JPH0924635A - Thermal print head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a wiring pattern to implement ICs for driving a heat resisting element on a head by partially-disposing the ICs, an output pad for driving signals, respective input pads of GND, VDD signals and STR signals, output pads of data, clock and latch signals at respective sides. SOLUTION: In driving ICs 1 for a thermal printer head, an output pad train 2 corresponding to 64 bits and is constituted of 64 output pods 21 in the vicinity of the upper side. An input pad train 3 which is constituted of three pairs of input pads 33 of GND, an input pad 32 for VDD signals, and an input pad 33 for STR signals is fitted in the vicinity of the lower side. An input pad train 4 which is constituted of an input pad 41 for clock signals, an input pad 42 for data signals, and an input pad 43 for latch signals is fitted in the vicinity of the left side. An output pad 5 for output signals corresponding to respective input signals is fitted in the vicinity of the right side, and input/output pads 41, 51: 43, 53 are connected by use of pattern in the IC 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal print head for use in a heat-sensitive type or thermal transfer type facsimile or printer.

[0002]

2. Description of the Related Art A thermal print head used in a facsimile, a printer or the like generally has a heating resistor extending in a print scanning direction and a driving IC for driving the resistor.
And a wiring pattern for connecting the resistor and the IC. The thermal print head has a heating resistor corresponding to the number of print dots, and several resistors are provided in order to send a data signal for driving the resistor according to the print dot pattern to each resistor. ICs are provided in a number corresponding to the number of sets combined.

In this driving IC, as shown in FIG. 4, generally, all the output pads 101 that send out signals for driving the heating resistors are arranged near one side of the upper surface of the IC 100 to form an output pad row 102. , All input pads 103 for receiving input signals (data, clock, latch, GND, V _DD , STR, etc.) are arranged in the vicinity of the opposite side,
The input pad row 104 is used.

[0004]

By the way, in most thermal print heads, data, clock, latch,
Since only one system is used for each of GND and V _DD signals, signals of each IC are connected on a ceramic substrate or a flexible cable. The STR signal is divided into several systems for use.

However, when the wiring connection of the driving IC as described above is made on the ceramic substrate, the output pad is set to 1
Since the input signals are concentrated on one side, the wiring for input signals is on the other side facing each other, and it is necessary to form a complicated wiring pattern on the substrate or perform multilayer wiring. Not only that, but to prevent the voltage drop of V _DD and GND, V _DD and G
Although the wiring pattern width corresponding to ND must be made as large as possible, it is difficult to form a pattern having a sufficient width in a limited wiring region because the output pads are arranged on one side. .

Further, when wiring is performed on a flexible cable, the number of signals at the connecting portion with the ceramic substrate increases, which leads to deterioration of reliability and high cost. in this way,
Considering the difference in the pattern resistance between the wiring on the ceramic substrate and the wiring on the flexible cable, and the relationship between the signal system necessary for using the IC and the unnecessary signal system, the conventional driving IC is a normal ceramic substrate. Alternatively, the wiring must be provided on either the flexible cable, but in reality, almost all the wiring is performed on the ceramic substrate or the flexible cable, which causes the problems such as the voltage drop and the deterioration of reliability.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a thermal print head which simplifies a wiring pattern, prevents a voltage drop in the wiring pattern, and improves reliability.

[0008]

In the thermal print head according to claim 1 of the present invention which achieves the above object, a glaze layer is formed on an insulating substrate, and a heating resistor is formed on the glaze layer. An electrode pattern for energizing a resistor is formed, and a driving IC for driving a heating resistor is provided. The driving IC generates heat along the vicinity of one side on the upper surface of the IC having a quadrangular shape in plan view. The resistor driving signal output pads are arranged at equal intervals, the GND input pad is arranged in the middle of both ends in the vicinity of the opposite side of this side, and the V _DD signal input pad and the STR signal are arranged between the GND input pads. Input pads for data, clock, and latch signals are arranged at equal intervals along the vicinity of one of the remaining sides, and data, clock, and latch signals are arranged along the vicinity of another remaining side. Latch signal Characterized in that it is made of the output pad arranged at equal intervals.

Further, in the thermal print head according to the present invention, a glaze layer is formed on the insulating substrate, a heating resistor is formed on the glaze layer, and a wiring pattern for energizing the heating resistor is formed to generate heat. Driving IC for driving resistor
In the driving IC, the output pads of the heating resistor driving signals are arranged at equal intervals along the vicinity of one side on the upper surface of the IC having a quadrangular shape in plan view, and the pads on the opposite side of this side are arranged. A GND input pad is arranged at both ends and in the middle of the vicinity, and a _VDD signal input pad and an S pad are provided between the GND input pads.
The TR signal input pad is arranged, the data, clock and latch signal input pads are arranged at equal intervals along the vicinity of one of the remaining sides, and the data signal is output near the other remaining side. It is characterized in that pads are arranged.

