JPH10154825A - Light emitting/receiving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting/receiving device which can be suitably employed in a bidirectional full duplex communication system and can reliably prevent invasion of crosstalk light from a light emitting element to a light receiving element in a front-end part. SOLUTION: A light emitting diode 28 and a photodiode 29 are provided as spaced from each other on a conductor such as a lead frame, integrally molded with covering layer of epoxy resin to form light emitting and receiving lenses. A groove 37 is made in the covering layer between the light emitting and receiving elements to be open to the light emitting direction of the light emitting element and to the light incident direction of the light receiving element. As a result, it can be prevented that light from the light emitting element is passed and refracted through an inner face 38 of the groove on its light emitting element side and then invaded into the light receiving element, or that light from the light emitting element is totally reflected at the inner face on the light emitting element side and then advanced into the atmosphere air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-emitting / light-receiving device having a light-emitting element and a light-receiving element and suitably used for data communication. Related to a communication device.

[0002]

2. Description of the Related Art Infrared data communication has been widely used between different computers and between personal computers and peripheral devices. Conventional infrared data communication is based on IrDA (Infrared Data Associati
on), the half-duplex system has been standardized conventionally. IrDA is a cordless communication using infrared rays (Ir) and is a name of a standardization organization aiming at establishing and disseminating a standard for interconnecting information equipment, communication equipment, etc., and was established in 1993. Was done.

In the half-duplex transmission method, when two communication units perform transmission and reception, each communication unit is configured not to perform transmission while receiving, and not to receive while transmitting. That is, the two communication units do not transmit at the same time, but start after one of the communication units has finished transmitting, and then the other communication unit transmits. Thus, transmission and reception are performed alternately. .
Therefore, in the half-duplex system, while one communication unit is transmitting, the other communication unit cannot transmit,
Only receiving. So there is a loss of time,
There is a demand for faster communication.

As devices such as personal computers have become faster and more sophisticated, it has become important to increase the amount of transmission and shorten the transmission time. Therefore, it is desired that the communication units that communicate with each other can transmit in full-duplex mode in which transmission and reception are simultaneously performed, and transmission in a full-duplex mode is required. This full-duplex transmission allows for faster and more efficient transmission.

In IrDA, between personal computers, between a personal computer and a portable terminal device,
In addition, since the standardization of infrared wireless data communication between a personal computer and a peripheral device has been established, wireless data communication has rapidly spread. Ir
DA, the standard IrDA1.0 and IrDA1.
1 was adopted. Conventionally, AV (Analogue Visual)
Remote control (abbreviated remote control) method and A
Each transmission scheme of the SK (Amplitude shift keying) scheme is known. Table 1 summarizes these features.

[0006]

[Table 1]

In Table 1, PDA indicates a portable terminal (Personal Digital Assistant), and notebook PC indicates a notebook personal computer.

As shown in Table 1, although various transmission techniques have conventionally existed, bidirectional full-duplex communication is required for data communication applications such as personal computers. In a full-duplex communication device, a particular problem in the front-end section, which is a light emitting / receiving device, is that infrared light, which is its own transmission signal, is mixed into its own receiving side. This is to generate crosstalk light, which is light to be mixed, which may cause a malfunction. The problem of the crosstalk light will be further described with reference to FIGS.

FIG. 13 is a longitudinal sectional view of a part of the prior art. A chip of a light emitting diode (abbreviated as LED) 2 is connected to a conductor 1 such as a lead frame, and a chip of a photodiode (abbreviated as PD) 3 for receiving light is connected. Further, an integrated circuit for driving the light emitting diode 2 and an integrated circuit for signal processing of the photodiode 3 are connected to the conductor 1. These components 1 to 3 are simultaneously formed integrally with the coating layer 4 of the light-transmitting synthetic resin.
Thus, the front end unit 5 is configured. The front end unit 5 is provided in one communication unit that performs full-duplex transmission. Light from the light emitting diode 2 is emitted as indicated by reference numerals 6 and 7, and is received by the photodiode at the front end of the other communication unit. Light from the light emitting diode in the front end portion of the other communication unit is incident on the photodiode 3 and received as indicated by reference numerals 8 and 9.

The coating layer 4 includes a light emitting lens 10 formed in front of the light emitting diode 2, a light receiving lens 11 arranged in front of the photodiode 3, and these lenses 1.
And a connecting portion 12 extending between 0 and 11.

In the prior art shown in FIG.
And the photodiode 3 are connected to a single common conductor 1 so that it is easy to keep the positional relationship between the light emitting diode 2 and the photodiode 3 constant, and the covering layer 4 uses the same lead frame. It can be integrally molded, thereby eliminating variations in the characteristics of the front end portion 5 and improving the productivity.

When the coating layer 4 is made of, for example, an epoxy resin, its refractive index n is about 1.54, and thus the light 13 emitted from near the side of the light emitting diode 2 is
When the light travels to the outer wall 14 in the connecting portion 12, its incident angle i
Is approximately 41 degrees or more, the light is totally reflected and is received by the photodiode 3 as crosstalk light as indicated by reference numeral 15.

