Optical level detection device

Abstract

To determine an abnormality of an optical detector when detecting a level of liquid using a plurality of optical detectors.SOLUTION: An optical level detection device 1 includes a sensor unit 100 having a plurality of optical detectors 110 and a control unit 200. Each of the plurality of optical detectors 110 includes a light emitter 111, a prism 113, a light guide section 117, and a light receiver 112. The prism 113 is configured to transmit light from the light emitter 111 in liquid and to reflect and guide the light from the light emitter 111 to the light receiver 112 outside the liquid. The light guide section 117 is configured to guide a part of the light from the light emitter 111 to the light receiver 112. The control unit 200 causes the respective light emitters 111 of the plurality of optical detectors 110 to emit light, and compares a voltage output from the light receiver 112 included in each of the optical detectors 110 with a first threshold value for detecting the presence or absence of liquid and a second threshold value for diagnosing a malfunction of the optical detector 110.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical level detection device, and more particularly to an optical level detection device capable of determining an abnormality in any of a plurality of optical detection bodies when detecting the level of a liquid using the plurality of optical detection bodies. [Background technology]

[0002] There is known a level detection device for detecting the level (height of the liquid surface) of a liquid such as fuel stored in a container. This level detection device is provided with a plurality of optical detection bodies in the vertical direction, each of which is made up of a light emitter, a light receiver, and a right-angle prism, and is configured to detect the level of the liquid by the difference between the reflection and transmission of light at the right-angle prism. This type of optical level detection device is described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-110663 A Summary of the Invention [Problem to be solved by the invention]

[0004] The optical level detection device described in Patent Document 1 is configured by arranging multiple optical detectors in the vertical direction, each of which uses a light emitter, a light receiver, and a right-angle prism. When the optical detector is located in liquid, the light emitted from the light emitter travels toward the liquid from the surface that is in contact with the 90° corner of the right-angle prism. Therefore, the light emitted from the light emitter does not reach the light receiver. On the other hand, when the optical detector is not in the liquid but outside the liquid, the light emitted from the light emitter is reflected at the 90° angle of the right-angle prism and travels toward the light receiver. Thus, the light emitted from the light emitter reaches the light receiver. In this way, the liquid level can be detected based on the presence or absence of a light receiving signal in each of the multiple optical detectors.

[0005] On the other hand, in any of the multiple optical detection bodies, an abnormality in at least one of the light emitter and the light receiver may cause the light receiver to not output a light reception signal. In this case, the phenomenon in which the light receiver does not output a light reception signal is the same as when the optical detection body 110 is in a liquid, and cannot be distinguished. For this reason, there is a problem in that it is difficult to determine the abnormality of the optical detection body.

[0006] For this reason, it has been desired that an optical level detection device be able to determine whether an abnormality has occurred in the optical detection body. The present invention has been made to solve the above-mentioned problems, and aims to provide an optical level detection device that is capable of determining abnormalities in multiple optical detection bodies when detecting the level of a liquid using the optical detection bodies. [Means for solving the problem]

[0007] The optical level detection device of the present invention is an optical level detection device comprising a sensor unit having a plurality of optical detectors, and a control unit, each of the plurality of optical detectors comprising an light emitter, a prism, a light guide unit, and a light receiver, the prism being configured to transmit light from the light emitter in the liquid and to reflect and guide the light from the light emitter to the light receiver outside the liquid, the light guide unit being configured to guide a portion of the light from the light emitter to the light receiver, and the control unit causing the light emitter of each of the plurality of optical detectors to emit light, and comparing the voltage output from the light receiver of each of the plurality of optical detectors with a first threshold value for detecting the presence or absence of liquid and a second threshold value for determining abnormality in the optical detector.

[0008] In the optical level detection device according to the present invention, the light guiding section is configured to guide a smaller amount of light from the light emitter to the light receiver than the amount of light reflected by the prism.

