JPS6128240A - Signal transmitting system between boards - Google Patents

Abstract

PURPOSE:To attain ease of wiring design of a circuit between boards and to attain immunity to noise by replacing a part or all of wirings between printed circuit boards into an optical guide plate by optical transmission. CONSTITUTION:An electric signal from the back side of a board A100 is given to a light emitting element 310 via a terminal 111 of an electronic component 110, subjected to electrooptic conversion E/O and irradiated on the optical guide plate 200 as an optical signal. The light in a direction satisfying the condition of full reflection among radiated lights repeates full reflection on a wall of the transparent board and is transmitted in the board in every direction or in a prescribed direction. The optical signal is received by a photodetector 410 connected to an optional position of the optical guide plate 200, converted into an electric signal by optoelectric conversion O/E and given to an electronic component terminal 111' of the other board B. In using light emitting elements 310, 320, 330 irradiating the light with different wavelength distribution as the light emitting elements, the signal between specific elements only is transmitted in two ways by using photodetectors having a function passing selectively through a specific wavelength.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is configured so that ICs, LSIs, resistors, capacitors, and other various electronic components are connected to each other by wiring formed in advance on a substrate in a predetermined arrangement. The present invention relates to a signal transmission system between printed circuit boards.

[Conventional technology]

Printed circuit boards make it possible to process electrical signals from various electronic components in a small space, and while they have various advantages such as being smaller and lighter, expanding functionality, and lowering prices, they also allow electrical circuits to be highly integrated. As a result, the wiring between boards is extremely close together, or the wiring is complicated, and the wiring is not only complicated, but also responds sensitively to electromagnetic fields, static electricity, and other unnecessary external energy, making devices susceptible to noise. It has the disadvantage that it produces

Additionally, flat cables with multiple parallel wires are used for vanu line transmission between printed circuit boards, but this is inflexible and therefore requires special consideration in placement, making the layout design of the circuit increasingly complex. Unfortunately, this is a drawback of integration.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide an inter-printed-board signal transmission system that facilitates wiring design of inter-board circuits and is resistant to noise.

[Means for solving problems]

The present invention replaces part or all of the wiring between printed circuit boards with an optical waveguide plate, which is resistant to electric field and electromagnetic induction noise due to its characteristics, has excellent electrical insulation properties, and is suitable for high-speed transmission. achieved.

That is, the present invention is an electric signal transmission method between a plurality of printed circuit boards on which electronic components are mounted, in which signals are transmitted from one of the circuit boards! A process of converting the complete signal into light using a light emitting element and emitting it as an optical signal into a leading wave plate, a process of optically transmitting the optical signal within the optical waveguide plate, and a process of transmitting the transmitted optical signal through a light receiving element. This is an inter-board signal transmission method that consists of the process of converting light to electricity and transmitting it as an electrical signal to the other board.

The optical waveguide plate used in the present invention is an optically transparent plate capable of transmitting light in a plane direction, and its thickness is usually 1 to 10 m+.

FIG. 3 shows an optical waveguide plate (2
00) is shown.

The optical waveguide plate basically consists of multiple optical waveguide regions (210) that have the ability to transmit light. The material for this region may be inorganic or organic, but a transparent plastic material such as polymethyl methacrylate or polycarbonate is preferable because it is lightweight and difficult to break.

The outer periphery of the optical waveguide region is preferably covered with a reflective layer (220). In this case, the reflective layer is a direct reflective layer formed by coating or vapor deposition with a metal such as aluminum or mercury amalgam, or a coating layer formed by mixing light-scattering fine particles such as titanium dioxide or magnesium oxide into the transparent material. These include a reflective layer that utilizes scattering, and a reflective layer that utilizes total reflection by coating a transparent material with a lower refractive index than the material used for the optical waveguide region. By providing the reflective layer, the optical waveguide plate has less loss of light due to scratches and dirt, and can improve transmission efficiency. As shown in FIG. 3, the leading wave plate is usually provided with a light-shielding layer (230) for blocking noise caused by incident external light. The light-shielding layer is made of a light-impermeable material such as a black paint or a metal film.

If the substrate and the light emitting element or the light receiving element are integrated, there may be fewer electrical transmission parts, and the connection is usually fixed by soldering or the like, but it may also be a built-in type using a connector or the like. Further, as for the connection portion on the board, a light emitting element or a light receiving element can be connected directly to a heavy component terminal, a terminal using printed wiring, or a terminal using a lead wire.

The connection between the optical waveguide plate and the light emitting element or the light receiving element is preferably made by forming a recess in the optical waveguide plate according to the shape of the light emitting part or the light receiving part of the light emitting element or the light receiving element. You can also use the method of wearing clothes.

The connection site can be set arbitrarily, such as on the plane or side surface of the leading wave plate.

As the light-receiving element and light-emitting element used in the present invention, small-sized ones such as light-emitting diodes (LEDs), photodiodes (PD), and photodiodes (APD) that are normally commercially available are used as they are. However, if necessary, the signal can be further amplified by an amplifier. In particular, it is preferable to use a light-receiving element in which a color filter-1 amplifier is integrated.

