JPH03178230A - Circuit board and board unit - Google Patents

Abstract

PURPOSE:To effectively utilize a free space between boards and to attain optical connection with high density by providing a means leading an optical signal sent from a light emitting element to a light receiving element arranged between a circuit board provided with the light emitting element and a circuit board provided with the light receiving element opposite to the light emitting element onto the board. CONSTITUTION:A circuit board 1-1 with a light emitting element 2-1 mounted thereon and a circuit board 1-4 with the light receiving element 3-1 mounted thereon are arranged opposite to each other, and a light sent from the light emitting element 2-1 of the circuit board 1-1 is detected directly through a space by the light receiving element 3-1 of another circuit board 1-4 to apply optical connection. Moreover, when one or plural circuit boards 1-2, 1-3 held between the circuit boards is present thereon, means 4-1, 4-2 leading the light through the use of transmission, deflection or reflection, etc., provided on the circuit boards lead the light from the light emitting element 2-1 to the light receiving element 3-1 for the detection. Thus, the optical connection of the circuit boards separated from each other is implemented dynamically, the space between the circuit boards is utilized effectively and the wiring density between the space of the boards is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides high-density optical connection by effectively using the space between multiple circuit boards in which electrical circuits and optical circuits are mixed in a device. The present invention relates to a circuit board and a board unit suitable for transmission devices and the like.

[Prior Art] Conventionally, signal transmission between a large number of printed circuit boards (circuit boards) arranged in a transmission device involves electrical wiring on a backboard and interconnection using electrical cables such as flat cables and coaxial cables and electrical co-connectors. Connections were made using so-called metal. However, the recent l5
The need for high-speed services such as moving image services using CATV is increasing, and the speed of signals transmitted within devices is becoming faster than before. In addition, multiplex signal transmission technology using light has also developed, and for example, 150 Mb/S video signals can be multiplexed over several channels to transmit 600 Mb/S.
It is being considered to increase the speed to 2.4 Gb/s or 2.4 Gb/s, and to transmit it through -1 optical fibers. Therefore, as the transmission speed of wiring and connected signals within a transmission device becomes faster, the effects of noise from reflected pulses, noise from multiple crosstalk, noise from EMI (electromagnetic interference), etc. increase with metal connection methods. There was a drawback that reliable signal transmission between printed W boards could not be performed. In addition, with the wiring method between printed circuit boards using metal, when attempting to route a large amount of data at high speed, the number of wires between the boards increases, resulting in a shortage of wiring space and making it difficult to design and manufacture the backboard. This has the disadvantage that it becomes complicated and it is difficult to achieve higher wiring density and higher functionality.

As a means to solve the problems when using the electrical connection method between printed circuit boards as described above,
Connection techniques such as Japanese Patent Application Laid-open No. 1-16629 and Japanese Patent Application Laid-Open No. 1-173214' have been devised. Japanese Patent Publication No. 1-1662
In the connection technology disclosed in Publication No. 9, optical signals are transmitted using a film-shaped leading waveguide array, and parallel signals are processed all at once without parallel/serial conversion. Uses electrical connectors. Also, JP-A-1
The connection technology disclosed in Japanese Patent No.-173214 employs a signal optical wiring method using multi-fiber ribbons and multi-fiber connectors.

[Problem to be solved by the invention] However, in the above-mentioned conventional technology,
In the connection technology disclosed in Publication No. 629, optical signals are transmitted in the form of a film using a waveguide array, but since electrical connectors are used in the signal input/output section of the board, the above-mentioned noise problem remains unsolved. It remains as it is. In addition, in this conventional technology, 2
Film optical waveguides, optical connectors, electrical connectors, light emitting/light receiving element arrays, etc. are arranged in order between the printed circuit boards to perform signal transmission. Therefore, when transmitting signals with multiple other printed circuit boards, it is necessary to use signal media and components connected in the same order, which increases the number of media components and connects multiple printed circuit boards. The problem was that it could not be done dynamically.

In addition, the connection technology disclosed in Japanese Patent Application Laid-Open No. 1-173224,
From the viewpoint of preventing an increase in optical loss due to fiber bending and preventing mechanical breakage, the bending radius cannot be made small (bending at right angles), and extra wiring length is always required, which occupies extra space.

Therefore, it is not possible to wire between the boards with the shortest distance,
There was a problem in that it was difficult to increase the wiring density in the space inside the device.

The present invention was devised to solve the above problems, and provides a circuit board and a board unit that enable high-density optical connections by effectively utilizing the free space between the boards. With the goal.