[0009] In the optical level detection device according to the present invention, a light-shielding portion is provided between the light-emitting body and the light-receiving body, and the light-guiding portion includes a light-transmitting portion, which is provided at any position on the light-shielding portion.

[0010] In the optical level detection device according to the present invention, the light guide portion includes a reflecting portion, and the reflecting portion is configured to reflect a portion of the light from the light emitter that is about to pass through the prism and guide it to the light receiver.

[0011] In the optical level detection device of the present invention, the voltage output from the photoreceptor is in one of the following states: a first voltage output from the photoreceptor that receives light from the light-emitting element reflected by the prism when each of the multiple optical detectors is located outside the liquid; a second voltage output from the photoreceptor that receives light from the light-emitting element guided by the light-guiding section when each of the multiple optical detectors is located in the liquid; and a third voltage output from the photoreceptor when an abnormality occurs in the light-emitting element or photoreceptor of each of the multiple optical detectors, and the control section compares one of the first voltage, second voltage, and third voltage output from each photoreceptor with a first threshold value and a second threshold value. Effect of the Invention

[0012] In the optical level detection device of the present invention, a portion of the light from the light-emitting element is guided to the light-receiving element by a light-guiding section, and the light-emitting element provided in each of the multiple optical detectors is caused to emit light. The voltage output from the light-receiving element provided in each of the multiple optical detectors is compared with a first threshold value for detecting the presence or absence of liquid and a second threshold value for determining an abnormality in the optical detectors, making it possible to determine an abnormality in the optical detectors when detecting the level of liquid using multiple optical detectors. [Brief description of the drawings]

[0013] [Figure 1] 1 is a configuration diagram showing a configuration of an optical level detection device according to a first embodiment. [Diagram 2] 1 is an explanatory diagram showing a configuration of a main part of an optical level detection device according to a first embodiment. [Diagram 3] 1 is a configuration diagram showing an overall configuration of an optical level detection device according to a first embodiment. [Figure 4] 2 is a circuit diagram showing the connection between a light emitter and a light receiver of the optical level detection device according to the first embodiment. FIG. [Diagram 5] 13 is an explanatory diagram showing a detection state of a liquid level in a comparative example. FIG. [Figure 6] 2 is an explanatory diagram showing a detection state of a liquid level of the optical level detection device according to the first embodiment. FIG. [Figure 7] 10 is a characteristic diagram showing the characteristics of a sensor output signal when a liquid level is detected by a normal optical detection body. FIG. [Figure 8] FIG. 13 is a characteristic diagram showing the characteristics of a sensor output signal when detecting a liquid level in a comparative example including an abnormal optical detection body. [Figure 9] 4 is a characteristic diagram showing the characteristics of a sensor output signal when detecting a liquid level in the optical level detection device according to the first embodiment. FIG. [Figure 10] FIG. 11 is an explanatory diagram illustrating a difference between a comparative example and an embodiment. [Figure 11] 10 is an explanatory diagram showing a configuration of a main part of an optical level detection device according to a second embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical level detection device according to an embodiment of the present invention will now be described with reference to the drawings. In the drawings, the same parts are designated by the same reference numerals.

[0015] Embodiment 1 First, the basic configuration of an optical level detection device 1 in the first embodiment will be described with reference to FIGS. Fig. 1 is a configuration diagram showing the configuration of an optical level detection device 1 according to embodiment 1. Fig. 2 is an explanatory diagram showing the configuration of a main part of the optical level detection device 1 according to embodiment 1. Fig. 3 is a configuration diagram showing the overall configuration of the optical level detection device 1 according to embodiment 1. Fig. 4 is a circuit diagram showing the connection between a light emitter and a light receiver of the optical level detection device 1 according to embodiment 1.

