JPH0517895Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field This invention relates to an LED printing head used in an optical printer, and particularly relates to improvements in the wiring pattern on the printing head substrate.

(b) Prior art and its drawbacks In an LED printing head in which LED chips are mounted by wire bonding,
When designing a board for an LED head with a dot pitch of about 12 dots/mm, it is necessary to carefully consider the placement of the pads on the chip to ensure wire bonding. Therefore, conventional LED
In the printing head, pads on the top surface of the LED chip are provided on both ends of the light emitting part, that is, on both sides of the top surface of the chip, in order to achieve the precision of wire bonding.
Wire bonding is performed from the pads on both sides of the top surface of this chip to the upper and lower pads formed on the upper and lower sides of the board with the LED chip in between, and these upper and lower pads are mounted on the upper side of the LED array, respectively. drive IC
and the drive IC mounted on the lower side, respectively, using drive signal wiring patterns.
FIG. 6 is a diagram showing the arrangement of the LED array and drive IC of such an LED print head. In the figure, reference numeral 1 denotes a printing head substrate, on which an LED array 2 is mounted approximately in the center, and drive ICs 3 and 4 are mounted on the upper and lower parts thereof.

However, in the LED printing head configured as described above, since the driving ICs are arranged on both sides of the upper and lower sides of the LED array, the size of the head in the width direction becomes large, which hinders the trend toward miniaturization of optical printers.

Furthermore, in conventional LED heads, the width of the wiring pattern that connects the conductor pattern that contacts the common electrode formed on the bottom of the LED array and the common pattern formed at any position on the board is extremely narrow. Therefore, it was not possible to increase the current capacity. In other words, it is not possible to drive all the LED chips at the same time, and the drive must be divided, making it impossible to increase the speed. In order to solve this problem, the thickness of the wiring pattern that connects the common pattern and the common electrode conductor pattern can be made thicker, but this increases the number of times of printing, which complicates the process and increases costs. There was a drawback of doing so.

(c) Purpose of the invention The purpose of this invention is to improve the conductor pattern on the board, including the arrangement positions of the upper and lower pads, and to form the bottom of the LED array into a laminated structure. The object of the present invention is to provide an LED printing head that can be placed only on one side of an array, thereby reducing the overall size and increasing the current capacity.

(d) Structure of the idea This idea is structured as follows.

The LED array has pads formed on both sides of the top of each LED chip. Also, upper and lower pads are formed on the upper and lower parts of the substrate with this LED array in between, which are connected to the pads on the chip by wire bonding.

Further, the upper pad and the lower pad are formed in a staggered manner, and a plurality of conductor patterns spaced apart from each other are laminated on the plurality of conductor patterns at the bottom of the LED array, and a portion of each conductor pattern is opened. forming a printed film with a laminated structure consisting of a through-hole insulating film and a common electrode conductor film laminated on the through-hole insulating film, mounting an LED array on the common electrode conductor film, and mounting the LED array on the common electrode conductor film; A common pattern is formed above the upper pad, and conductor patterns connecting the common pattern and each of the plurality of conductor patterns are formed between the upper pads.

The wiring pattern on the board is configured as described above, and the driver IC is mounted on one side of the LED array.

With this configuration, the LEDs can be connected from the upper pad on the board formed on the top of the LED array.
A wiring pattern for drive signals can be formed up to the drive IC mounted at the bottom of the array. In other words, since each pad is formed in a staggered pattern at the upper and lower pads, it is possible to pass between the pads by bending the wiring pattern, and at the bottom of the LED array, the conductor patterns are spaced apart. The wiring pattern can be passed between them.

In addition, a common pattern is formed on the top of the LED array, and since the top pads are staggered and the drive IC is not mounted on the top of the LED array, they are formed at the bottom of the LED array at a distance from each other. Wiring patterns can be connected to the common pattern by stitching between the upper pads from a plurality of conductor patterns.

