JP2015072167A - Sticking object detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sticking object detection device in which deterioration in detection accuracy of a sticking object is suppressed.SOLUTION: The sticking object detection device detects a sticking object stuck on a transparent plate (200). The sticking object detection device comprises: a light-emitting element (10) irradiating the transparent plate with light; a light-receiving element (20) converting light reflected by the transparent plate into a photoelectric signal; a sticking object determination unit (30) determining the presence or absence of a sticking object on the basis of the electric signal of the light-receiving element; a light guide lens (41) guiding light of the light-emitting element to the transparent plate; a case (50) storing therein each of the light-emitting element, the light-receiving element and the light guide lens; a first temperature sensor (60) detecting a temperature of the transparent plate; a second temperature sensor (70) detecting a temperature in the case; a humidity sensor (80) detecting humidity in the case; and a dew condensation determination unit (30) detecting a lens temperature of the light guide lens on the basis of the temperature of the transparent plate and the temperature in the case, and determining dew condensation of the light guide lens on the basis of the lens temperature and the humidity in the case.

Description

  The present invention relates to an adhering matter detection device for detecting adhering matter adhering to a transparent plate.

  Conventionally, as shown in Patent Document 1, for example, there has been proposed a raindrop detection device capable of calculating the raindrops attached to the outer surface of the windshield and the humidity of the inner surface of the windshield. This raindrop detection device includes a light emitting element that emits reference light, a light receiving element that outputs a signal corresponding to the intensity of the reference light reflected by the windshield, and an outer surface of the windshield based on a signal output from the light receiving element. Detecting means for detecting attached raindrops. The raindrop detection device includes an inner surface temperature detecting means for outputting a signal corresponding to the temperature of the inner surface of the windshield, an in-vehicle temperature detecting means for outputting a signal corresponding to the temperature inside the vehicle interior in the vicinity of the inner surface temperature detecting means, Vehicle interior humidity detection means for outputting a signal corresponding to the humidity inside the vehicle interior in the vicinity of the temperature detection means. The detection means described above detects raindrops adhering to the outer surface of the windshield based on a signal output from the light receiving element, and based on signals output from the inner surface temperature detection means, the vehicle interior temperature detection means, and the vehicle interior humidity detection means. Calculate the humidity inside the windshield.

  In addition to the above-described components, the raindrop detection device has a lens that is attached and fixed to the windshield. This lens refracts the light emitted from the light emitting element to reach the outer surface of the windshield, and collects the light reflected by the outer surface of the windshield and emits it to the light receiving element.

JP2013-11559A

  As described above, the raindrop detection apparatus disclosed in Patent Document 1 determines the humidity on the inner surface of the windshield, that is, the condensation that occurs on the inner surface of the windshield. However, as described above, the windshield is provided with a lens, and light passing through the lens enters the light receiving element from the light emitting element. And a detection means detects a raindrop based on the signal of a light receiving element. When condensation occurs in the lens in this configuration, the amount of light incident on the light receiving element fluctuates due to the condensation, which may reduce the detection accuracy of raindrops. For example, in the configuration described in Patent Document 1, it is conceivable that the temperature detected by the inner surface temperature detecting means is regarded as the temperature of the lens and the condensation of the lens is determined. However, since the temperature measured by the inner surface temperature detection means is not the temperature of the lens, dew condensation cannot be detected with high accuracy, and as a result, it has been difficult to accurately detect raindrops (attachments).

  Therefore, in view of the above problems, an object of the present invention is to provide an attached matter detection apparatus in which a decrease in attached matter detection accuracy is suppressed.

  In order to achieve the above-described object, the present invention is an attached matter detection apparatus that detects attached matter attached to the outer surface (200b) of a transparent plate (200) exposed to an external environment, and is isolated from the external environment. A light emitting element (10) that irradiates light on the inner surface (200a) of the transparent plate, a light receiving element (20) that receives light emitted from the light emitting element and reflected by the transparent plate, and converts it into an electrical signal; Based on the electrical signal converted by the element, the adhering matter determination unit (30) for determining the presence or absence of adhering matter, and fixed to the inner surface of the transparent plate, guides the light emitted from the light emitting element to the inner surface of the transparent plate. A light guide lens (41), a light emitting element, a light receiving element, and a case (50) for housing the light guide lens, a first temperature sensor (60) for detecting the temperature of the transparent plate, and the temperature in the case A second temperature sensor (70) to be detected; The lens temperature of the light guide lens is detected based on the humidity sensor (80) for detecting the humidity in the casing, the temperature of the transparent plate detected by the first temperature sensor, and the temperature in the case detected by the second temperature sensor. And a dew condensation determination unit (30) for determining dew condensation of the light guide lens based on the detected lens temperature and the humidity in the case detected by the humidity sensor.