[0016] The optical level detection device 1 mainly includes a sensor unit 100 and a control unit 200. The sensor unit 100 includes a case 101, a substrate 105, and a plurality of optical detection bodies 110. Here, as a specific example, a case in which the sensor unit 100 includes 16 optical detection bodies 110A to 110P as shown in FIG. The case 101 has a waterproof function to prevent liquid 400 and the like from entering the sensor unit 100. The substrate 105 is provided with wiring for supplying drive signals to the multiple optical detection bodies 110 and for supplying detection signals obtained from the multiple optical detection bodies 110 to the control unit 200. In Fig. 1, among the multiple optical detection bodies 110A to 110P, optical detection bodies 110A, 110B, 110C, 110O, and 110P are shown in an enlarged manner. In Fig. 2, optical detection bodies 110H and 110I are shown in a further enlarged manner. Each of the plurality of optical detection bodies 110A to 110P is configured to include a light emitting body 111, a light receiving body 112, a prism 113, light blocking portions 114 to 116, and a light guiding portion 117.

[0017] A so-called right-angle prism having an angle of 90° can be used as the prism 113. Note that as long as the prism 113 has a 90° angle located in the liquid or gas (outside the liquid), it may be a triangular prism having angles of 90°, 45°, and 45°, or a pentagonal prism having angles of 90°, 135°, 135°, 90°, and 90°. In addition, by adjusting the orientation of the light emitter 111 and the light receiver 112, it is possible to set the angle in the liquid or gas to a value other than 90°. For example, as the configuration and arrangement of the light emitter 111, the light receiver 112, and the prism 113, it is possible to use the configurations and arrangements of various prisms, light emitting elements, and light receiving elements described in Japanese Patent Application Laid-Open No. 2021-148590 by the present applicant.

[0018] In this embodiment 1, a prism 113 having a 90° angle is taken as a specific example, and the 90° angle of the prism 113 is disposed so as to be located in the liquid or gas. The light emitter 111 and the light receiver 112 are provided facing the surface of the prism 113 that faces the 90° angle. Light emitter 111 emits light from a surface facing the 90° angle of prism 113 toward one surface of prism 113 that is tangent to the 90° angle. Light receiver 112 receives the light reflected by the two surfaces that are tangent to the 90° angle of prism 113. In this specification, "reflected at a 90° angle" means "reflected by two surfaces that are tangent to the 90° angle."

[0019] The light shielding portion 114 blocks leakage of light from the light emitter 111 so that the light from the light emitter 111 does not reach the light receiver 112 of the adjacent optical detection body. The light shielding portion 115 is provided between the light emitter 111 and the light receiver 112. The light shielding portion 115 blocks leakage of light from the light emitter 111 so that the light from the light emitter 111 does not directly reach the light receiver 112, except in the case where the light guide portion 117 is used. The light shielding portion 116 blocks leakage of light from the adjacent optical detection body 110 so that the light from the light emitter 111 of the adjacent optical detection body does not reach the light receiver 112.

[0020] The light guiding section 117 is configured to guide a portion of the light from the light emitter 111 to the light receiver 112 within the same optical detection body. The light guiding section 117 is configured to guide an amount of light that is less than the amount of light reflected by the 90° angle of the prism 113 from the light emitter 111 to the light receiver 112 within the same optical detection body. The light guiding section 117 can be configured as a light transmitting section 117a at any position of the light blocking section 115 as shown in FIG. 2. It is also possible to configure the entire light blocking section 115 from a semitransparent material with a predetermined density or light transmittance to have the same characteristics as the light transmitting section 117a.

[0021] As shown in FIG. 3, the optical level detection device 1 is used to detect the height of a liquid surface 401 in a container 300 as the level of the liquid 400 by utilizing the reflection or transmission of light at a prism 113 in each of a plurality of optical detection bodies 110A to 110P included in the sensor unit 100.

[0022] The control unit 200 supplies drive signals to the optical level detection device 1 that cause the light emitters 111 of the multiple optical detection bodies 110A-110P to emit light sequentially at different timings, receives sensor output signals that are output sequentially at different timings from the light receivers 112 of the multiple optical detection bodies 110A-110P, and detects the level of the liquid 400 by processing the received sensor output signals. Furthermore, the control unit 200 compares the sensor output signal output from the light receiver 112 of each of the plurality of optical detection bodies 110A-110P with a plurality of threshold values ​​to determine whether any of the plurality of optical detection bodies 110A-110P is abnormal.

