JP2007028388A - Photoelectric switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric switch to save on power and also to manage a states of a projector and a light receiver if necessary. <P>SOLUTION: The photoelectric switch 10 comprises: the projector 12 provided with a first light projection means 11 for converting an electric signal into an optical signal and transmitting the optical signal; and the light receiver 14 provided with a first light receiving means 13 for receiving the first optical signal from the first light projection means 11. The light receiver 14 is provided with a signal transmission means 15 to be driven by an output from the first light receiving means 13, and the projector 12 is provided with a receiving means 16 for detecting a signal from the signal transmission means 15 and outputting an electric signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a photoelectric switch that detects a detection target such as an intruder.

Conventionally, in order to sense an object to be detected such as an intruder into a residence, for example, a projector that emits light such as infrared light and a light receiver that receives infrared light from the light projector are provided, and infrared light from the light projector is detected. A photoelectric switch (photoelectric sensor) that generates an alarm sound or the like when it is blocked by an object and does not reach the light receiver is used. The photoelectric switch includes (1) a transmission type in which a light projector and a light receiver are arranged with the optical axis aligned, and (2) a diffuse reflection type in which a light projector and a light receiver are arranged on one side to detect reflected light from a detection target, (3) A projector and a light receiver are arranged on one side, and a retroreflective plate is arranged on the other side. Usually, the reflected light from the retroreflective plate is detected, and when the optical path is interrupted, it is judged that there is an object to be detected. There was a shape (for example, refer patent document 1).

JP-A-6-5168

However, in a reflection type photoelectric switch that irradiates a detection target with light from a projector and receives light reflected by the detection target with a light receiver, the reflectivity of the light is reduced by the detection target, or the light is attenuated. In addition, there is a problem that the detectable distance becomes short. In this reflection type photoelectric switch, in order to increase the detectable distance, the intensity of light emitted from the projector has to be increased, and there is a problem that power saving cannot be achieved. In particular, the retroreflective photoelectric switch has a problem that it is difficult to align the retroreflector in addition to the problems described above.
In the case of a transmissive photoelectric switch, the above problems are solved and the detection distance is long. However, a power source is required for each of the projector and the light receiver, and it is generally difficult to secure a power source for the projector installed remotely. there were. In particular, since the projector always emits light, a battery cannot be used as a power source, and it has been difficult to implement outdoors such as forests, farmlands, lakes, rivers, or oceans where it is difficult to secure a power source.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a photoelectric switch that can save power and can manage the status of a projector and a photoreceiver in some cases.

A photoelectric switch according to the present invention that meets the above-described object receives a first light signal from a light projector having a first light projecting means that converts an electrical signal into an optical signal and transmits the light signal, and a first light signal from the first light projecting means. In a photoelectric switch having a light receiver including a first light receiving means,
The light receiver is provided with a signal transmitting means that operates in accordance with the output of the first light receiving means, and the light projector is provided with a receiving means that detects a signal from the signal transmitting means and outputs an electrical signal. It has been.
Here, as a signal transmitted from the signal transmission means, light including infrared rays, radio waves, or the like can be used. In the photoelectric switch according to the present invention, the signal transmitting means is a second light projecting means for transmitting a second optical signal, and the receiving means is a second light receiving means for receiving the second optical signal. There may be.

In the photoelectric switch according to the present invention, the first optical signal and the second optical signal are different from each other, and the second light receiving means and the second optical signal are in accordance with the first optical signal. Thus, it is preferable that the first light receiving means is not operated.
Here, the different light means that any one or two or more of the wavelength, light emission time, and code modulation of light are different (the same applies hereinafter).
In the photoelectric switch according to the present invention, when the first light receiving unit does not receive the first optical signal transmitted from the first light projecting unit at a predetermined time interval, the light receiver receives the second light projecting unit. A signal different from the second optical signal may be transmitted from the optical means.

In the photoelectric switch according to the present invention, the power source of the light receiver may be a battery.
In the photoelectric switch according to the present invention, the battery may include a solar battery.
In the photoelectric switch according to the present invention, when the voltage of the battery drops below a predetermined value, a signal for sending data of a digital signal or an analog signal in addition to the drop of the voltage is a signal from the signal transmission means. Is preferably included.