In practice, the outer diameter of each of the lenses 10 and 11 needs to be about 5 mmφ in order to sufficiently increase the amount of transmitted / received light. Therefore, the optical axis 16 of the light emitting diode 2 and the optical axis 17 of the photodiode 3 are required. Is set to about 6 mm in the juxtaposition direction (the left-right direction in FIG. 13). The distance a along the optical axis 16 from the light emission position of the light emitting diode 2 to the outer wall 14 is about 2 mm. Regarding the interval L, the distance a, and the incident angle i,

[0014]

(Equation 1)

The incident angle i in this prior art is

[0016]

(Equation 2)

## EQU1 ## From this, it is understood that the incident angle i is a value exceeding the critical angle of total reflection of about 41 degrees, and therefore almost all of the light emitted from the side of the light emitting diode 2 reaches the photodiode 3. Is done.

In a full-duplex communication device, when the front end unit 5 shown in FIG.
5 is received by the photodiode 3 and therefore cannot be distinguished from the lights 8 and 9 from the other communication units. Such a crosstalk light 1
3 and 15 and the normal incident light 8 and 9
It is difficult to remove the output by a signal processing circuit by an electrical configuration.

Communication is performed even when the transmission distance between the front end unit 5 of one of the two communication units for performing data transmission and the front end unit of the other communication unit is about 1 m or more and long. The gain of the amplifier circuit for amplifying the output of the photodiode 3 is set to a large value. Therefore, the crosstalk light 13,
It is necessary to reduce the mixing of 15 into the photodiode 3 as much as possible. The transmission data from the light emitting diode 2 is a coded signal, and the incident lights 8 and 9 from the other communication unit are also coded signals. Therefore, in a circuit that processes the output of the light emitting diode 3, the amplification gain is controlled to control the crosstalk light 13 and 15.
It is difficult to remove the data caused by the above and obtain only the data of the normal incident lights 8 and 9 alone.

Further, in data transmission, it is necessary to transmit every bit exactly. Therefore, from this, the data is transmitted to the photodiode 3 caused by the crosstalk lights 13 and 15 which become the own noise in the front end unit 5. It is necessary to reduce the incidence of light as much as possible. Therefore, it is necessary to remove the generation of noise caused by the crosstalk light 13 and 15 by devising the mechanical structure instead of removing it by an electrical configuration.

In another prior art for solving this problem, parts corresponding to those in the prior art of FIG. 13 shown in FIG. 14 are denoted by the same reference numerals. The light emitting diode 2 is attached to a lead wire 18, and the photodiode 3 is attached to another lead wire 19 and is integrally covered with light-transmitting synthetic resins 20 and 21 and molded. FIG.
In order to remove the crosstalk light 13 and 15 in the prior art, a member 22 made of a light-shielding synthetic resin material is provided, and this member 22 is provided with a partition plate 23 interposed between the light emitting diode 2 and the photodiode 3. Have.

The new problem of the prior art shown in FIG. 14 is that it is necessary to insert the light-shielding synthetic resin member 22 as a separate step in the production process, so that the productivity is low, the cost is low, and the shape is low. Is to be enlarged. Further, since the light emitting diode 2 and the photodiode 3 are individually connected to the two lead wires 18 and 19, the positional relationship between the light emitting diode 2 and the photodiode 3 cannot be accurately kept constant, and the front end portion is not provided. 5 cannot be suppressed.

[0023]

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate crosstalk light from a light emitting element to a light receiving element, to improve productivity with a simple structure, and to realize a light emitting device capable of further miniaturization. It is to provide a light receiving device.

Another object of the present invention is to eliminate the crosstalk light of the light-emitting / light-receiving device in each of the two communication units performing bidirectional full-duplex communication to prevent a malfunction in data transmission and perform accurate communication. And a bidirectional full-duplex communication device.

[0025]

According to the present invention, a light emitting element and a light receiving element are juxtaposed at an interval, and a light emitting direction of the light emitting element and an incident direction of light received by the light receiving element are defined as follows.
Regarding the juxtaposition direction of the light emitting element and the light receiving element, on one side,
In the light emitting / receiving device provided, wherein the light emitting element and the light receiving element are covered with a coating layer made of a light-transmitting synthetic resin, the coating layer is open to the one side between the light emitting element and the light receiving element. A light emitting / receiving device having a groove formed therein. According to the present invention, light is emitted from the light emitting element to the synthetic resin coating layer between the light emitting element and the light receiving element with respect to the juxtaposition direction of the light emitting element and the light receiving element (for example, the left and right direction in FIG. 1 described later). An open groove is formed on one side (upper side in FIG. 1) where light is emitted and light is incident on the light receiving element, so that light such as infrared rays radiated from the side (right side in FIG. 1) of the light emitting element Is a boundary surface that is an inner surface of the groove on the light emitting element side,
(A) the light is transmitted at a large refraction angle and travels to the atmosphere, and thus is prevented from entering the light receiving element side; or (b) light from the light emitting element is totally reflected on the inner surface on the light emitting element side, and The fact that a and b prevent the light-receiving element from proceeding. Thus, the crosstalk light from the light emitting element to the light receiving element is greatly reduced.

