Patent Publication Number: US-2021178108-A1

Title: Humidification apparatus and humidification and blowing apparatus for respiratory organs including the same

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a continuation of International Application No. PCT/JP2019/031966 filed on Aug. 14, 2019 which claims priority from Japanese Patent Application No. 2018-160393 filed on Aug. 29, 2018. The contents of these applications are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     The present disclosure relates to a humidification apparatus that humidifies gas to be humidified by vaporizing water and a humidification and blowing apparatus for respiratory organs including the humidification apparatus. 
     Various humidification mechanisms have conventionally been invented, and an optimal humidification mechanism among them is selected for use depending on a purpose of use of an applied product. A humidification and blowing apparatus for respiratory organs represents one of a group of products to which the humidification mechanism is applied. This humidification and blowing apparatus for respiratory organs includes a continuous positive airway pressure (CPAP) apparatus, a steam inhaler, and an oxygen inhaler. 
     The CPAP apparatus among them is used for treatment of sleep apnea syndrome and sends air into the airway of a sleeping user. More specifically, the CPAP apparatus is provided with a blower therein and keeps sending air through an air tube to a mask attached to the nose or the mouth of the user. The CPAP apparatus may incorporate a humidification apparatus, and the CPAP apparatus incorporating the humidification apparatus humidifies air sent to the user. 
     For example, a CPAP apparatus disclosed in Japanese Patent Laying-Open No. 2014-166495 (PTL 1) is available as the CPAP apparatus incorporating the humidification apparatus. In the CPAP apparatus disclosed in this literature, a heater is provided under a tank where water is stored, and water stored in the tank is heated as the heater is driven. An air passage is formed such that an air current generated by a blower passes through an upper portion of the tank, so that water vapor generated by heating by the heater described above is contained in the air current and humidified air is thus sent into the airway of the user. 
     PTL 1: Japanese Patent Laying-Open No. 2014-166495 
     BRIEF SUMMARY 
     In the humidification apparatus incorporated in the humidification and blowing apparatus for respiratory organs represented by the CPAP apparatus described above, however, a large amount of water vapor does not have to be generated at once, whereas a small amount of water vapor should continually be generated. The humidification apparatus as disclosed in the literature is not necessarily effective from a point of view of energy efficiency. 
     Humidification apparatuses to be incorporated in the humidification and blowing apparatuses for respiratory organs are various in construction in addition to the construction described above. The apparatus constructions, however, are complicated, or an expensive component is included. Therefore, from a point of view of reduction in size or manufacturing cost, those constructions are far from being effective. Furthermore, most of these humidification apparatuses are poor in ease of maintenance such as cleaning of the inside of the apparatuses that should be kept clean. 
     Therefore, the present disclosure is made in view of the problems described above, and an object thereof is to provide a compact humidification apparatus capable of efficient humidification and a humidification and blowing apparatus for respiratory organs including the same. 
     A humidification apparatus based on a first aspect of the present disclosure includes a flexible reservoir, a vaporizer, a water supply path, an accommodation portion, a pressurization source, and a controller. The flexible reservoir is in a shape of a bag where water is stored. The vaporizer vaporizes supplied water. The water supply path has one end detachably connected to the flexible reservoir and the other end connected to the vaporizer. In the accommodation portion, the flexible reservoir is accommodated. The pressurization source compresses the flexible reservoir by pressurizing a space outside the flexible reservoir and inside the accommodation portion. The controller controls an operation of the pressurization source. In the humidification apparatus based on the first aspect of the present disclosure, water stored in the flexible reservoir is supplied to the vaporizer through the water supply path by compressive force with which the flexible reservoir is compressed. 
     In the humidification apparatus based on the first aspect of the present disclosure, preferably, the pressurization source includes an ambient air introduction source that introduces ambient air into the space outside the flexible reservoir and inside the accommodation portion. 
     In the humidification apparatus based on the first aspect of the present disclosure, preferably, the ambient air introduction source includes a piezoelectric pump. 
     In the humidification apparatus based on the first aspect of the present disclosure, the accommodation portion may be defined by a pressure bulkhead. 
     In the humidification apparatus based on the first aspect of the present disclosure, the accommodation portion may be defined by a bag-shaped member. In that case, preferably, the flexible reservoir and the bag-shaped member are joined and integrated with each other to be in a two-ply bag structure. 
     A humidification apparatus based on a second aspect of the present disclosure includes an elastic reservoir, a vaporizer, a water supply path, a valve, a valve driver, and a controller. The elastic reservoir is in a shape of a bag where water is stored. The vaporizer vaporizes supplied water. The water supply path has one end detachably connected to the elastic reservoir and the other end connected to the vaporizer. The valve is provided in the water supply path. The valve in an open state allows flow of water through the water supply path and the valve in a closed state cuts off flow of water through the water supply path. The valve driver switches the valve to any of the open state and the closed state. The controller controls an operation of the valve driver. In the humidification apparatus based on the second aspect of the present disclosure, the elastic reservoir is elastically inflated and deformed by injection of water thereinto, so that water stored in the elastic reservoir is supplied to the vaporizer through the water supply path in the open state owing to elastic resilience of the elastic reservoir. 
     In the humidification apparatuses based on the first and second aspects of the present disclosure, preferably, a check valve that allows movement of fluid from the water supply path toward the vaporizer and restricts movement of fluid from the vaporizer toward the water supply path is provided at the other end. 
     In the humidification apparatuses based on the first and second aspects of the present disclosure, preferably, a flow path defining surface and/or an end surface of the other end are/is made water repellent. 
     In the humidification apparatuses based on the first and second aspects of the present disclosure, preferably, an orifice is provided in the water supply path. 
     In the humidification apparatuses based on the first and second aspects of the present disclosure, preferably, the vaporizer includes a heater that heats supplied water. 
     The humidification apparatuses based on the first and second aspects of the present disclosure preferably further include a temperature detector that detects a temperature of the heater and a power consumption detector that detects power consumed by the heater. In that case, preferably, the controller controls output from the heater to maintain the temperature of the heater at a constant temperature based on the temperature detected by the temperature detector. In that case, preferably, the controller controls an amount of supply of water to the vaporizer based on power consumption detected by the power consumption detector to adjust an amount of humidification. 
     A humidification and blowing apparatus for respiratory organs based on the present disclosure includes a blowing apparatus including a blower that sends gas into an airway of a user and any of the humidification apparatuses based on the first and second aspects of the present disclosure. An air current generated as the blower is driven is humidified by the humidification apparatus. 
     The humidification and blowing apparatus for respiratory organs based on the present disclosure may further include a breathing state sensing portion that senses a breathing state of the user. In that case, preferably, the controller determines whether the user is performing an inhalation operation or an exhalation operation based on a result of sensing by the breathing state sensing portion. In that case, preferably, when the controller determines that the user is performing the inhalation operation, the humidification apparatus performs a humidification operation, and when the controller determines that the user is performing the exhalation operation, the humidification apparatus stops the humidification operation. 
     The humidification apparatus based on the first aspect of the present disclosure may further include a pressure sensing portion that senses a pressure in the space outside the flexible reservoir and inside the accommodation portion. In that case, preferably, the controller controls an amount of supply of water to the vaporizer based on the pressure sensed by the pressure sensing portion to adjust an amount of humidification. 
     According to the present disclosure, a compact humidification apparatus capable of efficient humidification and a humidification and blowing apparatus for respiratory organs including the same can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a manner of attachment and detachment of a blowing unit and a humidification unit of a CPAP apparatus according to a first embodiment. 
         FIG. 2  is a perspective view at a different angle, of the manner of attachment and detachment shown in  FIG. 1 . 