The photoelectric switch according to any one of claims 1 to 7, wherein the light receiving device is provided with a signal transmitting means that is operated by an output of the first light receiving means, and an electric signal is output to the projector by detecting a signal from the signal transmitting means. Therefore, it is not necessary to always emit light from the projector, thus saving power.
In particular, in the photoelectric switch according to the second aspect, since the signal transmitting means is the second light projecting means for transmitting the second optical signal, the sensitivity can be increased.

In the photoelectric switch according to claim 3, the first optical signal and the second optical signal are different lights, and the second light receiving means is not operated by the first optical signal. Since the second optical signal transmitted from the first optical signal and the first optical signal reflected by the obstacle can be distinguished from each other and the first light receiving means is not activated by the second optical signal, the second optical signal is transmitted from the projector. The first optical signal can be distinguished from the second optical signal reflected by the obstacle, and the malfunction of the photoelectric switch can be prevented.
In the photoelectric switch according to claim 4, when the first light receiving unit does not receive the first optical signal transmitted from the first light projecting unit at a predetermined time interval, the light receiver receives from the second light projecting unit. Since a signal different from the second optical signal is transmitted, it can be confirmed that the first optical signal is blocked.

In the photoelectric switch according to the fifth aspect, since the power source of the light receiver is a battery, a power cord is not required, and there is no trouble such as wiring work, so that the apparatus is simplified.
In the photoelectric switch according to the sixth aspect, since the battery includes a solar battery, there is no need to replace the battery.
In the photoelectric switch according to claim 7, since the signal from the signal transmission means includes a signal notifying the voltage drop when the voltage of the battery drops below a predetermined value, Operation can be prevented. Further, since the signal from the signal transmission means includes a signal for sending digital signal or analog signal data, cordless data communication is possible.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is an explanatory diagram of a photoelectric switch according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a modification of a light receiver of the photoelectric switch.

A photoelectric switch 10 according to an embodiment of the present invention will be described with reference to FIG.
The photoelectric switch 10 includes a light projector 12 including a light emitting diode (an example of a first light projecting unit) 11 that converts an electrical signal into a first optical signal α and transmits the photo signal, and a photo that receives the optical signal α from the light emitting diode 11. And a light receiver 14 having a diode (an example of first light receiving means) 13. The light receiver 14 receives an electrical signal from the photodiode 13 and generates a predetermined signal, for example, a second optical signal β, which is a light emitting diode (an example of a second light projecting unit). An example) 15 is provided. Further, the projector 12 is provided with a photodiode (an example of a second light receiving unit) 16 that is an example of a receiving unit that detects the optical signal β and outputs an electrical signal.

The projector 12 further includes a first control unit 17 that sends an electrical signal to the light emitting diode 11 and generates a predetermined output signal based on a signal from the photodiode 16, and a power source that supplies power to the control unit 17. Part 18. For example, a large-capacity battery is used for the power supply unit 18. On the other hand, the light receiver 14 receives an electrical signal from the photodiode 13 and sends a predetermined electrical signal to the light emitting diode 15, and a power supply unit 20 that supplies power to the control unit 19. And have. For example, a dry battery is used for the power supply unit 20. Note that the power supply units 18 and 20 may be used by converting commercial power into direct current.

The light emitting diode 11 of the projector 12 and the light emitting diode 15 of the light receiver 14 are, for example, those that generate infrared light having a wavelength of 880 nm, and the optical signal α and the optical signal β transmitted from them are each about 40 kHz. It is modulated by pulses so that it can be clearly distinguished from other light (for example, light from sunlight, streetlights, etc.). In addition, as the photodiodes 13 and 16 that receive the optical signal α and the optical signal β, respectively, those that are sensitive to infrared rays of 880 nm are used.

Here, the optical signal α and the optical signal β are different from each other in one or more of different lights, that is, the wavelength, the light emission time, and the code modulation of the light, and there is an obstacle between the light projector 12 and the light receiver 14. When there is an object (detection target), the optical signal α transmitted from the light emitting diode 11 is reflected by the photodiode 16 by the light reflected by the obstacle, and the optical signal β transmitted from the light emitting diode 15 is reflected by the obstacle. As a result, the photodiodes 13 are not activated by the light, and malfunction of the photoelectric switch 10 can be prevented.