[Means for Solving the Problems] The structure of the circuit board of the present invention for achieving the above object is as follows: A plurality of circuit boards are arranged in a board unit in a device so that their front and back surfaces face each other, and electrical circuits and optical circuits are connected to each other. In a circuit board on which a combination of the above-mentioned and
The device is characterized in that means for guiding an optical signal sent from the light emitting element to the light receiving element is provided on the substrate.

Further, the configuration of the board unit of the present invention for achieving the above object is as follows: a plurality of circuit boards on which electrical circuits and optical circuits are mounted together are arranged in the device so that the front and back surfaces of each board are opposite to each other. A circuit board having a light-emitting element mounted thereon, and a circuit board having a light-receiving element disposed opposite to this circuit board and mounted with a light-receiving element that detects light directly transmitted into space from the light-emitting element, are included in the board unit. , or at least one circuit board of the present invention described above in addition to these circuit boards.

[Function] In the present invention, a circuit board on which a light emitting element is mounted and a circuit board on which a light receiving element is mounted are placed facing each other, and the light emitted from the light emitting element on one circuit board is directly transmitted through space to the other circuit board. Optical connections are made by detecting the light with the light receiving element. In addition, if there is one or more circuit boards sandwiched between these circuit boards, light can be guided from the light emitting element by means of transmission, deflection, reflection, etc. provided on these circuit boards. By guiding the light to the light receiving element and detecting it, it is possible to dynamically optically connect distant circuit boards. In this way, the space between the circuit boards is effectively utilized and the wiring density in the board space is improved.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a perspective view showing a first embodiment of the present invention. This embodiment is an example of a circuit board and a board unit in which a circuit board that is sandwiched between circuit boards that perform optical transmission is provided with a hole that allows light to pass through, thereby enabling optical transmission between the circuit boards. be. I-1゜1-2. IT3.1-4,1-5(
Hereinafter, each circuit board (hereinafter referred to as l when representing) is a circuit board on which an electronic circuit (N gas circuit) and an optical circuit are mixed, and a board unit is formed as an aggregate of these circuits. 21.2
-2.2-3.2-4 (hereinafter referred to as 2 when representing) is a light emitting element that sends out signal light, and 3-1.3-
2.3-3.3-4 (hereinafter referred to as 3 when representing) are light-receiving elements that detect the signal light, and are opposed to the front or back surface of the circuit board l, respectively. Place it.

For example, the surface of the circuit board 1-1 has a light receiving element 2-1.2.
-2 is arranged, and the signal light 5-1 of the light-emitting cable 2-1 (hereinafter,
A light receiving element 3-1 that receives light (denoted as 5 when representing) is placed on the back surface of the circuit board 1-4, and a light receiving element 3-2 that receives signal light 5-2 of the light emitting element 2-2 is placed on the circuit board. Place it on the back side of 1-2.

Similarly, the light emitting element 2-3 is arranged on the back surface of the circuit board 1-3, the light emitting element 2-4 is arranged on the back surface of the circuit board 1-5, and the light receiving elements of the respective signal lights 5-3, 5-4 are arranged. 3-3 and 3-4 are arranged on the surfaces of circuit boards 1-1 and 1-3, respectively. In this embodiment, when there is a circuit board l sandwiched between the light emitting element 2 and the light receiving element 3 facing each other, the signal light 5 of the light emitting element 2 is transferred to the light receiving element at a portion intersecting the optical path of the signal light 5. A hole 4 through which the signal light 5 passes is provided as a means for guiding the signal light 5 to the signal light 3. When turned over, the circuit board is sandwiched between the light emitting element 2-1 and the light receiving element 3-1 facing it! -2,
Holes 4-1 and 4-2 are made in each of i3 at a portion intersecting the optical path of the signal light 51. Similarly, a hole 4-3 is formed on the circuit board 1-2 between the pair of light-emitting element 2-3 and light-receiving element 3-3.
A hole 4-4 is formed on the circuit board 1-4 between the pair of light emitting element 2-4 and light receiving element 3-4. In the above,
The optical path of the signal light 5 may be in an oblique direction with respect to a plane parallel to the circuit board 1, as shown in the signal light 5-3, and can be made freely.

The operation and effects of the first embodiment configured as above will be described.

First, a case will be described in which circuit boards 1-1 and 1-4 are selected as a pair of circuit boards for transmitting signal light.

