JP2000357816A - Optical coupling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical coupling device for obtaining high detection accuracy by cutting disturbance light near the detection wavelength region of a photo detector chip with inexpensive and rational structure. SOLUTION: A short-wavelength region light-shielding resin for cutting light at the shorter wavelength-side light as compared with the detection wavelength region of a photo detector chip 11 that is set to a specific range, and a long- wavelength region light-shielding resin for cutting light at a longer wavelength side as compared with the detection region are used, a photo detector 10 is molded by either resin, and a case 30 is formed by the other resin. Then, incidence light being limited to a wavelength in the detection wavelength region through the shorter wavelength region light-shielding resin and the longer wavelength region light-shielding resin is detected by the photo detector chip 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a light-emitting element and a light-receiving element. Light emitted from the light-emitting element is incident on the light-receiving element according to the presence or absence of the object to be detected. The present invention relates to an optical coupling device for detecting a state.

[0002]

2. Description of the Related Art An optical coupling device called a photo-interrupter is used as an optical sensor for detecting the presence or absence and state of various detected objects in a non-contact state. 9 and 10
FIG. 9 is a sectional view showing a basic structure of this type of optical coupling device. FIG. 9 shows a transmission type photo interrupter, and FIG. 10 shows a reflection type photo interrupter.

In these optical coupling devices, a light-emitting element 1 and a light-receiving element 2 forming a pair are housed integrally in a case 3. In the transmission type photointerrupter, the light emitting element 1 and the light receiving element 2 are arranged to face each other with the detection groove 4 interposed therebetween.
In the reflection type photo interrupter, the light emitting element 1 and the light receiving element 2 are arranged in parallel on substantially the same plane toward the detection object P.

In the light emitting element 1, one electrode of a light emitting element chip 11 is die-bonded to one end of a first light emitting side lead frame 12, and the other electrode is connected to one end of a second light emitting side lead frame 12 by a wire. After bonding, it is formed by molding the periphery of the light emitting element chip 11 with a translucent resin such as an epoxy resin. Similarly, the light receiving element 2 is configured such that one electrode of the light receiving element chip 21 is die-bonded to one end of the first light receiving side lead frame 22 and the other electrode is connected to one end of the second light receiving side lead frame 22 by a wire. After bonding, it is formed by molding the periphery of the light receiving element chip 21 with a translucent resin.

The case 3 is made of, for example, a light-shielding resin such as a PPS (polyphenylene sulfide) resin, and is formed in a shape capable of properly holding the positions and postures of the light emitting element 1 and the light receiving element 2. A light-emitting window 31 for leading out the irradiation light and a light-receiving window 32 for introducing the light incident on the light-receiving element 2 are provided in front of the light-emitting element 1 and the light-receiving element 2, respectively.

In this type of optical coupling device, detection is usually performed in an infrared light region (800 to 1000 nm). As shown by a characteristic curve A in FIG. In many cases, the maximum emission wavelength of the irradiation light from is set to around 900 to 1000 nm. On the other hand, as shown by the characteristic curve B, the light receiving element chip 2
The sensitive wavelength region of 1 is generally set in a wide range of 400 to 1200 nm. Therefore, in this state,
The light receiving element chip 21 is located near the visible light region (400 to 800).
(nm) may cause malfunction. Therefore, conventionally, a light-receiving element 2 such as a filter 5 or a resin cover capable of cutting light on a shorter wavelength side than the infrared light region is used.
By providing the light on the side, light in an unnecessary wavelength region is removed from the light incident on the light receiving element 2.

[0007]

In recent years, such optical coupling devices have been widely used in recent years, particularly in sensors for detecting the presence or absence of paper in OA equipment such as copiers and printers. The environmental conditions used are also diversifying with the spread and miniaturization of the system. For example, FIG.
As shown by the characteristic curve C in 1, it is not unusual to use a fluorescent lamp having a relatively strong wavelength characteristic on the long wavelength side of 1000 nm or more. In such a case, in the conventional optical coupling device configured to cut off only light on the shorter wavelength side than the infrared light region, the light receiving element chip 21
However, there is a possibility that a malfunction may be detected by detecting fluorescent light near 1000 to 1100 nm.

In order to prevent this, for example, a special optical filter such as a thin-film interference filter is used, or a plurality of filters capable of cutting the short wavelength side and the long wavelength side are combined. It is required to limit the light incident on the element to a certain wavelength region suitable for detection.However, such means as described above may complicate the structure of the optical coupling device and increase the manufacturing cost. Not suitable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical coupling device that can obtain high detection accuracy by cutting disturbance light near a detection wavelength region that may cause a malfunction of a light receiving element. It is to provide a device and to provide such an optical coupling device with an inexpensive and rational structure.

