JPH0711343U - Thermal head - Google Patents

Abstract

(57) [Summary] [Object] To provide a small thermal head capable of forming a finer and higher quality printed image on a recording medium. [Structure] Electrically insulating substrate 1 having a large number of heating resistors 3
And the plurality of heating resistors 3 are connected to a plurality of blocks (A1
To A9) and the same number of driving ICs as the number of the blocks connected to each heating resistor 3 of each block.
6 and the driving IC 6 is mounted by being divided into both main surfaces 1a and 1b of the electrically insulating substrate 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a thermal head incorporated as a printer mechanism such as a word processor and a facsimile.

[0002]

[Prior art]

 Conventionally, a thermal head incorporated as a printer mechanism such as a word processor, as shown in FIG. 3, has an electrically insulating substrate 11 having a large number of heating resistors 12 arranged on one main surface 11a, and the heating resistors. A common electrode 13 commonly connected to one end of each of 12 and an individual electrode 14 individually connected to each of the other ends of the heating resistors 12, and mounted on one main surface 11a of the electrically insulating substrate 11. The plurality of heating resistors 12 are divided into a plurality of blocks, for example, six blocks B1 to B6, and are connected to the heating resistors 12 of each of the blocks B1 to B6 through individual electrodes 14. The same number (6) of driving ICs 15 as the number of blocks are provided, and a predetermined electric power is applied between the common electrode 13 and the individual electrode 14 as the driving ICs 15 are driven to generate heat resistance. With selectively Joule heat generation 12, were conducting emitting heated heat the recording medium of the thermal paper, etc., function as a thermal head I'm to form a predetermined print image on a recording medium.

The heating resistor 12, the common electrode 13, and the individual electrode 14 are formed on the main surface 11a of the electrically insulating substrate 11 by a thin film forming technique such as a sputtering technique and a photolithography technique. It is applied with a thickness.

[0004]

[Problems to be solved by the device]

 However, in this conventional thermal head, the driving ICs 15 are mounted on the one main surface 11a of the electrically insulating substrate 11 in the same number as the number of the blocks B1 to B6. In order to form a fine and high-quality printed image, when the distance between the adjacent heating resistors 12 is shortened and the array density of the heating resistors 12 is set to a high value such as 16 dot / mm or more, the heating resistors 12 As the array density increases and the number of heating resistors 12 increases, the number of driving ICs 15 connected to the heating resistors 12 via the individual electrodes 14 also increases. In order to mount all such driving ICs 15 on one main surface 11a of the electrically insulating substrate 11, the electrically insulating substrate 11 is made large, and one of the many driving It is necessary to secure a large area for mounting all of the ICs 15, and when the thermal head is manufactured using such a large electrically insulating substrate 11, there is a drawback that the entire structure of the thermal head becomes large.

[0005]

[The purpose of the device]

 The present invention has been made in view of the above drawbacks, and an object thereof is to provide a small thermal head capable of forming a finer and higher quality printed image on a recording medium.

[0006]

[Means for Solving the Problems]

 The thermal head of the present invention comprises an electrically insulating substrate having a large number of heating resistors, and a plurality of heating resistors which are divided into a plurality of blocks and which are connected to the heating resistors of each block. The number of driving ICs is the same as the number of driving ICs, and the driving ICs are mounted on both main surfaces of one main surface and the other main surface of the electrically insulating substrate.

[0007]

【Example】

 Hereinafter, the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a perspective view of a thermal head showing an embodiment of the present invention, FIG. 2A is a plan view seen from the X direction of FIG. 1, and FIG. 2B is a plane seen from the Y direction of FIG. 1 is an electrically insulating substrate, 3 is a heating resistor, 4 is a common electrode, 5 is an individual electrode, and 6 is a driving IC.

The electrically insulative substrate 1 is made of electrically insulative material such as alumina, and ceramic material powder such as alumina, silica, magnesia and the like is formed into a slurry by adding and mixing an appropriate organic solvent and solvent. At the same time, a ceramic green sheet is formed by adopting a conventionally well-known doctor blade method, and then the ceramic green sheet is punched into a predetermined shape and fired at a high temperature (about 1600 ° C). Produced.

The end face of the electrically insulating substrate 1 is R-face polished by using a grindstone or the like, and the R-face is covered with a heat storage layer 2 made of glass or the like.

