Abnormality detection circuit for light irradiation device

Abstract

To provide an abnormality detection circuit for a light irradiation device capable of both lighting a light emitting element and detecting abnormality of the light emitting element with one power supply.SOLUTION: An abnormality detection circuit according to an embodiment is an abnormality detection circuit for a light irradiation device having a plurality of first light emitting elements connected in series. The abnormality detection circuit includes a detection circuit having an operational amplifier. An anode side of the plurality of first light emitting elements connected in series is electrically connected to a power supply. A cathode side of the plurality of first light emitting elements connected in series is electrically connected to a non-inverting input terminal of the operational amplifier. A part of the first light emitting elements within the plurality of first light emitting elements connected in series is electrically connected to a positive side power supply terminal of the operational amplifier through a resistor, and a voltage applied to the plurality of first light emitting elements connected in series is voltage-divided and applied to the positive side power supply terminal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to an abnormality detection circuit for a light irradiation device. [Background technology]

[0002] There are light irradiation devices equipped with light emitting elements such as light emitting diodes. If the light emitting elements installed in the light irradiation device malfunction, light may no longer be emitted or the required irradiation intensity may not be obtained. For this reason, the light irradiation device is provided with an abnormality detection circuit that detects abnormalities in the light emitting elements.

[0003] For example, a light irradiation device has been proposed that includes a light emitting unit provided with a light emitting element, a power supply for lighting the light emitting element, an abnormality detection circuit for detecting abnormalities in the light emitting element, and a power supply for operating the abnormality detection circuit. If the abnormality detection circuit is provided, abnormalities in the light emitting element can be detected, and appropriate light irradiation can be performed.

[0004] However, when a commercially available power supply is used to light the light-emitting element, a separate abnormality detection circuit for the light-emitting element is required. In this case, a power supply is required to operate the abnormality detection circuit. This leads to problems such as a complex configuration of the light irradiation device and difficulty in reducing the price of the light irradiation device.

[0005] Therefore, there has been a demand for the development of an abnormality detection circuit for a light irradiation device that can turn on a light emitting element and detect abnormalities in the light emitting element using a single power supply. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2019-523535 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem that the present invention aims to solve is to provide an abnormality detection circuit for a light irradiation device that can turn on a light-emitting element and detect abnormalities in the light-emitting element using a single power supply. [Means for solving the problem]

[0008] The abnormality detection circuit according to the embodiment is an abnormality detection circuit for a light irradiation device having a plurality of first light-emitting elements connected in series. The abnormality detection circuit includes a detection circuit having an operational amplifier. The anodes of the plurality of first light-emitting elements connected in series are electrically connected to a power supply. The cathodes of the plurality of first light-emitting elements connected in series are electrically connected to a non-inverting input terminal of the operational amplifier. Some of the plurality of first light-emitting elements connected in series are electrically connected to a positive power supply terminal of the operational amplifier via resistors, and a voltage applied to the plurality of first light-emitting elements connected in series is divided and applied to the positive power supply terminal. [Effects of the Invention]

[0009] According to the embodiment of the present invention, it is possible to provide an abnormality detection circuit for a light irradiation device that can turn on a light emitting element and detect an abnormality in the light emitting element using a single power supply. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram illustrating a light irradiation device including an abnormality detection circuit according to an embodiment of the present invention; [Figure 2] FIG. 2 is a circuit diagram illustrating a light-emitting unit. [Figure 3] FIG. 10 is a circuit diagram illustrating an abnormality detection circuit. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be illustrated with reference to the drawings. In the drawings, like components are designated by like reference numerals and detailed descriptions thereof will be omitted where appropriate. FIG. 1 is a block diagram illustrating a light irradiation device 100 including an abnormality detection circuit 2 according to this embodiment. As shown in FIG. 1, the light irradiation device 100 includes, for example, a light emitting unit 1, an abnormality detection circuit 2, an AC-DC converter 3, and a controller 4.

[0012] FIG. 2 is a circuit diagram illustrating the light-emitting unit 1. As shown in FIG. 2, the light-emitting unit 1 has a plurality of light-emitting elements 11 (corresponding to an example of a first light-emitting element). The plurality of light-emitting elements 11 are connected in series, for example. The arrangement and number of the plurality of light-emitting elements 11 can be changed as appropriate depending on the application, size, etc. of the light irradiation device 100. The light emitting element 11 is, for example, a light emitting diode, a laser diode, an organic light emitting diode, or the like.