         FIG. 3  is a perspective view showing a state that the blowing unit has been attached to the humidification unit in the CPAP apparatus according to the first embodiment. 
         FIGS. 4A and 4B  are diagrams schematically showing a first state of use and a second state of use of the CPAP apparatus according to the first embodiment. 
         FIG. 5  is a diagram showing a configuration of a functional block in the first state of use of the CPAP apparatus according to the first embodiment. 
         FIG. 6  is a schematic cross-sectional view in the first state of use of the CPAP apparatus according to the first embodiment. 
         FIG. 7  is a schematic cross-sectional view along the line VII-VII shown in  FIG. 6 . 
         FIG. 8  is a flowchart showing an operation of a controller in the first state of use of the CPAP apparatus according to the first embodiment. 
         FIGS. 9A, 9B, and 9C  are timing charts for illustrating a humidification operation by the CPAP apparatus according to the first embodiment. 
         FIG. 10  is a schematic cross-sectional view in the first state of use of a CPAP apparatus according to a second embodiment. 
         FIGS. 11A, 11B, 11C, and 11D  are schematic cross-sectional views showing an exemplary construction of a drain outlet of a water supply path shown in  FIG. 10 . 
         FIG. 12  is a schematic cross-sectional view in the first state of use of a CPAP apparatus according to a third embodiment. 
         FIG. 13  is a diagram showing a configuration of a functional block in the first state of use of a CPAP apparatus according to a fourth embodiment. 
         FIG. 14  is a schematic cross-sectional view in the first state of use of the CPAP apparatus according to the fourth embodiment. 
         FIG. 15  is a flowchart showing an operation of the controller in the first state of use of the CPAP apparatus according to the fourth embodiment. 
         FIGS. 16A, 16B, and 16C  are timing charts for illustrating a humidification operation by the CPAP apparatus according to the fourth embodiment. 
         FIG. 17  is a schematic cross-sectional view in the first state of use of a CPAP apparatus according to a fifth embodiment. 
         FIG. 18  is a diagram showing a configuration of a functional block in the first state of use of the CPAP apparatus according to the fifth embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment of the present disclosure will be described in detail below with reference to the drawings. Embodiments shown below illustrate an application of the present disclosure to a CPAP apparatus as a humidification and blowing apparatus for respiratory organs and a humidification apparatus incorporated therein. In the embodiments shown below, the same or common elements in the drawings have the same reference characters allotted and description thereof will not be repeated. 
     First Embodiment 
       FIG. 1  is a perspective view showing a manner of attachment and detachment of a blowing unit and a humidification unit of a CPAP apparatus according to a first embodiment of the present disclosure and  FIG. 2  is a perspective view at a different angle, of the manner of attachment and detachment shown in  FIG. 1 .  FIG. 3  is a perspective view showing a state that the blowing unit has been attached to the humidification unit in the CPAP apparatus according to the present embodiment. A schematic construction of a CPAP apparatus  1 A according to the present embodiment and a manner of attachment and detachment thereof will initially be described with reference to  FIGS. 1 to 3 . 
     As shown in  FIGS. 1 to 3 , CPAP apparatus  1 A includes a blowing unit  100  as a blowing apparatus and a humidification unit  200 A as a humidification apparatus. Blowing unit  100  mainly includes a blower  140  (see  FIGS. 5 to 7 ) and humidification unit  200 A is mainly provided with a pressurization chamber  216  and a vaporization chamber  217  (see  FIGS. 6 and 7 ) that make up a humidification mechanism. 
     Humidification unit  200 A is attachable to and detachable from blowing unit  100 . CPAP apparatus  1 A according to the present embodiment can be used in two states of a state that humidification unit  200 A is attached to blowing unit  100  and a state that humidification unit  200 A is not attached to blowing unit  100 . 
     CPAP apparatus  1 A is constituted of a plurality of divided units and the plurality of units are attachable to and detachable from each other so that high convenience is exhibited not only at home but also in staying out. At home, humidification unit  200 A is attached to blowing unit  100  so that CPAP apparatus  1 A can be used in the first state of use described above. In staying out, CPAP apparatus  1 A can be used in the second state of use described above without attaching humidification unit  200 A to blowing unit  100 . 
     In CPAP apparatus  1 A according to the present embodiment, as blowing unit  100  is placed on humidification unit  200 A, humidification unit  200 A is attached to blowing unit  100 . 
     Blowing unit  100  has a low-profile outer geometry substantially like a parallelepiped and has an outer shell formed from a first housing  110 . First housing  110  includes an upper surface and a lower surface located as being aligned in a vertical direction during use and four side surfaces connecting the upper surface and the lower surface to each other. 
     The upper surface of first housing  110  defines an operation surface  111  where an operation portion  131  is provided. The lower surface of first housing  110  defines a placement surface  112  to be placed on humidification unit  200 A in a first state of use which will be described later and placed on a floor surface or a table in a second state of use which will be described later. One of the four side surfaces of first housing  110  defines a first connection surface  113  connected to humidification unit  200 A in the first state of use which will be described later. 
     Humidification unit  200 A has an elongated outer geometry substantially like a parallelepiped and has an outer shell formed from a second housing  210 . Second housing  210  includes an upper surface and a lower surface located as being aligned in the vertical direction during use and four side surfaces connecting the upper surface and the lower surface to each other, and a protrusion that protrudes upward is provided in one of four corners of the upper surface. 
     The lower surface of second housing  210  defines a placement surface to be placed on a floor surface or a table in the first state of use which will be described later. A portion except for the above-described protrusion of the upper surface of second housing  210  defines a stage surface  212  on which blowing unit  100  is carried in the first state of use which will be described later. An opening  212   a  is provided at a prescribed position in stage surface  212 . Opening  212   a  communicates with pressurization chamber  216  which will be described later, and a flexible reservoir  241  (see  FIGS. 5 to 7 ) which will be described later is put into and taken out of pressurization chamber  216  therethrough. A lid  214  is attachable to opening  212   a  and opening  212   a  is normally closed by lid  214 . 
     One of side surfaces of the protrusion described above defines a tube connection surface  211  to which an air tube  300  (see  FIGS. 4A, 4B and 5 ) is connected in the first state of use which will be described later and another one of the side surfaces of the protrusion described above defines a second connection surface  213  connected to blowing unit  100  in the first state of use which will be described later. 
     First connection surface  113  of first housing  110  is provided with a first inlet  121  for introducing air from the outside of first housing  110  and a first outlet  122  for emitting air from the inside of first housing  110 . 
     Second connection surface  213  of second housing  210  is provided with a second inlet  221  for introducing air from the outside of second housing  210  and tube connection surface  211  of second housing  210  is provided with a second outlet  222  for emitting air from the inside of second housing  210 . At prescribed positions in the side surface of second housing  210 , a piezoelectric pump  260  as an ambient air introduction source for intake of air as ambient air from the outside of second housing  210  into after-mentioned pressurization chamber  216  provided inside second housing  210  and an electromagnetic valve  270  as an exhaust valve for emitting air from pressurization chamber  216  to the outside of second housing  210  are provided. Piezoelectric pump  260  as the ambient air introduction source corresponds to the pressurization source that pressurizes pressurization chamber  216 . 
     As set forth above, while humidification unit  200 A is attached to blowing unit  100  by placing blowing unit  100  on humidification unit  200 A as shown in  FIG. 3 , placement surface  112  of first housing  110  is located as being opposed to stage surface  212  of second housing  210  and first connection surface  113  of first housing  110  is located as being opposed to second connection surface  213  of second housing  210 . Therefore, first outlet  122  provided in first connection surface  113  of first housing  110  is connected to second inlet  221  provided in second connection surface  213  of second housing  210 . Since first inlet  121  provided in first housing  110  is not covered with second housing  210  even in that state, the first inlet is open toward the outside. 
