JPH04330788A - Parallel optical signal transmitter - Google Patents

Abstract

PURPOSE:To reduce an optical signal crosstalk by bringing a coupling optical fiber array at an extremely near distance to the front of or into close contact with light emitting units of a light emitting element array, and so disposing optical axes of the respective fibers as to coincide one to one with the centers of the corresponding units. CONSTITUTION:An LED array 1 is secured in a state that its common cathode electrode surface is electrically connected by silver paste on a conductive pattern on a hard board 8, and anode electrodes are individually bonded to output electrodes of LED driving IC 5 via wirings 10. The IC 5 is similarly secured with silver paste on a conductive pattern on the board 8. A coupling optical fiber array 2 is brought at the front surface of the array 1 at the unit side as a coupling optical system A of an optical fiber array 4 into contact with or at an extremely near distance to light emitting surfaces of the array 1. Thus, reliability can be enhanced.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention converts a plurality of electrical signals into optical signals in parallel, and transmits the individual signals in parallel over a desired distance via a plurality of optical fibers corresponding to each other on a one-to-one basis. The present invention relates to a parallel optical signal transmission device used for signal transmission inside various devices and between short-distance devices.

0002

2. Description of the Related Art FIG. 5 shows an example of the internal structure of a transmitting unit of a conventional parallel optical signal transmission device, and FIG. 6 shows an optical path diagram when a transmission optical fiber array is connected to the transmitting unit of the same example.

In the conventional parallel optical signal transmission device, as shown in FIG. 5, a lens array 22 is installed as a coupling optical system in front of the light emitting part of each light emitting element of a light emitting element array 21 which is a light source. An optical fiber array connector 23 is installed on the light emitting end side of the array 22 (the surface opposite to the surface facing the light emitting element array).

The optical fiber array connector 23 can introduce the optical signals of each channel output from the individual lenses of the lens array 22 into the corresponding optical fibers of the signal transmission optical fiber array 24 on a one-to-one basis. It has a structure that allows it to be repeatedly installed in such positions.

Further, each light emitting element of the light emitting element array 21 is connected to a light emitting element driving IC 25. This light-emitting element driving IC 25 supplies current to each light-emitting element of the light-emitting element array 21, and externally supplies a signal input terminal 26 to the light-emitting element array 21.
It has a function to control the blinking of each light emitting element according to the electric signal inputted through the .

The light emitting element array 21, the lens array 22, the optical fiber array connector 23, and the light emitting element driving IC 25 are mounted in a metal package 27 to form an integrated unit.
The light emitting element driving IC 25 is hermetically sealed from the outside atmosphere by placing a lid on the package and sealing it.

In the above configuration, the optical signals emitted from the individual light emitting elements of the light emitting element array 21 are as shown in FIG.
The light enters each lens of the lens array 22 provided in one-to-one correspondence on the front surface of the light emitting part of each light emitting element, and is coupled to the optical fiber array connector 23 for each lens of the transmission optical fiber array 24. The light is focused onto the incident end face of the optical fiber at a position corresponding to the angle of incidence within the aperture angle of the optical fiber, and a portion of the light propagates within the transmission optical fiber.

[0008]

[Problems to be Solved by the Invention] In configuring a conventional parallel optical signal transmission device having the above function, it is necessary to connect channels between adjacent light emitting elements that simultaneously emit separate signal lights within the same device. Measures against optical signal crosstalk are an important requirement. For this reason, it is necessary to precisely align the coupling lens array during the assembly process, and the design and assembly method of the coupling optical system must be carefully considered to take into account misalignment between elements that may occur during use. There is a need.

Furthermore, as a more effective countermeasure, there are methods such as blocking light in areas other than the lens section of the lens array, and installing a light blocking wall between adjacent optical paths in the optical path section from the light emitting section to the lens. is taken.