[0013] Furthermore, a light-emitting element that emits light of a predetermined wavelength can be appropriately selected depending on the application of the light irradiation device 100. For example, when the light irradiation device 100 is used for removing organic matter attached to an object (light cleaning), sterilizing bacteria or inactivating viruses, or curing ultraviolet-curable resins, the light-emitting element 11 can be a light-emitting element that emits ultraviolet light having a predetermined wavelength. For example, when the light irradiation device 100 is used for illumination or display, the light-emitting element 11 can be a light-emitting element that emits visible light having a predetermined wavelength. Note that the applications of the light irradiation device 100 are not limited to those exemplified above.

[0014] FIG. 3 is a circuit diagram illustrating the abnormality detection circuit 2. As shown in FIG. 1 and 3, the abnormality detection circuit 2 includes, for example, a detection circuit 21, a transmission circuit 22, and a connection circuit 23. The detection circuit 21 detects the occurrence of an abnormality in the light-emitting elements 11 based on at least one of the current and voltage in the light-emitting elements 11. The connection circuit 23 transmits a signal from the detection circuit 21 to the transmission circuit 22. That is, when the occurrence of an abnormality is detected, a signal is transmitted from the detection circuit 21 to the transmission circuit 22 via the connection circuit 23. The transmission circuit 22 receives the signal from the detection circuit 21 and transmits it to the outside (controller 4).

[0015] As shown in FIGS. 1 to 3, the input side of the detection circuit 21 is electrically connected to a plurality of light-emitting elements 11 provided in the light-emitting unit 1. The output side of the detection circuit 21 is electrically connected to the input side of the connection circuit 23. The output side of the connection circuit 23 is electrically connected to the input side of the transmission circuit 22. The output side of the transmission circuit 22 is electrically connected to the controller 4.

[0016] An input side of the AC-DC converter 3 is electrically connected to an AC power source 200 such as a commercial power source. An output side of the AC-DC converter 3 is electrically connected to a plurality of light-emitting elements 11 of the light-emitting unit 1. The AC-DC converter 3 converts an AC voltage from the AC power source 200 into a predetermined DC voltage and applies the converted DC voltage to the plurality of light-emitting elements 11 of the light-emitting unit 1.

[0017] Furthermore, a DC power supply may be provided instead of the AC power supply 200 and the AC-DC converter 3. In the following, as an example, a case where the AC power supply 200 and the AC-DC converter 3 are provided will be described. Therefore, when a DC power supply is provided, the AC-DC converter 3 in the following description should be read as the DC power supply.

[0018] Details regarding the electrical connection between the detection circuit 21 and the multiple light-emitting elements 11, the electrical connection between the detection circuit 21 and the AC-DC converter 3, and the electrical connection between the detection circuit 21 and the transmission circuit 22 via the connection circuit 23 will be described later.

[0019] The input side of the controller 4 is electrically connected to the transmission circuit 22 of the abnormality detection circuit 2. The output side of the controller 4 is electrically connected to the AC-DC converter 3. The controller 4 may be, for example, a switching circuit having a switching element such as a transistor. The controller 4 may also be, for example, a control element (computer) having an arithmetic element, a memory element, etc.

[0020] Next, the configuration of the light-emitting unit 1 will be further described. As shown in FIG. 2, the light-emitting unit 1 has a plurality of light-emitting elements 11 connected in series. The anode sides of the plurality of light-emitting elements 11 connected in series are electrically connected to a terminal CN1. The terminal CN1 is electrically connected to a positive terminal of the AC-DC converter 3. The cathode sides of the plurality of light-emitting elements 11 connected in series are electrically connected to a terminal CN2. The terminal CN2 is electrically connected to a terminal IN of a detection circuit 21. The terminal OUT of the detection circuit 21 is electrically connected to a negative terminal of the AC-DC converter 3. That is, the terminal CN2 of the light-emitting unit 1 is electrically connected to the negative terminal of the AC-DC converter 3 via the detection circuit 21.

[0021] Furthermore, at least one of the plurality of light-emitting elements 11 connected in series is electrically connected between terminals CN2 and CN3. As shown in FIG. 1, terminal CN3 is electrically connected to terminal VS of detection circuit 21. Therefore, the current flowing through the plurality of light-emitting elements 11 connected in series is divided, and the divided current flows from terminal CN3 of the light-emitting unit 1 to terminal VS of the detection circuit 21. Furthermore, a divided voltage is applied to terminal VS of the detection circuit 21. For example, in the case of the light-emitting unit 1 illustrated in FIG. 2, a portion of the current flowing through the two light-emitting elements 11 flows to terminal VS of the detection circuit 21, and the voltage applied to the two light-emitting elements 11 is applied to terminal VS of the detection circuit 21. The applied voltage varies depending on the forward voltage of the light-emitting element 11. For example, if the forward voltage per light-emitting element 11 is 4 V (volts), a voltage of approximately 8 V (volts) is applied to terminal VS of the detection circuit 21.