Further, the present invention is characterized in that the inner surface of the groove is formed in an arc shape along the outer periphery of the light emitting element and the light receiving element. According to the present invention, as shown in FIG. 9, since the inner surface of the groove is formed in an arc shape along the outer periphery of the light emitting element and the light receiving element, the groove is exposed to the atmosphere from the boundary surface which is the inner surface on the light emitting element side. The refracted transmitted light hardly reenters the arc-shaped inner surface on the light receiving element side, and is reflected into the air on the inner surface on the light receiving element side. Thus, crosstalk light to the light receiving element can be prevented.

[0027] The present invention is also characterized in that a groove opened to the other side in the juxtaposition direction is further formed between the light emitting element and the light receiving element in the covering layer. According to the present invention, regarding the juxtaposition direction of the light emitting element and the light receiving element,
Not only is a groove provided on one side, but a groove is further formed on the other side (lower in FIG. 10) opposite to the one side in the juxtaposition direction as in the embodiment of FIG. Is done. Thereby, crosstalk light from the light emitting element to the light receiving element can be more reliably prevented.

Further, in the present invention, the inner surface of the groove on the light emitting element side is inclined toward the light receiving element as it goes away from the light emitting element to the one side. According to the present invention, as described later with reference to FIG. 11, since the inner surface of the groove on the light emitting element side is inclined, light enters from the light emitting element to a boundary surface which is the inner surface on the light emitting element side. The angle of incidence of the light may be, for example, about 41 degrees or more at which total reflection occurs. In this way, the light from the light emitting element does not penetrate into the groove and travel therethrough.

Further, according to the present invention, the mutual position perpendicular to the juxtaposition direction between the light emitting element and the inner surface of the groove on the light emitting element side is defined as an incident angle i formed by light from the light emitting element with the inner surface of the groove on the light emitting element side.
However, as the refracted light transmitted through the inner surface on the light emitting element side travels to the one side from the portion of the coating layer covering the light receiving element, or the critical angle for total reflection on the inner surface on the light emitting element side or more. As described above, it is characterized in that it is determined. According to the present invention, as shown in FIG. 12, the light emitting element is shifted in a direction perpendicular to the juxtaposition direction (downward in FIG. 12), and the incident angle formed by the light from the light emitting element with the inner surface of the groove on the light emitting element side. i is increased. This prevents the refracted light emitted into the air from the inner surface on the light emitting element side from re-entering (a) the portion of the coating layer that covers the light receiving element, or (b) using the inner surface on the light emitting element side as a boundary surface. Total reflection. Thus, crosstalk light from the light emitting element to the light receiving element is reliably prevented.

Further, according to the present invention, the light emitting element is provided on a conductor, and the conductor has a light emitting element along the juxtaposition direction;
A step is formed between the groove and the inner surface on the light emitting element side, the step rising on the light receiving element side from the light emitting element side, and the step partially blocks light traveling from the light emitting element to the inner surface on the light emitting element side. It is characterized by doing. According to the present invention, FIG.
As in 2, a step is formed in a conductor on which a light emitting element is provided, for example, a conductor such as a lead of a lead frame.
Due to this step, light traveling from the light emitting element to the inner surface of the groove on the light emitting element side is partially blocked. Thus, crosstalk light from the light emitting element to the light receiving element can be reliably prevented.

The present invention also includes two communication units, each of which is (a) a light-emitting / light-receiving device, in which a light-emitting element and a light-receiving element are juxtaposed at an interval,
The light emitting direction of the light emitting element and the incident direction of light received by the light receiving element are provided on one side with respect to the juxtaposition direction of the light emitting element and the light receiving element, and the light emitting element and the light receiving element are
A light-emitting / light-receiving device, which is covered with a light-transmitting synthetic resin coating layer, wherein the coating layer has a groove opened on one side between the light-emitting element and the light-receiving element; and (b) data to be transmitted. Transmitting means for driving the light emitting element by modulating
Receiving means for demodulating the output from the light receiving element to obtain the data, receiving light from the light emitting element of one communication unit by the light receiving element of the other communication unit, and light emitting element of the other communication unit The bidirectional full-duplex communication device is characterized in that light from the first communication unit is received by the light receiving element of the one communication unit to perform full-duplex communication. According to the present invention, the crosstalk light from the light emitting element to the light receiving element in the light emitting / receiving device can be removed, so that the transmission distance between the light emitting / light receiving device of the two communication units can be increased. Even if the configuration is such that the amplification gain is set high, erroneous operation can be prevented and data transmission can be performed accurately. The light emitting / receiving device of the present invention can be used not only for bidirectional full-duplex communication, but also for bidirectional half-duplex communication. And other data transmission communications. not only that,
The present invention can also be embodied as a so-called reflective photointerrupter or the like that reflects light from a light emitting element on a detected object and receives the reflected light on a light receiving element, thereby detecting the detected object. The invention can be implemented in connection with still other uses.