  Thus, in the present invention, based on the temperature of the transparent plate (200) where the light guide lens (41) is fixed to the inner surface (200a) and the temperature of the case (50) where the light guide lens (41) is housed. The lens temperature of the light guide lens (41) is detected, and the condensation of the light guide lens (41) is determined based on the lens temperature and the humidity in the case (50). According to this, the dew condensation of the light guide lens (41) can be detected with higher accuracy than the configuration in which the temperature of the transparent plate (200) is regarded as the lens temperature and the dew condensation of the light guide lens (41) is determined. . Therefore, the fall of the detection accuracy of a deposit | attachment is suppressed.

  A fixing member (90) for fixing the light guide lens to the inner surface of the transparent plate, and the dew condensation determination unit includes not only the temperature of the transparent plate and the temperature in the case, but also the transparent plate, the fixing member, the light guide lens, and The lens temperature is detected based on the thermal conductivity of each air.

  According to this, it is possible to detect the lens temperature with higher accuracy than the configuration in which the lens temperature is simply detected based on the temperature of the transparent plate (200) and the temperature in the case (50).

  In addition, although the elements described in the claims and the means for solving the problems are attached with parentheses, the parentheses are attached to each component described in the embodiment. This is to simply show the correspondence with the elements, and does not necessarily indicate the elements themselves described in the embodiments. The description of the reference numerals with parentheses does not unnecessarily narrow the scope of the claims.

It is sectional drawing which shows schematic structure of the raindrop detection apparatus which concerns on 1st Embodiment. It is a flowchart which shows condensation determination. It is a schematic diagram which shows the relationship of the temperature when dew condensation does not arise. It is a schematic diagram which shows the relationship of the temperature in case dew condensation arises on a transparent plate. It is a schematic diagram which shows the relationship of the temperature in case dew condensation arises in each of a transparent plate and a lens. It is a schematic diagram for demonstrating the detection principle of lens temperature.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which the attached matter detection device according to the present invention is applied to a raindrop detection device that detects raindrops as attached matter will be described with reference to the drawings.
(First embodiment)
Based on FIGS. 1-5, the raindrop detection apparatus which concerns on this embodiment is demonstrated. The raindrop detection device 100 detects raindrops attached to the outer surface 200b of the transparent plate 200 exposed to the external environment. As shown in FIG. 1, the raindrop detection apparatus 100 includes a light emitting element 10, a light receiving element 20, a determination unit 30, a lens 40, a case 50, a first temperature sensor 60, a second temperature sensor 70, a humidity sensor 80, and a fixing member 90. Have Light is emitted from the light emitting element 10 to the transparent plate 200, and the light receiving element 20 receives the reflected light reflected there. When raindrops are not attached to the transparent plate 200, the light incident on the transparent plate 200 is totally reflected, and the totally reflected reflected light enters the light receiving element 20. However, when raindrops are attached to the transparent plate 200, light passes through the raindrops, so that the amount of reflected light reflected by the transparent plate 200 decreases. Therefore, the reflected light incident on the light receiving element 20 is also reduced. Thus, the reflected light incident on the light receiving element 20 varies depending on the presence or absence of raindrops. Therefore, the determination unit 30 determines the presence or absence of raindrops based on the electrical signal of the light receiving element 20. The transparent plate 200 according to this embodiment is a vehicle windshield, and the raindrop detection apparatus 100 is provided in the vehicle.

  The lens 40 is attached and fixed to the inner surface 200 a of the transparent plate 200 via a fixing member 90, and light via the lens 40 enters the light receiving element 20. Each of the components 10 to 40 and the humidity sensor 80 are mounted on the wiring board 51, and the case 50 functions to store the wiring board 51. The first temperature sensor 60 functions to detect the temperature of the transparent plate 200 (hereinafter referred to as glass temperature), and the second temperature sensor 70 detects the temperature in the case 50 (hereinafter referred to as case temperature). Fulfill. The humidity sensor 80 functions to detect the humidity in the case 50 (hereinafter referred to as case humidity). The determination unit 30 also functions to determine the condensation of the lens 40 based on the temperature and humidity detected by the sensors 60-80. This dew condensation determination of the lens 40 is a main characteristic point of the raindrop detection apparatus 100. Therefore, the dew condensation determination is performed after detailed explanation of each component described above.

