JP2009300259A - Water level detector, vapor collecting device, and heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water level detector for detecting a water level by a water tank, to provide a vapor collecting device using the water level detector, and to provide a heating cooker having the vapor collecting device. <P>SOLUTION: The heating cooker 100 includes: the water tank 7a; an emission section 15a for emitting light toward an incidence surface 19-1; a light reception section 16a for generating a signal according to the quantity of light received through a reflection transmission section 20-1; and a control section 11 for determining the amount of water stored in the water tank 7a according to a signal from the light reception section 16a. The water tank 7a includes a recess 14a recessed toward the inside of the side in the water tank 7a. The recess 14a includes inclination sections inclined toward the inside of the water tank 7a; at least a partial plate thickness of the side of the water tank 7a for composing the inclination section is made different from that of other parts on the side of the water tank 7a; and the inclination sections are set to be an incidence plane 19-1 and the reflection transmission section 20-1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water level detection device for detecting a water level in a water tank, a steam recovery device using the water level detection device, and a cooking device equipped with the steam recovery device.

  2. Description of the Related Art Conventionally, there is a rice cooker that condenses steam by introducing it into a container containing cooling water and dissipating it into the cooling water. As such, “a frame, a storage case provided in the frame, an inner pot provided so as to be stored in the storage case, an openable / closable lid covering the inner pot, and one of the frames. A water container provided on the side, and a steam passage communicating the inside of the inner pot and the water container, and the steam generated from the inner pot is introduced into the water container through the steam passage and brought into contact with water. An electric rice cooker that liquefies and then has been proposed (see, for example, Patent Document 1).

  In addition, there is a liquid presence / absence detection device that detects the presence / absence of a liquid such as water stored in a water tank such as a water container. As such, “a device for detecting the presence or absence of liquid in a tank, in which a prism portion is integrally formed in a transparent tank, and the critical angle of total reflection determined by the refractive index of the liquid and the tank member. And the light from the light source is incident on the prism unit at an angle between two critical angles of the total reflection determined by the refractive index of the tank member and air, and the reflected light is detected to detect the reflected light. An apparatus for detecting the presence or absence of liquid in a tank configured to detect the presence or absence of liquid in the tank has been proposed (see, for example, Patent Document 2).

  Furthermore, there is an ink tank provided with an inexpensive ink remaining amount detection unit that can handle any color ink. As such, “in an ink tank filled with ink, an optical ink detection unit formed by a light transmissive member and having an interface with the ink having a predetermined angle with respect to the detection optical path, An “ink tank formed of the same material as the ink tank for the ink detection unit” has been proposed (for example, see Patent Document 3). That is, if the technique described in Patent Document 2 or Patent Document 3 is applied to the technique described in Patent Document 1, the water level stored in the tank accommodated in the electric rice cooker can be detected. become able to.

JP-A-10-192134 (2nd page, 3rd page, FIG. 1) JP 7-311072 A (3rd page, FIG. 5) JP-A-7-218321 (page 3, FIG. 1)

  When a device such as the liquid presence / absence detection device described in Patent Document 2 is applied to a water level detection device, a prism is provided on the side of the water tank to detect the water level, or a light emitting portion or a light receiving portion is sandwiched between corners. Part must be placed. Usually, a water tank accommodated in a heating cooker is manufactured by pouring a resin such as plastic into a large quantity and obtaining a product having the same shape in large quantities. Even if such a generally inexpensive manufacturing method is used to form a water tank having a prism, an accurate water tank shape may not be obtained.

  This is because the prism needs to be twice as thick as the thickness of the side surface other than the prism portion of the water tank. In other words, when a prism is formed on a part of the side surface of the water tank, only a part of the water tank that becomes the prism must be thick, and the resin in that part contracts, and the molding surface undulates. This is because an accurate shape cannot be obtained. In addition, since an accurate water tank shape cannot be obtained, there is a problem that the surface accuracy required for the optical reflection / transmission surface of the prism formation surface cannot be obtained. Note that a similar problem occurs when a prism is formed in a part of the ink tank described in Patent Document 3.

  In addition, in the case of detecting the water level in the water tank by sandwiching the corner of the side surface of the water tank with a uniform thickness between the light emitting part and the light receiving part, try to reduce the outer shape of the heating cooker that houses the water tank. Then, a space for arranging the light emitting unit and the light receiving unit is required, and it may be impossible to reduce the size. This is because a corner portion for detection must be added to the side surface of the water tank in order to arrange the light emitting unit and the light receiving unit, and the shape of the side surface of the water tank is greatly bent. Moreover, when the water tank of such a shape is accommodated in a heating cooker, it is inconvenient to attach and detach the water tank, and the burden required for cleaning and the like is increased. Furthermore, there is a possibility of giving a sense of incongruity on the design (design) of the cooking device.

  The present invention has been made to solve the above-described problems, and includes a water level detection device that realizes water level detection using a water tank, a steam recovery device using the water level detection device, and the steam recovery device. It aims at providing the cooking device provided with.

  The water level detection device according to the present invention emits light toward the reflection / transmission part, a water tank at least part of which is constituted by a reflection / transmission part in which the amount of reflection and transmission of light changes depending on the presence or absence of liquid. A light emitting unit, a light receiving unit that generates a signal according to the amount of light received through the reflection / transmission unit, and a water amount determination unit that determines the amount of water stored in the water tank from the signal of the light receiving unit, The water tank has a recess that is recessed toward the inside of the side surface of the water tank, the recess has an inclined portion that is inclined toward the inside of the water tank, and the water tank that constitutes the inclined portion The thickness of at least a part of the side surface is different from the thickness of the other portion of the side surface of the water tank, and the inclined portion is the reflection / transmission portion.

  The water level detection device according to the present invention emits light toward the reflection / transmission part, a water tank at least part of which is constituted by a reflection / transmission part in which the amount of reflection and transmission of light changes depending on the presence or absence of liquid. A light emitting unit, a light receiving unit that generates a signal according to the amount of light received through the reflection / transmission unit, and a water amount determination unit that determines the amount of water stored in the water tank from the signal of the light receiving unit, Two ribs projecting into the water tank are provided in parallel on a part of the inner wall surface of the water tank, and each tip portion of the rib has an inner side of the two parallel ribs and an outer side thereof. It is formed in the longer inclined surface, The said inclined surface is used as the said reflective transmission part, It is characterized by the above-mentioned.

  The water level detection device according to the present invention emits light toward the reflection / transmission part, a water tank at least part of which is constituted by a reflection / transmission part in which the amount of reflection and transmission of light changes depending on the presence or absence of liquid. A light emitting unit, a light receiving unit that generates a signal according to the amount of light received through the reflection / transmission unit, and a water amount determination unit that determines the amount of water stored in the water tank from the signal of the light receiving unit, A rib having a predetermined height rising from the bottom to the top of the water tank is provided on a part of the inner wall of the water tank, and the upper end of the rib is inclined downward from the inner wall of the water tank to the inside of the tank. The inclined surface is used as the reflection / transmission part.

  The water level detection device according to the present invention emits light toward the reflection / transmission part, a water tank at least part of which is constituted by a reflection / transmission part in which the amount of reflection and transmission of light changes depending on the presence or absence of liquid. A light emitting unit, a reflection plate provided in the water tank and reflecting light emitted from the light emitting unit, and a light receiving unit that generates a signal corresponding to the amount of light reflected by the reflection plate and received through the reflection / transmission unit. And a water amount determination unit that determines the amount of water stored in the water tank from a signal of the light receiving unit, and the light emitting unit is disposed to face the reflector plate through a side surface of the water tank The light receiving unit can receive light from the light emitting unit reflected by the reflecting plate when water at a predetermined water level is not stored in the tank, and water at a predetermined water level is received in the tank. When stored, water A position where the light does not reach from the light emitting portion by total reflection, characterized in that it is located on the side outside of the water tank.

  The steam recovery apparatus according to the present invention includes the above-described water level detection device, a steam guide path that guides the generated steam to the water tank, and when a predetermined water level is detected by the water level detection device, And a control unit for informing so as to promote the treatment of water.

  A heating cooker according to the present invention includes the steam recovery device described above.

  According to the water level detection device of the present invention, it is possible to manufacture a water tank having a reflection / transmission portion at low cost by using a general mold, and to accurately detect the water level in the water tank. it can. In addition, the shape of the water tank can be formed relatively simply, improving the handleability such as design, cleaning, maintenance, and ease of carrying.

  Since the steam recovery apparatus according to the present invention includes the above-described water level detection device, the effect of the water level detection device is exhibited. Moreover, according to the heating cooker which concerns on this invention, since said steam recovery apparatus is provided, there exists an effect which this heating cooker has.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a side view showing a state in which the internal configuration of heating cooker 100 according to Embodiment 1 of the present invention is viewed from the side. Based on FIG. 1, the structure and operation | movement of the heating cooker 100 are demonstrated. The heating cooker 100 cooks the heated object by heating the inner pot containing the object to be heated (rice, water, etc.) with heating means such as an induction heating coil, and collects the steam generated at this time in a water tank. To do. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

  The cooking device 100 is covered with a lid 3 so that the top surface thereof can be freely opened and closed, and a main body 1 in which the rice cooker 2 and the water tank 7 are detachably stored, and a heated object to be cooked are placed. A rice cooker 2 that is detachably stored in the lid, a lid 3 that covers the upper surface of the main body 1 through a hinge portion (not shown) pivotally supported on the upper rear portion of the main body 1, and the inside of the lid 3 Is attached detachably and covers the upper opening of the rice cooker 2 so as to be openable and closable, the heating body 5 such as an induction heating coil for heating the rice cooker 2, and a predetermined amount of water are stored, and steam is stored. It is composed of a water tank 7 that recovers steam by cooling and condensing, and a steam pipe 6 that connects the rice cooker 2 and the water tank 7 and conducts the steam. The main body 1 and the lid 3 constitute the outer shape of the heating cooker 100.

  The main body 1 has an opening on the upper surface, and accommodates the heating body 5 in addition to the rice cooker 2 and the water tank 7. The upper surface of the rice cooker 2 is formed with an opening, and the opening is covered with an inner lid 4 so that the inside is sealed. The lid 3 covers the upper surface of the main body 1 so as to be freely opened and closed when a user operates an open / close switch or the like (not shown). In addition, a vapor pipe 6 is detachably attached to the lid 3. The inner lid 4 closes the inside of the rice cooker 2 by closing the upper opening of the rice cooker 2 during cooking. A heating body is arrange | positioned at the bottom face side of the rice cooker 2, and heats the rice cooker 2 by carrying out energization control, and it heats and cooks it.

  The steam pipe 6 is connected to a steam introduction pipe 13 having one end (the right end portion on the paper surface) inserted into the substantially central portion of the inner lid 4 and the other end (the left end portion on the paper surface) inserted into the water tank 7. The hook 2 and the water tank 7 are connected. The water tank 7 stores a predetermined amount of water therein, and cools and collects the steam circulated through the steam pipe 6. The water tank 7 is stored beside the position where the rice cooker 2 is stored. The water tank 7 has an upper surface formed with an opening, and has a tank lid 12 that detachably covers the opening. Further, a vapor introduction pipe 13 is fixed to the tank lid 12 so as to penetrate therethrough.

