JP3234003B2 - Thermal head - 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, and aims at improving the reliability and reducing the cost of the thermal head.

[0002]

2. Description of the Related Art When manufacturing a thermal head having a recording width of A1 or more, in a conventional method,
First, a long alumina substrate 5 is prepared as shown in FIG.
A heating resistor 51 and a conductor pattern 52 are formed on the alumina substrate 5. Next, after attaching the alumina substrate 5 to the aluminum base 2 having a heat radiation function, the printed board 3 as a wiring board is attached corresponding to the conductor pattern 52. In this conventional example, a required number of chip-like ICs 4 as an electric circuit are mounted as the printed circuit board 3 in advance. The conductor pattern 52 and the corresponding IC 4 are connected by wire bonding or the like. Although not shown, a connector is attached to the printed circuit board 3 to obtain a control signal and power from the outside, so that a desired thermal recording element can be heated by inputting a recording signal as a control signal. Thus, desired recording with a wide recording width can be performed.

[0003]

The thermal head having such a large recording width has the following two problems since it is manufactured as described above. The first problem is that the thermal expansion coefficients of the alumina substrate 5 which is a thermal head substrate and the printed substrate 3 are greatly different from each other, and the second problem is that the printed substrate 3 needs to be manufactured to be long. It is a problem for some reason.

The first problem is that the alumina substrate 5
Due to the difference in thermal expansion between the printed circuit board 3 (having a small coefficient of thermal expansion) and the printed board 3 (generally having a large coefficient of thermal expansion), the printed board 3 expands and contracts during operation of the thermal head 1. Stress is frequently applied to the connection (wire bonding) between the chip-shaped IC 4 and the alumina substrate 5. Therefore, in order to prevent inconveniences such as disconnection, various measures have conventionally been taken, and this has led to an increase in the price of the thermal head.

[0005] In the second problem, in the conventional apparatus, the printed circuit board 3 is formed with substantially the same length as the alumina substrate 5. However, there is a drawback in that it becomes expensive because of the necessity of preparing the. The present invention has been made to improve these points, and provides an inexpensive and highly reliable thermal head.

[0006]

[Means for Solving the Problems]

Therefore, according to the present invention, a large number of thermal recording elements arranged in a row and a direction intersecting the upper and lower sides of the arrangement direction of the thermal recording elements in order to supply current to the thermal recording elements. A thermal head substrate having upper and lower conductor patterns composed of a number of conductors formed so as to extend and connect to any of the thermal recording elements ,
An electrical circuit group formed selectively current supplied chipped in the upper or lower conductor pattern for performing the desired recording by selectively act the thermogram element in accordance with a recording signal from an external In a thermal head having a plurality of wiring boards for supplying the control signal or the power to the group of chip-like electric circuits, the plurality of thermal recording elements are grouped by a predetermined number so as to correspond to the group. Arrangement
A wiring board is provided, and for at least one of the upper or lower conductor patterns, the entire width dimension of the plurality of conductor groups connected to the thermal recording elements belonging to the respective groups is set to a corresponding wiring board. Width dimension
An electric circuit formed by patterning so as to become narrower toward the outside according to the above, providing a wiring board corresponding to one or more of the plurality of conductor groups, and forming the conductors belonging to the respective patterns into the chip shape Through the wiring board.

[Action]

[0008] Since a wiring board as a printed board is provided for each of one or a plurality of conductor groups, a plurality of wiring boards having a predetermined length may be used. Can be greatly reduced. Furthermore, since the printed circuit boards can be standardized to a predetermined length, components can be standardized and the cost can be reduced overall.

【Example】

FIGS. 1 to 3 are explanatory views showing the structure of a thermal head according to a first embodiment of the present invention.
1 is a front view thereof, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG.
FIG. 4 is a schematic view for explaining a method of manufacturing a thermal head.
In these drawings, 1 is a thermal head, 2 is an aluminum base also serving as a heat sink, 31 to 36 are printed boards, 4 is a control circuit IC, 5 is an alumina board, 51 is a heating resistor, 521 is an upper conductor pattern, 522 is a lower conductor pattern.

Referring to FIG. On the alumina substrate 5,
One heating resistor 51 is formed in the longitudinal direction. A lead conductor group is formed above and below so as to contact and cross the heating resistor 51 alternately. In the thermal head according to this embodiment, the portion of the heating resistor 51 sandwiched between the adjacent lead conductors of the lead conductor group that alternately contact and intersect forms one thermal recording element. Therefore, in these thermal heads 1, a large number of thermal recording elements are arranged in rows. In the thermal head 1 according to this embodiment, these many thermal recording elements are grouped by a predetermined number. The group of lead conductors connected to the thermal recording elements belonging to each of these groups is patterned so that the entire width thereof is reduced outward. Here, each of the lead conductor groups thus patterned is referred to as an upper conductor pattern and a lower conductor pattern, respectively. Therefore, the thermal head 1 shown in FIG. 1 has three upper conductor patterns 521 and three lower conductor patterns 522.