[0032]

FIG. 1 is a cross-sectional view of a part of a front end section 26 which is a light emitting / receiving device in a two-way full-duplex communication device according to an embodiment of the present invention. A light-emitting diode 28 as a light-emitting element and a photodiode 29 as a light-receiving element are provided on a conductor 27 which is a lead of a lead frame made of a metal such as iron, in the juxtaposed direction which is the horizontal direction in FIG. The conductor 27 is also provided with an integrated circuit 47 for driving the light emitting diode 28 and an integrated circuit 49 for processing the signal of the photodiode 29. Light emitting diode 28 and photodiode 2
9 comprises a semiconductor chip. The light emitting diode 28, the photodiode 29, the conductor 27, and the like are integrally molded and covered with a covering layer 31 of a translucent synthetic resin material, for example, an epoxy resin which is a thermosetting synthetic resin.
The coating layer 31 may have a characteristic of selectively blocking frequency.

The light for data transmission from the light emitting diode 28 travels through reference numerals 32 and 33 as transmission light.
The received light travels as indicated by reference numerals 34 and 35 and is received by the photodiode 29. Thus, the light emitting diode 28 for the transmitting light 32, 33 and the receiving light 34,
Light is emitted / received on one side (upward in FIG. 1) with respect to the juxtaposition direction (horizontal direction in FIG. 1) with the photodiode 29 for 35.

The coating layer 31 has a light emitting lens 44 for converting light from the light emitting diode 28 into parallel light parallel to the optical axis 43, and light 34 parallel to the optical axis 45 is incident on the photodiode 29. At that time, the light 34 is
9 has a light receiving lens 46 for condensing light on the light receiving surface. These lenses 44 and 46 may be substantially hemispherical convex lenses.

FIG. 2 is a sectional view showing the entire structure of the front end section 26 shown in FIG. The integrated circuit 47 for driving the light emitting diode 28 is provided on the conductor 48 and connected to the light emitting diode 28 by wire bonding. Signal processing integrated circuit 4 for photodiode 29
9 is provided on the conductor 51 and connected to the photodiode 29 by wire bonding.

FIG. 3 is a plan view of the front end portion 26. The grooves 37 are formed on the cover layer 31 on both sides (vertical direction in FIG. 3) of the lenses 44, 46 on both sides (vertical direction in FIG. 3) of an imaginary plane including the juxtaposition direction and the one side.
The connecting portions 52 and 53 are connected between them. This improves the strength.

Light emitting diode 28 and photodiode 29
Are provided on a single common conductor 27,
The mutual positional relationship between the light emitting diode 28 and the photodiode 29 is accurately set. Therefore, the optical axes 43 and 45 can be set, for example, in parallel in the plane of FIG.

As shown in FIG. 4, the conductor 27 has a bottomed cap-shaped cap portion 54 on which the light emitting diode 28 is provided. The cap part 54 is provided with the light emitting diode 2.
8 includes a bottom 55, and an inclined portion 56 having a substantially hollow truncated cone shape formed to have an inner diameter that increases toward the one side (the upper side in FIGS. 1 and 2). The light from the side of the light emitting diode 28 is reflected by the inner surface of the inclined portion 56, and is reflected to the one side as indicated by reference numeral 57 in FIG.

According to the present invention, when a part of the light from the light emitting diode 28 travels toward the photodiode 29 as indicated by reference numeral 36, the light 36
9, the light-emitting diode 28 and the photodiode 2
9 and the groove 3 opened to one side (upper side in FIG. 1).
7 is formed. As a result, (a) the refracted light 39 passing through the inner surface 38 which is the boundary surface of the groove 37 on the light emitting diode 28 side travels to the one side and is prevented from being incident on the light receiving element and the photodiode 29. b) The light 36 is totally reflected by the inner surface 38 and travels as indicated by reference numeral 41, and does not enter the atmosphere with the inner surface 38 as a boundary surface. Thus, the inner surface 4 which is the boundary surface of the groove 37 on the photodiode 29 side is formed.
No light from the light-emitting diode 28 enters the light emitting diode 2.