(d) Effect of the invention As described above, according to this invention, the upper and lower pads on the substrate formed on the upper and lower parts of the LED array are formed in a staggered manner, and
At the bottom of the LED array, there is a laminated layer consisting of a plurality of conductor patterns spaced apart from each other, a through-hole insulating film in which the conductor patterns have windows, and a common electrode conductor film laminated on the through-hole insulating film. Since the wiring pattern for driving signals from the upper pad and the lower pad is formed so as to thread between these pads and between the plurality of conductor patterns, the driving IC can be mounted on both the upper and lower parts of the LED array. Since this is no longer necessary, it only needs to be mounted on one of the two sides, and the size of the print head in the width direction can be reduced.

In addition, since the driver IC can be mounted on one side of the LED array, a common pattern can be formed on the side where the driver IC is not mounted, and since there is no driver IC on the side where the common pattern is formed, the common pattern can be formed on the side where the driver IC is not mounted. A wiring line connecting the pattern and the plurality of conductor patterns can be formed relatively easily. Further, in this invention, since the upper pad and the lower pad are staggered, there is an advantage that it is easier to form a wiring pattern connecting the common pattern and the plurality of conductor patterns.

(e) Embodiment FIG. 1 is a plan view of an LED printing head that is an embodiment of this invention, and FIG. 2 is a front view. The LED array 1 is mounted on an LED printing head substrate (not shown) made of ceramic, and this substrate is provided on a heat sink 2 made of aluminum or the like.
A convergent light transmitter 4 is arranged above the LED array 1. Both ends of the convergent light transmitting body 4 are fixed to holders 3 provided at both ends of the heat sink 2 . The LED array 1 includes:
Drive IC mounted on the above board behind it
(not shown) and is covered by a cover glass 5. This cover glass 5 protects the LED elements and wiring patterns by filling the inside with an inert gas such as nitrogen gas and sealing the periphery with a resin material. Further, behind the cover glass 5, the wiring from the drive IC is pulled out as a flexible cable, and the upper part thereof is covered with a cover 10 for protection. The end of the flexible cable is connected to a connector 7 provided protruding from the back surface of the heat sink 2.

FIG. 3 shows the LED array mounting portion of the LED printing head. FIG. 4 is a diagram showing a part of the wiring pattern of the LED printing head.

The LED array 1 consists of multiple LED chips,
A common electrode 10 for these chips is formed on the bottom surface. Each side of the top surface of LED array 1 has
A pad 11 of LED chips is formed. The LED is mounted on the substrate 20 made of ceramic.
A drive IC 30 is mounted on the lower side (front side) of the array 1. A conductor wiring pattern is formed on the substrate above the drive IC 30. As will be described later, the upper and lower pads included in this pattern are formed in a staggered manner. LED
At the bottom of the array 1, a plurality of conductor patterns 40 spaced apart from each other are formed. A drive signal wiring pattern 50 that connects the drive IC 30 and the upper and lower pads is threaded between the plurality of conductor patterns. Furthermore, a common pattern 60 is formed above the plurality of conductor patterns 40. This common pattern 60 is connected to the plurality of conductor patterns 40.

FIG. 4 shows a part of these wiring patterns. 70 is an upper pad, which is formed in a staggered shape. 80 is a lower pad, which is formed in a staggered manner like the upper pad. Upper pad 70
is connected to a chip-shaped pad 11 formed on the upper side of the chip top surface of the LED array 1 by wire bonding. The lower pad 80 is connected to a chip-shaped pad formed on the lower side of the upper surface of the chip by wire bonding. A plurality of conductor patterns 40 located at the bottom of the LED array are spaced apart from each other, and a drive signal wiring pattern 50 extends from the upper pad 70 between these conductor patterns. Further, these drive signal wiring patterns 50 are also sewn between the pads of the upper pad 70 and the lower pad 80. That is, the drive signal wiring pattern 50 is formed so as to thread between the upper pads, between the lower pads, and between the conductor patterns. In this case, since the upper pads 70 and the lower pads 80 are arranged in a staggered manner, the distance between adjacent pads is longer than the distance between adjacent pads when the pads are arranged in a row. Therefore, even if the emission dot pitch is as small as 12 dots/mm, the drive signal wiring pattern can be passed between the upper and lower pads.

