 7 is connected to the solder 7a, and the other end of the flexible board 7 is circulated on the back side of the heat dissipation plate 4 to be soldered to the circuit board (or flexible board) 2a connected to the head board 2.
7b connected. Further, in the technique shown in FIG. 8, the width of the common electrode 21 itself included in the head substrate 2 is set to be larger than the common electrode width of the normal head substrate and thicker than the normal common electrode, and a protective film is formed on the upper surface. Forming 21a.

By the way, in the flexible board using method shown in FIG. 6, the flexible board 7 and the metal plate 8 are required, and in the long flexible board using method shown in FIG. However, there are drawbacks in that the work is complicated, the number of parts is large, and the man-hours are complicated. Further, the method of increasing the width of the common electrode itself shown in FIG. 8 has a drawback that the width of the head substrate 2 itself is widened and the cost is increased.

Therefore, the applicant of the present application can effectively utilize the previously proposed base substrate of the print head of FIG. 4 to solve the problems caused by thermal expansion and of course eliminate the voltage drop of the common electrode with a simple configuration. It is intended to provide a printhead.

(D) Means and Actions for Solving the Problem In order to achieve this object, the print head of the present invention has the following configuration.

The print head is a print head in which a base substrate is attached to the upper surface of a heat dissipation plate, and a head substrate is attached to the base substrate, and the outer peripheral portions of the three sides of the base substrate are exposed to the base substrate. As described above, the head substrate is adhered, the common electrode portion is formed on the outer peripheral portions of the three sides of the base substrate, and the common electrode portion of the base substrate is connected to the common electrode of the head substrate at a plurality of points by conductive members. It is characterized by having done.

In the print head having such a configuration, the ceramic base substrate is interposed between the heat dissipation plate and the head substrate, and the head substrate is adhesively fixed to the heat dissipation plate via the base substrate. Also, the base substrate is set to have a larger area than the head substrate, and a common electrode portion having a constant width (wide) is formed on the outer peripheral portion of the three sides of the base substrate (that is, the blank portion on which the head substrate is mounted). There is. Then, the common electrode portion and the common electrode of the head substrate are soldered at appropriate places (a plurality of places). Therefore, an ordinary head substrate (an ordinary head substrate with a narrow common electrode)
However, the width of the common electrode is consequently increased by connecting the narrow common electrode and the common electrode portion of the base substrate without being allowed to use as they are. Therefore, the voltage drop of the common electrode can be eliminated. Moreover, the head substrate is adhesively fixed to the heat sink through the base substrate (ceramic substrate), and the tensile force due to the thermal expansion (thermal expansion) of the heat sink is absorbed by the base substrate, resulting in the head at high temperature. It is possible to prevent the expansion of the gap between the substrates 2 and the concave curvature of the head, and to provide an inexpensive print head that does not require an extra number of components and has a small number of steps.

(E) Embodiment FIG. 2 is a perspective view showing a main part of the print head according to the present invention.

In the print head, a ceramic base substrate 1 is attached to the upper surface of a heat dissipation plate 4, and a plurality of head substrates (ceramic substrates) 2 and 2 are attached to the base substrate 1. Further, a conductor pattern 23 is patterned on the upper surface of the head substrate 2, and a heating resistance element array 22 and a common electrode 21 are provided on the conductor 23. A part of the conductor pattern 23, the heating resistor element array 22 and the common electrode 21 is covered with a protective layer 24 (see FIG. 1). That is, the head substrate 2 is a normal ceramic substrate having the narrow common electrode 21. Further, in that a plurality of head substrates 2 are arranged on the ceramic base substrate 1, there is no difference from the print head shown in FIG. 4 previously proposed by the applicant of the present application.

The feature of the present invention resides in that the common electrode portion is provided on the base substrate 1 described above.
11 is provided, and the common electrode portion 11 and the common electrodes 21 of the head substrates 2 and 2 are connected by the conductive member 3.