That is, according to the concept of the present invention, a groove 37 is formed in the coating layer 31 between the light emitting diode 28 and the photodiode 29, and the inner surfaces 38 and 42 are formed on the boundary surface between the coating layer 31 and the air. Become. The light 36 from the light emitting diode 28 strikes the inner surface 38 and is reflected by the inner surface 38 to become a reflected light 41. The intensity of the light 39 refracted from the inner surface 38 into the air is calculated from the intensity of the light 36 to the intensity of the reflected light 41. Is subtracted. Thus, the intensity of the light 39 traveling into the atmosphere is attenuated by the intensity of the reflected light 41. Thus, the intensity of the light 39 in the air is greatly reduced. Also, even if there is light incident on the inner surface 42, the light is partially reflected on the inner surface 42 and is incident,
Light traveling toward the photodiode 29 is attenuated. Thus, the crosstalk light to the photodiode 29 can be reduced or eliminated by the function of the groove 37.

Inner surface 38 of groove 37 on light emitting diode 28 side
When the incident angle of the incident light 36 with the normal 58 is i, the refraction angle of the light transmitted to the atmosphere is r, and the refraction index of the light of the coating layer 31 is n, 3 holds.

Sin r = n · sin i (3) When the coating layer 31 is an epoxy resin, the refractive index n is approximately 1.54, and when the incident angle i and the refraction angle r are small, the refractive index n is approximately. Equation 4 holds.

R = 1.54 · i (4) Accordingly, r> i, and the light 36 from the light emitting diode 28 becomes a refracted light 39 that is refracted so as not to easily enter the photodiode 29 on the receiving side. move on. That is, the refracted light 39 transmitted through the inner surface 38 from the light emitting diode 36
The refraction angle r becomes larger than the incident angle i, and escapes into the air, so to speak, so that it does not enter the light receiving lens 46 and its vicinity. Even if the refracted light 39
However, even if the light reaches the inner surface 42 on the other photodiode 29 side, at least partial reflection occurs on the inner surface 42, so that the crosstalk light incident on the photodiode 29 is greatly reduced.

FIG. 5 is a block diagram of one communication unit 58 of the bidirectional full-duplex communication device having the front end unit 26 shown in FIGS. FIG. 6 is an electric circuit diagram showing a specific configuration of the front end unit 26, and also shows a specific configuration of the front end unit 26a of the communication unit 59 that forms another pair. These communication units 58 and 59 have the same configuration, and the corresponding parts are indicated by the same numbers with the suffix a. Data to be transmitted from the processing circuit 61 realized by a microcomputer or the like is transmitted and received by a transmission / reception circuit UART (Universal).
Asynchronous Receiver / Transmitter) 62, the data is modulated by a modulation circuit 63, and is applied to a driving integrated circuit 47 which is a transmission circuit to drive the light emitting diode 28. A switching transistor 65 is connected to the light emitting diode 28 in series. The light emitting diode 28 emits infrared light having a wavelength of, for example, 850 to 900 nm. The transmission light 33 from the light emitting diode 28 is received by the photodiode 29a of the front end unit 26a in another communication unit 59. Light emitting diode 2 in front end section 26a
The reception light 34 radiated from 8a and received by the front end unit 26 is received by the photodiode 29, amplified by the signal processing integrated circuit 49 by the amplification circuit 63, binarized by the level discrimination circuit 64, and waveform-shaped. , Demodulation circuit 65. In this way, data from the communication unit 26a is obtained, supplied to the transmission / reception circuit 62, and processed by the processing circuit 61. The transmission / reception circuit 62 converts the parallel data from the processing circuit 61 into serial bits and supplies the serial bits to the modulation circuit 63, and also converts the serial bit data from the demodulation circuit 65 into parallel and supplies the data to the processing circuit 61.

FIG. 7 is a sectional view showing a specific structure of the light emitting diode 28. As shown in FIG. The light emitting diode 28 is a silicon crystal having a PN junction, and includes an N region 67 and a P region 68.
Are provided with electrodes 71 and 72. When a forward voltage is applied between the electrodes 71 and 72 by the power supply 66, the N region 67
From the P region 68 and holes from the P region 68.
, And recombine the electron density holes, thereby generating light 32. From the PN junction 69, the light 36,
57 is emitted.

FIG. 8 is a sectional view showing a specific structure of the photodiode 29. This photodiode 29 has N
The region 77 and the P region 78 are configured by PN junction.
When the incident light 35 enters the light receiving region 73, the electrons that have been bonded to the lattice are released from the bonds and become free electrons, and free electrons and holes are generated. These electrons and holes move to the depletion region 74 and are extracted from between the electrodes 75 and 76 as a current having an absolute value proportional to the intensity of light.

In another embodiment of the present invention, a semiconductor laser device may be used in place of the light emitting diode 28, or a semiconductor device which generates an electromagnetic wave such as light may be used. Alternatively, the light receiving element may be a phototransistor, a solar cell, or another semiconductor.