For each of the upper and lower conductor patterns,
Printed boards 31 to 36 are arranged correspondingly. The control circuit IC4 is mounted on each of the printed boards 31 to 36, and is connected to the corresponding lead conductor of each conductor pattern by wire bonding.

Referring to FIG. 2, which is a cross-sectional view taken along the line AA of FIG. An alumina substrate 5 is mounted on the upper surface of the center of the aluminum base 2. Then, printed boards 31 and 34 are provided close to the alumina board 5,
The IC 4 attached thereto and each lead conductor are connected by wire bonding 53. Connectors 61 and 64 are provided on the printed circuit boards 31 and 34, respectively.
Are attached. These connectors 61
And 64 are used for external signal transmission / reception and power supply.

Referring to FIG. In the first embodiment, mounting portions for mounting the alumina substrate 5 and the printed boards 31 to 36 are formed on the upper surface of the aluminum base 2. Then, as shown in FIG. 3, the printed circuit boards 31 to 36 to which the alumina substrate 5 and the connectors 61 to 63 are attached are attached.

FIG. 5 is a front view of a thermal head according to a second embodiment of the present invention, which is called an edge type thermal head. This thermal head 1 is provided with a common electrode 523 on the upper part and the left and right parts of the alumina substrate 5. The upper conductor pattern 521 above the heating resistor 51 is formed so as to be connected to the common electrode 523 as in the conventional case, and only the lower conductor pattern 522 below has the structure described above. In the thermal head 1 having this structure, unlike the above-described thermal head 1, the heating resistor 51 between the adjacent lead conductors of the upper conductor pattern 521 serves as a thermal resistance element. Thermal resistance elements are formed in rows. These large number of thermal resistance elements are grouped by a predetermined number, and the lower lead conductor group belonging to this group is patterned so that the entire width thereof is reduced outward. Printed boards 34, 35 and 36 are provided for one or more of these individual lower conductor patterns 522. As described above, these printed circuit boards 34, 35, and 36 exchange signals with the outside via the connectors.

In the second embodiment, a chip-like IC 4 as an electric circuit is attached to the lower end of an alumina substrate 5. Therefore, only the conductor pattern is formed on each printed board, and each conductor of the printed board and the IC 4 in the form of an alumina substrate 5 are wire-bonded.

In the above-described thermal head, when the thermal resistance elements are grouped by a predetermined number, for example, A4
It is more convenient and inexpensive if it is configured to group by the number corresponding to the standardized size such as the size, and to configure the size of the printed circuit board corresponding to these into the standardized size. There is an advantage that the goods can be used.

[0017]

As described above, according to the present invention,
A conductor pattern configuration in which a large number of rows of thermal recording elements are grouped by a predetermined number and lead conductor groups belonging to these groups are patterned so that the entire width thereof is directed outward. Furthermore, since a wiring board is provided for one or more of these conductor patterns, a short wiring board can be used even when materials having different coefficients of thermal expansion are used. Therefore, the stress on the connecting portion of the thermal head can be reduced without accumulating the influence of thermal expansion. Further, since it is easy to use a wiring board having a standardized size, the cost of the thermal head can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view of a thermal head according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the thermal head shown in FIG. 1 taken along the line AA.

FIG. 3 is an explanatory view schematically showing a method of manufacturing the thermal head shown in FIG.

FIG. 4 is a front view showing a configuration of a conventional thermal head.

FIG. 5 is a front view showing a second embodiment of the present invention.

[Explanation of symbols]

 1: Thermal head 2: Aluminum base 3: Printed circuit board 4: IC 5: Alumina substrate 6: Connector

Continuation of the front page (72) Inventor Takeshi Toyosawa 503-10 Shinanomachi, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Examiner, Katsumi Enari, Graphtec Co., Ltd. (56) References JP-A-63-185646 (JP, A) JP-A-61-112661 (JP, A) JP-A-2-145355 (JP, A) Japanese Patent Application No. Hei 3-62000 (Japanese Utility Model Application No. 4-89351) Microfilm (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/335 B41J 2/345

Claims (1)

(57) [Claims] 1. A plurality of thermal recording elements arranged in a row, and a plurality of thermal recording elements extending upward and downward in an arrangement direction of the thermal recording elements in order to supply current to the thermal recording elements and intersecting therewith. have the upper and lower conductor patterns consisting of a number of conductor formed so as to connect to the thermal printing elements
A thermal head substrate, selectively action is allowed to selectively electrically formed into chips for supplying a current to the upper or lower conductor pattern for performing the desired recording in accordance with recording signals the thermogram element and circuit group, in the thermal head having a plurality of wiring board, a for supplying a control signal or power from external to the chip-shaped electrical circuits, accesible group the number of thermal printing elements every predetermined number And arranging a wiring board so as to correspond to the group, and regarding at least one of the upper and lower conductor patterns, the entire width dimension of a plurality of conductor groups connected to the thermal recording elements belonging to the respective groups. the respective patterned to be narrower toward the outer side in response respectively to the width of the corresponding wiring board, belonging to the respective pattern The body to the tip form
Connected to the corresponding wiring board via the formed electric circuit
A thermal head designed to be used.