  The light emitting element 10 irradiates light to the inner surface 200a of the transparent plate 200 isolated from the external environment. The light emitting element 10 according to the present embodiment is an LED and is mounted on the wiring board 51. The light emitting element 10 irradiates light toward the lens 40 and causes the light to enter the transparent plate 200 through the lens 40.

  The light receiving element 20 receives the reflected light emitted from the light emitting element 10 and reflected by the transparent plate 200, and converts it into an electrical signal. The light receiving element 20 according to the present embodiment is a PD, and one light receiving element 20 is provided on the wiring board 51. As described above, the reflected light incident on the light receiving element 20 varies depending on whether or not raindrops are attached to the transparent plate 200. The light receiving element 20 functions to output an electrical signal corresponding to the amount of raindrops attached to the transparent plate 200 to the determination unit 30.

  The determination unit 30 determines the lens temperature based on the raindrop determination function that determines the presence or absence of raindrops based on the electrical signal converted by the light receiving element 20, and the glass temperature and case temperature detected by the temperature sensors 60 and 70. And a condensation determination function for determining the condensation of the lens 40 based on the calculated lens temperature and the case humidity detected by the humidity sensor 80. The determination unit 30 has a threshold value, and determines the presence or absence of raindrops by comparing the threshold value with the voltage level of the electric signal of the light receiving element 20. As described above, the determination unit 30 determines the condensation of the lens 40, and varies the voltage level of the above-described threshold based on the determination result of the condensation. The light emitted from the light emitting element 10 enters the transparent plate 200 through the lens 40, and the reflected light reflected by the transparent plate 200 enters the light receiving element 20 through the lens 40. Accordingly, when condensation occurs on the light entrance / exit surface 40 a of the lens 40, the light is scattered at each of the incidence of light to the lens 40 and the emission of light from the lens 40. Therefore, even if raindrops are not attached to the transparent plate 200, the amount of reflected light reflected by the transparent plate 200 is reduced, and the amount of reflected light incident on the light receiving element 20 is reduced. For this reason, when the determination unit 30 determines that condensation has occurred in the lens 40, the threshold voltage level described above is reduced below the threshold voltage level when it has been determined that condensation has not occurred in the lens 40. .

  The determination unit 30 detects the lens temperature based on the thermal conductivity of each of the transparent plate 200, the fixing member 90, the lens 40, and air, as well as the glass temperature and the case temperature. As described above, the lens 40 is fixed to the transparent plate 200 via the fixing member 90 and provided in the case 50. Therefore, the temperature in the case 50 is transferred to the lens 40 via air, and the temperature of the external atmosphere is transferred via the transparent plate 200 and the fixing member 90. This amount of heat transfer depends not only on the temperature in the case 50 and the temperature of the external atmosphere, but also on the thermal conductivity of the member in contact with the lens 40. Therefore, the determination unit 30 calculates the lens temperature based not only on the glass temperature and the case temperature, but also on the thermal conductivity of the member in contact with the lens 40. Specifically, the determination unit 30 weights the glass temperature and the case temperature based on the thermal conductivity of each of the transparent plate 200, the fixing member 90, the lens 40, and the air, and two weighted temperatures. The intermediate value is calculated, and the intermediate value is detected as the lens temperature. The determination unit 30 corresponds to each of the raindrop determination unit and the condensation determination unit described in the claims, and has both functions.

  The lens 40 functions as a light guide lens that guides the light emitted from the light emitting element 10 to the inner surface 200 a of the transparent plate 200 and the light emitted from the light emitting element 10 and reflected by the transparent plate 200 to the light receiving element 20. And a function as a condensing lens for condensing light. The lens 40 has an entrance / exit surface 40a through which light emitted from the light emitting element 10 enters / exits, and a fixed surface 40b fixed to the transparent plate 200 via the fixing member 90. The portion having the incident surface that receives the light emitted from the light emitting element 10 in the entrance / exit surface 40a functions as the above-described light guide lens, and the portion having the exit surface from which the light reflected by the transparent plate 200 is emitted. Fulfills the above-described function as a condensing lens. As shown in FIG. 1, the lens 40 includes a light guide lens 41 having a curved surface on which light emitted from the light emitting element 10 is incident, and a condensing lens having a curved surface from which light reflected by the transparent plate 200 is emitted. 42 and a connecting portion 43 that integrally connects the lenses 41 and 42. The connecting portion 43 has a cross-sectional shape in which the long side and the short side are connected in an L shape, the end of the short side is mechanically connected to the wiring board 51, and the end of the long side is the wiring. The connector 52 is in contact with the connector 52 mounted on the substrate 51. The lenses 41 and 42 are integrally connected to the inner surface of the long side of the connecting portion 43. In FIG. 1, in order to clarify the configuration of the constituent elements 41 to 43 of the lens 40, the boundaries between the constituent elements are indicated by broken lines. The lens 40 has both functions of the light guide lens and the condenser lens described in the claims.