FIG. 9 is a plan view of a front end portion 79 according to another embodiment of the present invention. This embodiment is similar to the configuration described in relation to FIGS. 1 to 8 described above, and corresponding portions are denoted by the same reference numerals. It should be noted that, in this embodiment, the inner surface 82 of the groove 81 on the light emitting diode 2 side and the inner surface 83 of the photodiode 3 side are connected to the light emitting lens 10.
Along the outer circumference of the light receiving lens 11, and thus the light emitting diode 28 and the photodiode 29, along the axes 43, 4.
5 forms a part of the outer surface of a virtual right circular cylinder centered at 5. Following the inner surfaces 82 and 83, the inner surfaces 84 and 85
The plane is perpendicular to an imaginary plane including 3, 45 and parallel to each other. The light from the light emitting diode 28 is generated radially. Therefore, the light 87 having an angle with respect to the y direction 86 perpendicular to the juxtaposition direction (the left-right direction in FIG. 9) of the light emitting diode 28 and the photodiode 29
The transmitted light 88 is transmitted through the inner surface 82 which is the boundary surface on the 8-side.
Is hard to re-enter the inner surface 83 on the photodiode 29 side, the light 88 is reflected on the inner surface 83, and the photodiode 29
Is suppressed. Therefore, the light 87 traveling from the light emitting diode 28 toward the inner surface 82 is prevented from being incident on the photodiode 29 as crosstalk light as described above.

FIG. 10 is a sectional view of a front end portion 89 according to another embodiment of the present invention. In this embodiment,
Similar to the embodiments of FIGS. 1 to 9 described above, corresponding parts are denoted by the same reference numerals. It should be noted that, in this embodiment, the covering layer 31 has a juxtaposition direction (the horizontal direction in FIG. 10) between the light emitting diode 28 and the photodiode 29.
A groove 91 which is open to the other side (lower in FIG. 10) is further formed. The inner surface 92 of the groove 91 on the light emitting diode 28 side and the inner surface 93 of the photodiode 29 side wrap around the conductor 27 from the light emitting diode 28 downward in FIG. The traveling light is prevented from being incident on the photodiode 29 side.

Thus, on the side opposite to the light emitting diode 28 with respect to the conductor 27 (the lower part in FIG. 10), the coating layer 31 is formed.
Can be an optical path of the crosstalk light from the light emitting diode 28, but by forming the above-mentioned groove 91, the crosstalk light can be reduced and the photodiode 29
Of noise due to crosstalk light into the camera. Groove 3
7 and 91, similarly to the above-described FIG. 9, may have an arc-shaped groove 81 formed therein.

FIG. 11 is a sectional view of a front end portion 95 according to another embodiment of the present invention. In this embodiment,
Similar to the previous embodiment, corresponding parts are denoted by the same reference numerals. It should be noted that in this embodiment, the inner surface 38 of the groove 37 formed in the covering layer 31 on the light emitting diode 28 side is separated from the light emitting diode 28.
As the distance from one side (upper side in FIG. 11) of the juxtaposition direction (horizontal direction in FIG. 11) with the photodiode 29 is increased, the angle is inclined by an angle θ1 toward the photodiode 29. The inner surface 38 is perpendicular to a plane including the optical axes 43 and 45. When the light 97 from the light emitting diode 28 is incident on the inner surface 38, which is the boundary surface, reflected light 98 is generated on the inner surface 38 and bent to transmit light 99. If the incident angle i of the light 97 from the light emitting diode 28 on the inner surface 38 is equal to or greater than the critical angle of total reflection, for example, about 41 degrees as described above, the refracted light 99 does not occur. Since the inner surface 38 has the angle θ1, the incident angle i is increased,
This ensures that the light 97 is totally reflected. Angle θ1
Is a value exceeding zero degree and less than 90 degrees with respect to the juxtaposition direction, and may be a value such as 70 degrees, for example. FIG.
The inner surfaces 38 and 42 of the shaft 1 are, as in FIG.
May be in the shape of an arc centered at.

FIG. 12 is a sectional view of a front end portion 101 according to still another embodiment of the present invention. This embodiment is similar to the above-described embodiment, and corresponding parts are denoted by the same reference numerals. Particularly in this embodiment, the conductor 27
The cap 54 of FIG.
, The incident angle i of the light 102 traveling to the groove 37 at the inner surface 38 is increased to be equal to or greater than the critical angle, and the light 102 is totally reflected to obtain a total reflected light 103, and the transmitted refracted light 10
4 is zero or negligible. Thus, the refracted light 104 transmitted through the inner surface 38 of the groove 37 on the light emitting diode 28 side.
(A1) travels to the side (upper side in FIG. 12) of the portion 105 of the coating layer 31 covering the photodiode 29, or (b1) the incident light 102 on the inner surface 38 on the light emitting diode 28 side. The upper and lower positions of the light emitting diode 28 in FIG. 12 are set so that a large incident angle i, which is a critical angle at which is totally reflected, is obtained. That is, the position of the light emitting diode 28 and the inner surface 38 of the groove 37 on the light emitting diode 28 side in the vertical direction in FIG. a
1, so that b1 is satisfied.

