JPH04332664A - Led printing head - Google Patents

Abstract

PURPOSE:To provide a connector on a single LED printing head substrate in an LED printing head. CONSTITUTION:Anode electrodes A11-1, A11-2 are provided on the both sides of each LED element A10. A wiring pattern provided with wire bonding pads A3-1, A3-2, A4-1, A4-2 to be connected to the anode electrodes of the LED elements A10 is provided on the both sides of LED array chips A5-1-A5-40 provided on an LED printing head substrate A1. The pattern width and distance of the wiring pattern serving as the wire bonding pads A3-1, A3-2, A4-1, A4-2 are both determined to be 50mum or more. In this manner, a wiring pattern can be formed by an etching technique by increasing a wiring pattern pitch. Therefore, a hard printing wiring board can be used, and through holes for connecting a connector can be perforated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED print head used in electrophotographic recording devices such as page printers and plain paper recording facsimiles.

0002

[Prior Art] There are two driving methods for LED print heads: a direct drive method in which one drive element drives one LED element, and a dynamic drive method in which one drive element drives multiple LED elements in a time-division manner. Can be divided. Among these, the dynamic drive method is a drive method that can reduce the cost because it can reduce the number of drive control ICs (drive control elements) in which drive elements are integrated.

[0003] A conventional LED print head using this dynamic drive system will be explained below with reference to the drawings.

FIG. 5 shows an A4 size, 300 dp resolution using a 64-bit LED array chip and drive control IC.
This figure shows a conventional example of a dynamic drive type LED print head board of i (Conventional Example 1).

A bundle B2 of 64 aluminum thin film patterns is formed in a meandering manner on the surface of the glass substrate B1, and bonding pads B3 for wire bonding are provided at both ends and at necessary parts in the middle. ing. Near the bonding pad B3, there is a corresponding L.
ED array chips B4-1 to B4-40 and drive control ICBs 5-1 and B5-2 are die-bonded.

[0006] Here, LED array chips B4-1 to B
4-40 is located on the bundle B2 of the aluminum patterns, so it is die-bonded onto the common wiring patterns B7-1 to B7-40 via the insulating layer B6 (see FIG. 6) using an inductive paste such as silver paste. The cathode electrode on the back surface of the LED array chip and the common wiring pattern are electrically connected.

[0007] Also, drive control ICB5-1, B5-2
Input and power supply patterns B8-1 and B8-2 are also formed near the drive control ICBs 5-1 and B8-2, respectively.
It is connected to the input terminal and power supply terminal of 5-2 by a gold wire. Similarly, the output terminals of the drive control ICBs 5-1 and B5-2 and the anode electrodes of the LED array chips B4-1 to B4-40 (64 pieces each) are connected to the corresponding portions of the bonding pad B3 using gold wires B9 (see FIG. 6). ) is wire bonded.

Looking at the connections on the output side of the drive control ICB 5-1 and B5-2, the output terminal of the drive control ICB 5-1 matches the output terminal of the LED array chip B4.
It can be seen that -2, B4-4, . . . , B4-40 are even numbers. Similarly, the odd-numbered LEDs match the output terminals of the drive control ICB 5-2.
It is an array chip. Therefore, even-numbered LED array chips are driven by the drive control ICB 5-1, and odd-numbered LED array chips are driven by the drive control ICB 5-2.

The overall structure of the substrate according to the first conventional example will be explained with reference to FIG. Since it is not possible to mount electrical components such as connectors and capacitors for connection with external circuits on the glass substrate B1, the F with reinforcement plate B10 is
It is configured in combination with a PC (flexible board) B11, and a connector B12, a capacitor (not shown), etc. are mounted on the FPCB11. Glass substrate B1
The electrical connection between the FPCB 11 and the FPCB 11 is made by pressure contact using a rubber B13. In addition, glass substrate B1 and FPCB
The pattern of the pressure contact portion B14 with 11 is plated with gold to improve the reliability of pressure contact.

