JP2002057367A - Reflective optical coupling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflective optical coupling device which does not require high precision for dimension of parts and assembly, resulting in a reduced cost. SOLUTION: A light-emitting element 3 and a light-receiving element 4 are mounted on the same frame 2. The light is emitted from the light-emitting element 3 to a passage hole 1a, and the light reflected on the surface of a Pachinko ball is detected with the light-receiving element 4. Thus, the direction and position of the lightemitting element 3 and the light-receiving element 4 are not required to be accurately set. So, the reflective optical coupling device is easily assembled in a manufacturing process for high productivity, resulting in a reduced cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type optical coupling device for detecting and counting steel balls such as pachinko balls.

[0002]

2. Description of the Related Art As is well known, as a device for detecting a steel ball such as a pachinko ball, a large number of pachinko balls are continuously dropped naturally, and the passage of the pachinko ball is detected one by one in the course of the fall. There is something. For example, an optical sensor that emits light into a passage hole through which a pachinko ball passes and detects light that has crossed the passage hole is provided. In all, pachinko balls are detected.

FIGS. 6 and 7 are a plan view and a side view showing an example of this type of a conventional apparatus. As shown in FIGS. 6 and 7, a through hole 101a for a pachinko ball is formed in the holder 101, and a first light guide 102 made of a light-transmitting synthetic resin is provided along the periphery of the through hole 101a. . Further, a printed circuit board 103 is fixed to the holder 101, and a light emitting element 104, a light receiving element 105, a capacitor 106, a resistor 107, a connector 108 and the like are mounted on the printed circuit board 103. The light receiving surface of the light receiving element 105 faces downward, and a second light guide 109 made of a light-transmitting synthetic resin is provided on the light receiving surface.

[0004] Light emitted from the light emitting element 104 reaches the light receiving element 105 via an optical path A shown by a dotted line. That is,
This light enters the first light guide 102, is reflected three times by the first light guide 102, crosses the passage hole 101 a, and is guided to the second light guide 109. Then, this light is reflected by the second light guide 109 and enters the light receiving surface of the light receiving element 105.

When the pachinko ball passes through the passage hole 101a, the optical path A is blocked, and the output of the light receiving element 105 changes. The pachinko ball can be detected based on the output change of the light receiving element 105.

[0006]

However, in the above-mentioned conventional device, the light emitted from the light emitting element 104 is reflected three times by the first light guide 102 and once by the second light guide 109, Furthermore, since the light is refracted when entering and exiting the first and second light guides 102 and 109, the optical path A becomes extremely complicated. For this reason, the positions and orientations of the light emitting element 104, the light receiving element 105, and the first and second light guides 102 and 109 must be accurately set. Invited. In addition, the first and second
Since the optical guides 102 and 109 are required to have high accuracy as optical components, the cost of the optical guides themselves is increased by the light guides themselves.

Further, since the first light guide 102 is provided at the periphery of the passage hole 101a of the pachinko ball, the first light guide 10 is provided.
There is a problem that the light incident surface and the light emitting surface of the light of No. 2 are easily stained, and the initial performance is deteriorated.

In addition, no special measures have been taken to narrow the detection range in the vertical direction. For this reason, the pachinko ball comes into contact with other pachinko balls or guides during the fall of the pachinko ball, and the pachinko ball naturally moves. If the ball is moved in a direction different from the direction in which the ball is dropped, the same pachinko ball may be repeatedly detected several times.

Furthermore, in order to detect each of the pachinko balls falling naturally continuously, the optical path A is set out of the contact position of each of the pachinko balls, and the light is passed through the gap of each of the pachinko balls, and this light is passed through. The light is received by the light receiving element 105. However, since the gap is narrow and the amount of light received by the light receiving element 105 is small, erroneous detection of a pachinko ball is likely to occur. Alternatively, the only way to increase the amount of light received by the light receiving element 105 and prevent erroneous detection of pachinko balls is to reduce the falling speed of each pachinko ball, resulting in a decrease in detection speed.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and does not require high precision in the dimensions and assembly of each part, and can reduce the cost. The purpose is to provide.