A through-hole insulating film 90 is laminated on the plurality of conductor patterns 40 by printing. A window portion (through hole) 91 is formed in this through hole insulating film 90 at a portion corresponding to each conductor pattern 40 . A common electrode conductor film 100 is further laminated on this through-hole insulating film 90 by printing. The above conductor pattern 40, through-hole insulating film 90 and common electrode conductor film 100
Due to the laminated structure, the conductive pattern 40 and the common electrode conductive film 100 are connected to the through-hole insulating film 90.
The contact state is reached through the window portion 91 of. in this case,
The drive signal wiring pattern 50 passing between the conductor patterns 40 is insulated from the common electrode conductor film 100 by the through-hole insulating film 90 .

With the above configuration, the LED array 1 is adhered onto the common electrode conductor film 100 using silver paste or the like.
In other words, the common electrode 10 on the bottom of the LED array 1
The LED is in contact with the common electrode film 100.
Array 1 is implemented.

In the above configuration, first the conductor pattern 40, the wiring pattern 50, and the upper pad 7 are placed on the substrate 20.
0, a lower pad 80 and a common pattern 60 are printed as a first conductor, and then an insulating film 90 is formed.
is printed. Furthermore, after that, a common electrode conductor film 100 is printed and formed on the insulating film 90. After completing the printing process in this manner, the LED array 1, drive IC 30, etc. are attached.

FIG. 5 shows an enlarged sectional view of section A-A' in FIG. 4. In the figure, 110 indicates the first conductor such as the conductor pattern 40 and the drive signal wiring pattern 50, and 120 indicates the through-hole insulating film 90.
130 indicates the common electrode conductor film 100. Region A corresponds to the window portion 91 and is a portion where the first conductor 110 and the second conductor 130 are in contact with each other, that is, the conductor pattern 40 and the common electrode conductor film 100 are in contact with each other.

In this example, the upper pad and the lower pad are arranged in a staggered manner as described above, and at the bottom of the LED array, a through-hole insulating film with a conductor pattern and a window formed therein and a common electrode conductor film are arranged at a distance from each other. Because of the laminated structure, it is possible to easily extend the drive signal wiring pattern from each of the upper and lower pads to each drive IC arranged only at the bottom of the LED array. This allows the entire LED printing head to be made smaller.
It is possible to realize miniaturization of LED printers.
Furthermore, in this embodiment, a common pattern 60 having a relatively large area is formed above the LED array 40, and the conductor pattern 40 is connected to this common pattern 60, so that the current capacity of the common electrode can be increased. This makes it possible to simultaneously drive all chips in the LED array and achieve high-speed printing.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an LED printing head that is an embodiment of this invention, and FIG. 2 is a front view thereof. In addition, Fig. 3 shows the configuration of the LED array mounting part of the LED printing head, Fig. 4 shows a part of the wiring pattern on the LED printing head board, and Fig. 5 shows the section A-A' in Fig. 4. An enlarged cross-sectional view is shown. Also the 6th
The diagram shows the LED array and drive of a conventional LED printing head.
FIG. 3 is a diagram showing the arrangement of ICs. 1...LED array, 10...Common electrode, 1
1... Pad on chip, 20... Board, 30...
Drive IC, 40... Multiple conductor patterns, 50...
... Wiring pattern for drive signal, 60 ... Common pattern, 70 ... Upper pad, 80 ... Lower pad, 90 ... Through-hole insulating film, 100 ... Conductor film for common electrode.

Claims (1)

[Claim for Utility Model Registration] An LED array consisting of multiple LED chips with pads formed on both sides of the top surface of the chip and a common electrode formed on the bottom surface is mounted on a substrate.
Upper and lower pads connected to the pads are formed on the substrate on both sides of the LED array, and these upper and lower pads are connected to a driving IC.
In the LED printing head on which a wiring pattern for drive signals is formed to connect to the LED array, the drive IC is mounted on one side of the LED array, the upper pad and the lower pad are formed in a staggered pattern, and the bottom of the LED array is mounted on one side of the LED array. , a plurality of conductor patterns spaced apart from each other, a through-hole insulating film laminated on the plurality of conductor patterns and having a window in each conductor pattern, and a common electrode laminated on the through-hole insulating film. an LED array is mounted on the common electrode conductor film, and a common pattern is formed above the upper pad, and the common pattern and the plurality of conductor patterns are connected to each other. An LED printing head characterized in that a conductor pattern is formed between the upper pads to connect the upper pads to each other.