Next, another conventional example will be explained with reference to FIG. FIG. 7 is also an example of A4 size and 300 dpi resolution using a 64-bit LED array chip and drive control IC (Conventional Example 2).
A bundle C3 of 64 wiring patterns for connecting each of the anode terminals 5-1 to C5-40 is wired in a matrix on the glass substrate C2. This matrix wiring is formed by laminating two layers of aluminum thin film patterns with an insulating film interposed therebetween, and the upper and lower aluminum thin film patterns are connected through contact holes as necessary.

The glass substrate C2 is a double-sided hard printed wiring board C.
LED array chips C5-1 to C5-40 and drive control ICC 6 are attached on the double-sided hard printed wiring board at positions corresponding to bonding pads 4 for wire bonding on the glass substrate. It is die-bonded to. The bonding pad C4 and the anode electrodes of the LED array chips C5-1 to C5-40 and the output terminal of the drive control ICC6 are wire-bonded using a gold wire C9 (see FIG. 8). LED array chip C5-
The cathode electrodes on the back surfaces of C1 to C5-40 are electrically connected to the common wiring patterns C7-1 to C7-40, respectively, using conductive paste such as silver paste. Further, the input terminal and power supply terminal of the drive control ICC 6 are wire-bonded to the input and power supply pattern C8.

Output terminal of drive control ICC6 and LE
Anode electrode 6 of D array chips C5-1 to C5-40
Since the order of all four pieces matches, drive control IC1
All 40 LED array chips can be driven in a time-division manner with a single chip.

The overall structure of the substrate according to the second conventional example will be explained with reference to FIG. Glass substrate C2 on which the matrix wiring was formed, LED array chips C5-1 to C5-
40 and the drive control ICC 6 are mounted on the double-sided rigid printed wiring board C1 as already mentioned, and the connector C10 for connection with an external circuit and electrical components such as capacitors (not shown) are also mounted on the double-sided hard printed wiring board C1. It is mounted on a rigid printed wiring board C1.

Next, the LED array chips used in Conventional Examples 1 and 2 will be explained with reference to FIG.

[0015] LED element (light emitting part) D1 is 300 dpi
There are 64 LED elements lined up in a straight line with a pitch corresponding to 84.7 microns (approximately 84.7μ pitch), and each LED element is connected to an anode electrode D2 for wire bonding arranged in a staggered manner. On the other hand, the cathode electrode is common to each LED element and is formed on the back surface of the chip. Book LED
GaAsP is usually used as the material for the array chip.

[0016]

[Problems to be Solved by the Invention] In the case of an LED print head with A4 size and resolution of 300 dpi using a 64-bit LED array chip and a drive control IC,
The anode electrodes of the array chip are arranged in a staggered manner with a pitch of about 83 μm, so the pitch of the corresponding bonding pads on the substrate side (dimension B in Figure 10) is also set to 83 μm to match the pitch of the anode electrodes. There is a need.

However, in order to arrange the bonding pads in a staggered manner with a width of 83 μm on the substrate, if the width of the bonding pads is 100 μm, the dimension A in FIG. 10 must be 66 μm.
The distance is .mu.m, and it is necessary to pass one pattern through this interval. A dimension is about 110μm at 200dpi, 300dp
Naturally, at a resolution higher than i, the resolution is 66 μm or less.

[0018]Thus, a thin film technology or a thick film technology is used, which requires the use of a highly heat-resistant substrate such as a glass substrate or a ceramic substrate. Glass substrates and ceramic substrates are expensive and have poor workability, that is, it is virtually impossible to drill holes, so it is impossible to mount connectors for connection with external circuits. For this reason, LED printheads are constructed in combination with rigid printed wiring boards or FPCs, but this increases the cost of LED printheads.

In view of the above, the present invention provides an LED that enables a connector for connection to an external circuit to be mounted on a single LED print head board, thereby reducing manufacturing costs.
The purpose is to provide print heads.