The base substrate 1 is set to have an area larger than the area in which the plurality of head substrates 2 and 2 are arranged in series, and is fixed on the outer peripheral portion of the three sides (a blank portion on which the head substrates 2 and 2 are placed). A wide (wide) common electrode portion 11 is formed in a planar U-shape. As shown in FIG. 3, the common electrode portion 11 and the narrow common electrodes 21 of the head substrates 2 and 2 are connected at a plurality of points. As shown in the cross-sectional view of the main part of FIG. 1, the common electrode portion 11 and the common electrode 21 are
They are connected by a conductive member such as solder or conductive resin 3, and the conductive member 3 and the common electrode portion 11 are covered with protective layers 31 and 12, respectively.

In the print head having such a configuration, the base substrate 1 is formed by the adhesive applied to the central portion of the upper surface of the heat dissipation plate 4.
Are bonded (see FIG. 4). A common electrode portion 11 corresponding to the common electrode 21 of the head substrate 2 attached to the upper surface is formed on the base substrate 1, and the common electrode 21 and the common electrode portion 11 are made of a conductive material ( Solder 3 is connected. Therefore, the ordinary head substrate (ordinary head substrate having a narrow common electrode) 2 cannot be used as it is, and the narrow common electrode 21 and the common electrode portion 11 of the base substrate 1 are solder-connected. The width of the common electrode is increased as a result of the extremely simple work process. As a result, the voltage drop of the common electrode 21 can be eliminated, and the deterioration of printing quality due to the voltage drop can be prevented.

Moreover, the head substrate 2 is adhesively fixed to the heat sink 4 via the base substrate (ceramic substrate) 1,
The tensile force due to the thermal expansion (thermal expansion) of is absorbed by the base substrate 1, and as a result, it is possible to prevent the expansion of the gap between the head substrates 2 and the concave curvature of the head at a high temperature, and the total number of parts is unnecessary. Therefore, it is possible to provide an inexpensive print head with a small number of steps.

In addition, although the thermal print head has been described in the above embodiment, the present invention can be applied to a print head such as an LED print head.

(F) Effects of the Invention In the present invention, as described above, the base substrate is attached to the upper surface of the heat dissipation plate, the head substrate is attached to the upper surface of the base substrate, and the outer peripheral portions of the three sides of the base substrate are attached. Since the common electrode portion is provided and the common electrode portion and the common electrode of the head substrate are connected to each other by the conductive member at a plurality of points, a normal head substrate (a normal head substrate having a common electrode with a small width is provided. ) Can be used as it is, and by connecting the common electrode portion of the base substrate and the common electrode, the width of the common electrode is consequently increased. Therefore, the problem of voltage drop can be solved. Moreover, the head substrate is adhesively fixed to the heat sink through the base substrate (ceramic substrate). Therefore, it is possible to prevent the expansion of the gap between the head substrates and the concave curvature of the head at a high temperature due to the thermal expansion of the heat dissipation plate, and the total number of extra parts is unnecessary, and the number of steps is small and the print head is inexpensive. It has an excellent effect of achieving the object of the invention.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an embodiment printhead,
FIG. 2 is a perspective view showing a main part of the print head of the embodiment,
FIG. 3 is a plan view showing a main part of the embodiment print head,
FIG. 4 is a perspective view showing a print head previously proposed by the applicant of the present application, FIG. 5 is an exploded perspective view showing a general thermal print head, and FIG. 6 is a view showing suppression of voltage drop of a common electrode. FIG. 7 is an explanatory diagram showing a conventional technique, FIG. 7 is an explanatory diagram showing a conventional technique for suppressing a voltage drop, and FIG. 8 is an explanatory diagram showing a conventional technique for suppressing a voltage drop. 1: base substrate, 2: bed substrate, 3: conductive member, 4: heat sink, 11: common electrode section, 21: common electrode.

Claims (1)

(57) [Claims] 1. A print head comprising a base plate attached to the upper surface of a heat dissipation plate, and a head substrate attached to the base substrate, wherein the outer periphery of three sides of the base substrate is exposed on the base substrate. As described above, the head substrate is adhered to form a common electrode portion on the outer peripheral portion of the three sides of the base substrate, and the common electrode portion of the base substrate is formed with a common electrode of the head substrate at a plurality of locations by a conductive member. A print head characterized by being connected.