JPH04356978A - Picture device - Google Patents

Abstract

PURPOSE:To eliminate an increase in size of a picture device, to obviate an irregularity in height of a light receiving/emitting section and to prevent scattering of a light due to a data bus by connecting both ends of an electrode to data bus wirings on a transparent board, and bridge-connecting the wirings by electrodes of a light receiving/emitting element array. CONSTITUTION:A light receiving/emitting array 2 is flip chip-connected to a transparent board 12 by a face down bonding, data bus wirings 14 of the array 2 are provided on the board 12, and connected to electrodes 6 of the array. The electrodes 6 of the array are so formed as to longitudinally cross a light receiving/emitting surface, the wirings 14 of the board are removed at corresponding position of the light receiving/emitting surface, and the wirings 14 are formed in a bridge of the electrodes 6 of the array 2, and connected. Thus, an increase in size of a picture device due to a wire bonding can be eliminated, an irregularity in the height of a light receiving/emitting section can be obviated, and shut-off of a light from the light emitting section or to the light receiving section can be prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image device such as an LED printer head or an image sensor, and more particularly to a connection between an image element array and a transparent substrate.

0002

2. Description of the Related Art FIG. 9 shows a conventional image device. In the figure, 02 is a light emitting diode array, 04 is a light emitting part thereof, 06 is a substrate, and 08 is a data bus, and the data bus 08 and the electrode 010 are wire-bonded. However, this image device has a problem in that the size of the image device increases because wire bonding is used. This is because in order to prevent short-circuiting of the wire lines used for wire bonding, it is necessary to provide a large bonding interval. Further, in this image device, there is a problem in that variations in the height of the light emitting diode array 02 appear as variations in the height of the light emitting section 04, reducing focus accuracy.

[0003] As a countermeasure to these problems, face-down connection using a flip-chip method or the like can be considered. FIG. 10 shows an example of an image device using flip-chip connection (see Japanese Patent Laid-Open No. 62-261,465). In the figure, 012 is a flip-chip type light emitting diode array, 014 is a drive circuit provided for each light emitting diode array 012, and 016 is a data bus that connects the drive circuit 014 to the light emitting diode array 012. 018 is a common line and is used as a ground. In this conventional example, a light emitting diode array 012 is arranged face down on a transparent substrate, and individual electrodes and a common electrode are connected to the light emitting portion facing the transparent substrate. The individual electrodes are connected to a data bus 016 and the common electrode is connected to a common line 018. As is clear from the figure, this conventional example is not intended to be a dynamic drive (time division drive), but a static drive in which a drive circuit 014 is connected to each light emitting diode array 012.

When the flip-chip connection method shown in FIG. 10 is applied to the conventional example shown in FIG. 9, the problem shown in FIG. 11 occurs. In the figure, 08 is the data bus, 020 is a light emitting section, and 02
2 is an electrode bump connected to the individual electrode of the light emitting part 020, and 0
24 is a common electrode, and 026 is a transparent substrate. In this case, the wiring of the data bus 08 appears directly below the light emitting section 020, blocking light from the light emitting section 020. In the light emitting diode array 012, the light emitting parts 020 are usually formed at high density, and it is difficult to deform the data bus 08 and bypass the light emitting parts 020. Ultimately, this makes it difficult to apply it to a flip-chip type dynamic drive type image device.

[0005]

[Problems of the Invention] The object of this invention is to provide a face-down bonding method for a dynamic drive type image device, (1) to solve the problem of increasing the size of the image device due to wire bonding, and (2) to reduce the height of the light receiving and emitting element array. (3) prevent the data bus from blocking light from the light emitting section or from blocking light to the light receiving section; There is a particular thing.

[0006]

[Structure of the Invention] The image device of the present invention has a
A light receiving/emitting element array is arranged such that the light receiving/emitting parts face the substrate, and data bus wiring is arranged on the transparent substrate except for the position where the light receiving/emitting parts face each other, and the light receiving/emitting element array is The present invention is characterized in that electrodes are formed that run longitudinally through the light receiving and emitting parts, and both ends of the electrodes are connected to data bus wiring on a transparent substrate, and the data bus wiring is bridge-connected with the electrodes of the light receiving and emitting element array.

[0007]

According to the present invention, no data bus is provided at a position corresponding to the light receiving/emitting section, thereby preventing light scattering due to the data bus. In order to make this possible, electrodes are provided that traverse the light-receiving and emitting parts, and both ends of the electrodes are connected to the data bus, so that the data bus is bridge-connected by the electrodes.

[0008]

[Embodiment] An embodiment will be described using a printer head using a light emitting diode array as an example. FIG. 1 shows the main parts of the embodiment. In the figure, 2 is a light emitting diode array, 4 is a light emitting part thereof, 6 is an electrode provided vertically across the light emitting part 4, and 8 is a solder bump provided at both ends of the electrode 6. For example, Pb/Sn
Use materials. 10 is a common electrode of the light emitting diode array 2. 12 is a transparent substrate made of glass or the like, 14 is one wire of a data bus, and 16 is a lead foil connected to a common electrode.

FIG. 2 shows the surface of the light emitting diode array 2 on the transparent substrate 12 side. In the light emitting diode array 2, for example, 64 light emitting sections 4 are arranged in a straight line, and each light emitting section 4 is provided with an electrode 6 at right angles to the straight line. Here, the electrode 6 was shaped to vertically traverse the center of the light emitting section 4, and the data bus 14 was connected by the electrode 6 as a bridge. Further, the electrode 6 has an area as small as possible, and is cut vertically through the center of the light emitting part 4 so that current can be uniformly supplied to the entire surface of the light emitting part 4. This electrode 6 also has a feature that even if the position of the electrode 6 is shifted in the vertical direction in the figure with respect to the light emitting part 4, the performance is not affected. It is important that the electrodes be able to cross the light emitting section 4 for bridge connection to the data bus 14 and to be able to uniformly supply current to the light emitting section 4. Another such example is shown in FIG. 3 is a new light emitting diode array, and 7 is a □-shaped electrode that covers the edge of the light emitting section 4. A feature of the electrode 7 is that even if the electrode 7 is shifted vertically or horizontally within the range indicated by x in the figure, the state of contact with the light emitting section 4 does not change much, and the performance is not affected. The electrode may be any electrode that traverses the light emitting section 4.

