JP2002158371A - Photoelectric conversion module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion module which does not easily interfere with an electromagnetic wave from outside and has the emission of an electromagnetic wave from itself to a degree free from causing a trouble in practical use, and to provide an electric circuit forming an inductance element and (or) a capacitance element by providing a circuit pattern on an electronic circuit board. SOLUTION: A photoelectric conversion module is obtained by arranging a component consisting of a light emitting element 2, a light receiving element 3 and a driver IC4 for driving these elements on the surface of an electric circuit substrate 1. The whole component except for the path of light is covered with a shielding case 5, the electronic circuit substrate is made from electromagnetic wave absorption material 52 obtained by diffusing soft magnetic material powder in the matrix of synthetic resin, and the shielding case is made from electromagnetic wave absorption material obtained by diffusing soft magnetic material powder in the matrix of synthetic resin on both of the sides of a foil made of soft magnetic metal. The electric circuit consisting of the inductance element and the capacitance element is formed on the electronic circuit board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a photoelectric conversion module, and provides a photoelectric conversion module in which interference of electromagnetic waves is prevented and signal transmission by optical communication is ensured.

[0002]

2. Description of the Related Art Infrared light is widely used to wirelessly exchange signals between various electronic devices, OA devices, and FA devices. This communication requires conversion between an electric signal and an optical signal, and for this purpose, a photoelectric conversion module in which a light emitting element (LED) and a light receiving element (PD) are normally used is used. ing.

[0003] Although optical communication itself has the advantage that it is not affected by electromagnetic waves, the effects of electromagnetic waves cannot be avoided because the photoelectric conversion module is an electronic device. In addition to being disturbed by an external electromagnetic wave, there is a possibility that the electromagnetic wave itself generates an electromagnetic wave and interferes with other electronic devices. In order to prevent or reduce such interference by electromagnetic waves, various shielding means have been sought.

The present inventors have also pursued means for shielding electromagnetic waves in a photoelectric conversion module, and have found that it is effective to use an electromagnetic wave absorbing material obtained by dispersing a soft magnetic substance powder in a synthetic resin matrix. The headline and the way of application to specific photoelectric conversion modules were established.

[0005]

SUMMARY OF THE INVENTION Accordingly, a general object of the present invention is to establish an electromagnetic wave from the outside, which has been established by the inventors, and to reduce the emission of the electromagnetic wave from itself. An object of the present invention is to provide a photoelectric conversion module reduced to a level that does not hinder the photoelectric conversion module. A special object of the present invention is to provide such a photoelectric conversion module in which an inductance element and / or a capacitance element are formed by providing a circuit pattern on an electronic circuit board.

[0006]

A basic aspect of a photoelectric conversion module according to the present invention, which meets the above-mentioned objects, is as shown in FIGS. 1 and 2, in which a light emitting element (1) is provided on the surface of an electronic circuit board (1). 2) and / or a light-receiving element (3) and a photoelectric conversion module in which components including a driver IC (4) for driving these elements are arranged. The electronic circuit board (1) is made of an electromagnetic wave absorbing material obtained by dispersing a soft magnetic substance powder in a synthetic resin matrix, and the shielding case (5) is made of a soft magnetic metal. An electromagnetic wave absorbing material (52) obtained by dispersing a soft magnetic substance powder in a synthetic resin matrix is used on both sides of the foil (51).

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As is often the case, the back side of an electronic circuit board (1) is usually covered on its entire surface with a GND layer (1) formed by bonding a conductor layer, for example, a rolled copper foil.
1) is provided, and the end of the soft magnetic metal foil (51) constituting the shielding case (5) is preferably connected to this GND line through the through hole (12).

[0008] Most photoelectric conversion modules have both a light emitting element and a light receiving element. It is recommended to provide a partition wall (53) of an electromagnetic wave absorbing material in which a powder of a soft magnetic substance is dispersed in a matrix of a synthetic resin. Thereby, the effect of isolation between the light receiving element and the light emitting element can be obtained.

Suitable soft magnetic substance powders dispersed in a synthetic resin matrix include ferrite, sendust, Fe, Fe-Si alloy, Fe-Ni alloy, Fe-Ni alloy.
It is a powder of a soft magnetic substance selected from a Co alloy and an Fe-Cr-Al alloy.

The synthetic resin used as the matrix is preferably selected from polyphenylene sulfide, epoxy resin and liquid crystal polymer (LCP). The electronic circuit board is not limited to a single layer, but may be a multilayer of two or three or more layers. Adhesion between layers in the case of a multi-layer may be achieved by using, for example, an epoxy resin.

As shown in FIG. 3, a modification of the photoelectric conversion module according to the present invention is an electronic circuit comprising an inductance element and / or a capacitance element in addition to the above components on an electronic circuit board (1). Is also formed. Means for forming such an electronic circuit on the substrate are arbitrary, such as screen printing of conductive ink, bonding and etching of rolled copper foil, electroless plating and subsequent electrolytic plating. Metal insert injection molding is also available.

In the example of FIG. 4, a GND line (11) is provided on the back surface of the electronic circuit board (1), and between the circuit pattern (6) formed on the front surface and the GND line (11),
The capacitance element is formed. This capacitance becomes, for example, a part of an oscillation circuit or a noise filter (low-pass filter).

FIG. 5 shows an example in which the electronic circuit board has a multilayer structure of two or more layers, circuit patterns are provided between layers, and a circuit pattern (61) formed on the surface and a circuit pattern (62) between layers are provided. The capacitance element is formed between them.