     While humidification unit  200 A is not attached to blowing unit  100 , first connection surface  113  of first housing  110  is exposed to the outside. Therefore, first inlet  121  and first outlet  122  provided in first connection surface  113  of first housing  110  are both open toward the outside. 
       FIGS. 4A and 4B  are diagrams schematically showing a state of use of the CPAP apparatus according to the present embodiment, with  FIGS. 4A and 4B  showing the first state of use and the second state of use, respectively. The first state of use and the second state of use of CPAP apparatus  1 A according to the present embodiment will now be described with reference to  FIGS. 4A and 4B . 
     As shown in  FIG. 4A , in the first state of use, CPAP apparatus  1 A is used with humidification unit  200 A being attached to blowing unit  100  as described above. In that case, air tube  300  has one end connected to second outlet  222  provided in humidification unit  200 A and has the other end connected to mask  400 . 
     Though details will be described later, in the first state of use, blower  140  provided in blowing unit  100  is driven to suction air through first inlet  121  provided in blowing unit  100  into CPAP apparatus  1 A and suctioned air is emitted from second outlet  222  provided in humidification unit  200 A to the outside of CPAP apparatus  1 A. Air emitted from second outlet  222  is thus sent into the airway of a user through air tube  300  and mask  400 . 
     As shown in  FIG. 4B , in the second state of use, CPAP apparatus  1 A is used with humidification unit  200 A not being attached to blowing unit  100  as described above. In that case, air tube  300  has one end connected to first outlet  122  provided in blowing unit  100  and the other end connected to mask  400 . 
     In the second state of use, blower  140  provided in blowing unit  100  is driven to suction air through first inlet  121  provided in blowing unit  100  into CPAP apparatus  1 A and suctioned air is emitted from first outlet  122  provided in blowing unit  100  to the outside of CPAP apparatus  1 A. Air emitted from first outlet  122  is thus sent into the airway of the user through air tube  300  and mask  400 . 
     Mask  400  is attached, for example, as being applied to cover the nose or the mouth of a user. Mask  400  of a shape or a structure in conformity with a user can be selected from among various types of masks, and the shape or the structure shown in  FIGS. 4A and 4B  are merely by way of example. 
     CPAP apparatus  1 A is an apparatus that keeps sending air into the airway to open the airway in order to prevent apnea during sleep while sending of air is timed to coincide with breathing by the user. Therefore, in CPAP apparatus  1 A, in any of the first state of use and the second state of use described above, a controller  130  (see  FIG. 5 ) which will be described later carries out various types of control such as feedback control or feedforward control based on a flow rate and a pressure detected by a flow rate sensor  133  and a pressure sensor  134  (see  FIG. 5 ) which will be described later. The number of revolutions of blower  140  is thus increased or decreased to adjust an amount of sent air, so that the user is prevented from falling into apnea during sleep. 
     CPAP apparatus  1 A according to the present embodiment is mainly characterized by humidification unit  200 A as the humidification apparatus. Therefore, of the first state of use and the second state of use described above, description will be given below, with focus being placed on the first state of use in which humidification unit  200 A is used in addition to blowing unit  100 , and description of the second state of use in which only blowing unit  100  is used without using humidification unit  200 A is not provided. 
       FIG. 5  is a diagram showing a configuration of a functional block in the first state of use of the CPAP apparatus according to the present embodiment. The configuration of the functional block in the first state of use of CPAP apparatus  1 A according to the present embodiment will now be described with reference to  FIG. 5 . 
     As shown in  FIG. 5 , CPAP apparatus  1 A includes controller  130 , operation portion  131 , a temperature and humidity sensor  132 , flow rate sensor  133 , pressure sensor  134 , a power consumption sensor  135 , blower  140 , a silencer  150 , a flexible reservoir  241 , a heater  250 , a temperature sensor  251 , piezoelectric pump  260 , and electromagnetic valve  270 . Among these, controller  130 , operation portion  131 , temperature and humidity sensor  132 , flow rate sensor  133 , pressure sensor  134 , power consumption sensor  135 , blower  140 , and silencer  150  are provided in blowing unit  100 . Flexible reservoir  241  is accommodated in after-mentioned pressurization chamber  216  provided in humidification unit  200 A. Heater  250 , temperature sensor  251 , piezoelectric pump  260 , and electromagnetic valve  270  are provided in humidification unit  200 A. Humidification unit  200 A is also provided with a water supply path  230  which will be described later. 
     First housing  110  of blowing unit  100  is provided with a first flow path  120  in addition to first inlet  121  and first outlet  122  described above. First flow path  120  connects first inlet  121  and first outlet  122  to each other. 
     First flow path  120  is provided with blower  140 . For example, a centrifugal fan is adopted as blower  140 . Blower  140  is provided in an after-mentioned blower chamber  117  (see  FIGS. 6 and 7 ) provided in first housing  110 , and thus arranged over first flow path  120 . 
     Blower  140  includes a casing  142 , and casing  142  is provided with a suction port  143  and an emission port  144  of blower  140 . Therefore, first flow path  120  includes an upstream flow path portion  120 A that connects first inlet  121  provided in first housing  110  and suction port  143  provided in blower  140  to each other and a downstream flow path portion  120 B that connects emission port  144  provided in blower  140  and first outlet  122  provided in first housing  110  to each other. 
     Upstream flow path portion  120 A which is a portion of first flow path  120  located between first inlet  121  and suction port  143  is provided with silencer  150 . Silencer  150  suppresses leakage of noise (operating noise of a drive motor provided in blower  140  or wind noise) generated in blower  140  to the outside through first inlet  121 , details of which will be described later. 
     Second housing  210  of humidification unit  200 A is provided with a second flow path  220  in addition to second inlet  221  and second outlet  222  described above. Second flow path  220  connects second inlet  221  and second outlet  222  to each other. 
     In second flow path  220 , a humidification mechanism which will be described later humidifies air that passes therethrough. In the first state of use, moderate moisture (that is, water vapor  501  shown with a wavy dashed arrow in a figure) is thus provided to air sent toward the airway of a user. 
     Water supply path  230  is provided in humidification unit  200 A as described above. Water supply path  230  connects flexible reservoir  241  and heater  250  as the vaporizer to each other, and serves to send water stored in flexible reservoir  241  to heater  250 . Flexible reservoir  241  is formed from a bag-shaped member where water is stored, and it is attachable to and detachable from water supply path  230 . 
     Heater  250  serves to vaporize supplied water by heating the same. Piezoelectric pump  260  is an air pump that delivers air. Though details of piezoelectric pump  260  will be described later, the piezoelectric pump serves to take in air outside humidification unit  200 A and to pressurize pressurization chamber  216  which will be described later. Though details of electromagnetic valve  270  will be described later, the electromagnetic valve serves to emit air in pressurization chamber  216  to the outside of humidification unit  200 A and to reduce a pressure in pressurization chamber  216 . 
     Controller  130  includes, as its main constituent elements, a central processing unit (CPU) that executes a program, a read only memory (ROM)/random access memory (RAM), driving units that drive blower  140 , heater  250 , piezoelectric pump  260 , and electromagnetic valve  270 , respectively, and a computing unit that performs various types of computation based on various types of information provided from temperature and humidity sensor  132 , flow rate sensor  133 , pressure sensor  134 , power consumption sensor  135 , and temperature sensor  251 . The ROM/RAM includes a ROM that stores data in a non-volatile manner and a RAM that stores in a volatile manner, data generated as a result of execution of the program by the CPU or data provided through operation portion  131 . The constituent elements of controller  130  are connected to one another through a data bus. 