[0023] In the optical level detection device 1, the light emitter 111 and the light receiver 112 in each of the multiple optical detection bodies 110A-110P can be configured as light emitter-light receiver composite elements A1-A4, B1-B4, C1-C4, and D1-D4 (hereinafter, these will be referred to as A1-D4) in a 4-row by 4-column matrix circuit with rows 1-4 and columns A-D, as shown in Fig. 4. The light emitter-light receiver composite elements A1-D4 correspond to the light emitter 111 and the light receiver 112 in each of the optical detection bodies 110A-110P. Here, the light emitter 111 is configured with a photodiode, and the light receiver 112 is configured with a phototransistor.

[0024] In the above-described 4 row x 4 column matrix circuit, the light emitters 111 of each of the light-emitting and light-receiving composite elements A1 to D4 selectively emit light at different timings in response to the column A to column D selection signals and row 1 to row 4 selection signals from the control unit 200. Correspondingly, when the light receiver 112 of each of the light-emitting and light-receiving composite elements A1 to D4 receives light from the light emitter 111, it outputs a light reception signal as a sensor output. Since the light reception signal from the light receiver 112 is obtained in synchronization with the light emission of the light emitter 111, the control unit 200 can detect the level of the liquid 400 based on the presence or absence of a light reception signal.

[0025] Hereinafter, the optical level detection device 1 will be described with reference to Figures 5 to 9 with regard to this embodiment in which, when detecting the level of a liquid 400 using multiple optical detection bodies 110A to 110P, abnormalities in each of the multiple optical detection bodies 110A to 110P are determined.

[0026] Fig. 5 is an explanatory diagram showing the detection state of the liquid level in a comparative example. Fig. 6 is an explanatory diagram showing the detection state of the liquid level of the optical level detection device 1 according to embodiment 1. Fig. 7 is a characteristic diagram showing the characteristics of the sensor output signal when the liquid level is detected by a normal optical detection body. Fig. 8 is a characteristic diagram showing the characteristics of the sensor output signal when the liquid level is detected in a comparative example including an abnormal optical detection body. Fig. 9 is a characteristic diagram showing the characteristics of the sensor output signal when the liquid level is detected by the optical level detection device 1 according to embodiment 1. The sensor output signals in the characteristic diagrams of Figures 7 to 9 show specific examples in which the phototransistors in the matrix circuit shown in Figure 3 are configured with NPN transistors and the power supply voltage Vcc is +5V. If the matrix circuit of Figure 3 is configured with PNP transistors, the characteristics will be the inverse of 0V and 5V in the characteristic diagrams of Figures 7 to 9. Also, by changing the power supply voltage Vcc, a sensor output signal of any voltage can be obtained.

[0027] When the level of the liquid 400 is detected using a plurality of optical detection bodies 110A to 110P, if all of the optical detection bodies 110A to 110P are normal, the sensor output signal of FIG. 7 can be obtained. In the optical detection bodies 110I-110P located outside the liquid, the light from the light emitter 111 is reflected by the prism 113 and reaches the light receiver 112. As a result, a current flows in the light receiver 112 of each of the optical detection bodies 110I-110P in response to the light from the light emitter 111, and the light receiver 112 outputs a first voltage near 0 V as a sensor output signal.

[0028] Furthermore, in the optical detection bodies 110A to 110H positioned in the liquid, the light from the light emitter 111 travels through the liquid from the prism 113. As a result, the light receivers 112 of the optical detection bodies 110A to 110H do not receive the light from the light emitter 111 and no current flows, so that they output a second voltage of around 5 V as a sensor output signal. Then, a control unit (not shown) can detect the level of the liquid 400 as being the height of the optical detection body 110H by comparing the sensor output signal of the first voltage and second voltage as described above with a liquid level threshold value Vth set halfway between the first voltage and the second voltage.