[0010]

The optical coupling device of the present invention comprises:
A light emitting element formed by molding a light emitting element chip,
A light receiving element formed by molding a light receiving element chip;
A case in which the light-emitting element and the light-receiving element are housed and integrally held, and one of the light-receiving element and the case is on the shorter wavelength side than the detection wavelength region of the light-receiving element chip set in a predetermined range. One of the light receiving element and the case is formed of a short wavelength region light shielding resin that cuts light on a longer wavelength side than the detection wavelength region. The incident light transmitted through the region light-shielding resin and the long wavelength region light-shielding resin is detected by a light receiving element chip.

Further, the optical coupling device of the present invention accommodates a light emitting element formed by molding a light emitting element chip, a light receiving element formed by molding a light receiving element chip, and the light emitting element and the light receiving element. And a case to hold together,
A light-emitting window and a light-receiving window formed in the case facing the light-emitting element and the light-receiving element, respectively, and a window filter incorporated in at least the light-receiving window among the light-emitting window and the light-receiving window; The other part is formed of a light-shielding resin, and one of the light receiving element and the window filter is a short wavelength light that cuts light on a shorter wavelength side than the detection wavelength region of the light receiving element chip set in a predetermined range. One of the light receiving element and the window filter is formed of a long wavelength region light shielding resin that cuts light on a longer wavelength side than the detection wavelength region,
It is characterized in that incident light transmitted through the short wavelength region light shielding resin and the long wavelength region light shielding resin is detected by a light receiving element chip.

That is, the present invention provides a short-wavelength region light-shielding resin for cutting light on a shorter wavelength side than a detection wavelength region of a light-receiving element chip set in a predetermined range, and a light on a longer wavelength side than the detection region. Using a long-wavelength region light-shielding resin to be cut, and molding at least the light-receiving element of the light-emitting element and the light-receiving element with one of the resins, and forming the case or the window filter incorporated in the case with the other resin It is. By detecting the incident light limited to the wavelength within the detection wavelength region by transmitting light through the short wavelength region light shielding resin and the long wavelength region light shielding resin with the light receiving element chip, high accuracy not affected by disturbance light near the detection wavelength region Can be detected.

In a reflection type optical coupling device in which a light emitting element and a light receiving element are arranged in parallel in a case toward an object to be detected, the window filter is formed in a lens shape so that the light emitting element and the light receiving element are separated from each other. The loss due to the diffusion of the irradiating light is prevented, and the amount of light incident on the light receiving element is secured,
Further, optically efficient detection becomes possible.

Further, in the reflection type optical coupling device, a part of the case including the light emitting window and the light receiving window is formed to be detachable from the case, so that the window filter incorporated in the light emitting window and the light receiving window is formed. The optical characteristics can be easily changed, and the case that houses the light emitting element and the light receiving element can be shared to reduce the manufacturing cost.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In addition, common names and reference numerals are used for parts and components having common functions and characteristics in each embodiment.

FIG. 1 shows the structure of a transmission type optical coupling device according to a first embodiment of the present invention. This optical coupling device includes a light emitting device 10 formed by molding a periphery of a light emitting device chip 11 connected to a light emitting side lead frame 12.
And a light receiving element 20 formed by molding the periphery of the light receiving element chip 21 connected to the light receiving side lead frame 22.
Are housed in the case 30 in a state where they are opposed to each other.

As shown by a characteristic curve D in FIG. 2, the light emitting characteristics of the light emitting element chip 11 are set so that the maximum light emitting wavelength is around 900 nm. On the other hand, as shown by the characteristic curve E, the light receiving characteristic of the light receiving element chip 21 is 400
It has a sensitive wavelength range of up to 1200 nm, and is set so that the maximum sensitivity is obtained at around 950 nm. The light emission characteristics and light reception characteristics are almost the same as those in the above-mentioned conventional general optical coupling device.

In this optical coupling device, the light emitting element 10
As a resin for molding the light receiving element 20, a resin having a specific transmittance characteristic is used. This resin is
For example, it is formed by adding a dye having a certain light-shielding property to a translucent resin such as an epoxy resin, and has a transmittance characteristic of 90% as shown by a characteristic curve F in FIG.
It is set so as to cut a short wavelength region of 0 nm or less. In the present invention, this resin is referred to as "short wavelength region light-shielding resin" for convenience of explanation.