[0010] However, these requirements are an obstacle to miniaturizing the device, improving performance such as improving reliability, and reducing assembly costs.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a parallel optical signal transmission device that reduces crosstalk between channels, is compact, highly reliable, inexpensive, and easy to assemble.

0012

Means for Solving the Problems The means for solving the problems according to claim 1 of the present invention, as shown in FIGS. 1 to 4, includes a light emitting element array 1 consisting of a plurality of light emitting elements that can be individually controlled to blink;
In order to transmit a plurality of optical signals emitted from the individual light emitting elements constituting the light emitting element array 1 in a temporally parallel manner in a spatially separated state, one pair is provided for each light emitting element of the light emitting element array 1. an optical fiber array 4 for signal transmission consisting of optical fibers provided in correspondence with each other; and a coupling optical system for introducing optical signals emitted from the light emitting elements of the light emitting element array 1 into the optical fiber array 4 for signal transmission. A, and an optical fiber connector 3 for repeatedly optically joining and separating the signal transmission optical fiber array 4 and the coupling optical system A, in which the coupling optical system A
As an element, the optical fiber array 4 for signal transmission has the same spacing pitch as the optical axis spacing of the optical fibers of the optical fiber array 4 for signal transmission and the spacing of the light emitting parts of the light emitting element array 1.
A short coupling optical fiber array 2 is used, which is composed of optical fibers having a smaller core diameter and numerical aperture than the individual optical fibers constituting the light emitting element. The distance between the light emitting element array 1 and the coupling optical fiber array 2 is set so that the center of each light emitting part of the array 1 coincides with the center of each light emitting part of the array 1, and the distance between the light emitting element array 1 and the coupling optical fiber array 2 is such that the optical signal emitted from the light emitting elements of the adjacent channel is connected to the light of the coupling optical fiber array 2. The beam is set to enter at an angle greater than the aperture angle of the fiber.

Further, the problem solving means according to claim 2 is the parallel optical signal transmission device according to claim 1, in which at least the light emitting element array 1, the coupling optical system A and the optical fiber connector 3 are integrally formed by molding resin. The light emitting element array 1 is molded, and at least the light emitting element array 1 is hermetically sealed with the molding resin.

[0014]

[Operation] In the problem solving means according to claim 1, a part of the optical signal emitted from each light emitting part of the light emitting element array 1 of the light source is transmitted through a coupling optical fiber provided in front of the light emitting part of the light emitting element array 1. Array 2 is reached.

At this time, the coupling fiber array 2 is arranged such that the optical axis of each optical fiber constituting it corresponds one-to-one to the center of each light-emitting part of the light-emitting element array 1, and the light-emitting elements The distance between the array 1 and the coupling optical fiber array 2 is set so that the angle of incidence of the light rays emitted from the light emitting elements other than the corresponding channel at the front is larger than the aperture angle of the coupling optical fiber. , the optical signals emitted from each light emitting element other than the predetermined channel are hardly optically coupled, making it possible to effectively reduce optical signal crosstalk between adjacent channels.

Further, a part of the optical signals coupled to each optical fiber of the coupling optical fiber array 2 and propagated within the fibers is coupled one-to-one to each output surface by the optical fiber connector 3. The coupling optical fiber 2 has a smaller core diameter and numerical aperture than the transmission optical fiber 4 coupled to the output side of the fiber. Therefore, even when the optical fiber array 4 for transmission and the optical fiber array 2 for coupling are misaligned due to the attachment and detachment of the optical fiber connector 3, inter-channel optical signal crosstalk is less likely to occur.

[0017] In the problem solving means according to claim 2,
Since the light emitting element array 1, the coupling optical fiber array 2, and the optical fiber connector 3 are integrally formed by resin molding, optical positional deviation between these elements is less likely to occur, and the light emitting element array Since it is hermetically sealed from the outside atmosphere, it is possible to prevent the adhesion of dust and the like.