  The case 50 stores the components 10 to 30 and 70. As shown in FIG. 1, a connector 52 is mounted on a mounting surface 51 a on which the elements 10 and 20, the determination unit 30, and the humidity sensor 80 are mounted on the wiring board 51. The connector 52 has a terminal (not shown). The terminal is thermally connected to the wiring pattern (not shown) formed on the wiring board 51 and the transparent plate 200 via the heat conductive sheet 91. Each of the temperature sensors 10 is electrically connected.

  As shown in FIG. 1, the mounting surface 51 a of the wiring board 51 is located in the space constituted by the connector 52 and the lens 40, and the wiring board 51 and the lens 40 are each constituted by the connector 52 and the case 50. Located in. Accordingly, each of the components 10 to 30 and 70 is provided in the case 50, and the lens 40 is also provided in the case 50. With this configuration, heat is transferred from the air in the case 50 to the entrance / exit surface 40 a of the lens 40 that contacts the air in the case 50. Further, the heat of the external atmosphere is transferred to the fixed surface 40b that is in contact with the transparent plate 200 via the fixing member 90 in the lens 40. In this way, the heat of the air in the case 50 and the heat of the external atmosphere are transferred to the lens 40. Therefore, the lens temperature is determined by these two heats, and the amount of heat is determined by the thermal conductivity and the like.

  The first temperature sensor 60 detects the glass temperature, and is attached and fixed to the inner surface 200 a of the transparent plate 200 via the heat conductive sheet 91. With this configuration, the heat of the external atmosphere is transferred to the first temperature sensor 60 through the transparent plate 200 and the heat conductive sheet 91. Since the temperature (glass temperature) of the transparent plate 200 is considered to be the external ambient temperature, the glass temperature detected by the first temperature sensor 60 corresponds to the external ambient temperature. The first temperature sensor 60 according to the present embodiment is a thermistor.

  The second temperature sensor 70 detects the case temperature, is mounted on the wiring board 51, and is located in the case 50. Since it is located inside the case 50 in this way, the case temperature is detected by the second temperature sensor 70. The second temperature sensor 70 according to the present embodiment is a thermistor.

  The humidity sensor 80 detects the case humidity, is mounted on the wiring board 51, and is located in the case 50. Since it is located in the case 50 as described above, the humidity of the case is detected by the humidity sensor 80. The humidity sensor 80 according to the present embodiment detects humidity according to the amount of change in capacitance.

  The fixing member 90 thermally couples the lens 40 while mounting the lens 40 on the transparent plate 200. The fixing member 90 is a substance having a transmittance equivalent to that of the lens 40 and the transparent plate 200. Unlike this configuration, even in a configuration in which the fixing member 90 is not provided between the lens 40 and the transparent plate 200, the angle of the reflected light reflected at the interface between the outer surface 200b of the transparent plate 200 and the air. And the amount does not change.

  Next, the dew condensation determination of the raindrop detection apparatus 100 described in the present embodiment will be described with reference to FIGS. As illustrated in FIG. 2, the determination unit 30 receives signals from the sensors 60 to 80. The determination unit 30 stores a map in which a physical quantity corresponding to the voltage level of each signal is stored, and selects a physical quantity corresponding to the input voltage. By doing so, the determination unit 30 detects the glass temperature, the case temperature, and the case humidity. The above is a detection process (step S10).

  After the detection step, the determination unit 30 calculates the lens temperature of the lens 40 based on the detected glass temperature and case temperature. The determination unit 30 calculates the absolute humidity of the case 50 based on the case humidity (relative humidity). The above is the first calculation step (step S20).