  One end (upper end) of the steam introduction pipe 13 is detachably connected to the steam pipe 6 and the other end (lower end) thereof is located inside the water tank 7 in a state where the tank lid 12 is attached to the water tank 7. It is like that. That is, the steam pipe 6 is separated from the steam introduction pipe 13 when the lid 3 is opened, and the steam pipe 6 is connected to the steam introduction pipe 13 when the lid 3 is closed. The steam pipe 6 and the steam introduction pipe 13 function as a steam guide path that guides the steam generated during rice cooking into the water tank 7, and the water tank 7 uses the water that has flowed in via the steam introduction pipe 13 as water. Condensation is performed and the recovered water 9 is stored, and these constitute a steam recovery device.

  Further, in the main body 1, a control unit 11 that performs energization control of the heating body 5 and a water level detection device 8 that detects the water level of the recovered water 9 stored in the water tank 7 are provided. The control unit 11 is disposed on the bottom surface of the main body 1 and below the heating body 5, and controls energization to the heating body 5 based on a signal output from the water level detection device 8. The water level detection device 8 is provided on the side surface of the water tank 7 and detects whether or not the water level of the recovered water 9 in the water tank 7 is equal to or higher than a preset water level 10. When detecting that the water level of the recovered water 9 is equal to or higher than the water level 10, the water level detection device 8 inverts the signal output to the control unit 11 from the High level to the Low level and outputs it.

Here, a specific control operation of the control unit 11 will be described.
If the control part 11 detects the start of rice cooking through user operation, such as a switch provided in the upper surface of the cover body 3, it will determine whether the signal from the water level detection apparatus 8 is a High level or a Low level. When the signal from the water level detection device 8 is at a high level, the control unit 11 starts cooking rice according to a user operation. On the other hand, when the signal from the water level detection device 8 is at the low level, the control unit 11 determines that the recovered water 9 in the water tank 7 has reached the water level 10. And the control part 11 displays the message which prompts the rice cooking stop and drainage of the collection | recovery water 9 on the display part comprised, for example with the lamp | ramp provided on the upper surface of the cover body 3, a liquid crystal display etc., and buzzer sound Etc. to inform the user.

  That is, the control unit 11 functions as a water amount determination unit that determines the amount of water stored in the water tank 7, and when it is determined that the recovered water 9 in the water tank 7 exceeds the water level 10. Since there is a high possibility that condensation will occur around the main body 1 and the lid 3 or the recovered water 9 will overflow, this will be notified to the user either visually or audibly or both. It has become. If dew condensation occurs around the main body 1 or the lid 3 or the recovered water 9 overflows, safety and cleanliness are impaired, and internal devices (particularly the control unit 11) are adversely affected. Is likely to be. Therefore, in order to prevent such a situation, the user is notified.

  Moreover, the control part 11 determines whether the signal from the water level detection apparatus 8 is inverted to the Low level at the end of rice cooking. When the signal from the water level detection device 8 is inverted to the Low level, the control unit 11 displays a message for prompting the drainage of the recovered water 9 on the display unit provided on the upper surface of the lid 3, for example. In addition, the user is notified with a buzzer sound or the like. In addition, it may replace with a buzzer sound and you may make it alert | report to a user using the audio | voice message by a speaker.

  In the heating cooker 100 configured as described above, the rice cooker 2 containing a heated object such as rice and water is housed in the main body 1, the lid 3 is closed, and the rice cooking start switch is operated. Then, the control part 11 determines whether the signal from the water level detection apparatus 8 is a High level. When the input signal from the water level detection device 8 is at a high level, the control unit 11 starts energizing the heating body 5 and transmits heat to the object to be heated via the rice cooker 2. Steam is generated from the object to be heated in the rice cooker 2 by this heating operation.

The steam generated in the rice cooker 2 is led into the water tank 7 through the steam pipe 6 and the steam introduction pipe 13, and comes into contact with the water injected into the water tank 7, resulting in a decrease in temperature and condensation. It becomes water and is stored as recovered water 9. Although it depends on the amount of cooked rice, the amount of water collected by one cooked rice is about 50 to 100 mL. For example, when the bottom of the water tank 7 is a rectangle of 20 cm × 5 cm and the area is 100 cm ² , the water level of the recovered water 9 rises by about 0.5 to 1 cm by one rice cooking. .

  On the other hand, when the start of cooking rice is detected and the signal from the water level detection device 8 is at a low level, the control unit 11 determines that the recovered water 9 in the water tank 7 has reached the upper limit water level 10. The user is notified of the rice cooking stoppage and the urge to drain the recovered water 9. Moreover, the control part 11 determines whether the signal from the water level detection apparatus 8 is inverted to the Low level at the end of rice cooking. When the signal from the water level detection device 8 is inverted to the low level at the end of rice cooking, the control unit 11 determines that the recovered water 9 in the water tank 7 has reached the upper limit water level 10, and the recovered water 9 The user is notified of the drainage prompt. This is because it can be determined that the water level of the recovered water 9 has reached the water level 10 by repeating cooking. Note that the high level and low level of the signal from the water level detection device 8 may be mutually inverted signals.

  According to the heating cooker 100 according to the first embodiment, steam generated during rice cooking can be collected in the water tank 7, and the steam is not released to the outside. Further, when it is detected through the water level detection device 8 that the recovered water 9 has reached the water level 10 at the start of rice cooking, the user is prompted to drain the recovered water 9 and the rice cooking stop is displayed. When it is detected through the water level detection device 8 that it has reached 10, the user is encouraged to drain the recovered water 9, so that the occurrence of condensation around the main body 1 and the lid 3 can be suppressed. Furthermore, it is possible to prevent the recovered water 9 in the water tank 7 from overflowing, and it is possible to obtain a steam recovery device and a heating cooker 100 with good maintainability.

Here, a specific mechanism for detecting the water level in the water tank 7 will be described.
FIG. 2 is a perspective view showing the external shape of a water tank 7 a which is an example of the water tank 7. FIG. 3 is an explanatory diagram for explaining the water tank 7a and the light emitting and receiving unit. Based on FIG.2 and FIG.3, the specific mechanism of the water level detection in the water tank 7 is demonstrated with the arrangement | positioning relationship and operation | movement of the water tank 7a and a light emitting / receiving element. In FIG. 3, the state which looked at the water tank 7a and the light emitting / receiving part from three directions is shown, respectively, and FIG. 3 (a) is a plan view showing the state where the water tank 7a and the light emitting / receiving part are seen from above. FIG. 3B is a side view showing the state of the water tank 7a and the light emitting / receiving section viewed from the lateral side of the water tank 7a, and FIG. 3C is the water tank 7a and the light emitting / receiving section of the water tank 7a. The side view which shows the state seen from the longitudinal direction side is shown, respectively. In FIG. 3, the optical path of light emitted from the light emitting unit 15a and received by the light receiving unit 16a is indicated by arrows (solid line arrows and broken line arrows).

  The water tank 7a shown in FIGS. 2 and 3 has the same function as the water tank 7 shown in FIG. The water tank 7a is made of a material that transmits light (polystyrene or the like). A concave portion 14a is formed on the side surface of the water tank 7a (one side surface in the longitudinal direction of the water tank 7a). The recess 14a is formed so that a part of one side surface in the longitudinal direction of the water tank 7a becomes a groove having a predetermined depth along the height direction of the water tank 7a. The recess 14a has two tank outer inclined surfaces (incident surfaces) and two tank inner inclined surfaces (reflection / transmission portions).

  The light emitting portion 15a side of the tank outer inclined surface is the incident surface 19a-1, the light receiving portion 16a side of the tank outer inclined surface is the incident surface 19a-2, and the light emitting portion 15a side of the tank inner inclined surface is the reflection / transmission surface 20a. -1 and the light receiving part 16a side of the inclined surface inside the tank is shown as a reflection / transmission surface 20a-2. The incident surface 19a-2 is formed at a symmetrical position of the incident surface 19a-1 with the center line in the height direction of the recess 14a as an axis, and the reflection / transmission surface 20a-2 is a center line in the height direction of the recess 14a. Is formed at a symmetrical position of the reflection / transmission surface 20a-1. In the following description, the incident surface and the reflection / transmission surface may be collectively referred to as an inclined portion of the recess 14a.

  Moreover, as shown in FIG. 3, the light emitting part 15a and the light receiving part 16a, which are light emitting and receiving parts, are arranged substantially at right angles to the longitudinal side surface of the water tank 7a. The light emitting unit 15a, the light receiving unit 16a, and the water tank 7a constitute a water level detection device. Moreover, as shown in FIG.3 (b), the light emission part 15a and the light-receiving part 16a are arrange | positioned on the extension line | wire of the water level 10 of the water tank 7a. As shown in FIG. 3A, when the position corresponding to the water level 10 in the water tank 7a is air, that is, when the recovered water 9 is not stored up to the water level 10, the optical path becomes a solid line arrow 17, and the recovered water 9 Is stored in excess of the water level 10, the optical path becomes a dashed arrow 18. The solid line arrow 17 corresponds to the arrow in FIG.

  That is, when the recovered water 9 is not stored up to the water level 10, the light emitted from the light emitting element which is a constituent element of the light emitting unit 15a passes through the incident surface 19a-1 as shown by the solid line arrow 17, and reaches the tank wall surface. Proceeds toward the inside of the tank, is reflected by the reflection / transmission surface 20a-1, travels along the tank wall surface along the tank wall surface direction, is reflected by the reflection / transmission surface 20a-2, and passes through the tank wall surface toward the outside of the tank. The light travels toward the light receiving portion 16a through the incident surface 19a-2. On the other hand, when the recovered water 9 is stored up to the water level 10, the light emitted from the light emitting element which is a constituent element of the light emitting unit 15a passes through the incident surface 19a-1 as shown by the broken line arrow 18, and reaches the tank. It proceeds toward the inside of the wall toward the inside of the tank and proceeds so as to pass through the reflection / transmission surface 20a-1 and toward the inside of the tank.

Here, a more specific operation of the water level detection device will be described.
FIG. 4 is an enlarged plan view showing a part of the water tank 7a in an enlarged manner. Based on FIG. 4, detailed operation | movement of the light emission part 15a and the light-receiving part 16a which comprise a water level detection apparatus is demonstrated. FIG. 4 illustrates a part of the water tank 7a, that is, the incident surface 19a-1 and the reflection / transmission surface 20a-1 on the light emitting portion 15a side of the recess 14a, together with the optical path of light. In FIG. 4, the optical path of the light emitted from the light emitting section 15a is indicated by four solid arrows (arrows 17a to 17c and 18c). Further, FIG. 4 shows the water tank 7a together with various dimensions. The dimensions of the water tank 7a will be described in detail later.