The heat storage layer 2 accumulates and dissipates heat generated by a heat generating resistor 3 described later to maintain a good thermal response characteristic of the thermal head, and is suitable for glass powder. The solvent and the glass paste obtained by adding and mixing the solvent are applied to the end face of the electrically insulating substrate 1 by employing the conventionally well-known screen printing, and then the electrically insulating substrate is baked at a high temperature. 1 is attached to the end face.

The electrically insulating substrate 1 on which the heat storage layer 2 is deposited also has a large number of heating resistors 3 linearly arranged at an end surface thereof at a density of, for example, 16 d ot / mm. Since the heat-generating resistor 3 is made of tantalum nitride or the like and has a predetermined electric resistivity by itself, Joule heat is generated when a predetermined power is applied, and a printed image is formed on a recording medium. It generates heat at a required temperature, for example, a temperature of 300 to 450 ° C.

A large number of heating resistors 3 made of tantalum nitride or the like are attached to the end face of the electrically insulating substrate 1 by adopting a thin film forming technique such as a sputtering method and a photolithography technique. Substrate 1 is placed in a sputtering device so that the end face of the electrically insulating substrate 1 faces a sputtering target made of tantalum nitride, and then the sputtering target is irradiated with argon ions or the like to tantalum nitride nitride. Is scattered from the sputtering target and is deposited on the end face of the electrically insulating substrate 1. Then, a part of the deposited tantalum nitride is etched by a photolithography technique and processed into a predetermined pattern. It is applied so as to be linearly arranged on the end face of the electrically insulating substrate 1. To be done.

The plurality of heating resistors 3 are further divided into a plurality of blocks, for example, nine blocks A1 to A9, and among the blocks, A1, A3, A5, A7 and A9. The heating resistor 3 of each block has individual electrodes 5 individually connected to one end thereof and extends to the one main surface 1a of the electrically insulating substrate 1, and a common electrode 4 is common to each block at each other end. And is extended to the other main surface 1b of the electrically insulating substrate 1.

On the other hand, among the blocks, the heating resistors 3 of the blocks A2, A4, A6 and A8 are connected to the common electrode 4 at one end of each of the blocks in common and the electrically insulating substrate 1 is provided. To the main surface 1a, the individual electrodes 5 are individually connected to the other ends, and extend to the other main surface 1b of the electrically insulating substrate 1.

The common electrode 4 and the individual electrode 5 are made of a metal material such as aluminum, and a predetermined electric power is applied to the heat generating resistor 3 located between the common electrode 4 and the individual electrode 5 to cause the heat generating resistor 3 to contact the heat generating resistor 3. It has the function of causing Joule heat generation.

Further, in this case, only the heating resistor 3 included in the block is commonly connected to the common electrode 4, and the amount of current flowing into the common electrode 4 flows from the heating resistor 3 in each block. Since the total current does not exceed the total current, even if a current is passed through all the heating resistors 3, a large current that causes a large voltage drop does not flow into the common electrode 4 at all. It is possible to form a good printed image without uneven density.

The common electrode 4 and the individual electrode 5 are formed from a thin film forming technique such as a sputtering method and a photolithography technique, and from the end face of the electrically insulating substrate 1 on which the heating resistor 3 is adhered to one main surface. 1a and the other main surface 1b are adhered to each other, and the electrical insulating substrate 1 is physically attached to the main surface 1a and the other main surface 1b. The sputtering target is placed in a sputtering apparatus so as to face the sputtering target, and then the sputtering target is irradiated with argon ions or the like to scatter aluminum from the sputtering target, and the aluminum is scattered from the end surface of the electrically insulating substrate 1. The main surface 1a and the other main surface 1b are deposited on both main surfaces, and then a part of the deposited aluminum is removed by photolithography. By etching with a graphic technique and processing into a predetermined pattern, the electrically insulating substrate 1 is adhered from the end face to both main faces 1a and 1b.

Further, the same number of driving ICs 6 as the number of blocks (9) are connected to the large number of heating resistors 3 via the individual electrodes 5, and the driving ICs 6 correspond to external electric signals. Thus, the application of electric power between the common electrode 4 and the individual electrode 5 is controlled, and Joule heat is selectively generated so that the heating resistor 3 can accurately obtain a desired print image on the recording medium.

The driving IC 6 is further mounted by being divided into two main surfaces, one main surface 1 a and the other main surface 1 b, of the electrically insulating substrate 1. The five driving ICs 6 are connected to the heating resistors 3 included in the blocks A1, A3, A5, A7 and A9 on the one main surface 1a, and the other main surface 1b of the electrically insulating substrate 1 is connected. The four driving ICs 6 are respectively mounted so as to be connected to the heating resistors 3 included in the blocks A2, A4, A6 and A8.