[0014]

EXAMPLE A liquid crystal polymer was used as a matrix material, and Fe-Cr-Al alloy powder (particle size: 20 μm) was used.
Hereinafter, 50% by volume of substantially spherical powder) was added to obtain a uniform mixture. This is extruded from a die and has a thickness of 1
mm, a sheet containing soft magnetic powder. A copper foil having a thickness of 18 μm was adhered to the back surface of this sheet with an epoxy resin adhesive to prepare an electronic circuit board having a GND line. Separately, a thickness of 12 μm between two sheets containing the same soft magnetic powder
One side wall was chipped by press forming under heating with the electromagnetic stainless steel foil interposed (to allow infrared light of LED to pass)
A shallow box-shaped shielding shield was manufactured. The end of the electromagnetic stainless steel foil is out of the sheet.

An infrared light emitting LED and its driver IC were mounted on the above-mentioned electronic circuit board, and the above was covered with the shielding case. The end of the electromagnetic stainless steel foil was connected to a GND line through a through hole.

While operating with the battery connected to the LED drive IC, the intensity of the electromagnetic wave around the shielding case is reduced by
The measurement was performed using a combination of a nearby electromagnetic field measuring instrument “ESV3000” (manufactured by Noise Laboratories, antenna probe band: electric field 250 to 1500 MHz) and a spectrum analyzer “MS2651A” (manufactured by Anritsu). For comparison, a circuit board in which the same circuit as described above was formed on a conventional glass fiber-containing epoxy resin board was also prepared.

As an example of the measurement results, 987 to 1020
FIGS. 6 (prior art) and FIG. 7 (embodiment) show contour maps of the electric field intensity in the region of MHz. From a comparison between FIG. 6 and FIG. 7, it was found that there was a difference of 15 dB in the electric field strength on the driver IC, and the effect of the present invention was confirmed.

[0018]

According to the present invention, it is possible to obtain a photoelectric conversion module which is substantially free from the influence of external interference electromagnetic waves and which is sufficiently shielded from the electromagnetic waves emitted from itself. By using this, it is possible to perform optical communication that is less likely to be affected by noise, and it is possible to fully enjoy the benefit of communication accuracy for various FA devices and OA devices. An embodiment in which a circuit pattern is provided on an electronic circuit board has a filter or other performance as a photoelectric conversion module.

Since the photoelectric conversion module of the present invention is easy to manufacture and suitable for mass production, the cost is low and it can be used in a wide range of fields.

[Brief description of the drawings]

FIG. 1 is a plan view showing a basic mode of a photoelectric conversion module according to the present invention, with a part cut away to show the inside.

FIG. 2 is a view in the direction of the arrow in FIG. 1;

FIG. 3 is a plan view showing a modification of the photoelectric conversion module of the present invention, in which a shielding case is removed from FIG. 1 and an electronic circuit including an inductance element and a capacitance element is formed on a substrate.

4 is a cross-sectional view of a part of the circuit board, showing an example in which a GND layer is provided on the back surface of the electronic circuit board in the embodiment of FIG. 3 and a capacitance element is formed between the GND layer and a circuit pattern on the front surface.

FIG. 5 shows an example in which the electronic circuit board has two layers and a circuit pattern is provided between layers in the embodiment of FIG. 3;
FIG. 4 is a cross-sectional view of a part of a circuit board.

FIG. 6 shows data of a comparative example of the present invention, showing 987 to 1020 MH in the vicinity of an operating photoelectric conversion module.
FIG. 3 is a contour diagram of electric field intensity in a region z.

FIG. 7 shows data of an embodiment of the present invention, showing 987 to 1020 MH near an operating photoelectric conversion module.
FIG. 3 is a contour diagram of electric field intensity in a region z.

[Explanation of symbols]

Reference Signs List 1 electronic circuit board 11 GND line 12 through hole 2 light emitting element 3 light receiving element 4 driver IC 5 shielding case 51 soft magnetic metal foil 52 electromagnetic wave absorbing material
53 Partition wall 6 (61, 62) Circuit pattern

 ──────────────────────────────────────────────────続 き Continuation of the front page F term (reference) 5E321 AA02 AA14 AA17 AA22 AA32 BB23 BB25 BB31 BB32 CC12 GG05 GG11 5F089 AA01 AC11 AC23 AC26 CA11 FA10

Claims (6)

[Claims] 1. A photoelectric conversion module in which components including a light emitting element and / or a light receiving element and a driver IC for driving these elements are arranged on a surface of an electronic circuit board, and the entire components are left except for a light path. Is covered with a shielding case, and as the electronic circuit board, an electromagnetic wave absorbing material obtained by dispersing a soft magnetic substance powder in a synthetic resin matrix is used, and the shielding case is provided on both sides of a soft magnetic metal foil. A photoelectric conversion module using an electromagnetic wave absorbing material obtained by dispersing a soft magnetic substance powder in a synthetic resin matrix. 2. The photoelectric conversion device according to claim 1, wherein a GND line is provided on a back surface of the electronic circuit board, and an end of a soft magnetic metal foil constituting the shielding case is connected to the GND line through a through hole. module. 3. It has both a light emitting element and a light receiving element,
2. The photoelectric conversion module according to claim 1, wherein a partition wall made of an electromagnetic wave absorbing material in which a powder of a soft magnetic substance is dispersed in a matrix of a synthetic resin is provided between the two. 4. The photoelectric conversion module according to claim 1, wherein an electronic circuit including an inductance element and / or a capacitance element is formed on the electronic circuit board in addition to the above components. 5. The photoelectric conversion module according to claim 4, wherein a GND line is provided on a back surface of the electronic circuit board, and the capacitance element is formed between a circuit pattern formed on the front surface and the GND line. 6. An electronic circuit board comprising two or more layers,
The photoelectric conversion module according to claim 4, wherein a circuit pattern is provided between the layers, and the capacitance element is formed between the circuit pattern formed on the surface and the circuit pattern between the layers.