Further, the light 105 traveling from the light emitting diode 28 to the side is reflected by the inclined surface 56 of the cap portion 54 of the conductor 27 and becomes light 107 and travels to the one side (upward in FIG. 12). In the inclined surface 56 of the cap 54, the portion 56c closer to the inner surface 38, that is, closer to the photodiode 29, has a depth D1 lower than the upper surface 27c in FIG. 12 so as to reflect the light 105 as described above. The driving integrated circuit 47 which extends to the left of the light emitting diode 28 in FIG. 12 is easily connected from the light emitting diode 28 by a wire bonding conductor 106. The depth D2 of the inclined surface 56d is set shallow (D1> D2).

Each of the grooves 37 in FIGS. 11 and 12 may be formed as the arc-shaped groove 81 described with reference to FIG. 9 described above. Further, in each of the embodiments of FIGS. As shown in FIG. 10, another groove 91 may be formed on the other side, and this groove 91 may be formed in the same manner as the arc-shaped groove 81 in FIG.

In another embodiment of the present invention, FIGS.
2 each front end part 26, 79, 89, 9
5, 101 can be used not only as a front end part of two-way duplex communication, but also as a so-called reflective photointerrupter for detecting an object to be detected. At this time, the axes 43 and 45 of the light emitting diode 28 and the photodiode 29 may be inclined so as to approach each other toward the one side (upward in FIG. 1). In this reflective photointerrupter, the light from the light emitting diode 28 may be DC (direct current) light or continuous modulated light. When this modulated light is used, a bandpass filter or the like that selectively extracts only the modulated light is used as an output from the photodiode 29 that is the modulated light. As a result, the output level passing through the filter is level-discriminated at a predetermined discrimination level without being adversely affected by disturbance noise, so that a binary signal can be obtained and the proximity of the detected object can be detected.

In each of the above embodiments, the coating layer 31
When the light emitting diode 28, the photodiode 29, the conductors 27, 48, 51 and the like are integrally formed by using the method, for example, a transfer molding method and a casting method are employed. In the transfer molding method, a mold cavity is closed in advance, and a light-transmitting thermosetting synthetic resin material is placed under a high pressure from a material chamber provided in a part of the mold, that is, a pot portion. It is a method of pushing in. The casting method is a method in which the liquid material is poured into a mold and cured at room temperature or by heating. In particular, according to the casting method, the inner surface 38 having the angle θ1 in the groove 37 of the front end portion 95 described above with reference to FIG.
It is easy to mold with a mold. The coating layer 31
Instead of using a thermosetting synthetic resin material, it may be made of a thermoplastic synthetic resin material or a light-transmitting material such as ceramic.

[0057]

According to the first aspect of the present invention, between the light emitting element and the light receiving element, the coating layer made of the light-transmitting synthetic resin is formed with a groove opened to one side, thereby forming Crosstalk light from the light emitting element to the light receiving element can be removed. In addition, this configuration is simple, and is not a configuration in which a light-shielding plate or the like is arranged between the light emitting element and the light receiving element, so that the productivity is excellent and the size can be reduced.

According to the second aspect of the present invention, since the inner surface of the groove is arc-shaped, light transmitted from the inner surface on the light emitting element side to the air is less likely to be incident on the inner surface on the light receiving element side. The light is prevented from being reflected by the inner surface on the element side and entering the portion of the coating layer covering the light receiving element. This can prevent crosstalk light from the light emitting element from being incident on the light receiving element.

According to the third aspect of the present invention, the groove for removing the crosstalk light is not only on one side (upper side in FIG. 10) but also on the other side (upper side in FIG. 10) in the juxtaposition direction of the light emitting element and the light receiving element. 10), whereby the crosstalk light can be more reliably prevented from entering the light receiving element.

According to the fourth aspect of the present invention, the light from the light emitting element can be totally reflected by the inner surface on the light receiving element side by inclining the inner surface of the groove on the light receiving element side. Thereby, crosstalk light from the light emitting element to the light receiving element can be removed.

According to the fifth aspect of the present invention, the light emitting element is
The incident angle i formed by the light from the light emitting element and the inner surface on the light emitting element side is increased by shifting in the direction perpendicular to the juxtaposition direction (downward in FIG. 12). As a result, the refracted light transmitted through the inner surface on the light emitting element side is prevented from entering the air and entering the portion of the coating layer covering the light receiving element, or is totally reflected on the inner surface on the light emitting element side. Thus, the crosstalk light from the light emitting element is prevented from being incident on the light receiving element.

According to the sixth aspect of the present invention, a step is formed in a conductor such as a lead on which the light emitting element is provided to partially block light traveling from the light emitting element to the inner surface on the light emitting element side, thereby forming a cross. Talk light can be prevented.