[0022] In this way, the AC-DC converter 3 can be used as a power source for lighting the plurality of light-emitting elements 11 and a power source for operating the detection circuit 21. That is, a single power source can be used to light the light-emitting elements 11 and detect abnormalities in the light-emitting elements 11. In other words, it is no longer necessary to provide separate power sources for lighting the light-emitting elements 11 and for operating the detection circuit 11. This makes it easy to simplify the configuration of the light irradiation device 100 and reduce the price of the light irradiation device 100.

[0023] Next, the electrical connection between the detection circuit 21 and the plurality of light-emitting elements 11, and the electrical connection between the detection circuit 21 and the AC-DC converter 3 will be further described.

[0024] As shown in FIG. 3, the detection circuit 21 includes a regulator 21a and a detection unit 21b. As described above, the voltage applied to the plurality of light-emitting elements 11 connected in series is divided and applied to the terminal VS of the detection circuit 21. The voltage applied to the terminal VS serves as a reference voltage used when detecting the occurrence of an abnormality in the detection unit 21b.

[0025] Here, there is variation in the forward voltage characteristics of the light emitting element 11. Therefore, if the divided voltage described above is simply used as the reference voltage, the abnormality detection by the detector 21b will vary.

[0026] Therefore, a regulator 21a is provided in the detection circuit 21. The regulator 21a is electrically connected to the terminal VS. That is, the regulator 21a is electrically connected between the non-inverting input terminal (positive input terminal) of an operational amplifier 21b1 provided in the detection unit 21b, the positive power supply terminal of the operational amplifier 21b2, and some of the plurality of light-emitting elements 11 connected in series via resistors.

[0027] The regulator 21a outputs a voltage lower than the voltage applied to the terminal VS. In this case, taking into consideration variations in the forward voltage characteristics of the light-emitting element 11, the regulator 21a is configured to output a voltage lower than the lower limit of the voltage applied to the terminal VS. The provision of the regulator 21a makes it possible to generate and maintain a constant voltage even if the voltage applied to the terminal VS varies. For example, if the lower limit of the voltage applied to the terminal VS is about 8V (volts), the regulator 21a can output a voltage of 5V (volts).

[0028] The regulator 21a may be, for example, a series regulator or a shunt regulator. In this case, as shown in FIG. 3, it is preferable that the regulator 21a be a shunt regulator. If the regulator 21a is a shunt regulator, the amount of current required to output a desired voltage can be reduced compared to a series regulator. As described above, a portion of the current flowing through the plurality of light-emitting elements 11 flows through the terminal VS and, in turn, through the regulator 21a. Therefore, if the regulator 21a is a shunt regulator and the current flowing through the regulator 21a is reduced, the decrease in the current flowing through the plurality of light-emitting elements 11 can be suppressed accordingly. As a result, energy conservation of the detection circuit 21 can be achieved, and energy conservation of the light irradiation device 100 can be achieved.

[0029] The detection unit 21b includes, for example, an operational amplifier 21b1 and an operational amplifier 21b2. The non-inverting input terminal (positive input terminal) of the operational amplifier 21b1 is electrically connected to the IN terminal of the detection circuit 21. That is, the cathode sides of the plurality of light-emitting elements 11 connected in series are electrically connected to the non-inverting input terminal (positive input terminal) of the operational amplifier 21b1. The inverting input terminal (negative input terminal) of the operational amplifier 21b1 is electrically connected to the OUT terminal of the detection circuit 21 via a resistor. The positive power supply terminal of the operational amplifier 21b1 is electrically connected to the output side of the regulator 21a. That is, some of the plurality of light-emitting elements 11 connected in series are electrically connected to the positive power supply terminal of the operational amplifier 21b1 via a resistor. The voltage applied to the plurality of light-emitting elements 11 connected in series is divided and applied to the positive power supply terminal of the operational amplifier 21b1. The negative power supply terminal of the operational amplifier 21b1 is electrically connected to the COM terminal and OUT terminal of the detection circuit 21. The operational amplifier 21b1 is provided to amplify the detected voltage.

[0030] The non-inverting input terminal (positive input terminal) of the operational amplifier 21b2 is electrically connected to the output terminal of the operational amplifier 21b1. The inverting input terminal (negative input terminal) of the operational amplifier 21b2 is electrically connected to the output side of the regulator 21a via a voltage dividing resistor. The positive power supply terminal of the operational amplifier 21b2 is electrically connected to the output side of the regulator 21a. The negative power supply terminal of the operational amplifier 21b2 is electrically connected to the COM terminal and OUT terminal of the detection circuit 21. The output terminal of the operational amplifier 21b2 is electrically connected to the input side of the connection circuit 23. The output side of the connection circuit 23 is electrically connected to the input side of the transmission circuit 22. The operational amplifier 21b2 compares the output voltage of the operational amplifier 21b1 with a reference voltage, and when the output voltage of the operational amplifier 21b1 exceeds the reference voltage, it lights up a photocoupler in the connection circuit 23, which will be described later.