     Processing in the CPU is performed by hardware and software executed by the CPU. Such software is stored in advance in the ROM/RAM. Software also allows acceptance of an operation onto operation portion  131 , control of the drive motor that drives blower  140 , control of heater  250 , control of piezoelectric pump  260 , control of electromagnetic valve  270 , and various types of computation described above. 
     Controller  130 , blower  140 , heater  250 , piezoelectric pump  260 , and electromagnetic valve  270  are supplied with electric power by a not-shown internal power supply or a not-shown external power supply. For example, a not-shown alternating current (AC) adapter is used for connection with the external power supply. 
     Temperature and humidity sensor  132  is a sensor for measuring a temperature and a humidity of air introduced from the outside of CPAP apparatus  1 A and subsequently sent into the airway of a user, and it is provided in upstream flow path portion  120 A in first flow path  120 . The temperature and the humidity of air detected by temperature and humidity sensor  132  is provided to controller  130  and mainly used for a humidification operation by the humidification mechanism. 
     Flow rate sensor  133  is a sensor for measuring a flow rate of air between CPAP apparatus  1 A and air tube  300 , and pressure sensor  134  is a sensor for measuring a pressure of air sent from blower  140 . Flow rate sensor  133  and pressure sensor  134  correspond to the breathing state sensing portion and both of them are provided in downstream flow path portion  120 B in first flow path  120 . 
     Though detailed description is not provided, the flow rate and the pressure detected by flow rate sensor  133  and pressure sensor  134  are provided to controller  130  and controller  130  carries out control such as feedback control or feedforward control based on the flow rate and the pressure to increase or decrease the number of revolutions of blower  140 . The flow rate and the pressure of air detected by flow rate sensor  133  and pressure sensor  134  are used also for the humidification operation by the humidification mechanism. 
     Power consumption sensor  135  is a sensor for measuring electric power supplied to heater  250 , and it includes, for example, a current monitor. Power consumption detected by power consumption sensor  135  is provided to controller  130  and used mainly for the humidification operation by the humidification mechanism. 
     Temperature sensor  251  is a sensor for measuring a temperature of heater  250  and provided adjacently to heater  250 . The temperature of heater  250  detected by temperature sensor  251  is provided to controller  130  and used mainly for the humidification operation by the humidification mechanism. 
     CPAP apparatus  1 A may separately be provided with a display implemented by a liquid crystal display (LCD) or an organic electro-luminescence (EL) display. The display may be provided in blowing unit  100  or humidification unit  200 A. Operation portion  131  does not have to be provided as a button in a physical shape as shown in  FIGS. 1 to 3  but may be implemented, for example, by a touch panel provided on a display surface of the LCD. A button in operation portion  131  other than a button to switch ON and OFF the power supply of CPAP apparatus  1 A may be provided in humidification unit  200 A. 
     As shown in  FIG. 5 , in the first state of use, first outlet  122  provided in first housing  110  and second inlet  221  provided in second housing  210  are connected to each other. In the first state of use, second flow path  220  is thus connected to a downstream side of first flow path  120 . 
     Therefore, in the first state of use, as blower  140  is driven, air suctioned through first inlet  121  passes through first flow path  120  and second flow path  220  in this order and is emitted from second outlet  222 . Air emitted from second outlet  222  is thereafter sent into the airway of a user through air tube  300  and mask  400 . In the first state of use, first inlet  121  functions as an air intake port through which air is suctioned into the inside of CPAP apparatus  1 A and second outlet  222  functions as an exhaust port through which air is emitted from the inside of CPAP apparatus  1 A. 
       FIG. 6  is a schematic cross-sectional view in the first state of use of the CPAP apparatus according to the present embodiment and  FIG. 7  is a schematic cross-sectional view along the line VII-VII shown in  FIG. 6 . A detailed structure of CPAP apparatus  1 A according to the present embodiment and a flow of air in the inside of CPAP apparatus  1 A in the first state of use will be described below with reference to  FIGS. 6 and 7 .  FIGS. 6 and 7  schematically show a flow of air generated by an operation of blower  140  with an arrow. 
     As shown in  FIGS. 6 and 7 , a space within first housing  110  of blowing unit  100  is divided into a plurality of chambers by providing various walls or hoses. The plurality of chambers include a wide portion  115 , a narrow portion  116 , and a blower chamber  117 , and wide portion  115 , narrow portion  116 , and blower chamber  117  correspond to upstream flow path portion  120 A described above. 
     As shown in  FIG. 6 , wide portion  115  is provided adjacently to first inlet  121  provided in first connection surface  113  of first housing  110 . A cross-sectional area of wide portion  115  orthogonal to a direction of flow of air is relatively large to reduce pressure loss that may be caused at first inlet  121 . The cross-sectional area of wide portion  115  orthogonal to the direction of flow of air is larger than a cross-sectional area of after-mentioned narrow portion  116  orthogonal to the direction of flow of air. 
     At first inlet  121 , a filter  170  for catching a foreign matter such as dust contained in air is provided, and a filter cover  171  that defines a part of first housing  110  is attached to first connection surface  113  in order to fix filter  170  to first connection surface  113 . Filter cover  171  is provided with a plurality of holes in rows and columns, and the plurality of holes define first inlet  121 . 
     Narrow portion  116  is provided adjacently to wide portion  115 . Narrow portion  116  is defined by providing a bulkhead  114  in first housing  110 , and the cross-sectional area thereof orthogonal to the direction of flow of air is relatively small. The cross-sectional area of narrow portion  116  orthogonal to the direction of flow of air is smaller than the cross-sectional area of above-described wide portion  115  orthogonal to the direction of flow of air. 
     Blower chamber  117  is provided adjacently to narrow portion  116 , and blower  140  is accommodated therein. A cross-sectional area of blower chamber  117  orthogonal to the direction of flow of air is relatively large, and blower chamber  117  is provided as a relatively large space that occupies a most part of first housing  110 . The cross-sectional area of blower chamber  117  orthogonal to the direction of flow of air is larger than the cross-sectional area of above-described narrow portion  116  orthogonal to the direction of flow of air. 
     First flow path  120  in a portion corresponding to wide portion  115 , narrow portion  116 , and blower chamber  117  is a portion where the cross-sectional area orthogonal to the direction of flow of air is abruptly increased and decreased from the downstream side toward the upstream side in the direction of flow of air, and this portion functions as silencer  150  described above. By providing silencer  150  as such, noise generated in blower  140  is attenuated by irregular reflection while it passes through silencer  150 , and consequently, leakage of noise through first inlet  121  can be suppressed. 
     As shown in  FIGS. 6 and 7 , for example, a centrifugal fan is adopted as blower  140 , and blower  140  is fixed to a wall (that is, a bottom plate) that defines placement surface  112  of first housing  110  while the blower is accommodated in blower chamber  117 . Blower  140  includes an impeller  141 , a not-shown drive motor, and casing  142 . 
     Impeller  141  is fixed to a rotation shaft of the drive motor so that it rotates as the drive motor is driven. As impeller  141  rotates, air is agitated and centrifugal force is provided to air. An air current is thus generated in casing  142 , air is suctioned through suction port  143  provided in casing  142 , and air is emitted through emission port  144  provided in casing  142 . 
     Suction port  143  of blower  140  is provided in a part of casing  142  located above the shaft portion of impeller  141  and arranged as being opposed at a distance to an inner surface of a wall (that is, a top plate) that defines operation surface  111  of first housing  110 . When viewed along the shaft portion of impeller  141 , emission port  144  of blower  140  is provided in a part of casing  142  located in a tangential direction of an outer edge of impeller  141  and arranged at a prescribed distance from impeller  141 . 
