JPH0472702B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head, and more particularly to a thermal head using a plurality of driver ICs that directly drive a heating resistor.

Semiconductor ICs have become highly integrated as technology advances, and the external dimensions of ICs that achieve the same functions as conventional ICs have become significantly smaller by using highly integrated IC technology. For this reason, an IC with the same external dimensions as a conventional IC can realize twice the functionality of a conventional IC. For example, the number of heating resistors driven by a driver IC used in a thermal head is 64.
Assuming book (m=64)/IC, this IC has a width of 2
It is approximately 2.5 mm, and can be realized with a vertical dimension of approximately 6 to 8 mm.

Therefore, the resolution is 12 lines/mm and the total number of resistors is 2560.
Taking an A4 book thermal head as an example, the IC is
A total of 40 ICs will be arranged in parallel on the board with a pitch of 5.418 mm, but the gap between the ICs should be 1 to 2 mm.
It can be formed widely. This effect remains the same even when the resolution of the heating resistor is increased from about 8 lines/mm to about 16 lines/mm.

Therefore, the present invention provides a recording current grounding conductor in the above-mentioned gap, and supplies image signals in parallel to an IC that requires parallel input of image signals by means of a conductor provided near the recording current grounding conductor. It's about doing.

A basic thermal head of this configuration is disclosed in, for example, Japanese Patent Application No. 59-42332. This will be explained with reference to FIG. One end of the heating resistor array is connected to a conductor branched into a rectangular shape from the common electrode. The other ends of the resistors are connected to individual conductors L ₁ -L _n , respectively. Therefore, if a single IC drives 64 resistors, m
=64. The individual conductors L ₁ to L _n are formed to extend to connection terminals T ₁ to _{T n} to the IC. Terminal T ₁ ~
As shown in FIG. 1, T _n is separated for each different IC by a recording current ground conductor _PG . That is, the recording current ground conductor _PG is arranged near the center of the connection terminals T ₁ to _{T n} of adjacent ICs. The conductor P _G can be formed by extending it to the terminal part of the board every 1 IC as shown in Fig.
If each external terminal is formed to extend to the terminal portion of the board, the number of external terminals for driving the thermal head will be extremely reduced. In this case, the signal lines S ₁ to
S _K can also be commonly connected between ICs.

The IC mounted on the board is connected to the board by wire bonding, TAB method, etc. Among the multiple ICs installed and connected, the recording current grounding conductor _PG is divided into two, and a new image signal is provided near the center of the IC to which image signals are input in parallel. An image signal is supplied from the input conductor S′ _P , that is, the first image signal input conductor S _P
is transmitted from the connection terminal T _P1 placed at one end of the IC column to the first shift register in the IC, and the image signal is sequentially transferred through the shift registers in the IC to the connection terminal T _P2 that should output the image signal. Output to. The connection terminal T _P2 is connected to the connection terminal T _P1 to which the image signal of the next IC is to be input. Therefore, the image signal is pushed through shift registers in a plurality of ICs and transferred. However, the connection terminal T _P1 of the first IC to which the image signal should be input in parallel
is not connected to the image signal output terminal T _P2 of the adjacent IC, but is connected to a second image signal input conductor S′ _P which is arranged in the center by dividing the recording current ground conductor.

A thermal head having such a configuration includes a first image signal input conductor S _P and a driver.
A recording current grounding conductor P _G is connected between the connection terminals T ₁ to _{T n} of the IC and the connection terminals T ₁ to _{T n} of the adjacent driver IC.
A second image signal input conductor S _P ' placed in the center of this conductor allows the desired IC to be
Image signals are supplied in parallel to the image signal input terminals of the head, and the present invention provides an inexpensive and highly reliable thermal head that has substantially a single conductor layer.

However, in the thermal head of this configuration, since the recording current ground conductor P _G is arranged on both sides of the image signal input conductor S _P ',
When the resolution of the heating resistor becomes higher and the gap between the ICs becomes narrower, the pattern width of the conductor becomes narrower, resulting in a disadvantage that the conductor resistance of the conductor through which a large current should flow increases.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks, to provide a thermal head in which the width of the recording current grounding conductor is wide and the loss voltage is low.