On the other hand, as shown in a characteristic curve G, a resin formed so as to cut a long wavelength region of 1000 nm or more is used for the case 30 for housing and holding the light emitting element 10 and the light receiving element 20. I have. In the present invention,
This resin is referred to as a “long wavelength region light shielding resin”. In this embodiment, a light emitting element 10 and a light receiving element 20 molded with a short wavelength region light shielding resin are covered by a case 30 made of a long wavelength region light shielding resin over the entire light emitting surface and light receiving surface.

FIG. 3 shows a structure of a reflection type optical coupling device according to a second embodiment of the present invention. In this optical coupling device, the light emitting element 10 and the light receiving element 20 are arranged in parallel, but the light emitting element 1 and the light receiving element 20 are arranged in the same manner as in the first embodiment.
Each of the light-emitting element 10 and the light-receiving element 20 is molded with a short-wavelength-area light-shielding resin, and the light-emitting element 10 and the light-receiving element 20 are covered with a case 30 made of a long-wavelength-area light-shielding resin over their light-emitting surface and light-receiving surface. Have been.

According to the optical coupling device according to the first embodiment and the second embodiment, the light receiving element chip 21
In the incident light, the long wavelength region of 1000 nm or more is cut by the long wavelength region light shielding resin forming the case 30, and the short wavelength region of 900 nm or less is further cut by the short wavelength region light shielding element forming the light receiving element 20. As a result, it is narrowed down to the wavelength region indicated by the hatched portion in FIG. Thus, the light receiving element chip 21 can receive only light in the wavelength region necessary for the detection. As a result, even when the optical coupling device is used under the fluorescent light as shown in FIG. 11, the detection accuracy of the light receiving element chip 21 is increased, and the malfunction does not easily occur.

In each of the above-described embodiments, the light emitting element 10 and the light receiving element 20 may be molded with a long wavelength region light shielding resin, while the case 3 may be formed with a short wavelength region light shielding resin. As described above, even when the wavelength characteristics of the resin for molding the light emitting element 10 and the light receiving element 20 and the resin for forming the case 3 are reversed, the light in the detection wavelength region required by the light receiving element chip 21 is both shielded. If it is set so as to be obtained through the resin, the same effect as described above can be obtained.

FIG. 4 shows a structure of a transmission type optical coupling device according to a third embodiment of the present invention, and FIG. 5 shows a structure of a reflection type optical coupling device according to the fourth embodiment. Is shown. In these optical coupling devices, the light emitting element 10 and the light receiving element 20 are molded with a short wavelength region light shielding resin, and the light emitting element 10 and the light receiving element 20 are formed.
However, like the conventional optical coupling device shown in FIGS. 9 and 10, it is housed in a case 3 made of a light-shielding resin for shielding the entire wavelength region. A light-emitting window 31 is provided on the front surface of the light-emitting element 10 in the case 3 to guide irradiation light from the light-emitting element 10. A window 32 is provided. Further, a window filter 50 is incorporated in each of the light emitting window 31 and the light receiving window 32, and the window filter 50 is formed of a long wavelength region light shielding resin. The transmittance characteristics of the short wavelength region light shielding resin and the long wavelength region light shielding resin in these embodiments are the same as those shown in FIG.

According to the optical coupling devices according to the third and fourth embodiments, the effects obtained by the optical coupling devices according to the first and second embodiments can be reduced. In addition, the light emitting window 31 and the light receiving window 3 of the case 3
Since the portion other than 2 is covered with the light-shielding resin, the direction of diffusion of irradiation light from the light emitting element 10 and the direction of incidence of incident light on the light receiving element 20 are limited, and more accurate detection is possible.

The light emitting window 31 and the light receiving window 3 of the case 3
In order to incorporate the window filter 50 in the case 2, the case 3 and the window filter 50 may be integrally formed by a two-color molding method or the like, or the case 3 and the window filter 50 formed separately may be fitted. They may be combined.

FIG. 6 shows a structure of a reflection type optical coupling device according to a fifth embodiment of the present invention. This optical coupling device is the same as the optical coupling device according to the fourth embodiment, except that the window filter 50 incorporated in the light emitting window 31 and the light receiving window 32 is formed in a convex lens shape. Light-emitting window 3
The lenticular window filter 51 incorporated in 1 and the lenticular window filter 51 incorporated in the light receiving window 32 are arranged so as to form a predetermined opposite angle in accordance with the optical axis of the irradiation light and the incident light. ing. Accordingly, loss due to diffusion of the irradiation light from the light emitting element 10 can be prevented, the amount of light incident on the light receiving element 20 can be secured, and more optically efficient detection can be performed.

