JP3241790B2 - Thermal head with connector pins - 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 with connector pins used by being pressed against a platen.

[0002]

2. Description of the Related Art In a facsimile or a printer, a thermal head used in a state pressed against a platen is used.
It is frequently used for printing. Generally, in a thermal head, as shown in FIGS.
0, the heating resistors 51 arranged in the print scanning direction.
In addition, an IC (usually used as a chip) 52 for driving the heating resistor 51 and a conductor 53 connecting the two are formed. A predetermined circuit is formed by the heating resistor 51, the IC 52 and other electronic components, and the conductor 53 connecting the electronic components, and this circuit is formed on the surface of the head substrate 50. The conductor pattern of the circuit (for example, conductor 5
3) extends to the rear end of the head substrate 50 in the longitudinal direction and is connected to an external connection connector pin 54 as an interface mounted near the center of the rear end. In addition, IC
52 is covered and protected by a resin mold 55, and the head substrate 50 is not used alone, but is usually fixed on a support plate that also serves as heat radiation.

In such a thermal head, a head substrate 50 is pressed against a platen (not shown), and printing paper such as thermal paper fed between the platen and the heating resistor 51 is heated by the heating resistor 51. And print it.

[0004]

When the heating resistor 51 is to generate heat, a voltage is generally applied to the common electrode and the individual electrodes to cause the resistor corresponding to each dot to generate heat. Although the number of individual electrodes is equal to the number of dots, the number of common electrodes is one over the entire heating resistor 51, and a predetermined voltage is applied to the common electrode from both ends. However, in this case, since the applied voltage gradually decreases toward the center of the heating resistor 51 due to the voltage drop, the resistor near the center does not generate sufficient heat, which causes a deterioration in print quality.

[0005] On the other hand, with the recent trend toward various electronic devices becoming lighter, thinner and smaller, there is an increasing tendency to make components built in the devices smaller and lighter, and thermal heads are no exception. For this reason, in the thermal head, the head substrate 5
Zero reduction is particularly important. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a thermal head capable of minimizing a reduction in voltage applied to a heating resistor and reducing the size of a head substrate.

[0006]

The above object is achieved by a thermal head with connector pins according to the present invention. That is,
The thermal head according to the present invention is characterized in that the side edge of the substrate surface in the longitudinal direction is
Common electrode formed along the part and the inside of this common electrode
A circuit having a heating resistor arranged in the print scanning direction along the line, an IC for driving the heating resistor, and a conductor connecting the common electrode, the heating resistor, and the IC are distributed to the front and back of the substrate. Provided, at least the common electrode on the side
Connecting from the edge to the conductor pattern of the circuit on the back of the board
In the conductor pattern of the circuit board sides connect to connector pins for external connection mounted on the side end portion in the longitudinal direction of the substrate, that is connected to the conductor pattern of the table and / or the back of the circuit board Features.

In the thermal head according to the present invention, the circuits on the front and back surfaces of the substrate are appropriately distributed and arranged by effectively utilizing the area of the front and back surfaces of the substrate, so that the degree of freedom in circuit design is considerably increased. Therefore, as shown in the following embodiments, by appropriately allocating the circuit and selecting the method of providing the pattern of the common electrode, it is possible to considerably suppress the decrease in the voltage applied to the heating resistor, It is also possible to make the substrate smaller.

[0008] circuit provided on the front and back of the substrate, a common electrode, a heating resistor formed of a conductor to contact an electronic component and electronic parts such as IC, these electronic components may be provided on either sides, the common The electrode is located on the side edge of the substrate surface in the longitudinal direction.
The heating resistor is provided along the inside of the common electrode.
You . Also, the circuit on the front and back of the board uses the common electrode in the longitudinal direction of the board.
From the side edge of the board to the conductor pattern of the circuit on the back of the board
In this case , the circuit patterns are connected to the connector pins, so that all the circuits are connected, and electric signals from outside the board are conducted to the circuit on the front and back of the board through the connector pins. I will

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A thermal head with connector pins according to the present invention will be described below based on embodiments. FIG. 1 shows a plan view (surface view) of the thermal head according to the embodiment. On the surface of the insulating head substrate 10, heating resistors 11 are arranged in the print scanning direction. ICs (not shown) for driving the heating resistor 11 and other electronic components are appropriately distributed on the front surface and the back surface of the substrate 10, and are respectively mounted on the conductor patterns. In this embodiment, the common electrode 12 is formed on the surface of the head substrate 10 along the front side end and the left and right side ends of the substrate 10 in the longitudinal direction. As can be seen from FIG. 1, the common electrode 12 extends on the front side along the heating resistor 11, and external connection connector pins 15 are attached to portions of the common electrode 12 on both sides of the rear end of the substrate 10. Have been. Furthermore, in the approximate center of the front end of the substrate 10,
Another external connection connector pin 1 that contacts the common electrode 12
6 are attached. These connector pins 15, 16
Thereby, the conductor patterns of the circuits distributed on the front and back of the substrate 10 are connected, and one circuit is constituted as a whole.