[0029] FIG. 5 shows, as a comparative example, optical detection bodies 110A to 110C, 110E to 110G, and 110M to 110P out of the plurality of optical detection bodies 110A to 110P, and optical detection bodies 110D and 110H to 110L in an enlarged manner. Here, it is assumed that among the multiple optical detection bodies 110A to 110P, optical detection bodies 110D, 110I, and 110K are abnormal, and the rest are normal. The sensor output signals from the optical detection bodies 110A to 110P at this time are shown in FIG.

[0030] In optical detection bodies 110J and 110L to 110P that are not abnormal and are outside the liquid, the light from light emitter 111 is reflected by prism 113 and reaches light receiver 112. Therefore, a current flows in light receiver 112 of optical detection bodies 110J and 110L to 110P in response to the light from light emitter 111, and a first voltage near 0 V is output as a sensor output signal. In optical detection bodies 110A-110C and 110E-110H that are not abnormal and are located in the liquid, the light from light emitter 111 travels from prism 113 through the liquid and does not reach light receiver 112. For this reason, light receiver 112 of optical detection bodies 110A-110C and 110E-110H outputs a second voltage of approximately 5 V as a sensor output signal. In the abnormal optical detection bodies 110D, 110I, and 110K, the light receiving signal is not output from the light receiving body 112 due to the abnormality of at least one of the light emitter and the light receiving body. Therefore, the optical detection bodies 110D, 110I, and 110K are in the same state as being in liquid. Therefore, the light receiving bodies 112 of the optical detection bodies 110A to 110C and 110E to 110H output a second voltage of about 5V as a sensor output signal.

[0031] In the optical detection body 110D, as shown in [D] of FIG. 8, an abnormality in at least one of the light emitter or light receiver causes the sensor output signal to become the second voltage. However, this is the same second output voltage as when the body is immersed in liquid, and it is unclear whether the body is immersed in liquid or has an abnormality, so it is not possible to determine that there is an abnormality. Similarly, in the optical detection body 110I, as shown in [I] of Figure 8, an abnormality in at least one of the light emitter or light receiver causes the sensor output signal to become the second voltage, but this is the same second output voltage as when it is located in liquid, and it is unclear whether it is located in liquid or abnormal, so it cannot be determined that there is an abnormality. In optical detection body 110K, as shown in [K] in Figure 8, an abnormality in at least one of the light emitter or light receiver causes the sensor output signal to become the second voltage. However, since the adjacent optical detection bodies 110J and 110L indicate the first voltage outside the liquid, it is clear that optical detection body 110K is located outside the liquid, and therefore it can be determined that there is an abnormality. When the sensor output signal of the first and second voltages described above is compared with a liquid level threshold Vth set halfway between the first and second voltages, the level of the liquid 400 is detected as being at a height of the optical detection body 110I that is different from the actual height.

[0032] FIG. 6 shows an enlarged view of optical detection bodies 110D and 110H-110L among the multiple optical detection bodies 110A-110P in the optical level detection device 1 according to the first embodiment, with optical detection bodies 110A-110C, 110E-110G, and 110M-110P omitted. Here, it is assumed that among the multiple optical detection bodies 110A to 110P, optical detection bodies 110D, 110I, and 110K are abnormal, and the rest are normal.The sensor output signals from the optical detection bodies 110A to 110P at this time are shown in FIG. In optical detection bodies 110J and 110L to 110P that are not abnormal and are outside the liquid, the light from light emitter 111 is reflected by prism 113 and reaches light receiver 112. Therefore, a current flows in light receiver 112 of optical detection bodies 110J and 110L to 110P in response to the light from light emitter 111, and a first voltage near 0 V is output as a sensor output signal.