     Suction port  143  of blower  140  communicates with blower chamber  117 . Emission port  144  of blower  140  is provided across blower chamber  117 , and has one end connected to the other end of a hose  160  connected to first outlet  122  provided in first housing  110 . A space inside hose  160  corresponds to downstream flow path portion  120 B described above. 
     First outlet  122  is provided in first connection surface  113  of first housing  110 . First outlet  122  is in a shape like a nozzle such that second inlet  221  provided in second connection surface  213  of second housing  210  and air tube  300  can both be connected thereto. 
     As shown in  FIGS. 6 and 7 , the space inside second housing  210  of humidification unit  200 A is divided into pressurization chamber  216  and vaporization chamber  217  by providing a partition wall  215 . A part of vaporization chamber  217  of these chambers corresponds to second flow path  220  described above. 
     Pressurization chamber  216  is defined by the wall of second housing  210  including partition wall  215 , and it is a portion where flexible reservoir  241  is accommodated. Walls of second housing  210  including partition wall  215  that define pressurization chamber  216  correspond to the accommodation portion where flexible reservoir  241  is accommodated, and each of them is provided as a pressure bulkhead. Therefore, even when pressurization chamber  216  is pressurized, the walls can maintain an internal pressure. Piezoelectric pump  260  and electromagnetic valve  270  are assembled to the wall of second housing  210  that defines pressurization chamber  216 . 
     A diaphragm pump making use of electrostriction of a piezoelectric body in a form of a thin plate is adopted as piezoelectric pump  260 , and piezoelectric pump  260  is an air pump capable of suctioning air and delivering air as described above. Piezoelectric pump  260  is provided such that a suction port thereof faces the outside of second housing  210  and an emission port thereof faces pressurization chamber  216  provided inside second housing  210 , so that pressurization chamber  216  can be pressurized by taking ambient air into pressurization chamber  216 . 
     A diaphragm valve making use of electrostriction of a piezoelectric body in a form of a thin plate is adopted as electromagnetic valve  270 , and electromagnetic valve  270  is provided in a prescribed wall of second housing  210  so as to be able to emit air in pressurization chamber  216  to the outside of humidification unit  200 A and to reduce a pressure in pressurization chamber  216 . Electromagnetic valve  270  is preferably provided to allow pressure reduction in pressurization chamber  216  prior to detachment of lid  214  from a point of view of securing safety in operating lid  214  in taking flexible reservoir  241  out of pressurization chamber  216 . 
     Pressurization chamber  216  is located below opening  212   a  provided in stage surface  212  which is the upper surface of second housing  210  and communicates with opening  212   a.  Opening  212   a  is closed by lid  214  as described above. Between a wall surface of second housing  210  that defines opening  212   a  and lid  214 , a not-shown sealing material (gasket) for securing hermeticity in that portion is provided. 
     Flexible reservoir  241  is formed from a bag-shaped member where water  500  is stored, and includes a connection port  242  through which stored water  500  can be emitted. Flexible reservoir  241  is formed from a soft member that is freely deformable without allowing leakage of water  500  stored therein, and accommodated in pressurization chamber  216  described above such that it can be put into and taken out of pressurization chamber  216 . Connection port  242  provided in flexible reservoir  241  is detachably connected to a connection port  231  of water supply path  230  which will be described later. Flexible reservoir  241  is formed, for example, from a resin member or a metal member like a film. 
     Flexible reservoir  241  is preferably disposable from a point of view of hygiene, and it may be disposed of after it is used a plurality of times or once. In an example where the flexible reservoir is disposed of after it is used a plurality of times, preferably, the flexible reservoir can readily be refilled with water  500  after water  500  is completely drained. 
     Vaporization chamber  217  is defined by the walls of second housing  210  including partition wall  215 , and provided to include in a part thereof, the above-described protrusion provided on the upper surface of second housing  210 . Water supply path  230  and heater  250  are arranged in vaporization chamber  217 . Heater  250  is provided in a lower portion in the space inside the protrusion described above, to divide vaporization chamber  217  into a space above heater  250  and a space below heater  250 . The space above heater  250  corresponds to second flow path  220  described above. 
     The space above heater  250  corresponding to second flow path  220  communicates with first flow path  120  provided inside first housing  110  through second inlet  221  provided in second connection surface  213  of second housing  210  and first outlet  122  provided in first connection surface  113  of first housing  110 . The space above heater  250  corresponding to second flow path  220  communicates with second outlet  222  provided in tube connection surface  211  of second housing  210 . Second outlet  222  is in a shape of a nozzle such that air tube  300  can be connected thereto. 
     Water supply path  230  is defined by a pipe bent substantially in an L shape, and one end thereof is provided to pass through partition wall  215  to reach pressurization chamber  216  and the other end thereof is connected to heater  250  from below. Heater  250  includes a heating plate and the other end of water supply path  230  is arranged to pass through the heating plate to face second flow path  220  described above. 
     Above-described one end of water supply path  230  corresponds to connection port  231  detachably connected to flexible reservoir  241  accommodated in pressurization chamber  216  and above-described the other end of water supply path  230  corresponds to a drain outlet  232  through which water  500  fed to water supply path  230  through connection port  231  is drained toward heater  250 . Connection port  231  described above corresponds to a water feed port through which water  500  stored in flexible reservoir  241  is fed toward water supply path  230 . 
     Pressurization chamber  216 , water supply path  230 , flexible reservoir  241 , heater  250 , and piezoelectric pump  260  described above mainly correspond to the humidification mechanism that humidifies gas to be humidified sent by blower  140 . The humidification operation by the humidification mechanism is performed as piezoelectric pump  260  is driven for a prescribed time period. 
     More specifically, by adopting the construction described above, pressurization chamber  216  is defined as a hermetically sealed space. Therefore, as piezoelectric pump  260  is driven, ambient air is taken into pressurization chamber  216  and pressurization chamber  216  is pressurized. An internal pressure in the space outside flexible reservoir  241  and inside the accommodation portion thus increases, and flexible reservoir  241  is accordingly compressed. 
     With this compressive force, water  500  stored in flexible reservoir  241  is introduced into water supply path  230  through connection ports  242  and  231 , and thereafter pushed out of water supply path  230  through drain outlet  232  and supplied to heater  250 . Water supplied to heater  250  is immediately heated and vaporized by heater  250  to become water vapor  501 , and water vapor is provided to air that passes through second flow path  220 . 
     At this time, a duration for which piezoelectric pump  260  is driven is determined based on a result of detection by power consumption sensor  135  that detects power consumed by heater  250 . As will be described later, in CPAP apparatus  1 A according to the present embodiment, controller  130  controls output from heater  250  so as to maintain a temperature of heater  250  at a predetermined set temperature. Therefore, as water  500  is supplied to heater  250  and heat of heater  250  is used for evaporation of water  500 , output from heater  250  relatively increases, and accordingly power consumed by heater  250  temporarily increases. 
     Since this increase in power consumed by heater  250  is basically in proportion to an amount of humidification (an amount of evaporation) with water  500 , the amount of humidification can be estimated by detecting power consumption. Therefore, humidification in a necessary amount can be carried out by stopping drive of piezoelectric pump  260  at the time point when a corresponding amount of consumed power corresponding to a target amount of humidification which will be described later is reached after start of the humidification operation. By setting a thermal capacity of heater  250  to be smaller, the amount of humidification can more minutely be estimated. Therefore, for example, a film heater is preferably employed as heater  250 . 