[0018]

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 perspective view showing the internal structure of a transmitting unit of a parallel optical signal transmission device according to an embodiment of the present invention, and FIG.
3 is a diagram showing the optical path when the transmission optical fiber array is joined to the transmitting unit, and FIG. 4 is an explanatory diagram of the installation distance conditions of the coupling optical fiber array with respect to the light emitting element array.

In FIGS. 1 and 2, reference numeral 1 denotes a light emitting element array of a light source for transmission, and the light emitting element array 1 is a monolithic structure consisting of a plurality of light emitting elements that can be individually controlled on and off, and has a common cathode electrode. A diode array (hereinafter referred to as an LED array) is used, the pitch between the light emitting parts is 0.25 mm, and the number of channels is 12.

This LED array 1, as shown in FIGS. 1 and 2,
The common cathode electrode surface is fixed and electrically connected to the conductive pattern printed on the hard substrate 8 with silver paste, and the anode electrode is the output of the LED driving IC 5 individually. The electrodes are wire bonded via electrical connection wires 10.

Similar to the LED array 1, the LED driving IC 5 is fixed and electrically connected to a conductive pattern printed on a hard substrate 8 using silver paste.

Further, on the hard substrate 8, in addition to the conductive printed wiring patterns for the LED array mount and the LED driving IC, there are also wiring patterns and power for inputting 12 channels of parallel electric signals to the IC from the outside. A wiring pattern for supplying power is provided by a printing method, and a power supply terminal 6 for inputting electric signals and for driving is drawn out from the end of the board to the outside of the unit package 7.

A light emitting element array 1 is installed on the front surface of the LED array 1 on the light emitting part side as a coupling optical system A for introducing signals emitted from the light emitting elements of the LED array 1 into an optical fiber array 4 for signal transmission, which will be described later. A coupling optical fiber array 2 is provided in close contact with or at a very close distance to the light emitting surface of the light emitting surface.

The coupling optical fiber array 2 is composed of quartz-based optical fibers with a core diameter of 0.05 mm, a numerical aperture of 0.2, and a graduated index type optical fiber, and the optical axis spacing is L.
A 12-channel one-dimensional array with the same dimensions as ED array 1 with a pitch of 0.25 mm is used, and its length in the optical transmission direction is 8 mm. Both end faces are polished to a plane perpendicular to the optical axis to prevent reflection. Membrane is coated.

As shown in FIG. 4, the optical axis of each optical fiber of the coupling optical fiber array 2 and each LE of the LED array 1 are
The distance L between the input end face and the LED array 1 is set so that the centers of the LEDs D coincide with each other and the optical signals emitted from adjacent channel LEDs enter the optical fibers of the coupling optical fiber array 2 at an angle greater than or equal to each opening of the optical fibers. is set.

That is, the distance L between the LED array 1 and the incident end face of the coupling optical fiber array 2 is determined by P, the pitch between the channels of the LEDs and the coupling optical system, and 2, the width of the LED.
W, the optical fiber core radius of the coupling optical fiber array is r
, if the optical fiber numerical aperture of the coupling optical fiber array is NA, then if the following formula is satisfied, the LE of the adjacent channel is
The optical signal emitted from D enters at an angle greater than the aperture angle of the optical fibers of the coupling fiber array 2.

L≦(P-W-r)/(tan θ) θ=sin-1NA In addition, the transmission optical fiber array 4 is optically connected to the light output end side of the coupling optical fiber array 2 from outside the unit. An optical fiber connector 3 that can be mechanically easily connected and disconnected is fixed to a hard substrate 8.

The transmission optical fiber array 4 is for transmitting a plurality of optical signals emitted from the individual LEDs constituting the LED array 1 in a temporally parallel manner in a spatially separated state. 1 for each individual LED in LED array 1
It consists of optical fibers arranged in a one-to-one correspondence.