[0020]

[Means for Solving the Problems] (1) The problem solving means according to claim 1 of the present invention is as shown in FIGS. 1 to 4, in which a plurality of LED elements are Dynamic drive type LED that drives A10 in time division
In the print head, the LED print head board A
-1, LED array chips A5-1 to A5-40 each having a plurality of LED elements A10 arranged in a row;
Each LED of the LED array chips A5-1 to A5-40
Drive control elements A6-1 and A6 that drive and control element A10
-2 and a connector A9 for connection with an external circuit are mounted, and an anode electrode A is mounted on both sides of the LED element A10.
11-1, A11-2 are arranged, and the LED print head board A-1 is connected to the LED array chip A5-1.
~A wiring pattern having wire bonding pads A3-1, A3-2, A4-1, A4-2 connected to the anode electrodes A11-1, A11-2 of each LED element A10 is formed on both sides of A5-40. It is what was done.

(2) The problem solving means according to claim 2 is that the LED print head board A-1 according to claim 1 has wire bonding pads A3-1, A3-2, A4-1,
Both the pattern width and the pattern interval of the wiring pattern in the portion A4-2 are 50 μm or more.

(3) The problem solving means according to claim 3 is that a single double-sided rigid printed wiring board is used as the LED print head board A-1 according to claims 1 and 2, and on the double-sided rigid printed wiring board, , LED array chip A5 according to claim 1.
-1 to A5-40, drive control elements A6-1, A6-2, and connector A9 are mounted.

[0023]

[Operation] In the above problem solving means, each LED element A1
0, anode electrodes A11-1 and A11-2 are arranged on both sides of the LE mounted on the LED print head board A1.
Each LED on both sides of D array chips A5-1 to A5-40
Wire bonding pads A3-1 and A3-2 connected to anode electrodes A11-1 and A11-2 of element A10
, A4-1, A4-2, wire bonding pads A3-1, A3-2 are formed.
, A4-1, and A4-2, both the pattern width and the pattern interval can be set to 50 μm or more.

In this way, the wire bonding pad A
By setting the pattern width and pattern spacing of the wiring patterns in the portions 3-1, A3-2, A4-1, and A4-2 to 50 μm or more, the wiring pattern pitch can be widened to 100 μm or more, so the wiring pattern can be etched. Can be formed using technology. Therefore, there is no need to use a glass substrate or a ceramic substrate as the LED print head substrate as in the past, and a normal hard printed wiring board can be used.

This rigid printed wiring board A1 is inexpensive, has good workability, and can be processed with through holes, so if wiring patterns are provided on both sides of the rigid printed wiring board A1, it can be used as a glass substrate or The connector A9 for connection with an external circuit can be mounted on the double-sided rigid printed wiring board A1 without combining the ceramic substrate with a rigid printed wiring board or FPC. Therefore, a single double-sided rigid printed wiring board is sufficient as the LED print head board.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a plan view of a main part of a substrate used in an LED print head according to an embodiment of the present invention, FIG. 2 is a sectional view of the entire substrate, and FIG. 3 is a diagram showing bonding pads provided on the substrate. FIG. 4 is a diagram showing the wiring pattern pitch of the same portion, and FIG. 4 is a diagram showing the configuration of the LED array chip.

As shown in the figure, this embodiment uses a 64-bit L
A4 width, 300d resolution using a drive control IC (drive control element) that integrates an ED array chip and drive elements.
This is a dynamically driven LED printhead from Pi.

First, in FIG. 4, the LEDs used in this example are shown.
Let's explain about array chips. LED element (light emitting part)
A10 supports 300dpi pitch (approx. 84.7μ
64 anode electrodes A1 are arranged in a straight line in a pitch (pitch) and connected to the odd numbered LED elements on one side.
1-2 and the anode electrode A11-2 connected to the even-numbered LED elements on the opposite side are each 166 μm.
They are arranged in a straight line. On the other hand, the cathode electrode is common to each LED element and is formed on the back surface of the chip. GaAsP is usually used as a material for LED array chips.