     As set forth above, in the first state of use, air suctioned through first inlet  121  is emitted from second outlet  222  through first flow path  120  and second flow path  220  in this order as described above, and sent into the airway of a user through air tube  300  connected to second outlet  222  and mask  400  connected to air tube  300 . By this time, air has moderately been humidified by being provided with water vapor  501  in second flow path  220 , and air is sent into the airway of the user. 
       FIG. 8  is a flowchart showing an operation of the controller in the first state of use of the CPAP apparatus according to the present embodiment.  FIGS. 9A, 9B and 9C  are timing charts for illustrating the humidification operation by the CPAP apparatus according to the present embodiment. Details of the humidification operation by CPAP apparatus  1 A according to the present embodiment will now be described with reference to  FIGS. 8, 9A, 9B, and 9C . 
     Referring to  FIG. 8 , as the user operates operation portion  131  of CPAP apparatus  1 A to start use thereof, initially, controller  130  provides a drive command to blower  140  in step Si. Blower  140  is thus driven to be turned ON. 
     Then, in step S 2 , controller  130  provides a drive command to heater  250 . Heater  250  is thus driven to be turned ON, and a temperature of heater  250  starts to increase. 
     Then, in step S 3 , controller  130  obtains the temperature of heater  250 . Specifically, controller  130  obtains the temperature detected by temperature sensor  251  annexed to heater  250 . 
     Then, in step S 4 , controller  130  determines whether or not the temperature of heater  250  is lower than a set temperature set in advance. When controller  130  determines the temperature of heater  250  as being lower than the set temperature (YES in step S 4 ), the process proceeds to step S 2  and controller  130  continues drive of heater  250 . When controller  130  determines the temperature of heater  250  as not being lower than the set temperature (NO in step S 4 ), the process proceeds to step S 5 . Though the set temperature of heater  250  is not particularly limited, it is set preferably to 60° C. or higher and further preferably to 80° C. or higher such that water  500  supplied to heater  250  is immediately heated and vaporized. 
     In step S 5 , controller  130  provides a drive stop command to heater  250 . Drive of heater  250  is thus stopped and the heater is turned OFF. 
     Then, in step S 6 , controller  130  obtains a temperature and a humidity of air to be humidified. Specifically, controller  130  obtains the temperature and the humidity of air to be humidified detected by temperature and humidity sensor  132  provided in upstream flow path portion  120 A in first flow path  120 . 
     Then, in step S 7 , controller  130  obtains a flow rate and a pressure of air to be humidified. Specifically, controller  130  obtains the flow rate and the pressure of air to be humidified detected by flow rate sensor  133  and pressure sensor  134  provided in downstream flow path portion  120 B in first flow path  120 . 
     Then, in step S 8 , controller  130  determines a corresponding amount of consumed power. This determination is based on the temperature and the humidity of air to be humidified detected by temperature and humidity sensor  132  described above and the flow rate and the pressure (in particular, the flow rate) of air to be humidified detected by flow rate sensor  133  and pressure sensor  134  described above. For example, the ROM described above stores a data table where correlation between the temperature, the humidity, the flow rate, and the pressure of air to be humidified and the corresponding amount of consumed power corresponding to an optimal amount of humidification in accordance therewith is determined in advance, and controller  130  determines the corresponding amount of consumed power by referring to the data table. 
     Then, in step S 9 , controller  130  determines whether or not a user is performing an inhalation operation. This determination is based on the flow rate and the pressure detected by flow rate sensor  133  and pressure sensor  134  described above. When controller  130  determines that the user is not performing the inhalation operation (that is, the user is performing the exhalation operation) (NO in step S 9 ), it resets the corresponding amount of consumed power determined in step S 8 , and thereafter the process proceeds to step S 3  and returns to obtainment of the temperature of heater  250 . When controller  130  determines that the user is performing the inhalation operation (YES in step S 9 ), the process proceeds to step S 10 . 
     In step S 10 , controller  130  starts constant temperature control of heater  250 . Constant temperature control of heater  250  refers to control of output from heater  250  by controller  130  so as to maintain the temperature of heater  250  at the predetermined set temperature. 
     Then, in step S 11 , controller  130  provides a drive command to piezoelectric pump  260 . Piezoelectric pump  260  is thus driven to be turned ON, and supply of water  500  stored in flexible reservoir  241  to heater  250  through water supply path  230  is started. 
     Then, in step S 12 , controller  130  obtains a cumulative amount of power consumed by heater  250  from the time point of start of drive of piezoelectric pump  260 . Specifically, while controller  130  obtains the amount of consumed power detected by power consumption sensor  135 , it calculates the cumulative amount of consumed power by computation based thereon. 
     Then, in step S 13 , controller  130  determines whether or not the cumulative amount of consumed power has reached the corresponding amount of consumed power. When controller  130  determines that the cumulative amount of consumed power has not reached the corresponding amount of consumed power (NO in step S 13 ), the process proceeds to step S 12  and controller  130  calculates again the cumulative amount of consumed power. When controller  130  determines that the cumulative amount of consumed power has reached the corresponding amount of consumed power (YES in step S 13 ), the process proceeds to step S 14 . 
     In step S 14 , controller  130  provides a drive stop command to piezoelectric pump  260 . Drive of piezoelectric pump  260  is thus stopped and the piezoelectric pump is turned OFF, so that supply of water  500  stored in flexible reservoir  241  to heater  250  through water supply path  230  is stopped. 
     Then, in step S 15 , controller  130  stops constant temperature control of heater  250 . 
     Then, in step S 16 , controller  130  determines whether or not a stop command to CPAP apparatus  1 A has been provided. This determination is made specifically based on whether or not a command to stop use thereof has been provided by an operation by the user onto operation portion  131  of CPAP apparatus  1 A. When controller  130  determines that no stop command to CPAP apparatus  1 A has been provided (NO in step S 16 ), the process proceeds to step S 3  and returns to obtainment of the temperature of heater  250 . When controller  130  determines that the stop command to CPAP apparatus  1 A has been provided (YES in step S 16 ), the process proceeds to step S 17 . 
     In step S 17 , controller  130  provides a drive stop command to blower  140 . Drive of blower  140  is thus stopped and the blower is turned OFF, and all operations by CPAP apparatus  1 A are completed as above. 
     As controller  130  operates in accordance with the series of control flows described above, a duration for which piezoelectric pump  260  is driven is appropriately controlled so that flexible reservoir  241  is appropriately pressurized and water  500  in an amount necessary for humidification is supplied to heater  250 . The humidification operation as shown in  FIGS. 9A, 9B, and 9C  are thus performed. 
     As shown in  FIG. 9A , the user repeatedly and alternately performs the inhalation operation and the exhalation operation by breathing, and a flow rate of air in first flow path  120  is varied therewith. This variation in flow rate of air is detected by flow rate sensor  133 , and controller  130  determines whether the user is performing the inhalation operation or the exhalation operation. 
     As shown in  FIGS. 9B and 9C , when controller  130  determines that the user is performing the inhalation operation, drive of piezoelectric pump  260  is started and drive of piezoelectric pump  260  is stopped at the time point when the cumulative amount of power consumed by heater  250  reaches a prescribed value corresponding to a target amount of humidification. Air to be humidified can thus be humidified in an optimal amount of humidification. 
     When the configuration is such that the humidification operation described above is completed while the user is performing the inhalation operation, the humidification operation is thus not performed while the user is performing the exhalation operation. Therefore, according to such a configuration, water vapor provided to air in second flow path  220  can be prevented from flowing backward by exhalation by the user to reach first flow path  120 . Therefore, failure of various types of equipment (representatively, blower  140 ) accommodated in first housing  110  due to attachment of moisture thereto or proliferation of germs due to attachment of moisture to an inner wall of first housing  110  can be suppressed, and a CPAP apparatus excellent in aspects of hygiene and ease in maintenance by cleaning can be provided. 