In the thermal print heads of claims 1 and 2, all the output pads of any driving IC are arranged near one side of the IC as in the conventional case, and all the input pads are arranged near the opposite side. Unlike the arrangement, the GND input pad, the V _DD signal input pad, and the STR signal input pad among all the pads are located near one side facing the side where the heating resistor driving signal output pad is provided. Placed in
An input pad for data, clock and latch signals is arranged near one of the remaining sides, and an output pad for data, clock and latch signals (only the data signal in claim 2) is arranged near another remaining side. I am doing it. That is, conventional IC
In contrast, while the pads are arranged only on two sides, in the IC in the thermal print head of the present invention, the signal system is classified in consideration of the signal necessary for control and the pattern resistance,
According to the signal system, the pads are also arranged on the other side orthogonal to the IC row, so that the wiring pattern can be simplified and the pattern width can be increased. As a result, the voltage drop in the wiring pattern is prevented, and the reliability of the thermal print head is improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. However, the present invention is characterized by the driving IC, and the forms of the glaze layer and the heating resistor on the insulating substrate are not particularly different from the conventional ones. Therefore, the driving IC and its wiring pattern will be mainly described below. .

FIG. 1 shows a plane of a driving IC in the thermal print head of the embodiment. This drive I
C1 is an output pad row 2 corresponding to 64 bits in the vicinity of one side (the upper side in the figure, the side on which the heating resistor exists).
Is provided. The output pad row 2 is composed of 64 output pads 21, and the output pads 21 are arranged in parallel at equal intervals. The output pad 21 outputs a signal for driving the heating resistor of the thermal print head, and sends each print output signal to the corresponding heating resistor.

In the vicinity of the opposite side of the upper side (lower side in the figure),
An input pad row 3 for GND, V _DD and STR signals is provided. In the input pad row 3, the input pad 31 in which two pads are arranged close to each other at both ends and in the middle is GND.
An input pad 32 for the V _DD signal and an input pad 33 for the STR signal are arranged between them. An input pad row 4 in which a clock signal input pad 41, a data signal input pad 42, and a latch signal input pad 43 are arranged in this order is provided near another one side (the left side in the drawing). An output pad row 5 for an output signal corresponding to each input signal is provided near the opposite side (right side in the figure). Clock signal input pad 41 and output pad 51, latch signal input pad 4
3 and the output pad 53 are connected by a pattern in the IC 1. The output pad row 5 includes a clock signal output pad 51, a data signal output pad 52, and a latch signal output pad 53.

In such a driving IC 1, one system of signals (clock, data, latch signal) is provided on the left and right sides of the IC.
Since the input / output pads are arranged, the signal system wiring pattern may be formed on the lower side of the IC and wire bonding may be performed between each pad and the wiring pattern, or between adjacent IC pads. You may wire-bond.
Further, since the spacing between the pads in the input pad row 3 arranged on the lower side (the side opposite to the side where the output pads are arranged) is sufficiently large, the signal system (GND, V _DD ,
Not only can the wiring pattern associated with the (STR) input pad be simplified, but the pattern can be made wider.

When this IC1 is mounted on a thermal print head, for example, a normal A4 size head (200
When applied to DPI, 27 64-bit IC1 shown in FIG. 1 are used. FIG. 2 is a diagram illustrating a connection form of each IC 1 when mounted on the head. GN arranged in the input pad row 3 for each (or 2 to 7) ICs
Connect each pad of D, V _DD and STR to the corresponding wiring pattern on the ceramic substrate by wire bonding, and
Three signals of ND, V _DD and STR are input from each pattern.

In order to combine the pads of other signals (clock, data, latch) in the input / output pad rows 4 and 5 into one system for all ICs, the wiring pattern of the other signal system is in the left and right direction under the IC1. This IC is formed parallel to
For No. 1, three wires corresponding to each pad are arranged in parallel. The connection between each input / output pad and the wiring pattern is performed by wire bonding. Alternatively, as shown in FIG. 2, the pads may be directly connected by wire bonding 60. Alternatively, direct wire bonding 60
In addition to the above, a relay point (pad) for wire bonding is provided between each IC, and the wire from the pad on the IC is bonded to the relay point, and the wire from the corresponding pad of the adjacent IC is also the same relay point. It does not matter how the bonding is performed.