[0033] In optical detection bodies 110A to 110C and 110E to 110H that are not abnormal and are located in the liquid, most of the light from light emitter 111 travels through the liquid from prism 113, but a portion of the light from light emitter 111 reaches light receiver 112 through light guide 117. For this reason, a current flows in light receiver 112 of optical detection bodies 110A to 110C and 110E to 110H in response to the portion of the light from light emitter 111, and a second voltage of about 4 V is output as a sensor output signal. The second voltage can be adjusted between the first voltage and the third voltage depending on the amount of light that reaches light receiver 112 through light guide 117. In the abnormal optical detectors 110D, 110I, and 110K, due to an abnormality in at least one of the light emitter and the light receiver, no current flows through the light receiver 112, and no light reception signal is output from the light receiver 112. For this reason, the optical detectors 110D, 110I, and 110K output a sensor output signal of a third voltage around 5 V, as shown in [D], [I], and [K] in FIG.

[0034] That is, the voltage output from the photoreceptor 112 is a first voltage output from the light receiver 112 that receives light from the light emitter 111 reflected by the prism 113 when each of the plurality of optical detectors 110 is located outside the liquid; a second voltage output from the light receiver 112 that receives light from the light emitter 111 guided by the light guide unit 117 when each of the plurality of optical detectors 110 is located in the liquid; and a third voltage output from the light receiver 112 when an abnormality occurs in the light emitter 111 or the light receiver 112 of each of the plurality of optical detectors 110; It can be one of the following.

[0035] The control unit 200 predetermines a first threshold Vth1 as a liquid level threshold midway between the first and second voltages, and a second threshold Vth2 as an abnormality determination threshold midway between the second and third voltages. The control unit 200 can then determine whether there is an abnormality in the optical detection bodies 110 when detecting the level of the liquid 400 using multiple optical detection bodies 110 by comparing any one of the first voltage, second voltage, and third voltage output from each photoreceptor 112 with a first threshold value Vth1 and a second threshold value Vth2.

[0036] In the optical detection body 110D, as shown in [D] of Fig. 9, an abnormality in at least one of the light emitter and the light receiver causes the sensor output signal to become a third voltage. This third voltage can be distinguished from the second voltage of the sensor output signal when the optical detection body 110D is located in liquid by comparison with the second threshold value Vth2. Therefore, the optical detection body 110D can be distinguished as abnormal. As shown in FIG. 9[I], the optical detection body 110I also has a sensor output signal that becomes a third voltage when at least one of the light emitter and the light receiver is abnormal. This third voltage can be distinguished from the second voltage of the sensor output signal when the optical detection body 110I is located in liquid by comparison with the second threshold value Vth2. and It can be distinguished. In the optical detection body 110K, as shown in [K] of Fig. 9, an abnormality in at least one of the light emitter and the light receiver causes the sensor output signal to become a third voltage. This third voltage can be determined to be abnormal by comparison with the second threshold value Vth2. Therefore, comparison with the adjacent optical detection bodies 110J and 110L is not necessary, the abnormality determination process is simplified, and abnormality determination can be performed more quickly than in the comparative example.

[0037] As described above, by comparing the sensor output signals of the first voltage, the second voltage, and the third voltage with the first threshold value Vth1 and the second threshold value Vth2, the control unit 200 can accurately detect the level of the liquid 400 as being the height of the optical detection body 110H, and can also determine abnormalities in the optical detection bodies 110D, 110I, and 110K. The control unit 200 outputs to the outside the level of the liquid 400 detected by the optical level detection device 1, and also outputs to the outside, as abnormality information, any of the optical detection bodies 110A-110P that are determined to be abnormal.

[0038] The differences in the voltages of light emission, transmission, reflection, light reception, and sensor output signals between the comparative example and embodiment 1 described above are summarized in a table format in Fig. 10. Fig. 10 is an explanatory diagram for explaining the differences between the comparative example and the embodiment. In the above description, a voltage near 0V is indicated as "LO", a voltage near 5V is indicated as "HI", and a voltage near 4V is indicated as "MID", meaning an intermediate voltage.