[For production]

In the present invention, an electrical signal in one of the substrates is VO'ed by a light emitting element connected thereto, and then radiated into the optical waveguide plate as an optical signal. Since the optical waveguide plate is a flat plate and has the ability to transmit light in the plane direction, the emitted optical signal can be received at any position on the optical waveguide plate.

Next, the optical signal is received by a light-receiving element at an arbitrary position, subjected to optical-to-electrical conversion (Φ1), and then transmitted as an electrical signal to a predetermined position in the other substrate, thereby forming an inter-board signal transmission system.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments with reference to the drawings.

FIG. 2 is a schematic plan view of an embodiment of the printed circuit board transmission system according to the present invention, seen from the optical waveguide side, and FIG. 1 is a schematic plan view of the printed circuit board taken along the arrow AA/ in FIG. FIG.

In the figure, ttoo, 100' is an LSI, and resistor c.

There are substrate bodies A and B on which various electronic components (110, 110') are mounted, and an optical waveguide plate (200) is connected to the bottom surface thereof via a light emitting element (310) and a light receiving element (410). .

As can be seen from Figure 1, electrical signals are transmitted from the back side of one board A (1,00) to the terminal (11
1) is connected to the light emitting element 310 via electricity/light exchange (
Elo) and is radiated into the optical waveguide plate (200) as light IB. Of the emitted light, the light in the direction that satisfies the conditions for total reflection is repeatedly totally reflected on the wall of the transparent substrate.
It is transmitted within the board in all directions or in a predetermined direction.

Such an optical signal is received by a light receiving element 410 connected to an arbitrary position of the optical waveguide plate (200) and undergoes optical/electrical conversion (0/
E) is converted into an electric signal and connected to the electronic component terminal 111' of the other board B main body.

As shown in Fig. 2, when light emitting elements (31o, 320.33o) that emit light with different wavelength distributions are used as light emitting elements, a color filter or a dichlumic filter made of a multilayer dielectric film is used as a light receiving element. By using a device that has the ability to selectively pass specific wavelengths, it is possible to bidirectionally transmit signals only between specific elements. That is, the optical signal emitted from the light emitting element 320 with wavelength input 2 is received by the light receiving element (420) which receives only the light with wavelength input 2, and the light signal emitted from the light emitting element (330) with wavelength input 3 is received by the light receiving element (420) which receives only the light with wavelength input 2. The signal is received by a light-receiving element (430) that receives only light of wavelength 3.

By installing multiple light receiving elements, for example, one wavelength
The light emitted from the 0 light emitting element (3] 0) is received in parallel by a plurality of light receiving elements (410, 411, 412) that receive only the wavelength i.

FIGS. 4 and 5 show schematic cross-sectional views showing other embodiments of the present invention. In FIG. 4, a light emitting element (30
0) is connected to an electronic component terminal (11 white) at a predetermined position on the board (100) via a lead wire (500).Although a lead wire is used in this example, this is not connected to the board.
It is also possible to use ordinary printed wiring.

As shown in FIG. 5, three or more printed circuit boards (100) can be installed for the optical waveguide plate (200).

In this case, the optical signals are transmitted between printed circuit boards in parallel.

As shown in the schematic plan view in FIG.
) is also free to be fractionated into any fraction iIK. At this time, the compartment boundary wall (600) can also be blocked to prevent optical signals from entering adjacent compartments and becoming noise. When using the division boundary wall in a more multifunctional manner, light may be selectively transmitted through polarization or interference. Using this optical waveguide plate enables higher-order transmission between substrates.

In the present invention, by adding a baffle-route serial conversion element and a serial-to-parallel conversion element when outputting to the light emitting element and the light receiving element, it is possible to transmit a large number of signals using a small number of light receiving and emitting elements. It becomes necessary to use .

The signal transmission method between printed circuit boards of the present invention may be used in conjunction with the conventional signal transmission method between printed circuit boards using only electrical signals. Only a portion can be transmitted by a leading wave plate.

〔Effect of the invention〕

According to the present invention, restrictions on noise consideration in designing printed circuits can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a printed circuit board bag device used in the present invention, and FIG. 2 is a plan view of the board device as viewed from the printed wiring side. FIG. 3 is an enlarged sectional view illustrating the structure of the optical waveguide plate used in the present invention. 4 to 6 are explanatory diagrams showing other embodiments of the transmission system of the present invention, FIGS. 4 and 5 are sectional views, and FIG. 6 is a plan view. In the figure, 100.100' is the board body, 110.1]O'
111.111' are the terminals of each electronic component; 200 is an optical waveguide; 300, 31 are electronic components to be placed on the board;
0.320.330 is a light emitting element, 400.410.41
1.412.420.430 is a light receiving element, 500 is a lead wire, and 600 is a division boundary wall.

Claims (1)

[Claims] In an electrical signal transmission system between multiple printed circuit boards on which electronic components are mounted, a process in which an electrical signal transmitted from one board is converted from electrical to optical by a light emitting element and emitted as an optical signal within an optical waveguide plate; An inter-board signal transmission method comprising a step of optically transmitting the optical signal within an optical waveguide plate, and a step of converting the transmitted optical signal into an electric signal via a light receiving element and transmitting it as an electric signal to the other substrate.