That is, the light emitting element 2-1 arranged on the circuit board J&1-1
Consider a case where a light emitting element 3-1 disposed on the circuit board 14 detects signal light 5-1 emitted from the circuit board 14. In the conventional method, the signal light emitted from the light emitting element 2-1 was guided to the backboard using an optical fiber, and then transmitted to another board via an optical connector placed on the backboard. . In contrast, in this embodiment, the opposing circuit board 1
A hole 4-1 and a hole 4-2 are formed in the circuit boards 1-2 and 1-3 sandwiched between the circuit boards 1 and 1-4, respectively, and the signal light 5-! is emitted from the light emitting element 21. can pass through the holes 4-1 and 4-2 in order and be detected by the light receiving element 3-1, so the space between the boards can be used effectively, and the space between the light transmitting and receiving elements can be passed through the holes 4-1 and 4-2 in order. can be connected over the shortest distance.

Similarly, when circuit boards 1-5 and 1-3 are selected as a pair of circuit boards, the signal light 5-4 emitted from the light emitting element 2-4 disposed on the circuit board 1-5 is transmitted to the opposite circuit board 1-5. -5
A hole 4- made in the circuit board 1-4 sandwiched between and 1-3.
4 and placed on the circuit board 1-3.
Detected at 4.

In addition, if the optical path of the signal light is not orthogonal to the board, for example, the signal light 5-3 emitted from the light emitting element 2-3 disposed at the bottom of the circuit board 1-3 may be Even in the case of an oblique optical connection such as connecting to the light receiving element 33 arranged on the upper part, if the hole 4-3 is made at the position where the optical path of the signal lights 5 to 3 of the circuit board 1-2 intersects with the circuit board 12, The signal light 5-3 can be detected by the light receiving element 3-3 by passing it through the shortest distance. The beam diameter of the signal light 5 can be set to about 1 mm or less by installing an optical lens such as a SELFOC microlens immediately after the light emitting element 2, so the size of the hole in the circuit board I can be set to about 2 mm or less. It can be made smaller. Therefore, a sufficiently large number of holes can be provided for connection between substrates, and the density can be increased. However, care must be taken to ensure that the optical path is not blocked by other electrical or optical components. In this way, as the space between the boards is effectively used, there is no need to provide special connection parts between the boards or extra wiring space for them, and it is possible to dynamically optically connect a number of circuit boards. .

Therefore, the wiring density in the space between the substrates can be improved, and the wiring distance can be minimized, so that the problem of delay time can be solved.

In addition, in the first embodiment described above, a method was adopted in which a hole was provided at a desired location on the circuit board l through which the signal light 5 passed.
A transparent substrate material may be embedded in a location on the circuit board I through which the signal light 5 passes. Further, the first embodiment is an embodiment in which an optical connection is made by making a minimum necessary hole 4 through which the signal light 5 passes at an arbitrary location on the circuit board l through which the signal light 5 passes. Light passing connections can be made even if the entire structure is made of transparent material. In this case, there is no need to make a hole in the substrate and it can pass through any location, allowing for more dynamic optical connections. Examples of materials used for the substrate in the above case include highly transparent resins using fluororesin having high electrical insulation properties.

FIG. 2 is a sectional view showing a second embodiment of the invention.

This embodiment is an example in which optical connections are made by placing optical components at arbitrary locations within the board through which light passes. I-6,1-
7, 1-8 is a circuit board on which an electronic circuit (1! circuit) and an optical circuit are mixed, 3-5° 3-6 3-7 3-8 is a light receiving element mounted on the circuit board 1-6, 3 -9 is circuit board 1-
The light receiving element mounted on 7, 4-5.4-6.4-7 is a hole through which the signal light passes, which is made in the circuit board 1-8, 5-55-
6 5-7 is a signal light sent out from a light emitting element of a circuit board (not shown). 6 is a polarizing element using a birefringent crystal, and the signal light 5-5 transmitted through the hole 4-5 of the circuit board 1-8
The signal light 55 is embedded in the position where the optical path intersects the circuit board 17, and the signal light 55 is intersected with the circuit board 17! Branches in two directions on -6.

The light receiving element 3-5.36 that detects this signal light 5-5 is
The circuit board 1-6 is placed on the optical path of the branched signal light in two directions. Reference numeral 7 denotes a constant polarization prism, which is embedded and provided at a position where the optical path of the signal light 5-6 transmitted through the holes 46 of the circuit boards 1 to 8 intersects the circuit board 17.
The signal light 56 is refracted by a predetermined angle with respect to the circuit board Jfi, 1-8, and the light receiving element 3- is placed at that position.
Leads to 7. 8 is a half mirror, and the optical path of the signal light 5-7 transmitted through the hole 4-7 of the circuit board 1-8 is the half mirror of the circuit board 1-8.
7, and the - part is connected to the circuit board 1-6.
and a part of it is reflected in the direction of the surface of the circuit board 1-7. A light receiving element 3- that detects this signal light 5-7
8 is arranged at a position where the optical path of the transmitted light crosses the circuit board 1-6, and the other light receiving element 3-9 is arranged on the optical path of the reflected light on the circuit board 17.