[0011]

In order to solve the above problems, a reflection type optical coupling device according to the present invention comprises a light emitting element for emitting light toward a path through which a sphere passes, and a light receiving element for receiving light. , A frame on which the light emitting element and the light receiving element are mounted, and optical means for changing the direction of the light emitted from the light emitting element and reflected by the sphere, and causing the light to enter the light receiving element.

According to the present invention having such a configuration, the light emitted from the light emitting element and reflected by the sphere is made incident on the light receiving element through the optical means. Here, since the light emitting element and the light receiving element are mounted on the same frame, the structure and the manufacturing process of the device can be simplified. In this case, since at least the direction of the light receiving surface of the light receiving element is restricted, the direction of the light reflected by the sphere is changed by optical means, and this light is incident on the light receiving element. Further, the optical path is a simple one of light emitting element → sphere → optical means → light receiving element, and it is not necessary to set the positions and directions of the light emitting element, the optical means and the light receiving element as accurately as in the conventional apparatus. For these reasons, cost can be reduced.

Further, in the present invention, a slit is provided between the path through which the sphere passes and the optical means to narrow the light reflected by the sphere.

By such a slit, the detection range of the sphere is narrowed. If this detection range is too large compared to the size of the sphere, light reflected on the upper oblique upper surface or lower oblique surface of the sphere may be received by the light receiving element, and at this time, the sphere slightly bounces. Also, the output of the light receiving element greatly fluctuates, the detection result of the sphere becomes unstable, and erroneous detection is likely to occur. On the other hand, if the detection range is sufficiently small compared to the size of the sphere, the light reflected by the sphere returns only when the approximate center of the sphere enters the detection range, and this light Is incident on the light receiving element. As a result, the output of the light receiving element is stabilized, and erroneous detection of a sphere can be prevented.

Further, in the present invention, a conductor of the ground potential of the reflection type optical coupling device is provided near the path through which the sphere passes.

When the sphere is charged, the electric charge of the sphere may destroy the elements of the reflection type optical coupling device. For this reason, a conductor having a ground potential is provided at a position where the sphere contacts, and the electric charge of the sphere is removed through the conductor.

In the present invention, light is emitted from the side of the light emitting element on the frame, the upper end face of the light emitting element is covered with an electrode having a light-shielding property, and the light receiving element is separated from the path through which the sphere passes. ing.

In this case, the electrodes on the upper end face reduce the light emission angle range of the light emitting element, and separate the light receiving element from the path of the sphere, thereby narrowing the detection range of the sphere. Also in this case, similarly to the case where the slit is provided, only when the approximate center of the sphere enters the detection range, the light reflected by the sphere returns, and this light enters the light receiving element through the optical means. Therefore, erroneous detection of a sphere can be prevented.

Further, in the present invention, a cylindrical lens is provided in front of the light receiving element for condensing light that spreads in a direction perpendicular to the direction in which the sphere passes.

When a lens is provided in front of the light receiving element and light is collected on the light receiving surface of the light receiving element, the output of the light receiving element increases. However, if the light is condensed too much, the light may deviate from the light receiving surface of the light receiving element. Therefore, a cylindrical lens that collects light only in a direction perpendicular to the direction in which the sphere passes is applied.

In the present invention, the cross-sectional shape of the path through which the sphere passes is a regular polygon of at least a regular hexagon.

In this case, the rotation of the sphere is appropriately suppressed,
The sphere moves quickly along the path.

On the other hand, the reflection type optical coupling device of the present invention comprises: a light emitting element for emitting light toward a path through which a sphere passes; a light receiving element for receiving light emitted from the light emitting element and reflected by the sphere; Synchronization detecting means is provided for comparing the light emission timing of the light emitting element with the light reception timing of the light receiving element, and if the two timings are continuously synchronized two or more times, it is determined that the sphere has passed.

As described above, when the light emission timing of the light emitting element and the light reception timing of the light receiving element are continuously synchronized two or more times, if it is considered that the sphere has passed, it is possible to prevent erroneous detection due to disturbance light. it can.

In the present invention, the cycle of the light emission timing of the light emitting element fluctuates randomly.

In this case, erroneous detection due to artificial disturbance light can be prevented.

In the present invention, the cycle of the light emission timing of the light emitting element may be constant.

Further, in the present invention, the synchronization detecting means includes a one-shot circuit for outputting a pulse each time the output of the light receiving element reaches a predetermined threshold.