Further, in front of the light emitting diode 11, in front of the photodiode 13, in front of the light emitting diode 15, and in front of the photodiode 16, a lens 21 made of polycarbonate resin that collects an optical signal in a predetermined direction and a predetermined range, respectively. ˜24 are arranged. The focal positions of the lenses 21 and 23 arranged in front of the light-emitting diodes 11 and 15 can be changed according to the distance or direction of the projector 12 and the light receiver 14. The installation positions of the light emitting diodes 11 and 15 are shifted from the focal positions of the lenses 21 and 23 (within the normal focal length). As a result, the reception directivity angle is changed.

Normally, when the photoelectric switch 10 transmits the optical signal α from the light emitting diode 11 of the projector 12 at a predetermined time interval, for example, every second, and receives the optical signal α by the photodiode 13 of the light receiver 14, it receives light. The optical signal β is transmitted from the light emitting diode 15 of the device 14 after a predetermined time has elapsed, for example, after 0.5 seconds. However, when the optical signal α is blocked by an obstacle or the like, that is, when the photodiode 13 does not receive the optical signal α at intervals of 1 second, the light is emitted from the light emitting diode 15 by the control unit 19 of the light receiver 14. An optical signal γ different from the signal α and the optical signal β is transmitted.

In this case, in the projector 12, the transmitted optical signal γ is received by the photodiode 16, and an electric signal output from the photodiode 16 by the control unit 17 causes an obstacle between the projector 12 and the light receiver 14. When it is determined that there is, a buzzer 25 provided in the projector 12 is operated to sound an alarm sound. Further, a light may be provided instead of the buzzer, and the presence of an obstacle may be notified by turning on or blinking the light.

The light projector 12 and the light receiver 14 are provided with voltmeters (not shown) that measure the voltages of the power supply units 18 and 20, respectively. In the projector 12, when the voltage of the power supply unit 18 measured by the voltmeter becomes equal to or lower than a predetermined value, the control unit 17 operates the buzzer 25 to sound an alarm sound. Further, in the light receiver 14, when the voltage of the power supply unit 20 measured with the voltmeter becomes a predetermined value or less, the light signal from the light emitting diode 15 is different from the light signal α, the light signal β, and the light signal γ by the control unit 19. An optical signal δ is transmitted. When the photodiode 16 receives the optical signal δ, the control unit 17 operates to sound an alarm sound from the buzzer 25. Here, the alarm sound from the buzzer 25 is different depending on the obstacle detection, the voltage drop of the power supply unit 18, and the voltage drop of the power supply unit 20, and the respective states are easy to grasp.

Next, an intruder detection method using a photoelectric switch will be described.
First, the optical axes of the projector 12 and the light receiver 14 are set so that the light emitting diode 11 and the photodiode 13 face each other, that is, the optical signal α transmitted from the light emitting diode 11 can be sensed by the photodiode 13. Place them together. In this case, the light-emitting diode 15 and the photodiode 16 are also adjusted so as to face each other and the optical axes coincide.
The optical signal α is transmitted from the light emitting diode 11 of the projector 12 at a predetermined time, for example, at intervals of 1 second. The light emission interval of the optical signal α is shorter than the time for the intruder to pass between the projector 12 and the light receiver 14, that is, the shortest time that the obstacle is considered to block the optical axis.

Here, when there is no obstacle between the projector 12 and the light receiver 14, the optical signal α is received by the photodiode 13 of the light receiver 14. The optical signal α is received by the photodiode 13 and converted into an electrical signal, then amplified by the control unit 19 and subjected to waveform shaping through the detection circuit, and the control unit 19 confirms reception of the optical signal α, After a lapse of time, for example, 0.5 seconds, the light signal β is transmitted from the light emitting diode 15. As described above, since the optical signal α and the optical signal β are transmitted with time, power is saved. The optical signal β is received by the photodiode 16 of the projector 12 and converted into an electrical signal, then amplified by the control unit 17, waveform shaping is performed through the detection circuit, and the control unit 17 confirms reception of the optical signal β. It is confirmed that there is no obstacle between the projector 12 and the light receiver 14.