FIGS. 7 and 8 show the structure of a reflection type optical coupling device according to a sixth embodiment of the present invention. This optical coupling device is obtained by separating a part of the case 3 from the optical coupling device according to the fifth embodiment, and configuring this as a separate filter unit 6. The filter unit 6 has a filter holding frame 60 made of the same light-shielding resin as the case 3.
Is provided with a light emitting window 61 and a light receiving window 62. In the light-emitting window 61 and the light-receiving window 62, the lens-shaped window filters 51 on the light-emitting side and the light-receiving side are respectively incorporated so as to form a predetermined opposing angle in accordance with the optical axes of the irradiation light and the incident light. ing.

Projecting ridges 63 are formed on both outer surfaces of the filter unit 6. On the other hand, on the front side of case 3,
A concave portion 33 that can accommodate the filter unit 6 is provided, and a guide groove 34 corresponding to the shape of the ridge 63 is formed on both inner side surfaces. The filter unit 6 can be easily attached to and detached from the case 3 by engaging and sliding the protrusions 63 of the filter unit 6 in the guide grooves 34.

In order to increase the detection accuracy in the reflection type optical coupling device, it is desired to change the facing angle and the focal length of the lens-shaped window filter 51 in accordance with the distance to the object P to be detected. A plurality of types of filter units 6 each having a different opposing angle and a different focal length of the filter 51 are formed separately from the case 3, and the filter units 6 are made compatible with each other by providing compatibility with each other. , An optimum filter unit 6 can be selectively incorporated. As described above, the case 3 accommodating the light-emitting element 10 and the light-receiving element 20 is shared, and the structure in which only the filter unit 6 can be attached and detached and replaced is adopted. And the optical characteristics of the window filter 51 can be easily changed according to the use conditions.

As described above, the present invention provides a short-wavelength region light-blocking resin that cuts light on a shorter wavelength side than the detection wavelength region of the light-receiving element chip 21 set in a predetermined range, A long-wavelength region light-blocking resin that cuts light on the long wavelength side is used, and the light emitting element 10 and the light receiving element 20 are molded with one of the resins, and the light emitting window 31 of the case 30 or the case 3 is molded with the other resin. And window filters 50 and 51 incorporated in the light receiving window 32. With such a configuration, only light that is transmitted through the short-wavelength region light-shielding resin and the long-wavelength region light-shielding tree and is limited to a wavelength within the detection wavelength region enters the light receiving element chip 21. As a result, it is possible to prevent the light receiving element chip 21 from malfunctioning by sensing disturbance light near the detection wavelength region.

Further, the optical coupling device of the present invention does not use a special optical filter or incorporate a multilayer filter, but includes a resin for molding the light emitting element 10 and the light receiving element 20 and a case 30 or a window filter 50. , 51
Can be manufactured by molding two types of resins, or three types of resins obtained by adding a light-shielding resin thereto. Therefore, it can be mass-produced with good manufacturing efficiency and at low cost.

The detection wavelength region of the light receiving element chip 21 is set in consideration of the light emitting characteristics of the light emitting element chip 11, the light receiving characteristics of the light receiving element chip 21, the use of the optical coupling device, the use environment conditions, and the like. However, the present invention is not limited to the wavelength region (900 to 1000 nm) described in the above embodiment.

In each of the above embodiments,
If the light emitting element 10 and the light receiving element 20 are molded with the same resin, but the light emitting characteristic of the light emitting element chip 11 and the light receiving characteristic of the light receiving element chip 21 have a relationship as shown in FIG. The resin for molding the element 10 may be a conventional general transparent resin having no light-shielding property. Window filter 5 provided on light emitting element 10 side
The same applies to 0 and 51. The emission wavelength region of the light emitting element chip 11 is limited to a relatively narrow range near the maximum sensitivity wavelength of the light receiving element chip 21, and it is not necessary to further limit the wavelength region of the light emitted from the light emitting element chip 11. Because there is no.

That is, in the present invention, at least the light incident on the light receiving element chip 21 is transmitted through the short wavelength region light shielding resin and the long wavelength region light shielding resin, so that the wavelength region may be limited. However, the light emitting element chip 11
In the case where the emission wavelength range is wider, it is effective to similarly limit the wavelength range of the irradiation light from the light emitting element chip 11 as well. Light emitting element 1
By molding the 0 and the light receiving element 20 with the same resin, it is possible to further increase the efficiency of the manufacturing process.