     As described above, with CPAP apparatus  1 A according to the present embodiment, a compact CPAP apparatus capable of efficient humidification can be provided. The reason why the apparatus can be compact is that the humidification mechanism described above (in particular, heater  250  as the vaporizer) can sufficiently be compact, and the reason why humidification can be efficient is that the humidification operation is performed only at timing when humidification is required and hence a total amount of energy necessary for vaporizing water  500  (that is, the sum of an amount of power consumed by heater  250  and an amount of power consumed by piezoelectric pump  260 ) can be suppressed. 
     Another reason why humidification can be efficient is ability to significantly suppress energy loss. In a conventional humidification method in which whole water stored in a tank is heated, an amount of heat dissipated from the tank to the outside is unignorably larger than an amount of heat necessary for vaporizing water, and consequently a larger total amount of energy is necessary. In contrast, in the humidification mechanism according to the present embodiment, such waste of energy can be suppressed and consequently humidification can be efficient. 
     CPAP apparatus  1 A according to the present embodiment described above obtains also an effect that, even though the user inadvertently causes the apparatus to topple over, water  500  stored in flexible reservoir  241  can be prevented from entering the inside of blowing unit  100  through second flow path  220  or entering air tube  300 . This is because water  500  in a portion located at drain outlet  232  of water supply path  230  communicating with second flow path  220  does not leak to second flow path  220  owing to surface tension of water  500  and thus failure of the equipment described above or flow of water  500  in a liquid state into the airway of the user can be prevented. 
     From a point of view of such prevention of unintended leakage of water  500  through drain outlet  232 , further preferably, a check valve that allows movement of water  500  from water supply path  230  toward heater  250  and restricts movement of water  500  and air that passes through second flow path  220  from heater  250  toward water supply path  230  is provided at drain outlet  232 , and instead thereof or in addition thereto, a flow path defining surface of water supply path  230  that defines drain outlet  232  and/or an end surface of drain outlet  232  are/is made water repellent. According to such a construction, not only leakage of water  500  in case of toppling over of CPAP apparatus  1 A as described above can be suppressed but also supply of water  500  in an amount more than necessary to heater  250  in the humidification operation can be prevented and the amount of humidification can more reliably and minutely be controlled. In making the vicinity of drain outlet  232  water repellent, the flow path defining surface and/or the end surface of above-described the other end of water supply path  230  provided with drain outlet  232  can be made water repellent. In that case, only a part of the flow path defining surface or only a part of the end surface may be made water repellent. 
     Furthermore, CPAP apparatus  1 A according to the present embodiment described above can obtain also an effect in an aspect of costs, because the humidification mechanism described above is of a very simplified construction and such a component as heater  250  or piezoelectric pump  260  necessary for making up the humidification mechanism is also relatively inexpensive. Therefore, the CPAP apparatus can inexpensively be provided. 
     Additionally, CPAP apparatus  1 A according to the present embodiment described above obtains also a secondary effect that air humidified soon after start of use can be sent into the airway of the user. This is because heater  250  can significantly be reduced in size as described above so that heater  250  can be increased in temperature to a set temperature earlier and consequently the humidification operation can be performed substantially without delay after start of use. 
     In CPAP apparatus  1 A according to the present embodiment described above, from a point of view of the amount of power consumed by heater  250  being in proportion to the amount of humidification, an algorithm for estimating the amount of humidification from the cumulative amount of consumed power is adopted. In actual, however, the amount of power consumed by heater  250  is varied also by such a factor as an ambient temperature, a temperature of water stored in flexible reservoir  241 , or an amount of air sent by blower  140 . Therefore, for more minute adjustment of the amount of humidification, the amount of humidification is desirably appropriately corrected based on the temperature detected by temperature and humidity sensor  132  or the flow rate detected by flow rate sensor  133 . 
     Second Embodiment 
       FIG. 10  is a schematic cross-sectional view in the first state of use of a CPAP apparatus according to a second embodiment of the present disclosure. A CPAP apparatus  1 B according to the present embodiment will be described below with reference to  FIG. 10 . 
     As shown in  FIG. 10 , CPAP apparatus  1 B according to the present embodiment is different from CPAP apparatus  1 A according to the first embodiment described above mainly in construction including a differently constructed humidification unit  200 B. 
     Humidification unit  200 B does not include a protrusion that protrudes upward from one of the four corners of the upper surface of second housing  210 , but instead includes a protrusion that protrudes downward from one of four corners of the lower surface. One of side surfaces of the protrusion provided on the lower surface of second housing  210  defines tube connection surface  211  to which air tube  300  is connected in the first state of use, and another one of the side surfaces of the protrusion described above defines second connection surface  213  connected to blowing unit  100  in the first state of use. 
     A portion except for the above-described protrusion of the lower surface of second housing  210  defines a placement surface  219  placed on blowing unit  100  in the first state of use. Accordingly, the upper surface of first housing  110  of blowing unit  100  defines a carrier surface  118  on which humidification unit  200 B is placed in the first state of use, and the lower surface of first housing  110  defines a placement surface placed on a floor surface or a table in the first state of use. 
     In CPAP apparatus  1 B according to the present embodiment, as humidification unit  200 B is placed on blowing unit  100 , humidification unit  200 B is attached to blowing unit  100 . The operation surface where the operation portion of blowing unit  100  is provided is defined by one side surface except for first connection surface  113  of the four side surfaces of first housing  110 . 
     A space inside second housing  210  is divided by partition wall  215  into pressurization chamber  216  and vaporization chamber  217 , and vaporization chamber  217  of these chambers is provided to contain as its part, the above-described protrusion provided on the lower surface of second housing  210 . Water supply path  230  and heater  250  are arranged in vaporization chamber  217 , and heater  250  is provided in a lower portion in the space inside the protrusion described above. Vaporization chamber  217  corresponds to second flow path  220  that connects second inlet  221  and second outlet  222  to each other. 
     Water supply path  230  is defined by a pipe bent substantially in the L shape, and one end thereof is provided to pass through partition wall  215  to reach pressurization chamber  216 . The other end of water supply path  230  is arranged above heater  250  so as to face heater  250 . Water supply path  230  thus connects flexible reservoir  241  and heater  250  as the vaporizer to each other. 
     Above-described one end of water supply path  230  corresponds to connection port  231  detachably connected to flexible reservoir  241  accommodated in pressurization chamber  216  and corresponds to a water feed port through which water  500  stored in flexible reservoir  241  accommodated in pressurization chamber  216  is fed toward water supply path  230 . Above-described the other end of water supply path  230  corresponds to drain outlet  232  through which water  500  fed to water supply path  230  through connection port  231  is drained toward heater  250 . 
     Since piezoelectric pump  260  and electromagnetic valve  270  provided to face pressurization chamber  216  are both similar to those in the first embodiment described above, description thereof will not be repeated. 
     With CPAP apparatus  1 B constructed as described above as well, similarly to CPAP apparatus  1 A in the first embodiment described above, by appropriately controlling a duration for which piezoelectric pump  260  is driven, flexible reservoir  241  is pressurized so that water  500  in an amount necessary for humidification is supplied to heater  250  and the humidification operation described previously can be performed. Therefore, an effect similar to the effect described in the first embodiment above can be obtained also when the construction is adopted. 
       FIGS. 11A, 11B, 11C, and 11D  are schematic cross-sectional views showing an exemplary construction of the drain outlet of the water supply path shown in  FIG. 10 . An exemplary construction of water supply path  230  of CPAP apparatus  1 B according to the present embodiment will now be described with reference to  FIGS. 11A, 11B, 11C, and 11D . 