  As shown in FIG. 4, the light from the light emitting portion 15a passes through the optical path indicated by the arrow 17a, is refracted and transmitted through the incident surface 19a-1, enters the tank wall surface, and passes through the optical path indicated by the arrow 17b. To the reflection / transmission surface 20a-1. Then, when the recovered water 9 is not stored up to the water level 10, it is reflected by the reflection / transmission surface 20a-1 and advances along the tank wall surface along the tank wall surface as indicated by the arrow 17 so that the recovered water 9 When the water level 10 is stored, the light is refracted and transmitted by the reflection / transmission surface 20a-1 and proceeds toward the inside of the water tank 7a as shown by an optical path indicated by an arrow 18c.

FIG. 5 is an explanatory diagram for explaining a mechanism of light reflection / transmission. FIG. 6 is a characteristic diagram showing the correlation between the incident angle of light and the reflectance. Based on FIG. 5 and FIG. 6, the principle regarding reflection and refraction used in the first embodiment will be described. In the first embodiment, the refractive index n _{1 of} air is 1.00, the refractive index n ₃ of water is 1.33, and the refractive index n _{2 of} polystyrene, which is an example of the constituent material of the water tank 7a, is 1.59. (See FIG. 4). If the water tank 7a is air, the refractive index n ₃ inside the tank is 1.00. In addition, Snell's law regarding refraction and Fresnel's formula regarding reflection / transmission are as follows.

Consider the case where light is incident, reflected, and refracted between medium 1 (n ₁ ) and medium 2 (n ₂ ) as shown in FIG.
here,
n ₁ : Refractive index of medium 1 (incident side) n ₂ : Refractive index of medium 2 (transmitting side) θ ₁ : Incident angle θ ₂ : Refraction angle θ ₃ : Reflection angle From Snell's law,
(1) θ ₁ = θ ₃ (incident angle and reflection angle are equal)
(2) n ₁ × sin θ ₁ = n ₂ × sin θ ₂
(Or sin θ ₁ / sin θ ₂ = n ₂ / n ₁ )
It becomes.

Further, the reflection coefficient rs and transmission coefficient ts when the criticality is perpendicular to the incident surface are calculated from the Fresnel formula as follows.
(3) rs = (n ₁ cos θ ₁ −n ₂ cos θ ₂ ) / (n ₁ cos θ ₁ + n ₂ cos θ ₂ )
= −sin (θ ₁ −θ ₂ ) / sin (θ ₁ + θ ₂ )
(4) ts = 2n ₁ cos θ ₁ / (n ₁ cos θ ₁ + n ₂ cos θ ₂ )
Rewriting using only the incident angle θ ₁ using Snell's law results in the following.
(5) rs = [cos θ ₁ − {(n ₂ / n ₁ ) 2 − (sin θ ₁ ) 2} 0.5] / [cos θ ₁ + (n ₂ / n ₁ ) 2 − (sin θ ₁ ) 2} 0 .5]
(6) ts = ₂ cos θ ₁ / [cos θ ₁ + {(n ₂ / n ₁ ) 2- (sin θ ₁ ) 2} 0.5]

The reflection coefficient rp and transmission coefficient tp when the criticality is horizontal with respect to the incident surface are as follows.
(7) rp = (n ₁ cos θ ₂ −n ₂ cos θ ₁ ) / (n ₁ cos θ ₂ + n ₂ cos θ ₁ )
= Tan (θ ₁ −θ ₂ ) / tan (θ ₁ + θ ₂ )
(8) ts = 2n ₁ cos θ ₁ / (n ₁ cos θ ₂ + n ₂ cos θ ₁ )
Rewriting using only the incident angle θ ₁ using Snell's law results in the following.
(9) rp = [− (n ₂ / n ₁ ) 2 × cos θ ₁ + {(n ₂ / n ₁ ) 2 − (sin θ ₁ ) 2} 0.5] / [(n ₂ / n ₁ ) 2 × cos θ ₁ + {(n ₂ / n ₁ ) 2- (sin θ ₁ ) 2} 0.5]
(10) tp = 2 × (n ₂ / n ₁ ) × cos θ ₁ / [(n ₂ / n ₁ ) 2 × cos θ ₁ + {(n ₂ / n ₁ ) 2 − (sin θ ₁ ) 2} 0.5 ]

Next, the reflectance R and the transmittance T are obtained as follows. The ratio of reflected energy to incident energy is called reflectance R, and the ratio of transmitted energy to incident energy is called transmittance T.
(11) R = r ₂ = 1/2 (rs ₂ + rp ₂ )
(12) T = t ₂ × (n ₂ cos θ ₂ / n ₁ cos θ ₁ )
Respectively.
An incident angle at which the refraction angle θ2 is 90 ° is called a critical angle, and at an incident angle higher than that, total reflection occurs. The critical angle θ ₁ rin (which occurs when n ₁ > n ₂ : e.g. from water n ₁ = 1.33 into the air n ₂ = 1.00) is determined by the following equation:
(13) θ ₁ rin = sin−1 (n ₂ / n ₁ )

  The reflectance angle characteristics between the respective media calculated using the above-described equations are as shown in FIG. In FIG. 6, the vertical axis represents the reflectance (%) and the horizontal axis represents the incident angle (deg). Also, the line (A) shows the reflectance angle characteristic of air → water (recovered water 9), the line (B) shows the reflectance angle characteristic of air → polystyrene (PS), and the line (C) shows the reflection angle of water → polystyrene. The rate angle characteristic, line (d) is the water → air reflectivity angle characteristic, line (e) is the polystyrene → air reflectivity angle characteristic, line (f) is the polystyrene → water reflectivity angle characteristic, Each is shown.

  That is, as for the reflectance angle characteristics between the media, total reflection occurs when water → air (line (d)), polystyrene → air (line (e)), polystyrene → water (line (f)). On the contrary, the reflectance angle characteristics between each medium are not totally reflected in air → water (line (b)), air → polystyrene (line (b)), water → polystyrene (line (c)), As the incident angle increases (the optical path approaches parallel to the surface), the reflectivity increases rapidly. The reflectance at the front (incident angle 0 °) is as small as several percent.

In FIG. 4, the thickness of the side surface of the water tank 7a (the thickness of the side plate of the water tank 7a at the start of the recess 14a) is H ₃ = 2 mm, the incident surface 19a-1 of the recess 14a is the bottom W ₁ = 3 mm, The height H ₁ (depth of the concave portion 14a) = 1.5 mm and the hypotenuse of a right triangle. Further, as a restriction condition for changing the thickness when the water tank 7a is formed, the thickness of a part of the side surface can be set to be within twice, preferably within 1.5 times the thickness of the other part. Here, since the thickness of the side surface of the water tank 7a is set to H ₃ = 2 mm, the thickness of the side surface of the water tank 7a constituting the bottom surface of the concave portion 14a (the side surface of the water tank 7a at the most concave portion of the concave portion 14a). The thickness was set to H ₄ = H ₃ × 1.5 = 3 mm.

The optical path is traced on the assumption that the incident angle of light from the light emitting portion 15a is tilted to the left by θ ₁ = 5 deg from the vertical direction of the tank plane. Incidentally, in order to calculate the behavior of light from the vertical direction, θ ₁ = 0 deg may be set. When the inclination of the incident surface 19a-1 is θx downward from the horizontal direction of the tank plane, θx = tan−1 (1.5 / 3) = 26.57 deg from the setting of the inclined surface. Further, the inclination of the reflection / transmission surface 20a-1 is defined as θy. The incident angle of the light (arrow 17a) from the light emitting portion 15a to the incident surface 19a-1 is θ ₂ = θ ₁ + θx = 5 + 26.57 = 31.57 deg. According to Snell's law, the refraction angle is θ ₃ = sin−1 {(n ₁ / n ₂ ) sin (θ ₂ )} = 19.2 deg, and light travels through the arrow 17b.

Next, reflection / transmission occurs at the reflection / transmission surface 20a-1, and it is only necessary to determine θy so that the optical path after reflection (arrow 17c) is parallel to the tank plane. In the reflection / transmission surface 20a-1, according to Snell's law, the incident angle θ ₅ = the reflection angle θ ₅ . When the optical path (the arrow 17b) an angle of the normal to the tank plane as theta _4, a _{θ 4 = θx-θ 3 =} 7.3deg. Therefore, θ ₅ = (90−θ ₄ ) /2=41.3 deg. Furthermore, the angle of the reflection / transmission surface 20a-1 corresponding to θ ₅ is θy = 90−θ ₅ = 48.7 deg.

Under the above conditions, the incident angle θ ₅ = 41.3 deg of the reflection / transmission surface 20a-1 satisfies the total reflection condition at the interface between the water tank 7a and the air. , The light is totally reflected and 100% of the light is reflected. The light in the optical path indicated by the arrow 17b is totally reflected and proceeds to the arrow 17c. In the case of water, the reflectance is low, about 2%, and 98% is transmitted into the water tank 7a. Incidentally, the refraction angle theta ₆ in this case, n ₃ = 1.33 as (water), and _{θ 6 = sin-1 {(} n 2 / n 3) × sinθ 5} = 52.1deg. The light in the optical path indicated by the arrow 17b is substantially transmitted and proceeds to the inside of the water tank 7a (arrow 18c).

When H ₄ = 3 mm and the size of the reflection / transmission surface 20 a-1 is determined, it becomes the hypotenuse of a right triangle having a base W ₂ = 2.2 mm and a height H 2 = 2.5 mm. When the inside of the water tank 7a is air, the light in the optical path indicated by the arrow 17c travels in the tank side surface at the bottom of the recess 14a, and is reflected at a position symmetrical to the incident surface 19a-1 and the reflection / transmission surface 20a-1. The light sequentially enters the transmission surface 20a-2 and the incident surface 19a-2, is reflected by the reflection / transmission surface 20a-2, is transmitted by the incident surface 19a-2, and reaches the light receiving unit 16a. On the other hand, when the water tank 7a is water, most of the amount of light is transmitted into the tank, so that almost no light reaches the light receiving portion 16a, which is about 2% × 2% = 0.04%.

  Thereby, when the light quantity which the light-receiving part 16a receives is large, it can discriminate | determine that the inside of the water tank 7a is air, and when there is almost no light quantity, the inside of the water tank 7a is water. That is, when the amount of light emitted from the light emitting unit 15a and received by the light receiving unit 16a is large, it can be determined that the recovered water 9 has not reached the water level 10 of the water tank 7a, and is emitted from the light emitting unit 15a. When the amount of light received by the light receiving unit 16a is small, it can be determined that the recovered water 9 has reached the water level 10 of the water tank 7a, and this is notified to the user.