[0035]

According to the optical coupling device of the present invention, a short-wavelength region light-shielding resin for cutting light on a shorter wavelength side than a detection wavelength region set in a predetermined range, and a short-wavelength region light-shielding resin on a longer wavelength side than the detection region are provided. Since the light-emitting element and the light-receiving element are molded with at least one of the light-emitting elements and the light-receiving element with the long-wavelength region light-blocking resin that cuts light, and the other resin forms a case or a window filter incorporated in the case, Light incident on the light receiving element chip is only light transmitted through these short wavelength region light shielding resin and long wavelength region light shielding resin,
High-precision detection that is not affected by disturbance light in the vicinity of the detection wavelength region becomes possible.

Further, the optical coupling device of the present invention can be manufactured by molding two kinds of resins, a short-wavelength region light-shielding resin and a long-wavelength region light-shielding resin, or three types of resins obtained by adding a light-shielding resin thereto. As a result, the production efficiency is high and mass production can be performed at low cost.

Further, in the reflection type optical coupling device, by forming the window filter incorporated in the case into a lens shape, loss due to diffusion of irradiation light from the light emitting element is prevented, and the amount of light incident on the light receiving element is reduced. Can be ensured, so that more optically efficient detection is possible.

Further, in the reflection type optical coupling device,
Part of the case including the light-emitting window and light-receiving window is separated from the case, and a filter unit that can be attached to and detached from and replaced with the case is used. In addition, the optical characteristics of the window filter incorporated in the filter unit can be easily changed according to use conditions and the like.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a transmission type optical coupling device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing light receiving / emitting characteristics and light blocking characteristics in the optical coupling device of the present invention.

FIG. 3 is a cross-sectional view illustrating a structure of a reflection-type optical coupling device according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing the structure of a transmission type optical coupling device according to a third embodiment.

FIG. 5 is a sectional view showing the structure of a reflection type optical coupling device according to a fourth embodiment.

FIG. 6 is a sectional view showing the structure of a reflection type optical coupling device according to a fifth embodiment.

FIG. 7 is a sectional view showing the structure of a reflection type optical coupling device according to a sixth embodiment.

FIG. 8 is a perspective view of an optical coupling device according to a sixth embodiment.

FIG. 9 is a cross-sectional view showing a structure of a conventional transmission type photo interrupter.

FIG. 10 is a cross-sectional view illustrating a structure of a conventional reflective photointerrupter.

FIG. 11 is a diagram showing a light receiving and emitting characteristic and a light emitting characteristic of fluorescent light in a conventional optical coupling device.

[Explanation of symbols]

 Reference Signs List 10 light emitting element 11 light emitting element chip 20 light receiving element 21 light receiving element chip 3, 30 case 31 light emitting window 32 light receiving window 50, 51 window filter

Claims (4)

[Claims] 1. A light emitting element formed by molding a light emitting element chip, a light receiving element formed by molding a light receiving element chip, and a case for accommodating and integrally holding the light emitting element and the light receiving element. One of the light-receiving element and the case is formed of a short-wavelength region light-blocking resin that cuts light on a shorter wavelength side than the detection wavelength region of the light-receiving element chip set in a predetermined range,
One of the light-receiving element and the case is formed of a long-wavelength region light-blocking resin that cuts light on a longer wavelength side than the detection wavelength region. An optical coupling device, wherein incident light is detected by a light receiving element chip. 2. A light emitting element formed by molding a light emitting element chip, a light receiving element formed by molding a light receiving element chip, a case for accommodating and integrally holding the light emitting element and the light receiving element, A light-emitting window and a light-receiving window formed in the case facing the light-emitting element and the light-receiving element, respectively, and a window filter incorporated in at least the light-receiving window of the light-emitting window and the light-receiving window; The other part is formed of a light-shielding resin, and one of the light receiving element and the window filter is a short wavelength light that cuts light on a shorter wavelength side than the detection wavelength region of the light receiving element chip set in a predetermined range. One of the light-receiving element and the window filter is formed of a region light-blocking resin, and the other is formed of a long-wavelength region light-blocking resin that cuts light on a longer wavelength side than the detection wavelength region. Is, the optical coupling device and detecting by the light receiving element chip incident light transmitted through the these short wavelength light-shielding resin and the long wavelength region light shielding resin. 3. A reflection type optical coupling device in which a light emitting element and a light receiving element are arranged in parallel in a case toward an object to be detected, wherein the window filter is formed in a lens shape. 3. The optical coupling device according to 2. 4. The optical coupling device according to claim 3, wherein a part of the case including the light emitting window and the light receiving window is formed to be detachable from the case.