Further, when there is an obstacle between the projector 12 and the light receiver 14, the optical signal α cannot be received by the photodiode 13 of the light receiver 14. The control unit 19 of the light receiver 14 determines that the optical signal α transmitted at a predetermined interval cannot be received, and transmits an optical signal γ indicating that the optical signal α is not received from the light emitting diode 15. The transmitted optical signal γ is received by the photodiode 16 of the projector 12, the electric signal is amplified by the control unit 17, waveform shaping is performed through the detection circuit, and the control unit 17 confirms reception of the optical signal γ. . Here, since the optical signal γ is different from the optical signal β, it is understood that the optical signal α cannot be received by the light receiver 14, and there is an obstacle between the projector 12 and the light receiver 14. It is confirmed. Further, when the light signal γ transmitted from the light receiver 14 cannot be received by the projector 12 and when the light signal β transmitted from the light receiver 14 cannot be received by the projector 12, the light signal between the light projector 12 and the light receiver 14 is also present. It is confirmed that there is an obstacle. At this time, the control unit 17 activates the buzzer 25 and sounds an alarm sound to inform the surroundings that there is an intruder.

When the voltage of the power supply unit 20 of the light receiver 14 drops below a predetermined value, the control unit 19 operates the light emitting diode 15 to transmit an optical signal δ different from the optical signal β and the optical signal γ. The transmitted optical signal δ is received by the photodiode 16 of the projector 12, and the control unit 17 confirms that the voltage of the power supply unit 20 of the light receiver 14 has decreased. The control part 17 operates the buzzer 25 which notifies the voltage drop of the power supply part 20 of the light receiver 14, and sounds an alarm sound. As a result, the battery can be replaced with a new battery before the capacity of the power supply unit 20 of the light receiver 14 is exhausted, and the malfunction of the photoelectric switch 10 due to the battery running out can be prevented. When the voltage of the power supply unit 18 of the projector 12 falls below a predetermined value, the control unit 17 activates the buzzer 25 that notifies the voltage drop of the power supply unit 18 to sound an alarm sound, and the power supply unit 18 is charged or The battery can be replaced with a new battery, and the malfunction of the photoelectric switch 10 due to power reduction can be prevented.

Further, the projector 12 and the light receiver 14 are respectively a setting switch 30 for performing settings for switching the projector 12 and the light receiver 14, setting an interval for transmitting the first optical signal α, and setting for not using the buzzer 25. , Light emitting diodes 11 and 15, photodiodes 16 and 13, buzzer 25, etc., operation indicator lamp 31, serial communication port 33 to which personal computer 32 or the like can be connected, thermometer, hygrometer, and illuminometer A signal input terminal 34 to which a sensor such as a signal can be connected, and a signal output terminal 35 for notifying an external device of the presence of an obstacle or a decrease in the voltage of the power supply are provided. The signal input terminal 34 and the signal output terminal 35 can be connected to one or more devices.

Here, for example, any one or two or more sensors such as a thermometer, a hygrometer, and an illuminometer are connected to the signal input terminal 34 of the light receiver 14, and the temperature, humidity, illuminance, etc. are measured at predetermined time intervals. It is measured and converted into a predetermined electrical signal by the control unit 19, and this electrical signal is included in the optical signal β and transmitted from the light emitting diode 15 to the projector 12. In the projector 12, the optical signal β is received by the photodiode 16 and converted into an electrical signal, and the data such as temperature, humidity, and illuminance included can be stored in the control unit 17. Furthermore, the personal computer 32 can be connected to the serial communication port 33 and the data stored in the control unit 17 can be analyzed by the personal computer 32. Thus, the photoelectric switch 10 can be used as a cordless environmental recording device. The personal computer 32 can be always connected to monitor temperature, humidity, illuminance, and the like. In addition, an illuminometer is connected to the signal input terminal 34 of the projector 12, and the transmission of the optical signal α for detecting an intruder at night is started by distinguishing day and night according to the value of the illuminometer. Good.