According to the present invention, the crosstalk light from the light emitting element to the light receiving element is removed by the mechanical structure, so that the transmission distance of data communication can be extended. Therefore, even if the output of the light receiving element is amplified with a high gain, malfunction of data communication due to the crosstalk light can be prevented, and accurate data transmission can be performed. As a result, communication is performed in a bidirectional full-duplex system, and high-speed data transmission using communication time effectively becomes possible. That is, such a light-emitting / light-receiving device is used, for example, for data communication, and in order to increase the data communication distance, the coating layer is formed into a shape such as a convex lens,
Even in the case of increasing the outer diameter, by forming the groove between the light emitting element and the light receiving element as described above,
Since crosstalk light can be removed, the configuration can be made as small as possible. In addition, since the crosstalk light does not mix into the light receiving element, even if the output of the light receiving element is amplified with a high gain in order to increase the data transmission distance as described above, noise generated by the crosstalk light may be reduced. Mixing is reliably prevented, and communication over a long transmission distance becomes possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a part of a front end unit 26 that is a light emitting / receiving device in a bidirectional full-duplex communication device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an entire configuration of a front end unit 26 shown in FIG.

FIG. 3 is a plan view of a front end section 26.

FIG. 4 is a plan view of the front end unit 26.

FIG. 5 shows one communication unit 58 of the bidirectional full-duplex communication device including the front end unit 26 shown in FIGS.
It is a block diagram of.

FIG. 6 is an electric circuit diagram showing a specific configuration of a front end unit 26.

FIG. 7 is a sectional view showing a specific configuration of the light emitting diode 28.

FIG. 8 is a sectional view showing a specific configuration of a photodiode 29.

FIG. 9 is a front end part 7 according to another embodiment of the present invention.
9 is a plan view of FIG.

FIG. 10 is a sectional view of a front end portion 89 according to another embodiment of the present invention.

FIG. 11 is a sectional view of a front end portion 95 according to another embodiment of the present invention.

FIG. 12 is a sectional view of a front end portion 101 according to still another embodiment of the present invention.

FIG. 13 is a longitudinal sectional view of a part of the prior art.

FIG. 14 is a longitudinal sectional view of a part of the prior art.

[Explanation of symbols]

 26, 79, 89, 95, 101 Front end part 28 Light emitting diode 29 Photodiode 31 Coating layer 44 Light emitting lens 46 Light receiving lens 47 Driving integrated circuit 49 Signal processing integrated circuit 54 Cap part 58, 59 Communication unit

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04B 10/28 10/02 10/18

Claims (7)

[Claims] 1. A light emitting element and a light receiving element are juxtaposed at an interval, and a light emitting direction of the light emitting element and an incident direction of light received by the light receiving element are related to a juxtaposition direction of the light emitting element and the light receiving element. A light-emitting / light-receiving device provided on one side, wherein the light-emitting element and the light-receiving element are covered with a light-transmitting synthetic resin covering layer; A light emitting / receiving device having an open groove on one side. 2. The light emitting / receiving device according to claim 1, wherein an inner surface of the groove is formed in an arc shape along an outer periphery of the light emitting element and the light receiving element. 3. The light-emitting device according to claim 1, wherein a groove that is open to the other side in the juxtaposition direction is further formed in the covering layer between the light-emitting element and the light-receiving element. / Light receiving device. 4. The light-emitting element side inner surface of the groove is inclined toward a light-receiving element as it goes away from the light-emitting element to the one side. 3. The light emitting / receiving device according to claim 1. 5. A mutual position perpendicular to the juxtaposition direction between the light emitting element and the inner surface of the groove on the light emitting element side, wherein an incident angle i formed by light from the light emitting element with the inner surface of the groove on the light emitting element side is: As the refracted light transmitted through the inner surface on the light emitting element side travels to the one side from the portion of the coating layer covering the light receiving element, or as a critical angle or more for total reflection on the inner surface on the light emitting element side, The light emitting / receiving device according to claim 1, wherein the light emitting / receiving device is set. 6. A light-emitting element is provided on a conductor, the conductor being provided between the light-emitting element along the juxtaposition direction and the inner surface of the groove on the light-emitting element side, on the light-receiving element side relative to the light-emitting element side. 6. A step which is raised by the step is formed, and the step partially blocks light traveling from the light emitting element to the inner surface on the light emitting element side.
The light emitting / receiving device according to claim 1. 7. A communication device comprising: (a) a light-emitting / light-receiving device, wherein a light-emitting element and a light-receiving element are juxtaposed at an interval, and a light-emitting direction of the light-emitting element; The light incident direction of the light received by the light receiving element is provided on one side with respect to the juxtaposition direction of the light emitting element and the light receiving element, and the light emitting element and the light receiving element are covered with a transparent synthetic resin coating layer. A light-emitting / light-receiving device in which the cover layer has an open groove on one side between the light-emitting element and the light-receiving element; and (b) a transmission unit that modulates data to be transmitted and drives the light-emitting element. And (c) receiving means for demodulating the output from the light receiving element to obtain the data, receiving light from the light emitting element of one communication unit by the light receiving element of the other communication unit, and Light emitting element of communication unit A two-way full-duplex communication device, wherein light from the first communication unit is received by the light receiving element of the one communication unit to perform full-duplex communication.