This makes it easy to determine the light receiving timing of the light receiving element.

[0030]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIGS. 1 and 2 are a plan view and a side view showing an embodiment of the reflection type optical coupling device of the present invention. The reflection type optical coupling device according to the present embodiment is for sequentially detecting a large number of pachinko balls continuously falling naturally.

As shown in FIGS. 1 and 2, the holder 1 has a through hole 1a for a pachinko ball. The cross-sectional shape of the passage hole 1a is a regular hexagon, and the pachinko sphere can easily come into contact with the pachinko sphere at a plurality of positions, whereby the rotation of the pachinko sphere can be stopped and the pachinko sphere can be quickly dropped. In addition, a shape having a small number of corners is selected, and the manufacture is easy.

Incidentally, the passage hole 1a may be a regular polygon having 25 or more corners.

A frame 2 is fixed to the holder 1. The frame 2 is simply a conductor frame, and may be a conductor pattern formed on a printed wiring board, ceramic, glass, insulating resin, or the like, as well as a metal frame or a metal lead frame. On this frame 2, a light emitting element 3, a light receiving element 4, a chip resistor 5, a chip capacitor 6, a connector 7, a ground conductor 8
And so on. These elements are connected to the frame 2 by silver paste or bonding wires to form a circuit.

The light emitting element 3 has an upper electrode covering the entire upper surface. The upper electrode blocks light upward from the light emitting element 3, and reduces the emission angle range of the light from the light emitting element 3 that spreads in the vertical direction. After connecting the light emitting element 3 with a bonding wire or the like, the light emitting element 3 is sealed with a synthetic resin 11 having a light transmitting property.
A cylindrical lens 12 is formed on one end face of the lens.
The cylindrical lens 12 passes the light of the light emitting element 3 as it is in the vertical direction and condenses it in the horizontal direction. Furthermore, the cylindrical lens 12 and the passage hole 1a
A plurality of slits 13 for narrowing the light from the cylindrical lens 12 only in the vertical direction are arranged at appropriate intervals.

Accordingly, the light emitting element 3 emits light having a small vertical emission angle range and a large horizontal emission angle range, and this light is condensed by the cylindrical lens 12 only in the horizontal direction. This light is narrowed down only in the vertical direction by each slit 13 and is emitted to the passage hole 1a.

The light receiving element 4 is arranged apart from the passage hole 1a. After connecting the light receiving element 4 with a bonding wire or the like, the light receiving element 4 is sealed with a synthetic resin 14 having a light transmitting property. A cylindrical lens 15 is formed on one end surface of the synthetic resin 14, and a prism 16 is formed on a part of the synthetic resin 14 above the light receiving surface 4 a of the light receiving element 4. Further, a plurality of slits 17 for narrowing the light from the passage hole 1a only in the vertical direction are arranged at appropriate intervals between the passage hole 1a and the cylindrical lens 15.

The light from the passage hole 1a is narrowed down only in the vertical direction by the slits 17 and the cylindrical lens 1
After being focused only in the horizontal direction by the prism 5, the prism 1
The direction is changed downward by 6, and the light enters the light receiving surface 4 a of the light receiving element 4.

Each of the synthetic resins 11 and 14 having translucency is used.
May be either a thermosetting resin or a thermoplastic resin, and is preferably a material having spectral characteristics matching the emission wavelength of the light emitting element 3 and the peak sensitivity wavelength of the light receiving element 4.

The connector 7 is connected to the frame 2 by soldering or electric spot welding. In addition, the ground conductor 8 is connected to a portion of the circuit on the frame 2 at the ground potential.

In the reflection type optical coupling device having such a configuration, the light emitted from the light emitting element 3 reaches the passage hole 1a through the space between the cylindrical lens 12 and each slit 13. At this time, when a large number of pachinko balls continuously fall naturally and pass through the passage hole 1a of the holder 1, for example, when the pachinko balls B enter the detection range H, light from the light emitting element 3 is emitted on the surface of the pachinko balls B. The light is reflected and enters the light receiving surface 4 a of the light receiving element 4 through the cylindrical lens 15 and the prism 16 between the slits 17.