  After the first calculation step, the determination unit 30 calculates the dew point temperature of the lens 40 based on the lens temperature and the absolute humidity. The above is the second calculation step (step S30).

  After the second calculation step, the determination unit 30 compares the lens temperature with the dew point temperature. As shown in FIG. 3, when the dew point temperature indicated by a broken line is lower than the glass temperature indicated by ◯, the lens temperature indicated by △, and the case temperature indicated by □, the determination unit 30 determines that the transparent plate 200 It is determined that no condensation occurs in each of the lenses 40. In contrast, as shown in FIG. 4, when the dew point temperature is higher than the glass temperature and lower than the lens temperature and the case temperature, the determination unit 30 determines that condensation has occurred on the inner surface 200 a of the transparent plate 200. . As shown in FIG. 5, when the dew point temperature is higher than the glass temperature and the lens temperature and lower than the case temperature, the determination unit 30 forms condensation on the inner surface 200a of the transparent plate 200 and the light entrance / exit surface 40a of the lens 40, respectively. Is determined (step S40 to step S60). Thus, the determination unit 30 determines not only the condensation of the lens 40 but also the condensation of the transparent plate 200.

  FIG. 2 shows only the relationship between the lens temperature and the dew point temperature. In step S40, the determination unit 30 compares the lens temperature with the dew point temperature. When the dew point temperature is lower than the lens temperature, the determination unit 30 determines that condensation has occurred in the lens 40 (step S50). On the other hand, when the dew point temperature is higher than the lens temperature, the determination unit 30 determines that no condensation has occurred on the lens 40 (step S60).

  Next, the effect of the raindrop detection apparatus 100 according to this embodiment will be described. As described above, the determination unit 30 detects the lens temperature based on the glass temperature and the case temperature, and determines the condensation of the lens 40 based on the lens temperature and the case humidity. According to this, the dew condensation of the lens 40 can be detected with higher accuracy than the configuration in which the dew condensation of the lens 40 is determined by regarding the glass temperature as the lens temperature. As a result, a drop in raindrop detection accuracy is suppressed.

  The determination unit 30 detects the lens temperature based on the thermal conductivity of each of the transparent plate 200, the fixing member 90, the lens 40, and air, as well as the glass temperature and the case temperature. According to this, it is possible to detect the lens temperature with higher accuracy than a configuration in which the lens temperature is simply detected based on the glass temperature and the case temperature.

  The determination unit 30 has a threshold value, and determines the presence or absence of raindrops by comparing the threshold value with the voltage level of the electric signal of the light receiving element 20. The surface of the transparent plate 200 is not always clean. Therefore, based on a comparison between the reference signal and a signal actually output from the light receiving element 20, using a signal output from the light receiving element 20 when no raindrops are simply attached to the outer surface 200 b of the transparent plate 200 as a reference signal. When the raindrop is determined, there is a possibility that it is erroneously determined that there is a raindrop although the raindrop to be detected does not adhere to the transparent plate 200. Therefore, as described above, a threshold value slightly lower (about 1%) than the reference signal is prepared, and the threshold value is compared with the signal actually output from the light receiving element 20. By doing so, erroneous determination of raindrops is suppressed.

  The determination unit 30 varies the voltage level of the above-described threshold based on the determination result of dew condensation. More specifically, if the determination unit 30 determines that condensation has occurred in the lens 40, the determination unit 30 lowers the voltage level below a threshold value when it is determined that condensation has not occurred in the lens 40. Thereby, dew condensation occurs on the entrance / exit surface 40a of the lens 40, and even if the reflected light incident on the light receiving element 20 is reduced due to the dew condensation, a decrease in raindrop detection accuracy is suppressed. The determination unit 30 may determine the condensation of each of the lens 40 and the transparent plate 200 and adjust the threshold voltage level based on the determination results.

  The determination unit 30 calculates the lens temperature based on the raindrop determination function that determines the presence or absence of raindrops based on the electrical signal of the light receiving element 20, the glass temperature, and the case temperature, and calculates the lens temperature and the case humidity. And a dew condensation determination function for determining dew condensation of the lens 40 based on the dew condensation function. According to this, an increase in the number of parts is suppressed compared to a configuration including a raindrop determination unit having a raindrop determination function and a condensation determination unit having a condensation determination function, in which the determination unit 30 is a separate body.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In this embodiment, the structural example which detects a raindrop as a deposit | attachment was shown. However, the deposit is not limited to the above example, and for example, ice can be detected.