In addition, although the case where the incident angle from the light emission part 15a is 5 deg was demonstrated, it is not limited to this. For example, if each angle is calculated when θ ₁ = 0 deg, the angle of the incident surface 19a-1 is the same, θx = 26.57deg, θ ₂ = θx = 26.57deg, θ ₃ = sin-1 { (1.0 / 1.59) sin (26.57)} = 16.34 deg, θ ₄ = θ ₃ −θx = 10.23 deg, θ ₅ = (90−θ ₄ ) /2=39.9 deg, θy = 90-θ ₅ = 50.1deg next, also in this case, similarly to the aforementioned theta ₁ = 5 deg, the air or the water in the water tank 7a, unlike the behavior of the reflection and transmission plane 20a-1, indicated by the arrow 17c The light level in the optical path changes greatly, and the water level can be detected.

However, in detail, the incident angle θ ₅ of the reflection / transmission surface 20a-1 is small, and the likelihood is reduced with respect to the total reflection angle 39deg on this surface. Further, by increasing θy, the reflection / transmission surface 20a-1 rises, and by limiting the wall thickness of the water tank 7a to 3 mm, W ₂ is reduced, and the area of the reflection / transmission surface 20a-1 is reduced. It turns out that the likelihood with respect to the positional deviation of incident light is also reduced. Further, the calculation is performed with respect to the central optical axis of the light emitting unit 15a. Strictly speaking, ambient light slightly shifted in angle reaches the light receiving unit 16a and contributes to its output. There is a possibility that the arrival of will decrease. Therefore, the optimum angle may be determined by considering these conditions according to the application.

  As described above, in Embodiment 1, the concave portion 14a is provided in a part of the side surface of the water tank 7a, and the thickness of the wall surface constituting the concave portion 14a is about 1.5 times the thickness of the other side surface. Therefore, it can be easily manufactured at low cost by general molding. In addition, the shape of the water tank 7a for detecting the water level using the light emitting and receiving part can be made less bent. Therefore, the cleanness of the shape of the water tank 7a improves the design, and also improves the ease of handling, such as cleaning, maintenance, and portability.

Next, a modification of the first embodiment will be described.
FIG. 7 is an enlarged plan view showing a part of a water tank 7b which is an example of the water tank 7 in an enlarged manner. Based on FIG. 7, the water tank 7b which made the recessed part 14b another shape is demonstrated. In FIG. 7, a part of the water tank 7 b, that is, the incident surface (incident surface 19 b-1 and incident surface 19 b-2) and reflective / transmissive surface (reflective / transmissive surface 20 b-1 and reflective / transmissive) of the concave portion 14 b on the light emitting unit 15 b side. The surface 20b-2) is shown together with the light path. In FIG. 7, the optical path of the light emitted from the light emitting unit 15b is indicated by a solid arrow. The incident surface 19b-1 and the reflection / transmission surface 20b-1 are opposed to each other, and the incident surface 19b-2 and the reflection / transmission surface 20b-2 are opposed to each other. Further, the incident surface and the reflection / transmission surface may be collectively referred to as an inclined portion of the recess 14b.

  As shown in FIG. 7, the concave portion 14 b is a portion where the thickness of the water tank 7 b is constant (a portion where the incident surface 19 b-2 and the reflection / transmission surface 20 b-2 face each other) in the inclined portion that forms the concave portion 14 b. ) Is different from the concave portion 14a. That is, the concave portion 14b is provided with a predetermined angle in a portion from the reflection / transmission surface 20b-1 to the reflection / transmission surface 20b-2, and the wall thickness between the incident surface 19b-2 and the reflection / transmission surface 20b-2 is constant. The wall thickness between the incident surface 19b-1 and the reflection / transmission surface 20b-1 is gradually increased toward the bottom surface of the recess 14b.

  In the concave portion 14b, the angle and arrangement of the incident surface 19b (the incident surface 19b-1 and the incident surface 19b-2) and the reflection / transmission surface 20b (the reflection / transmission surface 20b-1 and the reflection / transmission surface 20b-2) are arranged in the inclined portion. By changing the above, each surface is arranged so that reflection and transmission change depending on whether the water tank 7b is air or water. Therefore, when it is desired to lengthen the inclined portion of the recess 14b, it is not necessary to extend the incident surface 19b and the reflection / transmission surface 20b over the entire surface, and if each surface is disposed within a range necessary for light to pass through. Good.

  In addition, if the surfaces with different angles are lengthened due to the restriction of mold forming when forming the water tank 7b, the difference in thickness becomes large, and the molding becomes difficult. Therefore, as shown in FIG. 7, it is preferable to make the thickness constant at the portions of the incident surface 19b-2 and the reflection / transmission surface 20b-2, that is, the portions that do not affect the reflection / transmission of light from the light emitting portion 15b. . If it does so, the detection of a water level can be implement | achieved using the part other than that, ie, the part of incident surface 19b-1 and reflection transmission surface 20b-1.

  FIG. 8 is an enlarged plan view showing a part of a water tank 7 c which is an example of the water tank 7 in an enlarged manner. Based on FIG. 8, the water tank 7c which made the recessed part 14c another shape is demonstrated. In FIG. 8, a part of the water tank 7 c, that is, the incident surface (incident surface 19 c-1 and incident surface 19 c-2) and reflective / transmissive surface (reflective / transmissive surface 20 c-1 and reflective / transmissive surface) of the concave portion 14 c on the light emitting unit 15 c side. The surface 20c-2) is shown together with the light path. In FIG. 8, the optical path of the light emitted from the light emitting unit 15c is indicated by a solid arrow. The incident surface 19c-1 and the reflection / transmission surface 20c-1 are opposed to each other, and the incident surface 19c-2 and the reflection / transmission surface 20c-2 are opposed to each other. Further, the incident surface and the reflection / transmission surface may be collectively referred to as an inclined portion of the recess 14c.

  As shown in FIG. 8, the concave portion 14c has two portions with different thicknesses in the inclined portion forming the concave portion 14c (thickness between the incident surface 19c-2 and the reflective / transmissive surface 20c-2, the incident surface 19c). -1 and the thickness of the reflection / transmission surface 20c-1) is different from the recess 14a and the recess 14b. That is, the concave portion 14c is provided with a predetermined angle so as to reduce the thickness of the portion from the reflection / transmission surface 20c-1 to the reflection / transmission surface 20c-2, and the incident surface 19c-2 and the reflection / transmission surface 20c-2. And the wall thickness between the incident surface 19c-1 and the reflection / transmission surface 20c-1 are different from each other.

  In the concave portion 14c, similarly to the concave portion 14b, in the inclined portion, the incident surface 19c (the incident surface 19c-1 and the incident surface 19c-2) and the reflection / transmission surface 20c (the reflection / transmission surface 20c-1 and the reflection / transmission surface 20c-). By changing the angle and the arrangement of 2), each surface is arranged so that reflection and transmission are changed by air or water in the water tank 7c. Therefore, when it is desired to lengthen the inclined portion of the concave portion 14c, it is not necessary to extend the incident surface 19c and the reflection / transmission surface 20c over the entire surface, and if each surface is arranged within a range necessary for light to pass through. Good.

  In addition, if the surfaces having different angles are lengthened due to the limitation of mold forming when forming the water tank 7c, the difference in thickness becomes large, and the molding becomes difficult. Therefore, as shown in FIG. 8, it is preferable to change the thickness at the incident surface 19c-2 and the reflection / transmission surface 20c-2, that is, at the portion that does not affect the reflection / transmission of light from the light emitting portion 15c. If it does so, the detection of a water level is realizable using the part other than that, ie, the part of the entrance plane 19c-1 and the reflective transmission surface 20c-1.

  FIG. 9 is an enlarged plan view showing a part of a water tank 7d which is an example of the water tank 7 in an enlarged manner. Based on FIG. 9, the water tank 7d which made the recessed part 14d another shape is demonstrated. In FIG. 9, a part of the water tank 7d, that is, the incident surface (incident surface 19d-1 and incident surface 19d-2) and reflection / transmission surface (reflection / transmission surface 20d-1 and reflection / transmission surface 20d-2) of the recess 14d. Is shown together with the optical path of light. In FIG. 9, the optical path of the light emitted from the light emitting unit 15d is indicated by a solid arrow. The incident surface 19d-1 and the reflection / transmission surface 20d-1 are opposed to each other, and the incident surface 19d-2 and the reflection / transmission surface 20d-2 are opposed to each other. Further, the incident surface and the reflection / transmission surface may be collectively referred to as an inclined portion of the recess 14d.

  As shown in FIG. 9, the recess 14d does not have a flat surface constituting the bottom surface. In this respect, the concave portion 14d is different from the concave portions 14a to 14c having a flat surface constituting the bottom surface. Depending on the plastic material constituting the water tank 7d, the light transmittance may not be high. For example, polypropylene has a thickness of about 2 mm and a transmittance of about 80%. If the thickness of the flat portion at the bottom is 20 mm, the transmittance is approximately 0.8 (20/2) power = 0.107≈11%, and the amount of light is greatly attenuated by the transmission. In such a case, it is necessary to shorten the distance of the bottom part of the recessed part 14d. Therefore, if the shape is such that the inclined portion on the light emitting portion 15d side and the inclined portion on the light receiving portion 16d side are connected without using a plane like the concave portion 14d, the amount of light attenuation can be suppressed. .

  In the first embodiment, the shape of the recesses (recesses 14a to 14d) is formed as a groove-like shape by providing recesses that are continuous from the bottom surface side to the top surface side of the water tank side surface, and the incident surface and the reflection / transmission surface. Are formed at predetermined positions at predetermined angles. In this case, the water level can be detected by arranging the light emitting / receiving section at an arbitrary position in the vertical direction. In addition, the shape of the recess is not a continuous recess from the bottom surface side (lower part) to the upper surface side (upper part) of the water tank side surface, but a recess is formed in the tank side surface part around the position where the water level is to be detected. Even if the reflection / transmission surface is formed at a predetermined angle and at a predetermined position, the water level can be detected similarly (see FIG. 10).

  FIG. 10 is an explanatory diagram for explaining a water tank 7e which is an example of the water tank 7 in which a recess is formed around a position where the water level is desired to be detected. In FIG. 10, the state which looked at the water tank 7e and the light emitting / receiving part from three directions is shown, respectively, and FIG. 10 (a) is a plan view showing the state where the water tank 7e and the light emitting / receiving part are seen from above. FIG. 10 (b) is a side view showing the state of the water tank 7e and the light emitting / receiving section viewed from the lateral side of the water tank 7e, and FIG. 10 (c) is the water tank 7e and the light emitting / receiving section of the water tank 7e. The side view which shows the state seen from the longitudinal direction side is shown, respectively. In FIG. 10, the optical path of the light emitted from the light emitting unit 15e and received by the light receiving unit 16e is indicated by arrows (solid line arrows and broken line arrows). In FIG. 10, the description will focus on differences from the water tank shown in FIGS. 1 to 9.