If the pachinko ball does not enter the passage hole 1a, the light from the light emitting element 3 is dispersed and is not guided to the light receiving element 4. Even if the pachinko ball enters the passage hole 1a but does not enter the detection range H, the light from the light emitting element 3 is reflected upward or downward on the surface of the pachinko ball and guided to the light receiving element 4. Nothing.

Therefore, based on the output of the light receiving element 4, it is possible to detect the pachinko ball B entering the detection range H on the way of passing through the passage hole 1a.

By the way, even if the pachinko ball in the detection range H bounces, the amount of light received by the light receiving element 4 does not greatly change. For this reason, pachinko balls can be stably detected. That is, erroneous detection of a pachinko ball is prevented by specifying the detection range H in the vertical direction.

As described above, the detection range H is such that the entire upper surface of the light emitting element 3 is covered with the upper electrode to reduce the emission angle range of light that spreads in the vertical direction, and that the cylindrical lens 12 and the passage hole Each slit 13 for narrowing the light only in the vertical direction is disposed between the light receiving elements 4 and the slit 17 for separating the light only in the vertical direction between the through hole 1a and the cylindrical lens 15 by separating the light receiving element 4 from the through hole 1a. Is set by placing.

If, for example, the emission angle range of the light from the light emitting element 3 extending in the vertical direction is increased, and the incidence angle range of the light on the light receiving element 4 in the vertical direction is increased, the detection range H becomes very large. In this case, the light reflected on the obliquely upper surface or the obliquely lower surface of the pachinko ball may be received by the light receiving element 4. At this time, even if the pachinko ball slightly bounces, the output of the light receiving element 4 greatly varies. As a result, the detection result of the pachinko ball becomes unstable, and erroneous detection is likely to occur.

Further, since the light from the light emitting element 3 is condensed in the horizontal direction by the cylindrical lens 12, the degree of dispersion of the light reflected on the surface of the pachinko sphere can be suppressed. Then, the reflected light is condensed in the horizontal direction by the cylindrical lens 15 and then incident on the light receiving surface 4a of the light receiving element 4, so that the light receiving amount of the light receiving element 4 does not become insufficient.

In the reflection type optical coupling device of this embodiment, the light emitting element 3 and the light receiving element 4 are mounted on the same frame 2. In addition, since the light is emitted from the light emitting element 3 to the through hole 1a and the light reflected on the surface of the pachinko ball is received by the light receiving element 4, the directions and positions of the light emitting element 3 and the light receiving element 4 can be particularly accurately determined. No need to set. Therefore, the reflection type optical coupling device is easy to assemble in the manufacturing process, is excellent in mass productivity, and can reduce the cost.

When the light receiving element 4 is mounted on the frame 2, if the light receiving surface 4a of the light receiving element 4 is directed upward, the assembly is easy. For this reason, a prism 16 is provided, and the light reflected on the surface of the pachinko ball is
To the light receiving surface 4a of the light receiving element 4.

The slits 13 and 17 not only stop light but also prevent dust from entering and prevent the cylindrical lenses 12 and 15 from being stained.

Furthermore, pachinko balls that come into contact with various parts during the natural fall are likely to be charged with static electricity. Ground conductor 8
Removes the electric charge of pachinko spheres when they come into contact. Therefore, each element of the circuit is not destroyed due to the static electricity of the pachinko ball.

FIG. 3 is a block diagram showing a schematic configuration of a circuit of the reflection type optical coupling device of the present embodiment. In FIG. 3, a constant voltage circuit 31 is supplied with a voltage via a filter including a resistor 32 and a capacitor 33 and outputs a constant voltage V.
cc 'is supplied to the reflection type optical coupling device. Astable oscillator 3
4 generates a pulse signal P0 at a random cycle and applies the pulse signal P0 to the synchronization detection circuit 35 and the light emitting element drive circuit 36. The light emitting element driving circuit 36 supplies a constant current to the light emitting element 3 (for example, LED) in response to the pulse signal P0 to cause the light emitting element 3 to emit light. When the light from the light emitting element 3 is reflected on the surface of the pachinko ball B and enters the light receiving element 4 (for example, a photodiode), the light receiving element 4 outputs a pulse signal. The pulse-like signal is applied to an amplifier 37, amplified there, and then input to a comparator 39 via a capacitor 38 for blocking a DC component of the signal. Comparator 39
When the pulse-shaped signal level reaches a predetermined threshold value, the output Comp becomes high level. The one-shot circuit 40 applies a pulse signal P1 having a fixed width to the synchronization detecting circuit 35 every time the output Comp of the comparator 39 becomes high level. Upon receiving the pulse signal P0 from the unstable oscillator 34 and the pulse signal P1 from the synchronization detection circuit 35, the synchronization detection circuit 35 detects the synchronization between the pulse signal P0 and the pulse signal P1, and performs two or more consecutive synchronizations. Is detected, while the synchronization continues, the output Vout from the demodulation circuit 41 to the connector 7 is inverted to a low level.