  In this embodiment, the example in which the light emitting element 10 is LED was shown. However, the light emitting element 10 may be any element that emits light, and is not limited to the above example.

  In the present embodiment, an example in which one light emitting element 10 is mounted on the wiring board 51 is shown. However, the number of the light emitting elements 10 is not limited to the above example, and may be plural.

  In the present embodiment, an example in which the light receiving element 20 is a PD is shown. However, the light receiving element 20 may be any element that converts light into an electrical signal, and is not limited to the above example.

  In the present embodiment, an example in which one light receiving element 20 is mounted on the wiring board 51 is shown. However, the number of light receiving elements 20 is not limited to the above example, and may be plural.

  In this embodiment, the determination unit 30 calculates the lens temperature based on the raindrop determination function that determines the presence or absence of raindrops based on the electrical signal of the light receiving element 20, the glass temperature, and the case temperature, and the calculated lens temperature The example which has the dew condensation determination function which determines dew condensation of the lens 40 based on case humidity was shown. However, the structure which has the raindrop determination part which has the raindrop determination function in which the determination part 30 is a different body, and the dew condensation determination part which has a dew condensation determination function is also employable. The raindrop determination unit described above corresponds to the deposit determination unit described in the claims.

  In this embodiment, the determination part 30 showed the example which fluctuates the voltage level of a threshold value based on the determination result of the dew condensation of the lens 40. However, the determination unit 30 may detect raindrops with a constant threshold value regardless of the determination result of condensation.

  The determination part 30 showed the example which detects lens temperature not only based on glass temperature and case temperature but based on the thermal conductivity of each of the transparent plate 200, the fixing member 90, the lens 40, and air. However, the determination unit 30 may detect the lens temperature using only the glass temperature and the case temperature. In this case, the determination unit 30 may detect an intermediate value between the two temperatures as the lens temperature.

  Unlike the above configuration, the determination unit 30 may detect the glass temperature based not only on the glass temperature, the case temperature, and the thermal conductivity, but also on the thickness of the object and the contact area. FIG. 6 is a cross-sectional view for explaining the detection, but the fixing member 90 is omitted here for the sake of simplicity.

When the temperature of the air in the case 50 is higher than that of the external atmosphere, the heat of ΔQin flows from the air of the case 50 into the lens 40 as indicated by the white arrow, and the heat of ΔQout enters the external atmosphere via the transparent plate 200. leak. At this time, the lens 40 is thermally changed by ΔQ. Therefore, the following formula is established.

Further, the thickness of the transparent plate 200 is L1, the contact area with the lens 40 is A ₁ , the thermal conductivity is κ ₁ , the average thickness of the lens 40 is L ₂ , and the contact area with the air in the case 50 is _Assuming A ₂ , the thermal conductivity κ ₂ , the temperature of the air in the case 50 T _H , the temperature of the external atmosphere T _L , the lens temperature T _M , and the minute time Δt, according to Fourier's law, It is represented by the following formula.

Here, when both sides are divided by Δt, the left side is expressed as ΔQ / Δt. This shows a change in the amount of heat, but in a steady state, the change in the amount of heat of the lens 40 is zero. Therefore, ΔQ / Δt is zero, and Equation 2 is expressed by the following equation.

Solving for the lens temperature T _M, represented by the following formula.

Here, when α = (κ ₁ A ₁ ) / L ₁ and β = (κ ₂ A ₂ ) / L ₂ , Equation 4 is expressed by the following formula.

Further, when expressed as γ = β / α, Formula 5 is expressed by the following formula.

Here, γ is a value depending on the thermal conductivity, contact area, and thickness, but this is a specified value and is a constant value. The determination unit 30 holds this γ and Equation 6. The determination unit 30 calculates the lens temperature T _M by substituting the glass temperature T _L , the case temperature T _H , and the constant γ into Equation 6. Note that the value of γ may be obtained by repeating experiments based on Equation 6, or the value of γ may not be obtained based on the prescribed values of thermal conductivity, contact area, thickness, and the like. .

  The example in which the lens 40 has a function as a light guide lens and a function as a condenser lens is shown. However, the lens 40 may not have both functions. In addition, a configuration in which the lens 40 includes a separate light guide lens and a condensing lens may be employed.

  In the present embodiment, an example in which the first temperature sensor 60 is attached and fixed to the transparent plate 200 via the heat conductive sheet 91 is shown. However, the heat conductive sheet 91 may not be provided, and can be appropriately employed as long as the first temperature sensor 60 is attached and fixed to the transparent plate 200.