The individual optical fibers constituting the transmission optical fiber array 4 have larger core diameters and numerical apertures than the optical fibers constituting the coupling optical fiber array 2.
The LED array 1 and the coupling optical fiber array 2 are made of plastic optical fibers of about 0.2 mm and about 0.4 mm, respectively.
A 12-channel one-dimensional array with the same optical axis spacing pitch (0.25 mm) is used.

Note that the LED arrays 1 and L on the hard substrate 8
ED driving IC 5, wire 10 connecting these two
A part of the coupling optical fiber array 2 is integrally molded with a transparent silicone resin 9, and the silicone resin molded portion and the optical fiber connector 3 are also molded together.
The entire hard substrate including
It is becoming. In particular, the LED array 1 is hermetically sealed with mold resin.

In the above configuration, the driving power and 12 channels of parallel electrical signals input from the external electrical terminal 6 of the transmitting unit are transmitted from the lead frame to the LED driving IC 5 via the conductive wiring pattern on the hard substrate 8. is input to.

Then, the LED driving IC 5 supplies current to the LEDs corresponding to each channel of the LED array 1 via the respective bonding wires 10 in accordance with the input electrical signals of each channel, thereby driving the individual LEDs. Make it blink.

Here, among the optical signals emitted from each LED light emitting section of the LED array 1, the coupling light as an element of the coupling optical system A provided in close contact with or extremely close to the front surface of each light emitting section. A part of the optical signal that enters each optical fiber input end of the fiber array 2 at an angle of incidence less than the aperture angle thereof propagates within the same optical fiber and exits from the same output end.

At this time, the transmission optical fiber array 4 is inserted into the optical fiber connector 3, and as shown in FIG. 3, each fiber of the coupling optical fiber array 2 and each optical fiber of the transmission optical fiber array 4 are optically connected. , most of the optical signals propagated within each coupling optical fiber 2 are coupled to each optical fiber of the transmission optical fiber array 4 which is coupled in a one-to-one correspondence with each other, It propagates within the transmission optical fiber 4.

In this way, the incident end surface of the coupling optical fiber array 2 as an element of the coupling optical system A is located at a very close distance in front of each light emitting part of the LEDs of the LED array 1 or in close contact with the light emitting parts of the LEDs. Since the fibers of the coupling optical fiber array 2 are arranged in a one-to-one relationship with each light emitting part of the LE so that the optical axis of each fiber coincides with the center of the corresponding light emitting part, the LE
The optical signal emitted from each LED of D array 1 is
As a result, the light is incident on the fibers other than the coupling optical fiber arranged in front at an angle of incidence exceeding the aperture angle of these fibers, resulting in almost no optical coupling.

[0037] Therefore, it is possible to effectively reduce optical signal crosstalk between adjacent channels.

Furthermore, these coupling optical fibers are connected to a transmission optical fiber array 4 coupled to the output side of the same fibers.
Since the core diameter and numerical aperture are smaller than those of the optical fibers of is less likely to occur.

Furthermore, since the LED array 1, the coupling optical fiber array 2, and the optical fiber array connector 3 are integrally formed by resin molding, optical positional deviation between these elements is unlikely to occur. Additionally, since the LED array 1 is hermetically sealed from the outside atmosphere, it is possible to prevent dust from adhering to it.

[0040] For these reasons, it is small and highly reliable.
Furthermore, it is possible to provide a parallel optical signal transmission device that is easy to assemble.

Furthermore, the quartz-based graded index fiber array with a core diameter of 0.05 mm used as the coupling optical system A is sufficiently inexpensive in short lengths compared to conventional coupling lens arrays, and can be assembled into resin-molded packages. In addition to the formation of , an excellent effect on cost reduction can be expected.

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.

[0043]

As is clear from the above description, according to claim 1 of the present invention, the coupling optical fiber array is placed in front of each light emitting part of the light emitting element array at a very close distance or in close contact with each light emitting part, and Since the coupling optical system is constructed by arranging the optical fibers in the coupling optical fiber array one-to-one to the light emitting elements so that the optical axis of each optical fiber coincides with the center of the corresponding light emitting section, light emitted from each light emitting element in the light emitting element array is The optical signal is
As a result, the light is incident on fibers other than the coupling optical fibers arranged in front of each fiber at an incident angle exceeding the aperture angle of those fibers, resulting in almost no optical coupling.