[0039] In this embodiment, the abnormality determination may be performed as a fault diagnosis at the time of start-up or at the start of measurement, or may be performed based on the voltage obtained during measurement. When the characteristics of light guiding section 117 change due to aging, the second voltage in the first embodiment may change accordingly. In this case, it is preferable that control section 200 adjusts second threshold value Vth2 in response to the change in the second voltage.

[0040] Embodiment 2 Here, the basic configuration of the optical level detection device 1 in the second embodiment will be described with reference to Fig. 11. Fig. 11 is an explanatory diagram showing the configuration of the main parts of the optical level detection device 1 according to the second embodiment. Fig. 11 shows an enlarged view of optical detection body 110H and optical detection body 110I among the multiple optical detection bodies 110A to 110P. Note that the optical detection bodies 110A to 110G and 110J to 110P not shown here are also assumed to have the same configuration.

[0041] 11, the light guide 117 can be configured to include a reflector 117b in a partial region of the prism 113, so as to reflect a portion of the light from the light emitter 111 attempting to pass through the prism 113 and guide it to the light receiver 112. Here, the partial region of the prism 113 refers to any region of a surface sandwiching a 90° angle located in the liquid or outside the liquid. In this way, the reflector 117b can guide a smaller amount of light from the light emitter 111 to the light receiver 112 in the same optical detection body than the light reflected by the 90° angle of the prism 113. It is also possible to separate the reflecting portion 117b into two reflecting portions on either side of the 90° angle of the prism 113 to perform similar reflection.

[0042] It is possible to use a mixture of light transmitting portion 117a described in the first embodiment and reflecting portion 117b described in the second embodiment as light guiding portion 117. It is also possible to use both light transmitting portion 117a and reflecting portion 117b as light guiding portion 117.

[0043] [Effects obtained by the embodiment] The optical level detection device 1 described in the above embodiment includes a sensor unit 100 having a plurality of optical detection bodies 110, and a control unit 200. Each of the plurality of optical detection bodies 110 includes a light emitter 111, a prism 113, a light guide unit 117, and a light receiver 112. The prism 113 is configured to transmit light from the light emitter 111 in the liquid and to reflect and guide the light from the light emitter 111 to the light receiver 112 outside the liquid. The light guide unit 117 is configured to reflect the light from the light emitter 111. The control unit 200 causes the light emitter 111 provided in each of the multiple optical detectors 110 to emit light, and compares the voltage output from the light receiver 112 provided in each of the multiple optical detectors 110 with a first threshold value for detecting the presence or absence of liquid and a second threshold value for diagnosing a malfunction of the optical detector 110, thereby making it possible to determine an abnormality in the optical detector 110 when detecting the level of the liquid 400 using the multiple optical detectors 110.

[0044] In the optical level detection device 1 described in the above embodiment, the light-guiding section 117 guides a smaller amount of light than the light reflected by the prism 113 from the light emitter 111 to the light receiver 112, thereby making it possible to make the voltages output from the light receivers 112 different from one another, and making it possible to identify abnormalities in the optical detectors 110 when detecting the level of the liquid 400 using multiple optical detectors 110.

[0045] In the optical level detection device 1 described in the above embodiment, a light-shielding portion 115 is provided between the light-emitting body 111 and the light-receiving body 112, and a light-transmitting portion 117a is provided as a light-guiding portion 117 at any position of the light-shielding portion 115. This allows the light-guiding portion 117 to reliably guide a smaller amount of light from the light-emitting body 111 to the light-receiving body 112 than the light reflected by the prism 113, making it possible to determine abnormalities in the optical detectors 110 when detecting the level of the liquid 400 using multiple optical detectors 110.

[0046] In the optical level detection device 1 described in the above embodiment, the light-guiding section 117 is equipped with a reflecting section 117b, and a portion of the light from the light-emitting body 111 attempting to pass through the prism 113 is reflected by the reflecting section 117b and guided to the light-receiving body 112. This allows the light-guiding section 117 to reliably guide a smaller amount of light from the light-emitting body 111 to the light-receiving body 112 than the amount of light reflected by the prism 113 outside the liquid, making it possible to identify abnormalities in the optical detectors 110 when detecting the level of the liquid 400 using multiple optical detectors 110.