  The recess shown in FIGS. 1 to 9 is shaped like a groove formed from the bottom side to the top side of the side surface of the water tank, but the recess 14e shown in FIG. 10 is a tank around the position where the water level is desired to be detected. It is shaped like a rectangular cross section formed on the side portion. That is, the recess 14e has a shape in which a recess is provided in a tank side surface corresponding to a position where the water level is desired to be detected, and the incident surface and the reflection / transmission surface are formed at a predetermined position at a predetermined angle. Even if the concave portion 14e is configured in such a shape, the water level in the water tank can be detected in the same manner as the concave portion shown in FIGS.

  As described above, the water level detection device (light emitting unit, light receiving unit, and water tank) according to Embodiment 1 of the present invention can detect the water level in the water tank by interacting with the side shape of the water tank. I have to. Therefore, according to the water level detection device according to the first embodiment, it is possible to use a water tank that is less bent in the side surface shape. Therefore, since the water tank (water tank 7 and water tank 7a to water tank 7e) can be manufactured at low cost, there is no deterioration in cleanability, handling and design, and even if such a water tank is used, The water level in the tank can be reliably detected.

By the way, the case where a water level cannot be detected is demonstrated.
FIG. 11 is an enlarged plan view showing a part of the water tank 7 ′ that cannot detect the water level.
Based on FIG. 11, a water tank 7 ′ having a recessed portion 14 ′ having a different shape, which cannot detect the water level, will be described. In FIG. 11, a part of the water tank 7 ′, that is, the incident surface (incident surface 19 ′-1 and incident surface 19 ′-2) and reflective / transmissive surface (reflective / transmissive surface 20) of the concave portion 14 ′ on the light emitting unit 15 ′ side. '-1 and reflection / transmission surface 20'-2) are shown together with the optical path of light. In FIG. 11, the optical path of the light emitted from the light emitting unit 15 ′ is indicated by a solid arrow. The incident surface 19′-1 and the reflection / transmission surface 20′-1 are opposed to each other, and the incident surface 19′-2 and the reflection / transmission surface 20′-2 are opposed to each other. Further, the incident surface and the reflection / transmission surface may be collectively referred to as an inclined portion of the recess 14 '.

  As shown in FIG. 11, the concave portion 14 ′ has two portions (thickness between the incident surface 19′-2 and the reflection / transmission surface 20′-2) having different thicknesses in the inclined portion forming the concave portion 14 ′. , The thickness between the incident surface 19′-1 and the reflection / transmission surface 20′-1) is different from the concave portions 14a to 14c. That is, the concave portion 14 ′ is provided with a predetermined angle so as to thicken a portion from the reflection / transmission surface 20′-1 to the reflection / transmission surface 20′-2, and the incident surface 19′-2 and the reflection / transmission surface 20′−. 2 and the wall thickness between the incident surface 19′-1 and the reflection / transmission surface 20′-1 are different from each other.

  In FIG. 11, the light emitting portion 15 ′ enters light at a position away from the most concave portion of the concave portion 14 ′ (side surface portion of the water tank 7 ′ constituting the bottom surface of the concave portion 14 ′). Yes. Therefore, although the reflection / transmission changes due to the presence / absence of water occur on the incident surface 19′-1 and the reflection / transmission surface 20′-1, the reflected light is reflected by the inclined portion of the recess 14 ′, and the water tank 7 ′. The water level is not detected because the light passes through the inside and does not reach the bottom surface of the concave portion 14 'from the most concave portion of the concave portion 14', and the light quantity of the light receiving portion 16 'does not change. Further, when the light emitting portion 15 ′ is moved in the direction of the most recessed portion of the concave portion 14 ′, the incident surface 19′-2 and the reflection / transmission surface 20′-2 do not form a predetermined angle, The transmission / reflection state does not change due to the presence or absence of water in the water tank 7 ', and the water level cannot be detected.

Embodiment 2. FIG.
FIG. 12 is an explanatory diagram for explaining a water level detection device according to Embodiment 2 of the present invention. Based on FIG. 12, the structure and operation | movement of the water level detection apparatus based on this Embodiment 2 are demonstrated. In the second embodiment, differences from the first embodiment will be mainly described, and the same parts or the same elements as those in the first embodiment are denoted by the same reference numerals. In FIG. 12, the optical path of light emitted from the light emitting unit 15g and received by the light receiving unit 16g is indicated by arrows (solid arrow and broken line arrow).

  FIG. 12 shows a state where a water tank 7f and a light emitting / receiving unit as an example of the water tank 7 are viewed from three directions, respectively, and FIG. 12 (a) shows the water tank 7f and the light emitting / receiving unit viewed from above. FIG. 12B is a plan view showing the state, FIG. 12B is a side view showing the state of the water tank 7f and the light emitting / receiving section viewed from the lateral side of the water tank 7f, and FIG. The side view which shows the state which looked at the light-receiving part from the longitudinal direction side surface of the water tank 7f is each shown. In the first embodiment, the water tank side surface is recessed and the thickness of the inclined portion is changed to detect the water level. However, in the second embodiment, the water tank side surface is not changed. The water level is detected.

  As shown in FIG. 12, the water level detection device according to the second embodiment includes a light emitting unit 15f, a light receiving unit 16f, and a reflecting plate 21f. The light emitting unit 15f and the light receiving unit 16f have the same functions as the light emitting unit and the light receiving unit according to the first embodiment. The reflector 21f is attached to the steam introduction pipe 13 inserted into the water tank 7f, and reflects the light from the light emitting part 15f. That is, as shown in FIG. 12, in the second embodiment, the side surface of the water tank 7f is flat and has a constant thickness, and the water level in the water tank 7f is detected.

  The reflecting plate 21f is attached so as to be substantially parallel to the side surface of the water tank 7f so that the reflecting surface reflects the light from the light emitting portion 15f. That is, by arranging the reflecting plate 21f inside the water tank 7f, the light from the light emitting unit 15f is reflected by the reflecting plate 21f and enters the light receiving unit 16f. In other words, the water level detection device according to the second embodiment utilizes the fact that when there is a water surface in the optical path from the light emitting unit 15f to the light receiving unit 16f, total reflection occurs on the water surface and the optical path changes. Thus, the water level is detected.

The water level detection device according to the second embodiment will be described in more detail.
The light emitting portion 15f faces the reflecting plate 21f and faces upward by about 20 ° to 30 ° in a state where the reflecting plate 21f is disposed in the water tank 7f outside the side surface of the water tank 7f. Has been placed. The reflection plate 21f is disposed on the optical path of the light from the light emitting unit 15f. The light receiving part 16f is arranged so that light enters after the light from the light emitting part 15f is reflected by the reflecting plate 21f when the inside of the water tank 7f is air. Here, the light receiving portion 16f is disposed above the light emitting portion 15f. That is, light is emitted from the light emitting portion 15f obliquely upward.

  When the position corresponding to the water level 10 in the water tank 7f is air, that is, when the recovered water 9 is not stored up to a predetermined water level (water level 10), the optical path is a solid arrow 17f, and the recovered water 9 is at the water level 10 The optical path in the case of being stored in excess of is a broken line arrow 18f. As shown in FIG. 12B, when the recovered water 9 is stored beyond the water level 10, the light from the light emitting unit 15f is reflected by the water surface so that the optical path changes and does not reach the light receiving unit 16f. It has become. Of the intersections of the arrow 17f and the inner wall surface of the water tank 7f, the lower side is used as the intersection 22a and the upper side is used as the intersection 22b in the following description.

Next, the operation of the water level detection device will be described in detail.
First, when the water level 10 is low and the water surface position is below the intersection point 22a, the light from the light emitting portion 15f travels along the arrow 17f, passes through the intersection point 22a, is reflected by the reflecting plate 21f, and is reflected at the intersection point 22b. And enters the light receiving unit 16f. Then, when the water level 10 rises and there is a water surface at the position shown in FIG. 12B, that is, between the intersection point 22a and the intersection point 22b, the light from the light emitting portion 15f travels along the arrow 17f. , Passes through the intersection 22a and enters the water surface. The total reflection condition at the interface from the water surface to the air is an incident angle of 48 ° or more.

  In FIG. 12, since the light beam travels at 20 to 30 ° above the horizontal direction, the incident angle on the water surface corresponds to 70 to 60 °. Therefore, the light is totally reflected on the water surface and travels along the arrow 18f. It will be. This phenomenon occurs between the intersection point 22a and the intersection point 22b on the water surface. The light traveling along the arrow 18f does not enter the light receiving unit 16f. Next, when the water level further rises and the water surface position is above the intersection 22b, the light from the light emitting portion 15f travels along the arrow 17f, and the distance from the side surface of the water tank to the reflector 21f is short. Becomes substantially the same optical path as when the inside of the water tank 7f is air, is reflected by the reflecting plate 21f, passes through the vicinity of the intersection 22b, and enters the light receiving portion 16f.

  Therefore, the output of the light receiving unit 16f varies depending on the water surface position. That is, the light receiving unit 16f outputs a high level when the water level 10 is lower than the intersection 22a, a low level when the water level 10 is between the intersections 22a and 22b, and a high level when the water level 10 is higher than the intersection 22b. It is supposed to be. That is, it is possible to detect that the water level 10 exists between the intersection point 22a and the intersection point 22b by a signal from the light receiving unit 16f.

  As described above, the water level detection device (the light emitting unit 15f, the light receiving unit 16f, and the reflecting plate 21f) according to the second embodiment of the present invention does not form a concave portion on the side surface of the water tank 7f, and remains flat. It is possible to detect the water level in the tank 7f. Therefore, the water tank 7f can be molded more easily, a general molding machine can be used, and the manufacturing cost can be reduced. Further, since the outer side surface of the water tank 7f can be manufactured flat and inexpensively, the cleaning property, handling property and design property are not inferior.

  In addition, although the example which attached the reflecting plate 21f to the steam introduction pipe 13 was demonstrated to the example, it is not limited to this. For example, the same effect can be obtained even if the steam introduction pipe 13 itself is made of a glossy metal or the plastic is plated or painted to increase the reflectance of the steam introduction pipe 13 itself. Can be obtained. Further, the reflection plate 21f may be raised upward from the bottom surface of the water tank 7f without being attached to the steam introduction pipe 13, or the reflection plate 21f may be extended downward from the tank lid 12. May be.

Embodiment 3 FIG.
FIG. 13 is an explanatory diagram for explaining a water level detection device according to Embodiment 3 of the present invention. Based on FIG. 13, the structure and operation | movement of the water level detection apparatus based on this Embodiment 3 are demonstrated. In the third embodiment, differences from the first and second embodiments will be mainly described, and the same parts or the same elements as those in the first and second embodiments are denoted by the same reference numerals. ing. Further, in FIG. 13, an optical path of light emitted from the light emitting unit and received by the light receiving unit is indicated by arrows (solid line arrows and broken line arrows).

  FIG. 13A is a side view showing a state of the water tank 7g and the light emitting / receiving section as an example of the water tank 7 as viewed from the lateral side of the water tank 7g, and FIG. Graphs for explaining the change are shown respectively. In Embodiments 1 and 2, the water level is detected by a pair of light emitting units and light receiving units. However, in Embodiment 3, a plurality of pairs of light emitting units 15g (light emitting units 15g− 1 to the light emitting unit 15g-3) and the light receiving unit 16g (the light receiving unit 16g-1 to the light receiving unit 16g-3) detect the water level at a plurality of positions.