[0044] Therefore, it is possible to effectively reduce optical signal crosstalk between adjacent channels.

[0045] Furthermore, since these coupling optical fibers have a smaller core diameter and numerical aperture than the transmission optical fibers coupled to the output side of the same fibers, transmission problems caused by attaching and detaching the optical fiber array connector, etc. Inter-channel optical signal crosstalk is also less likely to occur due to positional deviation between the optical fiber for use and the optical fiber array for coupling.

Furthermore, by making the coupling optical fiber and array short, the cost becomes lower than that of conventional coupling lens arrays.

Further, according to claim 2, since the light emitting element array, the optical fiber array for coupling, and the optical fiber array connector are integrally formed by resin molding, mutual optical positional deviation between these elements is avoided. In addition, since the light emitting element array is hermetically sealed from the outside atmosphere, it is possible to prevent the adhesion of dust and the like.

[0048] For these reasons, it is small and highly reliable.
Furthermore, it is possible to provide a parallel optical signal transmission device that is inexpensive and easy to assemble, which is an excellent effect.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the internal structure of a transmitting unit of a parallel optical signal transmission device according to an embodiment of the present invention.

FIG. 2 is also a sectional view thereof.

FIG. 3 is a diagram showing an optical path when a transmission optical fiber array is connected to a transmission unit.

FIG. 4 is an explanatory diagram of installation distance conditions of a coupling optical fiber array to a light emitting element array.

FIG. 5 is a perspective view of an example of the internal structure of a transmitting unit of a conventional optical parallel signal transmission device.

FIG. 6 is a diagram showing optical paths when transmission optical fiber arrays are joined in the same unit.

[Explanation of symbols]

1 Light emitting element array 2 Optical fiber array for coupling 3. Optical fiber connector 4 Optical fiber array for transmission A Coupling optical system

Claims (2)

[Claims] 1. A light emitting element array consisting of a plurality of light emitting elements that can be individually controlled to blink, and a plurality of optical signals emitted from the individual light emitting elements constituting the light emitting element array, in a state in which they are spatially separated. In order to transmit data in parallel in time, an optical fiber array for signal transmission consisting of optical fibers provided in one-to-one correspondence with each light emitting element of the light emitting element array, and an optical fiber array for signal transmission consisting of optical fibers provided in one-to-one correspondence with the individual light emitting elements of the light emitting element array; It comprises a coupling optical system for introducing optical signals emitted from the light emitting elements of the light emitting element array, and an optical fiber connector for repeatedly optically joining and separating the signal transmission optical fiber array and the coupling optical system. In the parallel optical signal transmission device, as an element of the coupling optical system, the optical fiber array for signal transmission has the same spacing pitch as the optical axis spacing of the optical fibers of the optical fiber array for signal transmission and the spacing of the light emitting parts of the light emitting element array. A short coupling optical fiber array is used, which is composed of optical fibers having a smaller core diameter and numerical aperture than the individual optical fibers constituting the light emitting element array. The center of each light emitting section is aligned with the distance between the light emitting element array and the coupling optical fiber array so that the optical signal emitted from the light emitting elements of the adjacent channel has an aperture angle greater than or equal to the aperture angle of the optical fiber of the coupling optical fiber array. 1. A parallel optical signal transmission device characterized in that the parallel optical signal transmission device is configured to be incident at an angle. 2. The parallel optical signal transmission device according to claim 1, wherein at least the light emitting element array, the coupling optical system, and the optical fiber connector are integrally molded with a molding resin, and at least the light emitting element array is molded with the molding resin. A parallel optical signal transmission device characterized by being hermetically sealed.