In such a thermal head, as shown in FIG. 2, the heating resistor 1 is formed by a common electrode 12 and individual electrodes (not shown) using, for example, connector pins 15 and 16.
When a voltage of 24 V is applied to the resistor 1, the voltage can be applied from almost the center of the heating resistor 11, so that the resistance of the common electrode 12 itself to the heating resistor 11 becomes substantially equal. As a result, the voltage drop is smaller than the conventional one (about half of the conventional one), and the heating efficiency of the heating resistor is improved.
Printing quality is improved.

FIG. 3A is a front view of a thermal head according to another embodiment, and FIG. 3B is a rear view of the same. Here, a common electrode 22a along the heating resistor 21 is formed on the front surface of the head substrate 20 as in the previous embodiment, and a common electrode 22b having a similar pattern is formed on the back surface. The connector pins 25 attached to both sides of the rear end of the head substrate 20 contact the common electrode 22a on the front surface and the common electrode 22b on the back surface, and the connector pin 26 contacts only the common electrode 22b on the back surface. In the present embodiment, the common electrodes 22a and 22b are connected at regular intervals by appropriate terminals 27 at the front end of the head substrate 20 (see FIG. 3C). In this thermal head, since the area of the common electrode is substantially increased, the common electrode 22
The voltage drop at a and 22b can be minimized.

As a modified example for reducing the voltage drop, although not shown in the drawings, a common electrode is not provided on the front and back of the head substrate 20, but a heating resistor 21 is arranged near the center of the substrate 20 to generate heat. The area on the front side of the resistor 21 may be increased, and the area of the common electrode may be increased accordingly. In the embodiment as shown in FIG. 3, since the common electrodes on the front and back sides of the head substrate are connected by terminals, the portions of the common electrodes existing on the left and right side edges of the head substrate can be omitted. It is shown in FIG. As in the embodiment of FIG.
The common electrodes 32a and 32b are formed on the front and back of
No common electrode is provided on the left and right side edges of the substrate. For this reason, the left and right sides of the head substrate 30 can be shortened by the common electrode, and the head substrate can be reduced in size. The connector pins 35 are attached to substantially the center of the rear end of the head substrate 30 and are connected to the conductor pattern of the circuit.

FIG. 5 shows an example of a conductor pattern for a strobe signal among the conductor patterns of the circuit provided on the front and back of the head substrate 40. Here, the head substrate 40
The conductor patterns on the front and back are common, and the conductor patterns for the four-divided strobe signal provided on the surface are
Is divided into two by conductor patterns 48 and 49 provided on the back surface. That is, the conductor pattern and the conductor pattern 48 are short-circuited at the terminal 47 at the side end of the substrate, and the conductor pattern and the conductor pattern 49 are short-circuited at the terminal 47 '. As a result, the front and back conductor patterns are customized. A connector pin (not shown) that is electrically connected to the conductor pattern of the circuit is attached substantially at the center of the rear end of the head substrate 40.

In each of the above-described embodiments, a heater for preheating the heating resistor may be added to the circuit on the front surface or the back surface of the head substrate, as conventionally performed. By providing a heater, the heating resistor can be sufficiently warmed before printing is started, and printing defects are less likely to occur at the start of printing, and this is particularly effective in cold weather.

[0015]

Connector pin thermal head with the present invention according to the present invention, as described above, provided the circuit on the front and back of the substrate, group
Common electrode formed along the longitudinal side edge of the plate surface
From the side end to the conductor pattern of the circuit on the back of the board
By, connect the conductive pattern of the circuit on the front and back,
Furthermore, since the conductor pattern is connected to the connector pins for external connection, by appropriately allocating the circuit and selecting a method of providing the common electrode pattern, it is possible to prevent the voltage applied to the heating resistor from being reduced as much as possible. Alternatively, the head substrate can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view (front view) of a thermal head according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining how a voltage is applied to a heating resistor in the thermal head shown in FIG. 1;

FIG. 3 is a front view, a rear view, and a main part cross-sectional view of a thermal head according to another embodiment of the present invention.

FIG. 4 is a front view and a rear view of a thermal head according to still another embodiment of the present invention.

FIG. 5 is a partial view showing an example of a conductor pattern of a circuit provided on the front and back of a substrate in the thermal head of the present invention.

FIG. 6 is a plan view (surface view) of a thermal head according to a conventional example.

FIG. 7 is a sectional view taken along line AA in FIG. 6;

[Explanation of symbols]

10, 20, 30, 40 Head board 11, 21, 31 Heating resistor 15, 16, 25, 26, 35 Connector pin for external connection 27, 37, 47, 47 'Terminal

Claims (1)

(57) [Claims] 1. Formed along a longitudinal side edge of a substrate surface
A common electrode, a heating resistor arranged in the print scanning direction along the inside of the common electrode, an IC for driving the heating resistor, and a conductor connecting the common electrode, the heating resistor and the IC. Are provided separately on the front and back of the substrate, and at least the common electrode is disposed on the back of the substrate from the side end.
By connecting to the conductor pattern of the circuit surface, a conductor pattern of the circuit board sides connect to connector pins for external connection mounted on the side end portion in the longitudinal direction of the substrate table and / or the back of the substrate A thermal head with connector pins, wherein the conductor pattern of the circuit is connected.