  As shown in FIG. 13, the water level detection device according to the third embodiment is composed of three light emitting units 15g, three light receiving units 16g, and one reflecting plate 21g, and is at least necessary for a plurality of water levels, that is, steam recovery. The initial water level, the full water level for preventing the water from overflowing from the water tank 7g, and the intermediate water level between the initial water level and the full water level can be detected. The three light emitting units 15g and the three light receiving units 16g have the same functions as the light emitting unit and the light receiving unit according to the first and second embodiments. That is, in Embodiment 3, the side surface of the water tank 7g is flat and has a constant thickness, and the water level in the water tank 7g is detected.

  The reflection plate 21g is attached to the steam introduction pipe 13 inserted into the water tank 7g and reflects light from the three light emitting units. The reflecting plate 21g is attached so as to be substantially parallel to the side surface of the water tank 7g so that the reflecting surface reflects the light from the light emitting unit 15g-1 to the light emitting unit 15g-3. That is, by disposing the reflecting plate 21g inside the water tank 7g, the light from the light emitting unit 15g-1 to the light emitting unit 15g-3 is reflected by the reflecting plate 21g, and the light receiving unit 16g-1 to the light receiving unit 16g-3. I try to enter. Then, the water level detection device according to Embodiment 3 uses the fact that when the water surface exists in the optical path from the light emitting unit to the light receiving unit, total reflection occurs on the water surface, and the optical path changes. Is detected.

  The water level detection device will be described in more detail. The light emitting unit 15g-1 to the light emitting unit 15g-3 are opposed to the reflecting plate 21g and from about 20 ° in a state where the reflecting plate 21g is arranged in the water tank 7g outside the side surface of the water tank 7g. It arrange | positions so that it may face upward about 30 degrees. The light emitting unit 15g-1 is installed near the initial water level, the light emitting unit 15g-2 is installed near the intermediate water level, and 15g-3 is installed near the full water level. The reflecting plate 21g is disposed on the optical path of light from the light emitting unit 15g-1 to the light emitting unit 15g-3. The reflecting plate 21g has a reflecting surface that is longer in the vertical direction than the reflecting plate 21g according to the embodiment (longer than the length from the initial water level to the full water level).

  In the light receiving unit 16g-1, when the water tank 7g is air (when the position corresponding to the initial water level in the water tank 7g is air), the light from the light emitting unit 15g-1 is reflected by the reflecting plate 21g. After that, it is arranged so that light can enter. Here, the light receiving unit 16g-1 is disposed above the light emitting unit 15g-1. That is, light is emitted from the light emitting unit 15g-1 obliquely upward. The optical path when the position corresponding to the initial water level in the water tank 7g is air is a solid line arrow 17g-1, and the optical path when stored beyond the initial water level is a broken line arrow 18g-1. Of the intersections of the arrow 17g-1 and the inner wall surface of the water tank 7g, the lower side is the intersection 23a and the upper side is the intersection 23b, which will be used in the following description. These intersections are set according to the detection position of the initial water level.

  In the light receiving unit 16g-2, when the water tank 7g is air (when the position corresponding to the intermediate water level in the water tank 7g is air), the light from the light emitting unit 15g-2 is reflected by the reflecting plate 21g. After that, it is arranged so that light can enter. Here, the light receiving unit 16g-2 is disposed above the light emitting unit 15g-2. That is, light is emitted from the light emitting unit 15g-2 obliquely upward. The optical path when the position corresponding to the intermediate water level in the water tank 7g is air is a solid line arrow 17g-2, and the optical path when the position is stored beyond the intermediate water level is a broken line arrow 18g-2. Of the intersections of the arrow 17g-2 and the inner wall surface of the water tank 7g, the lower side is used as the intersection 23c and the upper side is used as the intersection 23d in the following description. These intersections are set according to the detection position of the intermediate water level between the initial water level and the full water level.

  In the light receiving unit 16g-3, when the water tank 7g is air (when the position corresponding to the full water level in the water tank 7g is air), the light from the light emitting unit 15g-3 is reflected by the reflecting plate 21g. After that, it is arranged so that light can enter. Here, the light receiving unit 16g-3 is disposed above the light emitting unit 15g-3. That is, light is emitted from the light emitting unit 15g-3 obliquely upward. The optical path when the position corresponding to the full water level in the water tank 7g is air is a solid arrow 17g-3, and the optical path when the water tank is stored beyond the full water level is a broken arrow 18g-3. Of the intersections of the arrow 17g-3 and the inner wall surface of the water tank 7g, the lower side is used as the intersection 23e and the upper side is used as the intersection 23f in the following description. These intersections are set according to the detection position of the full water level.

  As shown in the graph of FIG. 13 (b), the output from the light receiving unit also changes according to the change in the water level. FIG. 13B shows an output value (sensor (1) shown in the drawing) of the water level detection device 8-1 including the light emitting unit 15g-1 and the light receiving unit 16g-1 for detecting the initial water level, The output value (sensor (2) shown in the figure) of the water level detection device 8-2 configured by the light emitting unit 15g-2 and the light receiving unit 16g-2 for detecting the water level is used as the light emitting unit 15g-3 for detecting the full water level. And the three sensor output values of the output value (sensor (3) shown in the figure) of the water level detection device 8-3 configured by the light receiving unit 16g-3 are illustrated.

  When detecting the initial water level, the light receiving unit 16g-1 outputs a high signal when the light from the light emitting unit 15g-1 enters, and outputs a low signal when the light does not enter the light receiving unit 16g-1 due to water surface reflection (sensor). (1)). Similarly, when detecting the intermediate water level, the light receiving unit 16g-2 outputs a high signal when the light from the light emitting unit 15g-2 is incident, and outputs a low signal when the light is not incident on the light receiving unit 16g-2 due to water surface reflection. (Sensor (2)). Similarly, when detecting the full water level, the light receiving unit 16g-3 outputs a high signal when the light from the light emitting unit 15g-3 is incident, and outputs a low signal when the light is not incident on the light receiving unit 16g-3 due to water surface reflection. (Sensor (3)).

Next, the operation of the water level detection device according to the third embodiment will be described. In addition, each operation | movement of the water level detection apparatus 8-1 to the water level detection apparatus 8-3 is as having demonstrated in Embodiment 2. FIG.
When the heating cooker 100 performs steam recovery, water (initial water level) exceeding the minimum required water amount must be in the water tank 7g. That is, it is necessary to execute the steam recovery operation after detecting that there is a minimum amount of water (water exceeding the minimum required water amount) when executing the steam recovery operation. Therefore, the water level detection device 8-1 configured by the light emitting unit 15g-1 and the light receiving unit 16g-1 detects whether water at the initial water level or higher is stored in the water tank 7g as the recovered water 9. ing.

  Further, in order to prevent the recovered water 9 from overflowing from the water tank 7g, the amount of water in the water tank 7g must be equal to or less than a predetermined amount (full water level). That is, during the steam recovery operation, it must be detected that the recovered water 9 in the water tank 7g is below the full water level. Therefore, the water level detection device 8-3 configured by the light emitting unit 15g-3 and the light receiving unit 16g-3 detects whether the recovered water 9 is below the full water level. However, in the detection of the initial water level and the full water level, it is possible to detect that the water surface is at each water level, but it is impossible to detect the water surface below or above the initial water level and below or above the full water level.

  Therefore, in the third embodiment, it is necessary to detect that the water surface is between the initial water level and the full water level, and the water level detection device 8-2 configured by the light emitting unit 15g-2 and the light receiving unit 16g-2. Is added. The water level detection device 8-2 can detect that there is a water surface between the intersection 23c and the intersection 23d. By combining this signal with the signals of the water level detection device 8-1 and the water level detection device 8-3, it is possible to detect that there is a water surface between the initial water level and the full water level. In order to detect the water level with high accuracy so that there is no non-detection area, the interval between the light emitting part 15g-2 and the light receiving part 16g-2 is widened, the intersection 23c is below the intersection 23b, and the intersection 23d is the intersection. What is necessary is just to arrange | position so that it may become above 23e.

  However, in order to use the total reflection condition of water, the upward angle of the light emitting unit 15g-2 is about 40 °. Therefore, when the distance between the intersection 23b and the intersection 23e is large (for example, when the height of the water tank 7g is high), the three water level detection devices have non-detection regions. Therefore, a water level detection device may be additionally arranged to increase the detection area. That is, as shown in FIG. 13, the number of installed water level detection devices is not limited to three, and the number of installed water level detection devices may be determined according to the height of the water tank 7g.

  As described above, the water level detection device according to Embodiment 3 of the present invention can detect the water level in the water tank 7g while keeping the shape of the side surface of the water tank 7g flat. Therefore, the water tank 7g can be molded more easily, a general molding machine can be used, and the manufacturing cost can be reduced. Further, since the side surface of the water tank 7g can be manufactured flat and inexpensively, the cleaning property, handling property and design property are not inferior. Furthermore, since a plurality of water level detection devices are provided to detect a plurality of water levels, there is no omission in the detection region, and water level detection with higher accuracy is possible.

  Moreover, in FIG. 13, although the reflector 21g demonstrated to the example the form attached to the steam introduction pipe 13, it is not limited to this. For example, the same effect can be obtained even if the steam introducing pipe 13 itself is made of metal or the plastic is plated or painted to increase the reflectance of the steam introducing pipe 13 itself. Can do. Further, the reflection plate 21g may be raised upward from the bottom surface of the water tank 7g without being attached to the steam introduction pipe 13, or the reflection plate 21g may be extended downward from the tank lid 12. It may be.

Embodiment 4 FIG.
FIG. 14 is an explanatory diagram for explaining a water level detection device according to Embodiment 4 of the present invention. Based on FIG. 14, the structure and operation | movement of the water level detection apparatus based on this Embodiment 4 are demonstrated. In the fourth embodiment, differences from the first to third embodiments will be mainly described, and the same components as those in the first to third embodiments are denoted by the same reference numerals. Yes. Further, in FIG. 14, an optical path of light emitted from the light emitting unit 15 h and received by the light receiving unit 16 h is indicated by arrows (solid line arrows and broken line arrows).

  FIG. 14 shows a state where a water tank 7h and a light emitting / receiving unit as an example of the water tank 7 are viewed from three directions, respectively, and FIG. 14 (a) shows the water tank 7h and the light emitting / receiving unit viewed from above. FIG. 14 (b) is a plan view showing the state, FIG. 14 (b) is a side view showing the state of the water tank 7h and the light emitting / receiving section viewed from the lateral side of the water tank 7h, and FIG. The side view which shows the state which looked at the light-receiving part from the longitudinal direction side surface of the water tank 7h is shown, respectively. In the fourth embodiment, the water level is detected by processing the internal shape of the water tank 7h.