  Although not specifically described in the present embodiment, the determination result of the determination unit 30 is output to a CPU (not shown) mounted on the vehicle. The CPU controls the wiper based on the raindrop determination, and controls the air conditioner installed in the vehicle based on the condensation determination of the transparent plate 200. Specifically, the CPU drives the wiper when it is determined that there are raindrops, and stops driving the wiper when it is determined that there are no raindrops. The CPU performs fail control on the wiper when it is determined that the lens 40 has dew condensation. When it is determined that condensation occurs on the transparent plate 200, the CPU increases the temperature of the wind blown on the transparent plate 200 in order to eliminate condensation.

DESCRIPTION OF SYMBOLS 10 ... Light emitting element, 20 ... Light receiving element, 30 ... Determination part, 41 ... Light guide lens, 50 ... Case, 60 ... 1st temperature sensor, 70 ... 2nd Temperature sensor 80 ... Humidity sensor 100 ... Raindrop detection device 200 ... Transparent plate 200a ... Inner surface 200b ... Outer surface

Claims (9)

A deposit detection device for detecting deposits attached to the outer surface (200b) of the transparent plate (200) exposed to the external environment,
A light emitting element (10) for irradiating light to the inner surface (200a) of the transparent plate isolated from the external environment;
A light receiving element (20) for receiving light emitted from the light emitting element and reflected by the transparent plate and converting it into an electrical signal;
An adhering matter determination unit (30) for determining the presence or absence of the adhering matter based on the electrical signal converted by the light receiving element;
A light guide lens (41) fixed to the inner surface of the transparent plate and guiding light emitted from the light emitting element to the inner surface of the transparent plate;
A case (50) for housing each of the light emitting element, the light receiving element, and the light guide lens;
A first temperature sensor (60) for detecting the temperature of the transparent plate;
A second temperature sensor (70) for detecting the temperature in the case;
A humidity sensor (80) for detecting the humidity in the case;
The lens temperature of the light guide lens is detected based on the temperature of the transparent plate detected by the first temperature sensor and the temperature in the case detected by the second temperature sensor, and the detected lens temperature And a dew condensation determination unit (30) for determining dew condensation of the light guide lens based on the humidity in the case detected by the humidity sensor. A fixing member (90) for fixing the light guide lens to the inner surface of the transparent plate;
The condensation determination unit determines the lens temperature based not only on the temperature of the transparent plate and the temperature in the case, but also on the thermal conductivity of the transparent plate, the fixing member, the light guide lens, and air. The deposit detection apparatus according to claim 1, wherein the deposit detection apparatus detects the deposit.   The dew condensation determination unit performs weighting by weighting the temperature of the transparent plate and the temperature in the case based on the thermal conductivity of each of the transparent plate, the fixing member, the light guide lens, and air. The adhering matter detection apparatus according to claim 2, wherein an intermediate value between the two temperatures is calculated, and the intermediate value is detected as the lens temperature.   The adhering matter detection device according to any one of claims 1 to 3, further comprising a heat conductive sheet (91) that thermally connects the first temperature sensor and the inner surface of the transparent plate.   The said adhering matter determination part determines the presence or absence of the said adhering matter based not only on the electrical signal of the said light receiving element but the determination result of the said dew condensation determination part. The deposit | attachment detection apparatus of description. The adhering matter determination unit has a threshold value, and determines the presence or absence of the adhering matter by comparing the threshold value with a voltage level of an electric signal of the light receiving element.
6. The adhering matter detection apparatus according to claim 5, wherein the adhering matter determining unit varies a voltage level of a threshold based on a determination result of the dew condensation determining unit.   It has a condensing lens (42) which condenses the light emitted from the light emitting element, led to the inner surface of the transparent plate by the light guide lens, and reflected by the transparent plate to the light receiving element. The adhering matter detection apparatus according to any one of claims 1 to 6.   The attachment according to any one of claims 1 to 7, wherein the attached matter determination unit functions as the condensation determination unit, and the attached matter determination unit and the condensation determination unit are the same member. Kimono detection device. A wiring board (51) on which each of the light emitting element, the light receiving element, the adhering matter determination unit, the dew condensation determination unit, the second temperature sensor, and the humidity sensor is mounted;
The adhering matter detection apparatus according to claim 1, wherein the wiring board is accommodated in the case.

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