Here, the light emitting element 3 emits light in response to the pulse signal P0, and when the light of the light emitting element 3 is reflected on the surface of the pachinko ball, the reflected light enters the light receiving element 4 and the light is received. Since the pulse signal P1 is output in response to the output of the element 4, the pulse signal P0 and the pulse signal P1 are synchronized. Therefore, when the output Vout of the demodulation circuit 41 is at a low level, a pachinko ball has been detected.

FIG. 4 shows the waveform of each signal when a pachinko ball is detected. Since the pulse signal P0 and the pulse signal P1 are continuously synchronized twice from the time T0 to the time T1, the output Vout is inverted and set to the low level at the time T1. At time T2, when external noise (optical noise) is received by the light receiving element 4, the output Comp of the comparator 39 goes high in response to this, and the pulse signal P1 goes high while the pulse signal P0 goes high. Since the pulse signal P1 becomes asynchronous, the time T
At 3, the output Vout is inverted and set to high level.

FIG. 5 shows the waveform of each signal when a pachinko ball is not detected. Until time T10, the pulse signal P1 has never been at a high level, and the output Vout has been set at a high level. At time T10, external noise (optical noise) is received by the light receiving element 4, and in response to this, even if the pulse signal P1 becomes high level, the pulse signal P
Since 0 and the pulse signal P1 are asynchronous, the output Vout is maintained at a high level without being inverted.

As described above, the light emitting element 3 emits light intermittently,
By detecting the synchronization between the light emission timing and the light reception timing of the light receiving element 4 and detecting a pachinko ball based on the number of times of synchronization, it is possible to eliminate the influence of disturbance light and prevent erroneous detection of the pachinko ball. it can.

The present invention is not limited to the above embodiment, but can be variously modified. For example,
The light emitting element and the light receiving element may be of any type. Further, instead of the unstable oscillator 34, an oscillator that repeatedly outputs a pulse signal at a constant cycle may be applied. Further, the present invention may be applied to detect not only pachinko balls but also other types of steel balls.

[0058]

As described above, according to the present invention, since the light emitting element and the light receiving element are mounted on the same frame, the structure and the manufacturing process of the device of the present invention can be simplified. In this case, since at least the direction of the light receiving surface of the light receiving element is restricted, the direction of the light reflected by the sphere is changed by optical means, and this light is incident on the light receiving element. Further, the optical path is a simple one of light emitting element → sphere → optical means → light receiving element, and it is not necessary to set the positions and directions of the light emitting element, the optical means and the light receiving element as accurately as in the conventional apparatus. For these reasons, cost can be reduced.

According to the present invention, the detection range of the sphere is narrowed by the slit. If this detection range is too wide compared to the size of the sphere, light reflected on the upper surface or the lower surface of the sphere may be received by the light receiving element, and at this time, even if a slight bounce of the sphere occurs. In addition, the output of the light receiving element greatly fluctuates, the detection result of the sphere becomes unstable, and erroneous detection is likely to occur. On the other hand, if this detection range is sufficiently small compared to the size of the sphere,
Only when the approximate center of the sphere enters the detection range, the light reflected by the sphere returns and enters this light receiving element. As a result, the output of the light receiving element is stabilized, and erroneous detection of a sphere can be prevented.

Further, according to the present invention, a conductor of the ground potential is provided at a position where the sphere contacts, and the electric charge of the sphere is removed through the conductor. Can be prevented.