[0047] In the optical level detection device 1 described in the above embodiment, the voltage output from the photoreceptor 112 is in one of the following states: a first voltage output from the photoreceptor 112 that receives light from the light emitter 111 reflected by the prism 113 when each of the multiple optical detectors 110 is located outside the liquid; a second voltage output from the photoreceptor 112 that receives light from the light emitter 111 guided by the light guide section 117 when each of the multiple optical detectors 110 is located in the liquid; and a third voltage output from the photoreceptor 112 when the light emitter 111 or the photoreceptor 112 of each of the multiple optical detectors 110 fails. The control section 200 compares any of the first voltage, second voltage, and third voltage output from each photoreceptor 112 with a first threshold value and a second threshold value, thereby being able to reliably determine an abnormality in the optical detector 110 when the level of the liquid 400 is detected using the multiple optical detectors 110. [Explanation of symbols]

[0048] 1 Optical level detection device, 100 Sensor unit, 101 Case, 105 Board, 110, 110A to 110P Optical detection body, 111 Light emitter, 112 Light receiver, 113 Prism, 114, 115, 116 Light shielding unit, 117 Light guide unit, 117a Light transmitting unit, 117b Reflecting unit, 200 Control unit, 300 Container, 400 Liquid, 401 Liquid level, A1 to A4, B1 to B4, C1 to C4, D1 to D4 Light emitting and receiving composite elements.

Claims

1. An optical level detection device (1) comprising a sensor unit (100) having a plurality of optical detection bodies (110) and a control unit (200), Each of the plurality of optical detection bodies (110) is The light source comprises a light emitter (111), a prism (113), a light guide section (117), and a light receiver (112), the prism (113) is configured to transmit light from the light emitter (111) when in the liquid and to reflect the light from the light emitter (111) outside the liquid and guide the light to the light receiver (112); The light guide portion (117) is configured to guide a portion of the light from the light emitter (111) to the light receiver (112); The control unit (200) causing the light emitter (111) included in each of the plurality of optical detection bodies (110) to emit light; comparing a voltage output from the light receiver (112) provided in each of the plurality of optical detectors (110) with a first threshold value for detecting the presence or absence of a liquid and a second threshold value for determining an abnormality in the optical detector (110); Optical level detection device.

2. The light guide (117) is configured to guide a smaller amount of light from the light emitter (111) to the light receiver (112) than the amount of light reflected by the prism (113).

2. The optical level detection device according to claim 1.

3. a light shielding portion (115) is provided between the light emitter (111) and the light receiver (112); The light guiding portion (117) includes a light transmitting portion (117a), The light transmitting portion (117a) is provided at any position of the light blocking portion (115).

3. The optical level detection device according to claim 2.

4. The light guide portion (117) includes a reflecting portion (117b), The reflecting portion (117b) is configured to reflect a portion of the light from the light emitter (111) that is about to pass through the prism (113) and guide the light to the light receiver (112).

3. The optical level detection device according to claim 2.

5. The voltage output from the photoreceptor (112) is a first voltage output from the light receiver (112) that receives light from the light emitter (111) reflected by the prism (113) when each of the plurality of optical detectors (110) is located outside the liquid; and a second voltage output from the light receiver (112) that receives light from the light emitter (111) guided by the light guide portion (117) when each of the plurality of optical detectors (110) is located in liquid; and a third voltage output from the light receiver (112) when an abnormality occurs in the light emitter (111) or the light receiver (112) of each of the plurality of optical detectors (110); In one of the following states: The control unit (200) comparing any one of the first voltage, the second voltage, and the third voltage output from each of the photoreceptors (112) with the first threshold and the second threshold; The optical level detection device according to any one of claims 1 to 4.

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