Next, the structure of the LED print head board of this embodiment will be explained with reference to FIG. Thirty-two copper foil pattern bundles A2-1 and A2-2 are formed on the surface of a normal double-sided rigid printed wiring board A1, and bonding pads A3 for wire bonding are provided at both ends and at necessary parts in the middle. -1, A3-2, A4-1 and A4-2 are provided. The wiring pattern pitch of this part (B in Figure 3)
The dimensions) are 100 μm (pattern width 50 μm, pattern spacing 50 μm), and the distance between bonding pads (A in Figure 3) is 100 μm (pattern width 50 μm, pattern interval 50 μm).
dimension) is 66 μm (the bonding pad width is 10
The pitch is 0 μm) and can be formed using a normal hard printed wiring board.

[0031] And bonding pads A4-1, A
In the vicinity of bonding pads A3-1 to A3-2, LED array chips A5-1 to A5-40 are arranged in the vicinity of bonding pads A3-1 to A3-2, and LED array chips A5-1 to A5-40 are arranged in the vicinity of bonding pads A3-1 to A3-2. ICA6-1 for drive control,
A6-2 is die-bonded. The LED array chips A5-1 to A5-40 are die-bonded onto the common wiring pattern (not shown) using conductive paste such as silver paste, so the cathode electrode on the back of the chip and the common wiring pattern are electrically connected. The common wiring pattern is connected to the back side of the double-sided rigid printed wiring board A1 through a through hole, and is connected to the connector A9 (see Figure 2) for connection to an external circuit using the back pattern. . In addition, input and power patterns A7-1 and A7-2 are also formed near the drive control ICAs 6-1 and A6-2, and the input terminals and power supply patterns of the drive control ICAs 6-1 and A6-2 are respectively formed. Connected to the terminal with gold wire. Similarly, each of the 64 output terminals of the drive control ICAs 6-1 and 6-2 is connected to the corresponding portions of the bonding pads A3-1 and A3-2, respectively, to the LED array chips A5-1 to A5-4.
Each of the 64 anode electrodes of No. 0 is wire-bonded to corresponding portions of bonding pads A4-1 and A4-2 using gold wires (see FIG. 2).

Looking at the connections on the output side of the drive control ICA 6-1, the output terminals of the drive control ICA 6-1 and A6-2 match the output terminals of the LED array chip A5-1.
1, A5-3, . . . A5-39, it can be seen that it is an odd number. Similarly, even-numbered LED array chips match the output terminals of the drive control ICA 6-2. Therefore, the odd-numbered LED array chips are connected to the even-numbered LEDs by the drive control ICA6-1.
The D array chip is driven by the drive control ICA 6-2.

Conversely, in order to drive the even-numbered LED array chips with the drive control ICA 6-1 and the odd-numbered LED array chips with the drive control ICA 6-2, the LE
Form a pattern so that the bonding pads corresponding to No. 1 and 2 of the anode electrode of D array chip A5-1 are placed near the LED array chip, and the bonding pads corresponding to No. 63 and 64 are placed far from the LED array chip. This is possible by doing the following.

Furthermore, a drive control IC in which the order of output terminals is arranged in a staggered manner, which is opposite to that of the drive control IC shown in FIG.
This can be done by using an LED array chip in which the anode electrodes of the LED array chip are arranged such that even numbered electrodes are placed at positions A11-1 and odd numbered positions are placed at positions A11-2.

Since the board A1 is a double-sided rigid printing board, as shown in FIG.
9. Electrical components such as capacitors (not shown) can also be mounted on the double-sided printed wiring board A1, so this single board is sufficient as the board for the LED print head.
The cost of the D print head can be significantly reduced.