According to the present invention, in a thermal head in which a plurality of ICs are mounted on a wiring board having a substantially single conductor layer, and a first image input signal conductor is connected to one end of the plurality of ICs, Individual conductors connected to the heating resistor and extending from the resistor are connected to each IC as a group of connection terminals to each mounted IC.
A recording current grounding conductor is provided between each connection terminal group between adjacent mounted ICs to ground the recording current, and the connection of the IC to which the second image signal is to be input is provided. A second image signal input conductor is disposed between the terminal group and the recording current ground conductor, and the second image signal is to be input.
There is obtained a thermal head characterized in that the recording current grounding terminal of the IC is arranged on the recording current grounding conductor side. Furthermore, in such a thermal head, a new conductor is provided between the recording current ground conductor and the second image signal input conductor.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram showing an embodiment of the present invention.
As shown in the figure, the present invention arranges a conductor S _P ' to supply the second image signal between the recording current ground conductor P _G and the connection terminal T ₁ T _n ' to the IC, and Connect the recording current ground terminal T _G ′ of the IC to which the image signal is to be input to the image signal input conductor S _P ′ and connect the connection terminal to the IC.
It is arranged on the side opposite to the side of T ₁ to T _n ′. Therefore, in the thermal head of the present invention,
The electrode on the IC and the ground terminal T _G ' are connected by wire bonding.

In the thermal head implementing the present invention,
For example, if we take a thermal head with 12 lines/mm,
The width of the recording current grounding conductor could be approximately 0.6 mm. In contrast, in a conventional thermal head, the conductor width can be only about 0.4 mm, including the two conductors placed on both sides of the image signal input conductor. Therefore, since the thermal head of the present invention has a small conductor resistance, the loss voltage fluctuation of the printing recording voltage is small, and a thermal head with small printing unevenness can be provided.

Since the present invention exhibits the above-described effects, the use of the thermal head and the resolution of the heating resistor of the present invention,
There are no particular limitations on the number of image signal input conductors that should be input in parallel or the number of heating resistors that can be driven by _a single _{IC .} If T _G and T _G ′ are connected by the wire bonding method, there is no restriction on the method of mounting and connecting the IC.

In thermal heads, large currents flow through conductive parts such as the common electrode or the recording current grounding conductor, so the conductive parts are made thicker in some areas, or by plating, etc. However, the spirit of the present invention is not impaired in any way. Additionally, a new conductor is arranged between the second image signal input conductor S _P ′ and the recording current ground conductor P _G , and this new conductor is connected to the ground potential, the logic part power supply of the IC, or Of course, crosstalk noise superimposed on the image signal input voltage can be reduced by connecting a signal line or the like that periodically fluctuates between the ground potential and the logic section power supply potential. That is, an image signal output terminal or the like can be connected to the new conductor.
However, it is a matter of course that the image signal output terminal can be wired from any position to the board terminal section.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing a conventional thermal head, and FIG. 2 is a schematic plan view showing an embodiment of the thermal head of the present invention. L ₁ ~ _{L n} ... Individual conductor, T ₁ ~ _{T n} , T _n ′... IC
Connection terminal, T _G , T _G ′... Recording current ground terminal, T _P1
...Image signal input terminal, T _P2 ...Image signal output terminal, S _P , S _P ' ...Image signal input conductor, P _G ... Recording current grounding conductor, S ₁ to S _K ... Signal line.

Claims (1)

[Claims] 1. A plurality of ICs are mounted on a wiring board having a single conductive layer, and a first image input signal conductor S _P
In the thermal head to which one of the plurality of ICs is connected, the individual conductors L ₁ to _{L n} connected to the heating resistor are connected to each connection terminal group T ₁ to each IC.
A recording current grounding terminal T _G is arranged as _Tn on both sides of each mounted IC and is used to ground the recording current between each of the connection terminal groups T ₁ to _{T n} between adjacent mounted ICs,
A recording current grounding conductor P _G having T _G ′ is provided, and a second
Connecting terminal group T ₁ of the IC to which the image signal of is to be input
~T _n ′ and the recording current ground conductor P _G
image signal input conductor S _P ′ is disposed, and the recording current ground terminal which is connected to the IC to which the second image signal is inputted among the recording current ground terminals T _G and T _G ′; T _G ′ is arranged on the side of the recording current installation conductor _PG closer to the second image signal input conductor S _P ′, and is formed shorter than the recording current grounding terminal _TG . thermal head. 2. The thermal head according to claim 1, characterized in that a new conductor is disposed between the recording current ground conductor and the second image signal input conductor.