FIG. 4 shows the main part of the data bus wiring 14, and FIG.
2 shows the entire data bus 20. A solder bump 18 corresponds to the solder bump 8, and the data bus wiring 14 is cut at a portion corresponding to the electrodes 6 and 7. FIG. 6 shows the wiring on the board 12 before the light emitting diode array 2 is mounted, and FIG. 7 shows the wiring on the board 12 after the light emitting diode array 2 is mounted. 20 is a data bus, which connects electrode 6 of light emitting diode array 2;
, 7 are provided. The data bus 20 is folded back for each light emitting diode array 2 and arranged in a zigzag shape. Reference numeral 22 denotes wiring for connection to the common electrode 10, and is arranged between the data buses 20 that are folded back in a zigzag manner. 24 is a drive circuit for time division drive, which supplies data to the light emitting section 4 via the data bus 20. In the state shown in FIG. 6, the light emitting diode array 2 is positioned, and the solder bumps 8 and 18 are melted and soldered. Also common electrode 1
The lead foil 16 previously bonded to the wire 22 is soldered to the wire 22, and the common electrode 10 is connected to the wire 22. The common electrode 10 may be connected by wire bonding, and the common electrode 1
If 0 can be drawn out to the surface on the side of the light emitting part 4 and there is room for soldering, flip-chip connection may be performed face-down like the electrodes 6 and 7.

FIG. 8 shows a block circuit of the embodiment. For example, 40 light emitting diode arrays 2 are arranged face down in a straight line, a data bus 20 is connected between them by turning them in a diagonal manner, and data is supplied from a drive circuit 24. Further, the wiring 22 connected to the common electrode 10 is connected to, for example, 40 switching transistors T1 to Tn provided on another substrate 32, and the transistors T1 to Tn are turned on one by one to emit light at a duty ratio of 1/40. Time-division driving is performed for each diode array 2.

[0012] The features of the embodiment will be explained. Since the data bus wiring 14 is not provided at the position of the light emitting section 4, there is no loss of light due to the wiring 14, and the light from the light emitting section 4 is transferred to the transparent substrate 12.
Output via. A part of the light emitting section 4 is covered with electrodes 6 and 7, which are originally essential, and are arranged so as to uniformly supply current to the entire surface of the light emitting section 4 with a minimum electrode area. Furthermore, the electrodes 6 and 7 are arranged so that even if their positions shift, the effect on the light emission performance is minimized. Furthermore, the disconnected data bus wiring 14 is bridged and connected using electrodes 6 and 7. Since the connection uses soldering instead of wire bonding, there are no problems such as short circuits in the wires.
The bonding process is also simple, and the imaging device becomes smaller. Since the light emitting section 4 is arranged to face the transparent substrate 12,
Even if the height of the light emitting diode array 2 varies, the height of the light emitting section 4 does not vary.

Although the embodiment uses a light emitting diode array 2, a light receiving element array may be used instead of the light emitting diode array. In addition, a flip-chip method was used for connection with the data bus wiring, but beam leads were connected to the electrodes 6 and 7, and these beam leads were connected to the data bus wiring 1.
It may be connected to 4.

[0014]

[Effects of the Invention] This invention provides the following effects. (1) It is possible to eliminate the increase in the size of the image device due to wire bonding. (2) Due to variations in the height of the light receiving and emitting element array,
Variations in the height of the light receiving and emitting parts can be eliminated. (3) The data bus can prevent light from the light emitting section from being blocked or light from the light receiving section from being blocked. (4) By bridge-connecting the data bus with the electrodes of the light receiving and emitting element array, it becomes easy to connect the data bus to a large number of arrays and dynamically drive it.

[Brief explanation of the drawing]

[Figure 1] Cross-sectional view of the main parts of the imaging device of the example

[Figure 2]
Plan view showing electrode arrangement of image element array used in Examples

[Figure 3] A plan view showing a modification of the electrode arrangement of the image element array used in the example.

[Figure 4] Plan view showing data bus wiring on a transparent substrate used in the example

[Figure 5] A perspective view showing the data bus wiring on the transparent substrate used in the example

[Figure 6] Plan view of the embodiment before mounting the image element array

[
Figure 7: Plan view of the embodiment after mounting the image element array

[Figure 8] Block diagram of the embodiment

[Figure 9] Perspective view of a conventional imaging device

[Figure 10]
Block diagram of other conventional examples

[Figure 11] Cross-sectional view showing the problems of the conventional example in Figure 10

[Explanation of symbols]

2. Light emitting diode array 4 Light emitting part 6,7 Electrode 8 Solder bump 10 Common electrode 12 Transparent substrate 14 Data bus wiring

Claims (1)

[Claims] 1. A light emitting/receiving element array is arranged on a transparent substrate so that the light emitting and receiving parts face the substrate, and data bus wiring is arranged on the transparent substrate except for the position where the light receiving and emitting parts face each other. At the same time, an electrode is formed on the light receiving/emitting element array to extend across the light receiving/emitting section, and both ends of the electrode are connected to the data bus wiring on the transparent substrate, so that the data bus wiring is connected to the electrode of the light receiving/emitting element array. An imaging device characterized by being bridge-connected.