That is, the anode electrodes A11-1 and A11-2 are arranged on both sides of each LED element A10, and the LED array chip A is mounted on the LED print head board.
Wire bonding pads A3-1, A3-2, A4-1, A4- connected to the anode electrodes A11-1, A11-2 of each LED element A10 on both sides of 5-1 to A5-40.
2, wire bonding pads A3-1, A3-2, A4-1, A4-
Both the pattern width and the pattern interval of the wiring pattern of the portion 2 can be set to 50 μm or more.

In this way, the wire bonding pad A
By setting the pattern width and pattern spacing of the wiring patterns in the portions 3-1, A3-2, A4-1, and A4-2 to 50 μm or more, the wiring pattern pitch can be widened to 100 μm or more, so the wiring pattern can be etched. Can be formed using technology. Therefore, there is no need to use a glass substrate or a ceramic substrate as the LED print head substrate as in the past, and a normal hard printed wiring board can be used.

This rigid printed wiring board A1 is inexpensive, has good workability, and can be processed with through holes, so if wiring patterns are provided on both sides of the rigid printed wiring board A1, it can be used as a glass substrate or The connector A9 for connection with an external circuit can be mounted on the double-sided rigid printed wiring board A1 without combining the ceramic substrate with a rigid printed wiring board or FPC.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, the present invention is applicable to LED printheads with resolutions other than 300 dpi and to LED printheads using common anode type LED array chips.

[0041]

[Effects of the Invention] As is clear from the above explanation, according to the present invention, a double-sided rigid printed wiring board is used instead of a conventional combination of two substrates, a glass substrate or a ceramic substrate, and a rigid printed wiring board or FPC. Since it can be achieved with a single piece, LE
This has an excellent effect in that it becomes possible to significantly reduce the cost of the D print head.

[Brief explanation of drawings]

FIG. 1 is a plan view of a main part of a substrate used in an LED print head according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the entire substrate.

FIG. 3 is a diagram showing the wiring pattern pitch of a portion where bonding pads are provided on the same substrate.

FIG. 4 is a diagram showing the configuration of an LED array chip.

FIG. 5 is a plan view of a main part of a substrate used in an LED print head according to Conventional Example 1.

FIG. 6 is a sectional view of the entire substrate.

FIG. 7 is a plan view of a main part of a substrate used in an LED print head according to Conventional Example 2;

FIG. 8 is a sectional view of the entire substrate.

FIG. 9 is a diagram showing the configuration of an LED array chip used in the LED print head according to Conventional Examples 1 and 2.

FIG. 10 is a diagram showing the wiring pattern pitch of a portion where bonding pads are provided on the same substrate.

[Explanation of symbols]

A1 Double-sided rigid printed wiring board A2-1, A2-2 Bundle of 32 copper foil patterns A3-1, A3-2, A4-1, A4-2 Wire bonding pads A5-1 to A5-40 LED array chip A6 -1
, A6-2 Drive control ICA7-1, A7-2
Input, power pattern A8 Gold wire A9 Connector A10 LED element

Claims (3)

[Claims] [Claim 1] Multiple LEs in one drive control element
Dynamic drive LED that drives D elements in time division
In the print head, a plurality of LED elements are arranged in a row on an LED print head substrate.
A D array chip, a drive control element for driving and controlling each LED element of the LED array chip, and a connector for connection with an external circuit are mounted, anode electrodes are arranged on both sides of the LED element, and the LED print head is mounted with an anode electrode on both sides of the LED element. The substrate is characterized in that a wiring pattern having wire bonding pads connected to an anode electrode of each LED element is formed on both sides of the LED array chip.
D print head. 2. The LED print head board according to claim 1, wherein the pattern width and the pattern interval of the wiring pattern in the portion that becomes the wire bonding pad are both 50 μm or more. 3. A single double-sided rigid printed wiring board is used as the LED print head board according to claims 1 and 2,
An LED print head characterized in that the LED array chip, drive control element, and connector according to claim 1 are mounted on the double-sided rigid printed wiring board.