The same number of driving ICs 6 as the number of the blocks are mounted by being divided and mounted on both main surfaces 1a and 1b of the electrically insulative substrate 1, so that the drive ICs 6 can be made finer depending on the recording medium. In order to form a high quality printed image with a high density of heating resistors 3 and a large number of driving ICs 6, one main surface 1a of the electrically insulating substrate 1 or the other main surface Even if it is not possible to secure a large area for mounting all the driving ICs 6 in 1b, it is possible to mount all of the many driving ICs 6 on the electrically insulating substrate 1 and thereby the electrically insulating substrate. By making 1 smaller, the overall structure of the thermal head can be downsized.

For connection between the driving IC 6 and the individual electrode 5, for example, when a flip chip type IC having an electrode having solder bumps on the lower surface is adopted as the driving IC 6, The drive IC 6 is placed on the electrically insulating substrate 1 so that the solder bumps of the drive IC 6 come into contact with the individual electrodes 5, and then the whole is heated to a predetermined temperature to solder the drive IC 6 and the individual electrodes 5 to each other. It is done by joining.

A heat radiating plate 7 having a predetermined recess 7a is further in contact with the other main surface 1b of the electrically insulating substrate 1 on which the same number of driving ICs 6 as the number of the blocks are mounted. The plate 7 accommodates the driving IC 6 mounted on the other main surface 1b of the electrically insulating substrate 1 in the recess 7a thereof to bring the heat sink 7 into close contact with the other main surface 1b of the electrically insulating substrate 1 and to electrically insulate it. By absorbing part of the heat of the electrically insulating substrate 1, the electrically insulating substrate 1 maintains a good temperature condition.

The heat radiating plate 7 is manufactured, for example, by using an ingot (lump) of aluminum or the like by a conventionally known metal working method and forming it into a predetermined shape so as to form the concave portion 7a. The plate 7 is brought into contact with the other main surface 1b of the electrically insulating substrate 1 by a tape member having both surfaces coated with an adhesive material. At this time, the tape member bonds the electrically insulating substrate 1 and the heat sink 7 together with the common electrode 4 and the individual electrode 5 formed on the other main surface 1b of the electrically insulating substrate 1 and the heat sink 7. It is electrically isolated.

Thus, in the thermal head of the present invention, a predetermined electric power is applied between the common electrode 4 and the individual electrode 5 as the driving IC 6 is driven, and the heating resistor 3 is selectively heated by Joule heat. The heat generated is conducted to the recording medium to form a predetermined print image on the recording medium, thereby functioning as a thermal head.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the spirit of the present invention.

[0027]

[Effect of device]

 The thermal head according to the present invention has an electrically insulating substrate having a large number of heating resistors on its end surface, and divides the plurality of heating resistors into a plurality of blocks and connects them to a predetermined number of heating resistors included in the blocks. The number of the driving ICs is the same as that of the blocks, and the driving ICs are mounted on both main surfaces of the main surface and the other main surface of the electrically insulating substrate. If the array density of heating resistors is increased and the number of drive ICs is increased in order to form a fine and high-quality printed image, all the drive on one main surface or the other main surface of the electrically insulating substrate It becomes possible to mount all of the above-mentioned many driving ICs on the electrically insulating substrate without securing a large area for mounting the electrically insulating substrate, thereby making the electrically insulating substrate small. Whole thermal head It is possible to reduce the size of the granulation.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a thermal head of the present invention.

2A is a plan view seen from the X direction in FIG. 1, and FIG.
2 is a plan view seen from the Y direction in FIG. 1. FIG.

FIG. 3 is a perspective view of a conventional thermal head.

[Explanation of symbols]

 1 ... Electrically insulating substrate 1a ... One main surface 1b ... Other main surface 2 ... Heat storage layer 3 ... Heating resistor 4 ... Common electrode 5 ... Individual electrode 6 ... Driving IC for

Claims (1)

[Scope of utility model registration request] 1. An electrically insulating substrate having a large number of heating resistors, the same number of blocks as the plurality of heating resistors divided into a plurality of blocks and connected to each heating resistor of each block. The thermal head comprises a plurality of driving ICs, and the driving ICs are mounted on both main surfaces of the one main surface and the other main surface of the electrically insulating substrate.