Here, showing an actual size example of the 64-bit IC1 shown in FIG. 1, the dimension a is about 5 to 6 mm, and the dimension b is about 1.5 mm. When the IC1 of this size is wired as described above. Therefore, the pitch of the connection portion with the ceramic substrate on the flexible cable can be secured at about 2.7 mm. FIG. 3 is a partial view showing a head substrate on which a driving IC according to another embodiment is mounted. The driving IC 10 shown here is different from that shown in FIG. 2, and the pads 41, 42, 43 for the data, clock and latch signals are one of the sides orthogonal to the side on which the output pad row 2 is arranged. It is provided only on the side (the left side in the figure), and only the output pad 52 for the data signal is provided on the side (the right side in the figure) facing this side.

In this embodiment, wiring patterns 61, 6 for clock, data, and latch are formed on the upper surface of the substrate 20 in parallel with the output pad row 2 through the lower surface of each IC 10.
3 are formed, and between the ICs on the left and right sides of the ICs at the left and right ends and between the ICs, relay points (pads) 71, 41 corresponding to the pads 41, 42, 43 for each clock, data, and latch of the IC 72, 73 are provided, the relay points 71, 72, 73 on the left side of each IC 10 and the input pad 41,
42 and 43 are connected by bonding wires 81, 82 and 83. The data output pad 52 is connected to the data input relay point 42 on the right side of the IC 10. The data output pad 52 and the data input pad 42 of the next IC 10 may be directly connected by a bonding wire.

The IC 10 according to this embodiment does not require internal wiring for input and output for clock and latch signals.

[0020]

As described above, in the thermal print heads according to the first and second aspects of the present invention, the heating resistor driving ICs mounted on both are ICs having a quadrangular shape in plan view.
On the upper surface of the heater, a heating resistor driving signal output pad, a GND input pad, a V _DD signal input pad and S
An input pad for the TR signal, an input pad for the data, clock and latch signals, and an output pad for the data, clock and latch signals (only the data signal in claim 2) are separately arranged on each side according to the signal system. Therefore, when the IC is mounted on the head, the wiring pattern of the insulating substrate can be simplified or reduced, and the pattern width can be widened to reduce the pattern resistance. Therefore, the voltage drop in the wiring pattern is prevented, high reliability is obtained, and the cost is reduced.

Further, it is possible to meet a wide range of user custom requests.

[Brief description of drawings]

FIG. 1 is a plan view of a driving IC in a thermal print head according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a connection form of each IC when the IC of FIG. 1 is mounted on a thermal print head.

FIG. 3 is a diagram for explaining a mounting example of a driving IC and a connection form thereof in a thermal print head according to another embodiment of the present invention.

FIG. 4 is a plan view of a conventional general driving IC.

[Explanation of symbols]

1,10 Driving IC 2 Drive signal output pad row 3 GND, V _DD , STR signal input pad row 4 Clock, data, latch signal input pad row 5 Clock, data, latch signal output pad row

Claims (3)

[Claims] 1. A drive IC for driving a heating resistor by forming a glaze layer on an insulating substrate, forming a heating resistor on the glaze layer, forming a wiring pattern for energizing the heating resistor. In the provided thermal print head, the driving IC is mounted on the upper surface of the IC having a quadrangular shape in plan view.
Output pads for driving the heating resistor are arranged at equal intervals along the vicinity of the side, GND input pads are arranged at both ends and in the middle in the vicinity of the opposite side of this side, and V _DD is provided between the GND input pads. A signal input pad and an STR signal input pad are arranged, and data is provided along the vicinity of one of the remaining sides,
Clock and latch signal input pads are arranged at equal intervals, and data, clock and latch signal output pads are arranged at equal intervals along the vicinity of another remaining side. Print head. 2. A driving IC for driving a heating resistor, comprising forming a glaze layer on an insulating substrate, forming a heating resistor on the glaze layer, forming a wiring pattern for energizing the heating resistor. In the provided thermal print head, the driving IC is mounted on the upper surface of the IC having a quadrangular shape in plan view.
Output pads for driving the heating resistor are arranged at equal intervals along the vicinity of the side, GND input pads are arranged at both ends and in the middle in the vicinity of the opposite side of this side, and V _DD is provided between the GND input pads. A signal input pad and an STR signal input pad are arranged, and data is provided along the vicinity of one of the remaining sides,
A thermal print head, characterized in that input pads for clock and latch signals are arranged at equal intervals, and output pads for data signals are arranged near another remaining side. 3. Pads facing the input pads of the drive IC are formed in a wiring pattern portion on the substrate near the input pads of the data, clock and latch signals corresponding to the input pads of the drive IC. Then, a wiring pattern for individually connecting the pads of these wiring patterns is formed, and the input pad for the data, clock and latch signals of the driving IC and the corresponding pad of the wiring pattern are connected by a bonding wire. Claim 1 or Claim 2
The thermal print head described.