  As shown in FIG. 14, the water level detection device according to the fourth embodiment includes a light emitting unit 15h, a light receiving unit 16h, and a water tank 7h. The light emitting unit 15h and the light receiving unit 16h have the same functions as the light emitting unit and the light receiving unit according to the first to third embodiments. The water tank 7h has a function similar to that of the water tank 7 according to the first embodiment, and two ribs 24 (the inner wall surface of the water tank 7h project from the inner wall surface of the water tank 7h). Ribs 24a and ribs 24b) are formed. The rib 24a and the rib 24b are substantially the same thickness as the side surface of the water tank, and are formed at a predetermined height so as to rise upward from the bottom surface of the water tank 7h. Moreover, the wall surface of the protrusion front-end | tip part in the inside of the water tank 7h of the rib 24a and the rib 24b is processed diagonally.

  The rib 24a and the rib 24b are formed by protruding a predetermined length at a predetermined height on a part of the inner wall surface in the longitudinal direction of the water tank 7h. And the rib 24a and the rib 24b are provided in parallel with a predetermined space | interval. Further, the projecting tip portions of the ribs 24a and 24b are formed on inclined surfaces in which the inner sides of the parallel ribs 24a and ribs 24b are inclined longer than their outer sides. That is, the projecting tip is processed obliquely by processing the side (inner side) adjacent to the rib 24a and rib 24b longer than the far side (outer side). By processing the projecting tip at an angle, the state of reflection and transmission of light depending on the presence or absence of water is changed.

  And the protrusion front-end | tip part of the rib 24a is the reflection / transmission surface 25a, and the protrusion front-end | tip part of the rib 24b is the reflection / transmission surface 25b. The light emitting part 15h is arranged on the extension line of one rib 24a and perpendicular to the tank side face, and the light receiving part 16h is on the extension line of the other rib 24b and perpendicular to the tank side face. Are arranged in various directions. The water level detection device according to the fourth embodiment is arranged at a height position corresponding to the water level position to be detected. When the position corresponding to the water level 10 in the water tank 7h is air, that is, when the water level 10 is located below the light emitting portion 15h, the optical path becomes a solid arrow 17h, and the recovered water 9 exceeds the water level 10. In other words, the optical path when the water level 10 is located above the light emitting portion 15h is a broken line arrow 18h.

Next, the operation of the water level detection device according to the fourth embodiment will be described.
The light emitting portion 15h is disposed on the side of the tank at the position of the rib 24a, and the light emitted from the light emitting portion 15h first enters the tank side surface perpendicularly and enters the tank side surface. This light travels through the rib 24a and reaches the reflection / transmission surface 25a. When the light reaching portion of the reflection / transmission surface 25a is in the air, the light is reflected, and when it is in the water, the light is transmitted. That is, when light is transmitted, the light travels into the tank and does not reach the light receiving unit 16h.

  On the other hand, when reflected, the light passes through the side surface of the rib 24a and travels in the air, enters the side surface of the facing rib 24b, passes through the rib 24b, and enters the reflection / transmission surface 25b. The incident reflection / transmission surface 25b is reflected in the air, and the light is reflected and transmitted in the water. The reflected light travels through the rib 24b, passes through the tank side surface, and reaches the light receiving unit 16h. The angles of the reflection / transmission surface 25a and the reflection / transmission surface 25b are preferably about 45 °, assuming that the refractive index of air is 1.0, the refractive index of water is 1.33, and the refractive index of the plastic of the tank material is 1.59. Here, the thickness of the rib portion serving as the optical path is limited to about 1.5 times the thickness of the tank side surface. For example, when the thickness of a general tank side surface is 2 mm, the rib thickness is about 3 mm.

  FIG. 15 is a plan view of a water tank 7h and a light emitting / receiving portion showing a modification of the rib shown in FIG. 14 as viewed from above. Based on FIG. 15, the two ribs (24a-1 and 24b-1) formed to protrude into the water tank 7h will be described. As shown in FIG. 15, the ribs 24 a-1 and 24 b-1 are shorter in the protruding direction than the ribs 24 a and 24 b shown in FIG. 14. The operation is the same as described with reference to FIG. 14, but since the optical path length of the light traveling through the ribs 24a-1 and 24b-1 is short, attenuation of the light amount due to the transmittance of the plastic can be reduced. .

  As described above, since the length of the optical path of the light traveling in the rib 24a-1 and the rib 24b-1 is shortened, the attenuation in the tank material is suppressed, the amount of light is large, and the light is received and not received. The difference in the amount of light increases, and more accurate water level detection becomes possible. At the same time, since the protruding amount of the rib 24a-1 and the rib 24b-1 is small, the inside of the water tank 7h is excellent in cleanability, and a tank shape with high design can be obtained. That is, as shown in FIGS. 14 and 15, the length of the rib in the protruding direction can be changed as appropriate. Other configurations are as described with reference to FIG.

  As described above, the water level detection device according to the fourth embodiment of the present invention is capable of detecting the water level in the water tank by interacting with the inner side surface shape of the water tank, and is outside the water tank 7h. The water level in the water tank 7h can be detected while the shape of the side surface is flat. Therefore, the water tank 7h can be molded more easily, a general molding machine can be used, and the manufacturing cost can be reduced. Moreover, since the external side surface of the water tank 7h can be manufactured flat and inexpensively, the cleaning property, handling property and design property are not inferior. In addition, a rib approximately 1.5 times the thickness of the tank side surface is provided, and a reflection / transmission surface is formed at the tip of the rib, so that it can be molded with a general molding machine and an accurate shape can be manufactured at low cost. Can do.

Embodiment 5 FIG.
FIG. 16 is an explanatory diagram for explaining a water level detection device according to Embodiment 5 of the present invention. Based on FIG. 16, the structure and operation | movement of the water level detection apparatus which concerns on this Embodiment 5 are demonstrated. In the fifth embodiment, differences from the first to fourth embodiments will be mainly described, and the same components as those in the first to fourth embodiments are denoted by the same reference numerals. Yes. Further, in FIG. 16, an optical path of light emitted from the light emitting unit 15 i and received by the light receiving unit 16 i is indicated by arrows (solid line arrows and broken line arrows).

  FIG. 16 shows a state where a water tank 7i and a light emitting / receiving unit as an example of the water tank 7 are viewed from three directions, respectively, and FIG. 16 (a) shows the water tank 7i and the light emitting / receiving unit viewed from above. FIG. 16 (b) is a plan view showing the state, FIG. 16 (b) is a side view showing the state of the water tank 7i and the light emitting / receiving section viewed from the lateral side of the water tank 7i, and FIG. The side view which shows the state which looked at the light-receiving part from the longitudinal direction side surface of the water tank 7i is shown, respectively. In the fifth embodiment, the water level is detected by processing the internal shape of the water tank 7i.

  As shown in FIG. 16, the water level detection device according to the fifth embodiment includes a light emitting unit 15i, a light receiving unit 16i, and a water tank 7i. The light emitting unit 15i and the light receiving unit 16i have the same functions as the light emitting unit and the light receiving unit according to the first to fourth embodiments. The water tank 7i has a function similar to that of the water tank 7 according to the first embodiment, and is provided on the inner wall surface of the water tank 7i by one protruding from the bottom surface of the water tank 7i toward the upper surface. Ribs 26 are formed. The height of the rib 26 is the height up to the water level to be detected. Further, the reflection / transmission surface 27 is formed such that the surface of the upper end portion of the rib 26 is inclined downward from the tank inner wall surface toward the inside of the tank, that is, inward and downward.

  The light emitting unit 15i is disposed on the outer lower side of the bottom surface of the water tank 7i at a position that emits light upward, and the light receiving unit 16i is directed in a direction substantially perpendicular to the tank side surface in the vicinity of the height at which the water level is detected. Are arranged. The rib 26 is formed upward from the bottom surface inside the tank, and is inclined so as to form an angle of about 45 ° with the side surface of the tank with the upper surface as a reflection / transmission surface 27. Further, the central portion of the reflection / transmission surface 27 is arranged so as to be the height of the water level to be detected. The optical path when the central portion of the reflection / transmission surface 27 is air is a solid arrow 17i, and the optical path when the central portion of the reflection / transmission surface 27 is underwater is a dashed arrow 18i.

Next, the operation of the water level detection device according to the fifth embodiment will be described.
The light emitting portion 15i is disposed outside the bottom surface of the water tank 7i, and light emitted upward from the light emitting portion 15i first enters the tank bottom surface vertically, passes through the tank bottom surface, and passes through the rib 26. The interior proceeds from below to above (solid arrow 17i). This light travels through the rib 26 and reaches the reflection / transmission surface 27. When the part where the light of the reflection / transmission surface 27 reaches is in the air (for example, when the water level is low and the water level does not reach the reflection / transmission surface 27), the light is reflected by the reflection / transmission surface 27 and the water tank. It proceeds toward the side surface of 7i and enters the light receiving unit 16i.

  On the other hand, when the portion where the light on the reflection / transmission surface 27 reaches is in water (for example, when the water level is high and the water level reaches the reflection / transmission surface 27), the light is transmitted through the reflection / transmission surface 27, It proceeds toward the inside of the tank 7i and does not reach the light receiving part 16i. Therefore, when the water level is lower than the reflection / transmission surface 27, the light reaches the light receiving unit 16j, and when the water level is high, the light hardly reaches the light reception unit 16j, and the water at the position of the reflection / transmission surface 27 is low. The presence or absence can be determined. Here, the thickness of the rib 26 shall be formed within about 1.5 times the thickness of the tank side surface.

  As described above, the water level detection device according to the fifth embodiment of the present invention is capable of detecting the water level in the water tank by interacting with the inner side surface shape of the water tank, and the outside of the water tank 7i. The water level in the water tank 7i can be detected while the shape of the side surface is flat. Therefore, the water tank 7i can be molded more easily, a general molding machine can be used, and the manufacturing cost can be reduced. Moreover, since the external side surface of the water tank 7i can be manufactured flat and inexpensively, the cleaning property, handling property, and design property are not inferior. In addition, a rib approximately 1.5 times the thickness of the tank side surface is provided, and a reflection / transmission surface is formed at the tip of the rib, so that it can be molded with a general molding machine and an accurate shape can be manufactured at low cost. Can do.

  Although specific embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made without departing from the scope and spirit of the present invention. For example, in the first embodiment, for convenience of explanation, the water tank has been described as the water tank 7 and the water tank 7a to the water tank 7e, and the concave portions are described as the concave portions 14a to 14e. Good. Further, as described in the third embodiment, a plurality of pairs of water level detection devices may be provided to detect the water level. Furthermore, the features of each embodiment may be applied in combination.

  Note that LEDs (Light Emitting Diodes) can be used as the light emitting elements (light emitting units 15a to 15i), and photodiodes or phototransistors can be used as the light receiving elements (light receiving units 16a to 16i). . The wavelength of light may be visible light or near infrared light. Although the case where the water level detection apparatus which concerns on embodiment was applied to the heating cooker was demonstrated to the example, it is not limited to this, The application to the various apparatuses which perform a water level detection is possible.