Further, the operation indicator lamp 31 may be turned on or blinked due to a voltage drop of the power supply units 18 and 20. In particular, at night, it is preferable to activate the buzzer 25 only when an intruder is detected, that is, when the optical signal γ is detected, and the voltage drop is displayed on the operation indicator 31. Further, even when the buzzer 25 is not used (the alarm sound is stopped) by the setting switch 30, it is possible to know the voltage drop by the operation indicator lamp 31. Note that the voltage drop may be notified by both the buzzer 25 and the operation indicator lamp 31.
Furthermore, as a device connected to the signal output terminal 35, for example, a light, a buzzer, or a siren can be used.

With reference to FIG. 2, the light receiver 40 which is a modification of the light receiver 14 is demonstrated. The same components as those of the light receiver 14 are denoted by the same reference numerals, and detailed description thereof is omitted.
The light receiver 40 is different from the light receiver 14 in that a solar cell 42 is used as a power source 41 for driving the light receiver 40. The light receiver 40 also includes a secondary battery 43 that stores electricity generated by the solar battery 42 and a charge control unit 44, and can prevent malfunction of the photoelectric switch due to battery exhaustion as much as possible. Note that, when the voltage of the secondary battery 43 decreases, the light signal δ is transmitted from the light emitting diode 15 as in the case of the light receiver 14.

The present invention is not limited to the above-described embodiment, and can be changed without changing the gist of the present invention. For example, some or all of the above-described embodiments and modifications are possible. The case where the photoelectric switch of the present invention is configured by combining these is also included in the scope of the right of the present invention.
For example, in the photoelectric switch of the above embodiment, the signal transmitting means and the receiving means are the second light projecting means and the second light receiving means for transmitting and receiving the second optical signal by infrared rays, respectively. You may use the apparatus which transmits / receives light or an electromagnetic wave. Moreover, although the light emitting diode which generate | occur | produces infrared rays was used as a 1st and 2nd light projection means, visible light may be used and the light emitting element to be used is not restricted to a light emitting diode.

It is explanatory drawing of the photoelectric switch which concerns on one embodiment of this invention. It is explanatory drawing of the modification of the light receiver of the photoelectric switch.

Explanation of symbols

10: photoelectric switch, 11: light emitting diode, 12: projector, 13: photodiode, 14: light receiver, 15: light emitting diode, 16: photodiode, 17: first control unit, 18: power supply unit, 19: first 2 control unit, 20: power supply unit, 21-24: lens, 25: buzzer, 30: setting switch, 31: operation indicator, 32: personal computer, 33: serial communication port, 34: signal input terminal, 35: Signal output terminal, 40: light receiver, 41: power supply, 42: solar battery, 43: secondary battery, 44: charge control unit

Claims (7)

A projector having first light projecting means for transmitting an electrical signal converted into an optical signal; and a light receiver having first light receiving means for receiving a first light signal from the first light projecting means. In a photoelectric switch having
The light receiver is provided with a signal transmitting means that operates in accordance with the output of the first light receiving means, and the light projector is provided with a receiving means that detects a signal from the signal transmitting means and outputs an electrical signal. A photoelectric switch characterized by that. 2. The photoelectric switch according to claim 1, wherein the signal transmitting unit is a second light projecting unit that transmits a second optical signal, and the receiving unit is a second light receiving unit that receives the second optical signal. A photoelectric switch characterized by being 3. The photoelectric switch according to claim 2, wherein the first optical signal and the second optical signal are different lights, and the second light receiving means and the second light are in accordance with the first optical signal. 4. A photoelectric switch characterized in that the first light receiving means is not activated by a signal. The photoelectric switch according to any one of claims 2 and 3, wherein the first light receiving unit does not receive the first optical signal transmitted from the first light projecting unit at a predetermined time interval. The photoelectric switch transmits a signal different from the second optical signal from the second light projecting means. 5. The photoelectric switch according to claim 1, wherein a power source of the light receiver is a battery. 6. 6. The photoelectric switch according to claim 5, wherein the battery includes a solar battery. The photoelectric switch according to any one of claims 5 and 6, wherein when the voltage of the battery drops below a predetermined value, a signal for sending data of a digital signal or an analog signal in addition to the drop of the voltage. Is included in the signal from the signal transmission means.

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