According to the present invention, the range of the light emission angle of the light emitting element is reduced by the electrodes on the upper end face, and the light receiving element is separated from the path of the sphere to narrow the detection range of the sphere. . Also in this case, similarly to the case where the slit is provided, only when the approximate center of the sphere enters the detection range, the light reflected by the sphere returns, and this light enters the light receiving element. Therefore, erroneous detection of a sphere can be prevented.

Further, according to the present invention, since the cylindrical lens is provided in front of the light receiving element, light can be focused on the light receiving surface of the light receiving element, and the output of the light receiving element can be increased. However, if the light is condensed too much, the light may deviate from the light receiving surface of the light receiving element. Therefore, a cylindrical lens that collects light only in a direction perpendicular to the direction in which the sphere passes is applied.

Further, according to the present invention, since the cross-sectional shape of the path through which the sphere passes is a regular polygon of a regular hexagon or more, the rotation of the sphere is appropriately suppressed, and the sphere is quickly moved along the path. Moving.

On the other hand, according to the present invention, when the light emitting timing of the light emitting element and the light receiving timing of the light receiving element are continuously synchronized two or more times, it is considered that the sphere has passed. False detection can be prevented.

Further, according to the present invention, since the cycle of the light emission timing of the light emitting element fluctuates randomly, it is possible to prevent erroneous detection due to artificial disturbance light.

Further, according to the present invention, the synchronization detecting means comprises:
A one-shot circuit is provided for outputting a pulse each time the output of the light receiving element reaches a predetermined threshold. This makes it easier to determine the light receiving timing of the light receiving element.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of a reflection type optical coupling device of the present invention.

FIG. 2 is a side view showing the reflection type optical coupling device of FIG. 1;

FIG. 3 is a block diagram showing a schematic configuration of a circuit of the reflection type optical coupling device of FIG. 1;

FIG. 4 is a diagram showing waveforms of signals when a pachinko ball is detected in the circuit of FIG. 3;

FIG. 5 is a diagram showing waveforms of respective signals when a pachinko ball is not detected in the circuit of FIG. 3;

FIG. 6 is a plan view illustrating a conventional device.

FIG. 7 is a side view showing the apparatus of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Holder 1a Passing hole 2 Frame 3 Light emitting element 4 Light receiving element 5 Chip resistor 6 Chip capacitor 7 Connector 8 Grounding conductor 11,14 Synthetic resin 12,15 Cylindrical lens 13,17 Slit 16 Prism

Claims (9)

[Claims] 1. A light emitting element for emitting light toward a path through which a sphere passes, a light receiving element for receiving light, a frame on which the light emitting element and the light receiving element are mounted, and a light emitted from the light emitting element and reflected by the sphere A reflection type optical coupling device, comprising: optical means for changing the direction of the light and making the light incident on a light receiving element. 2. The reflection type optical coupling device according to claim 1, wherein a slit for narrowing light reflected by the sphere is provided between a path through which the sphere passes and the optical means. 3. The reflection type optical coupling device according to claim 1, wherein a conductor having a ground potential of the reflection type optical coupling device is provided in the vicinity of a path through which the sphere passes. 4. A light-emitting device according to claim 1, wherein light is emitted from a side portion of the light-emitting element on the frame, an upper end surface of the light-emitting element is covered with a light-shielding electrode, and the light-receiving element is separated from a path through which the sphere passes. The reflection type optical coupling device according to claim 1. 5. The reflection type optical coupling device according to claim 1, wherein a cylindrical lens for condensing light spreading in a direction orthogonal to a direction in which the sphere passes is provided in front of the light receiving element. 6. The cross-sectional shape of the path through which the sphere passes is positive 2
2. A regular polygon having four or more squares.
4. The reflection type optical coupling device according to 1. 7. A light emitting element for emitting light toward a path through which a sphere passes, a light receiving element for receiving light emitted from the light emitting element and reflected by the sphere, a light emitting timing of the light emitting element, and light receiving of the light receiving element A reflection type optical coupling device comprising: a synchronization detection unit that compares timings and, when the two timings are continuously synchronized two or more times, determines that a sphere has passed. 8. The reflection type optical coupling device according to claim 7, wherein the light emission timing of the light emitting element fluctuates at random. 9. The reflection type optical coupling device according to claim 7, wherein the synchronization detecting means includes a one-shot circuit that outputs a pulse each time the output of the light receiving element reaches a predetermined threshold. .