[0031] As shown in FIG. 3, the transmission circuit 22 includes a transistor 22a and a transistor 22b. The transistors 22a and 22b illustrated in FIG. 3 are PNP transistors. The base of the transistor 22a is electrically connected to the output side of the connection circuit 23. The collector of the transistor 22a is electrically connected to the collector of the transistor 22b. The emitter of the transistor 22a is electrically connected to the base of the transistor 22b. That is, the transistors 22a and 22b are Darlington-connected. The Darlington connection of the transistors 22a and 22b can increase the current amplification factor. Therefore, even if the signal from the detection circuit 21 is weak, an appropriate signal can be transmitted to the controller 4. The Darlington connection allows the collector current of the transistor 22b to be large even if the base current of the transistor 22a is small, which has the effect of enabling stable determination (power saving) even when the current flowing through the photocoupler is small.

[0032] Next, the electrical connection between the detection circuit 21 and the transmission circuit 22 via the connection circuit 23 will be further described. For example, there are cases where the AC power supply 200 and the AC-DC converter 3 are non-insulated. Even if the AC power supply 200 and the AC-DC converter 3 are insulated, a high voltage is applied to the light-emitting unit 1 when there are a large number of light-emitting elements 11. Therefore, in such cases, a high voltage may be applied to the detection circuit 21. In this case, it may become necessary to insulate the detection circuit 21, to which a high voltage is applied, from the transmission circuit 22.

[0033] Therefore, the connection circuit 23 transmits a signal from the detection circuit 21 to the transmission circuit 22 and electrically insulates the detection circuit 21 from the transmission circuit 22. The connection circuit 23 may include, for example, a photocoupler. As shown in FIG. 3, a light-emitting element (corresponding to an example of a second light-emitting element) of the photocoupler is electrically connected to the output side of the detection circuit 21 (detection unit 21b). A light-receiving element side of the photocoupler is electrically connected to the input side of the transmission circuit 22.

[0034] 1 and 3, the positive terminal of the controller 4 is electrically connected to the IN terminal of the transmission circuit 22. The negative terminal of the controller 4 is electrically connected to the OUT terminal of the transmission circuit 22. That is, the controller 4 serves as a power source for the transmission circuit 22. In addition, the transmission terminal CT of the transmission circuit 22 is electrically connected to the reception terminal RT of the controller 4.

[0035] A signal input from the detection circuit 21 to the transmission circuit 22 via the connection circuit 23 is transmitted from the transmission circuit 22 to the controller 4 . When the controller 4 receives a signal from the transmission circuit 22, it stops the operation of the AC-DC converter 3, for example. The controller 4 can also display the occurrence of an abnormality on a display unit or sound an alarm using a buzzer or the like.

[0036] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0037] 1 Light emitting unit, 2 Abnormality detection circuit, 3 AC-DC converter, 4 Controller, 11 Light emitting element, 21 Detection circuit, 21a Regulator, 21b Detection unit, 21b1 Operational amplifier, 21b2 Operational amplifier, 22 Transmission circuit, 23 Connection circuit, 100 Light irradiation device

Claims

1. An abnormality detection circuit for a light irradiation device having a plurality of first light-emitting elements connected in series, the abnormality detection circuit of the light irradiation device includes a detection circuit having an operational amplifier; anode sides of the plurality of first light-emitting elements connected in series are electrically connected to a power source; the cathode sides of the plurality of first light-emitting elements connected in series are electrically connected to a non-inverting input terminal of the operational amplifier; An abnormality detection circuit for a light irradiation device, in which some of the first light-emitting elements among the plurality of first light-emitting elements connected in series are electrically connected to a positive power supply terminal of the operational amplifier via a resistor, and a voltage applied to the plurality of first light-emitting elements connected in series is divided and applied to the positive power supply terminal.

2. 2. The abnormality detection circuit for a light irradiation device according to claim 1, further comprising a shunt regulator electrically connected between the non-inverting input terminal of the operational amplifier and some of the first light-emitting elements among the plurality of first light-emitting elements connected in series.

3. The abnormality detection circuit a connection circuit for transmitting a signal from the detection circuit; a transmitting circuit that transmits the signal from the connection circuit to the outside; The abnormality detection circuit for a light irradiation device according to claim 1 or 2, further comprising:

4. The transmission circuit a second light-emitting element electrically connected to the detection circuit; a light receiving element electrically connected to the transmitting circuit; 4. The abnormality detection circuit for a light irradiation device according to claim 3, further comprising:

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