The operation and effects of the second embodiment configured as above will be described.

First, a case where the polarizing element 6 is used will be explained. Polarizing element 6
is embedded in the circuit board 1-7, and the signal light 5-5 passing through the hole 4-5 made in the circuit board 1-8 is divided into two orthogonal linearly polarized lights by this polarizing element 6.
Each branched signal light is detected by light receiving elements 35 and 3-6 arranged on the circuit board 1-6. Here, if the polarizing element 6 is made to be able to rotate slightly, it is possible to change the branching direction of the two signal lights, which is different from the previous location (the light is detected by the light receiving element placed vertically). This becomes possible.Next, a case will be explained in which the constant declination prism 7 is used.The constant declination prism 7 is embedded in the circuit board 1-7, and the hole 4-6 made in the circuit board 18 is inserted into the circuit board 1-7. The passing signal light 56 is refracted by the angle determined by the constant polarization prism 7, and is detected by the light receiving element 3-7 arranged on the circuit board 1-6.Finally, the half mirror 8 A case will be explained in which half mirror 8 is connected to circuit board 1-7.
hole 4- made in the circuit board 1-8.
The signal light 57 passing through the half mirror 8 is split into transmitted light and reflected light. The transmitted light is the circuit board 1
-6 is detected by the light receiving element 3-8, and the reflected light is transmitted on the surface of the circuit board 1-7 and detected by the light receiving element 3-9. In this way, in this example, 11 optical components are used.
By branching or deflecting the signal light into two directions, the space between the boards can be used more effectively, and the optical connection can be
It becomes possible to increase the number of connections and freely set the connection direction, making it possible to perform signal connections even more dynamically, and improving the wiring density in the inter-board space.

In conventional optical backboard transmission, optical fiber cords with optical connectors have been used to connect circuit boards in order to improve operability and maintain mechanical strength. For this reason, the connection density depends on the outer diameter of the optical fiber bar code or the number of connections, and there is a limit to increasing the density in the limited space of equipment such as transmission equipment as long as connections are made using such tangible media. there were. On the other hand, if the embodiment of the present invention described above is used, a large number of different optical connection paths can be formed by optical elements such as light emitting and light receiving using the entire area of the space between the substrates. It has the advantage of greatly increasing the degree of freedom in settings and the number of connections. Further, if active elements such as a light modulation element or an acousto-optic effect element are used as optical components disposed within the circuit board 1, high functionality of the optical connection can be achieved. At this time, the fact that an electric circuit for controlling active elements can be mounted on the substrate to which the present invention is applied is effective in this embodiment.

Note that, as described above, the present invention can be applied in various ways in accordance with the gist thereof, and can take various embodiments.

[Effects of the Invention] As is clear from the above description, if the circuit board and unit according to the present invention are used, optical signals between a plurality of optical elements disposed on circuit boards placed apart in a transmission device can be transmitted. Without using a backboard connection,
It is possible to connect elements directly over the shortest distance, and
It will also be possible to make sophisticated connections. Therefore, dynamic high-density optical connections can be made by effectively utilizing the free space between the substrates.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention, and FIG. 2 is a sectional view showing a second embodiment of the present invention. 1... circuit board, 2... light emitting element, 3 ... Light receiving element, 4 ... Hole, 5
...Signal light, 6...Polarizing element, 7...Constant polarization prism, 8...Half mirror

Claims (3)

[Claims] (1) In a circuit board in which a plurality of circuit boards are arranged in a board unit in a device so that their front and back surfaces face each other, and a combination of electrical circuits and optical circuits are mounted, a circuit board equipped with a light receiving element and a circuit board facing this. What is claimed is: 1. A circuit board comprising: a circuit board having a light-receiving element; and means for guiding an optical signal sent from the light-emitting element to the light-receiving element. (2) In a board unit configured by arranging a plurality of circuit boards on which both electric circuits and optical circuits are mounted in a device so that the front and back sides of each board face each other, a circuit board on which a light emitting element is mounted and a circuit board on which a light emitting element is mounted and a circuit board mounted with a light-receiving element that is placed opposite to the circuit board and that detects light directly emitted into space from the light-emitting element. (3) The board unit according to claim 2, comprising at least one circuit board according to claim 1.