  Examples of home appliances that perform water level detection include a dehumidifier, a humidifier, and a water tank of an automatic ice maker in a refrigerator. Further, even if it is not water, it is possible to detect other liquids and solids depending on the refractive index and transmittance, and it can be easily applied to the detection of the amount of liquid in the antifreeze liquid tank and the amount of dust in the garbage tank of the cleaner. That is, in the said embodiment, although demonstrated as what detects the height position (water level) of the water stored in the inside for the water tank as an example, this invention is not a water tank but water. Even in a liquid tank in which the liquid is stored, the height position of the liquid can be detected in the same manner.

It is a side view which shows the state which looked at the internal structure of the heating cooker which concerns on Embodiment 1 from the side surface. It is a perspective view which shows the external appearance shape of a water tank. It is explanatory drawing for demonstrating a water tank and a light emission / reception part. It is an enlarged plan view which expands and shows a part of water tank. It is explanatory drawing for demonstrating the mechanism of reflection / transmission of light. It is a characteristic view which shows the correlation with the incident angle of light, and a reflectance. It is an enlarged plan view which expands and shows a part of example of a water tank. It is an enlarged plan view which expands and shows a part of example of a water tank. It is an enlarged plan view which expands and shows a part of example of a water tank. It is explanatory drawing for demonstrating an example of the water tank which formed the dent around the position which wants to detect a water level. It is an enlarged plan view which expands and shows a part of water tank which cannot detect a water level. It is explanatory drawing for demonstrating the water level detection apparatus which concerns on Embodiment 2. FIG. It is explanatory drawing for demonstrating the water level detection apparatus which concerns on Embodiment 3. FIG. It is explanatory drawing for demonstrating the water level detection apparatus which concerns on Embodiment 4. FIG. It is the top view which looked at the water tank and light emitting / receiving part which show the modification of the rib shown in FIG. 14 from upper direction. It is explanatory drawing for demonstrating the water level detection apparatus which concerns on Embodiment 5. FIG.

Explanation of symbols

  1 Main body, 2 Rice cooker, 3 Lid, 4 Inner lid, 5 Heated body, 6 Steam pipe, 7 Water tank, 7a Water tank, 7b Water tank, 7c Water tank, 7d Water tank, 7e Water tank, 7f Water tank 7g water tank, 7h water tank, 7i water tank, 8 water level detection device, 8-1 water level detection device, 8-2 water level detection device, 8-3 water level detection device, 9 recovered water, 10 water level, 11 control unit, 12 tank lid, 13 steam inlet pipe, 14 recess, 14a recess, 14b recess, 14c recess, 14d recess, 14e recess, 15 'light emitting part, 15a light emitting part, 15b light emitting part, 15c light emitting part, 15d light emitting part, 15e light emitting Part, 15f light emitting part, 15g light emitting part, 15g-1 light emitting part, 15g-2 light emitting part, 15g-3 light emitting part, 15h light emitting part, 15i light emitting part, 16 ' Light receiving part, 16a Light receiving part, 16e Light receiving part, 16f Light receiving part, 16g Light receiving part, 16g-1 Light receiving part, 16g-2 Light receiving part, 16g-3 Light receiving part, 16h Light receiving part, 16i Light receiving part, 17 arrow, 17a arrow , 17b arrow, 17c arrow, 17f arrow, 17g arrow, 17g-1 arrow, 17g-2 arrow, 17g-3 arrow, 17h arrow, 17i arrow, 18 arrow, 18c arrow, 18e arrow, 18g arrow, 18g-1 arrow , 18h arrow, 18i arrow, 19′-1 incident surface, 19′-2 incident surface, 19a-1 incident surface, 19a-2 incident surface, 19b-1 incident surface, 19b-2 incident surface, 19c-1 incident surface 19c-2 incident surface, 19d-1 incident surface, 19d-2 incident surface, 19e-1 incident surface, 19e-2 incident surface, 20'-1 reflection / transmission surface, 20'-2 reflection / transmission surface, 20a-1 reflection / transmission surface, 20a-2 reflection / transmission surface, 20b-1 reflection / transmission surface, 20b-2 reflection / transmission surface, 20c-1 reflection / transmission surface, 20c-2 reflection / transmission surface, 20d-1 reflection / transmission surface, 20d-2 reflection / transmission surface, 21f reflection plate, 21g reflection plate, 22a intersection, 22b intersection, 23a intersection, 23b intersection, 23c intersection, 23d intersection, 23e intersection, 23f intersection, 24a rib, 24a -1 rib, 24b rib, 24b-1 rib, 25a reflection transmission surface, 25b reflection transmission surface, 26 rib, 27 reflection transmission surface, 100 cooking device.

Claims (22)

A water tank that is at least partly configured with a reflection / transmission part in which the amount of reflection and transmission of light changes depending on the presence or absence of liquid;
A light emitting unit that emits light toward the reflective transmission unit;
A light receiving unit that generates a signal according to the amount of light received through the reflection and transmission unit;
A water amount determination unit for determining the amount of water stored in the water tank from the signal of the light receiving unit,
The water tank is
Having a recess recessed toward the inside of the water tank side surface;
The recess is
It has an inclined part inclined toward the inner side of the water tank, and the thickness of at least a part of the side surface of the water tank constituting the inclined part is different from the thickness of the other part of the side surface of the water tank. ,
The water level detection device, wherein the inclined portion is the reflection / transmission portion. The thickness of the side surface of the water tank that constitutes the inclined portion,
The water level detection device according to claim 1, wherein a thickness on a bottom side of the concave portion is made thicker than a start portion side of the concave portion. The thickness of the side surface of the water tank that constitutes the inclined portion,
The water level detection device according to claim 2, wherein the water level is gradually increased from the start side of the recess toward the bottom side of the recess. The part which made the board thickness the same is provided in a part from the start part side of the said recessed part to the bottom part side of the said recessed part in the said water tank side surface which comprises the said inclination part. The water level detection device described in 1. A part thinner than the thickness on the bottom side of the recess is provided in a part from the start side of the recess to the bottom side of the recess on the side surface of the water tank constituting the inclined portion. The water level detection device according to claim 2. The thickness of the thickest part of the inclined part is:
The water level detection device according to any one of claims 1 to 5, wherein the thickness is within twice the thickness of the thinnest portion of the inclined portion. The water level detection according to any one of claims 1 to 6, wherein at least a portion from the bottom side of the concave portion of the inclined portion to a portion having a different thickness of the inclined portion is formed by the reflection / transmission portion. apparatus. The recess,
It forms continuously from the upper part of the said water tank to the lower part. The water level detection apparatus as described in any one of Claims 1-7 characterized by the above-mentioned. The recess,
It forms in a part of position periphery which wants to detect the water level of the said water tank. The water level detection apparatus as described in any one of Claims 1-7 characterized by the above-mentioned. The light emitting unit and the light receiving unit are:
The water level according to any one of claims 1 to 9, wherein the water level of the water tank in which the concave portion is formed is arranged so as to be substantially perpendicular to the outer side surface in the vicinity of the position where the water level is to be detected. Detection device. A water tank that is at least partly configured with a reflection / transmission part in which the amount of reflection and transmission of light changes depending on the presence or absence of liquid;
A light emitting unit that emits light toward the reflective transmission unit;
A light receiving unit that generates a signal according to the amount of light received through the reflection and transmission unit;
A water amount determination unit for determining the amount of water stored in the water tank from the signal of the light receiving unit,
A part of the inner wall surface of the water tank is provided with two ribs protruding into the water tank so as to be parallel,
Each tip of the rib is
It is formed in the inclined surface which made the inner side of two parallel ribs longer than those outer sides,
The inclined surface is used as the reflection / transmission part. The water level detection device according to claim 11, wherein the length of the rib in the protruding direction is changeable. The light emitting unit and the light receiving unit are:
The water level detection device according to claim 11 or 12, wherein the water level detection device is arranged at a substantially right angle to an outer side surface near a position where the water level of the water tank in which the rib is formed is to be detected. A water tank that is at least partly configured with a reflection / transmission part in which the amount of reflection and transmission of light changes depending on the presence or absence of liquid;
A light emitting unit that emits light toward the reflective transmission unit;
A light receiving unit that generates a signal according to the amount of light received through the reflection and transmission unit;
A water amount determination unit for determining the amount of water stored in the water tank from the signal of the light receiving unit,
A rib having a predetermined height rising from the bottom to the top of the water tank is provided on a part of the inner wall surface of the water tank,
The upper end of the rib is
It is formed on an inclined surface that is inclined downward from the inner wall surface of the water tank to the inside of the tank,
The inclined surface is used as the reflection / transmission part. The light emitting unit
The rib is formed so as to be substantially perpendicular to the outside of the bottom surface of the water tank,
The light receiving unit is
The water level detection device according to claim 14, wherein the water level detection device is disposed at a substantially right angle to an outer side surface of the water tank near a position where the tip of the rib is formed. A water tank that is at least partly configured with a reflection / transmission part in which the amount of reflection and transmission of light changes depending on the presence or absence of liquid;
A light emitting unit that emits light toward the reflective transmission unit;
A reflector provided in the water tank and reflecting the light emitted from the light emitting section;
A light receiving unit that generates a signal according to the amount of light that is reflected by the reflection plate and received through the reflection / transmission unit;
A water amount determination unit for determining the amount of water stored in the water tank from the signal of the light receiving unit,
The light emitting unit
Arranged to face the reflecting plate through the side surface of the water tank,
The light receiving unit is
When the water at a predetermined water level is not stored in the tank, the light from the light emitting part reflected by the reflecting plate can be received, and the water at a predetermined water level is stored in the tank. The water level detection device is located at a position where light from the light emitting unit does not reach due to total reflection of the water surface, and is disposed outside the side surface of the water tank. Comprising at least two of the light emitting part and the light receiving part,
The water level detection device according to claim 16, wherein a plurality of water levels stored in the water tank can be detected. The water level detection device according to claim 17, wherein one detection range and the other detection range of the pair of the light emitting unit and the light receiving unit overlap each other. The water level detection device according to any one of claims 1 to 18, and
A steam guideway for guiding the generated steam to the water tank;
A steam recovery device, comprising: a control unit that informs the user to prompt the treatment of water in the water tank when a predetermined water level is detected by the water level detection device. The water level detection device according to any one of claims 16 to 18,
A steam guideway for guiding the generated steam to the water tank;
A control unit for notifying so as to prompt treatment of water in the water tank when a predetermined water level is detected by the water level detection device,
The reflector is
A steam recovery apparatus attached to the steam guide path. At least part of the steam guideway,
21. The vapor recovery apparatus according to claim 20, wherein the function of the reflecting plate is also made of glossy metal or gloss plated or painted plastic. A steam cooker comprising the steam recovery apparatus according to any one of claims 19 to 21.

Images