     In CPAP apparatus  1 B according to the present embodiment, the space inside flexible reservoir  241  is in a hermetically sealed state except for connection port  242 . Therefore, unless flexible reservoir  241  is compressed, water  500  basically does not leak from drain outlet  232 . From a point of view of more minute adjustment of the amount of humidification, however, preferably, water  500  reliably stays at drain outlet  232  while a pressure is not applied to flexible reservoir  241 . Exemplary constructions shown below show some examples for realizing this feature. 
     In an exemplary construction shown in  FIG. 11A , a check valve  234 A is provided at above-described the other end of water supply path  230 . Check valve  234 A is formed, for example, from an elastic body, and drain outlet  232  of water supply path  230  is thus defined by check valve  234 A. In this case, check valve  234 A normally does not allow movement of water  500  from water supply path  230  toward heater  250 . On the other hand, during a period from opening of check valve  234 A by increase in internal pressure in flexible reservoir  241  due to compression of flexible reservoir  241  until stop of increase in internal pressure, movement of water  500  from water supply path  230  toward heater  250  is allowed. 
     In exemplary constructions shown in  FIGS. 11B, 11C, and 11D , above-described the other end of water supply path  230  is provided with nozzles  234 B to  234 D. Nozzles  234 B to  234 D each include drain outlet  232  smaller than an inner diameter of water supply path  230 , so that surface tension produced in a part of water  500  in contact with drain outlet  232  is increased. According to such a construction, movement of water  500  from water supply path  230  toward heater  250  is normally not allowed, and water  500  is pushed out of water supply path  230  toward heater  250  owing to increase in internal pressure in flexible reservoir  241  as a result of compression of flexible reservoir  241 . 
     Nozzle  234 B in a shape shown in  FIG. 11B  is constructed such that a single hole defines drain outlet  232 , and nozzle  234 C in a shape shown in  FIG. 11C  is constructed such that a plurality of holes define drain outlet  232 . Nozzle  234 D in a shape shown in  FIG. 11D  is constructed such that a single hole increasing in cross-sectional area downward defines drain outlet  232 . With nozzle  234 C in the shape shown in  FIG. 11C , water  500  is supplied to heater  250  like a shower, and with nozzle  234 D in the shape shown in  FIG. 11D , water  500  is supplied over a wider range of heater  250 , so that an effect of vaporization of water  500  in heater  250  more accelerated than with nozzle  234 B in the shape shown in  FIG. 11B  is obtained. 
     Check valve  234 A shown in  FIG. 11A  described above and nozzles  234 B to  234 D shown in  FIGS. 11B, 11C, and 11D  described above may each be formed from a water repellent member. In that case, since drain outlet  232  defined by each of check valve  234 A and nozzles  234 B to  234 D repels water  500 , movement of water  500  from water supply path  230  toward heater  250  is normally not allowed and water  500  can be pushed out of water supply path  230  toward heater  250  owing to increase in internal pressure in flexible reservoir  241  as a result of compression of flexible reservoir  241 . 
     Third Embodiment 
       FIG. 12  is a schematic cross-sectional view in the first state of use of a CPAP apparatus according to a third embodiment of the present disclosure. A CPAP apparatus  1 C according to the present embodiment will be described below with reference to  FIG. 12 . 
     As shown in  FIG. 12 , CPAP apparatus  1 C according to the present embodiment is different from CPAP apparatus  1 A according to the first embodiment described above mainly in construction including a differently constructed humidification unit  200 C. 
     Though second housing  210  of humidification unit  200 C is basically similar in construction to second housing  210  of humidification unit  200 A according to the first embodiment, in the space therein, a space where flexible reservoir  241  is accommodated is not provided as the pressurization chamber but provided simply as an accommodation chamber  218 . In other words, accommodation chamber  218  does not necessarily have to hermetically be sealed, and accordingly, a sealing material such as gasket does not have to be provided either between a portion defining opening  212   a  provided in stage surface  212  of second housing  210  and lid  214 . Piezoelectric pump  260  should only be provided in the wall of second housing  210  and the electromagnetic valve does not have to be provided. 
     Flexible reservoir  241  accommodated in accommodation chamber  218  described above is provided as a part of a two-ply bag  240  covered with a bag-shaped member  243  where flexible reservoir  241  is accommodated. Preferably, bag-shaped member  243  is formed from a hard member less likely to deform than flexible reservoir  241  and corresponds to the accommodation portion where flexible reservoir  241  is accommodated. Bag-shaped member  243  is formed, for example, from a resin member or a metal member like a film. 
     Flexible reservoir  241  and bag-shaped member  243  that make up two-ply bag  240  are integrated by being joined to each other by bonding or welding. Connection port  242  of flexible reservoir  241  is drawn outward through bag-shaped member  243 , and a connection port  244  different from connection port  242  of flexible reservoir  241  described above is provided at a prescribed position in bag-shaped member  243 . 
     A space inside flexible reservoir  241  (that is, a space filled with water  500 ) thus communicates with an external space through connection port  242 , and a pressurization space  245  which is a space outside flexible reservoir  241  and inside bag-shaped member  243  communicates with the external space through connection port  244 . 
     While two-ply bag  240  is accommodated in accommodation chamber  218 , connection port  242  of flexible reservoir  241  is connected to connection port  231  of water supply path  230  and connection port  244  of bag-shaped member  243  is connected to piezoelectric pump  260 . Water can thus be fed from flexible reservoir  241  to water supply path  230  and pressurization space  245  can be pressurized by piezoelectric pump  260 . 
     As described above, in the present embodiment, bag-shaped member  243  is formed from a member harder than flexible reservoir  241 . Therefore, when pressurization space  245  is pressurized by driving piezoelectric pump  260 , the pressure is mainly applied to flexible reservoir  241  and flexible reservoir  241  is thus more efficiently compressed. 
     With this compressive force, water  500  stored in flexible reservoir  241  is introduced into water supply path  230  through connection ports  231  and  242 , and thereafter pushed out of water supply path  230  through drain outlet  232  and supplied to heater  250 . Water supplied to heater  250  is immediately heated and vaporized by heater  250  to become water vapor  501 , and water vapor is provided to air that passes through second flow path  220 . 
     With CPAP apparatus  1 C constructed as described above as well, as in CPAP apparatus  1 A in the first embodiment described above, by appropriately controlling a duration for which piezoelectric pump  260  is driven, flexible reservoir  241  is pressurized so that water  500  in an amount necessary for humidification is supplied to heater  250  and the humidification operation described previously can be performed. Therefore, an effect similar to the effect described in the first embodiment above can be obtained also when the construction is adopted. 
     Though an example in which accommodation chamber  218  for accommodating two-ply bag  240  is provided in second housing  210  is illustrated in the present embodiment, accommodation chamber  218  does not have to be provided and two-ply bag  240  may externally be attached to second housing  210 . In such a construction, humidification unit  200 C as a whole including two-ply bag  240  can significantly be reduced in size, and furthermore, while the apparatus is not used, two-ply bag  240  not filled with water  500  is also foldable and portable. Therefore, a highly convenient 
     CPAP apparatus can be provided. 
     Fourth Embodiment 
       FIG. 13  is a diagram showing a configuration of a functional block in the first state of use of a CPAP apparatus according to a fourth embodiment of the present disclosure and  FIG. 14  is a schematic cross-sectional view in the first state of use of the CPAP apparatus. The configuration of the functional block in the first state of use and a detailed structure of a CPAP apparatus  1 D according to the present embodiment will initially be described with reference to  FIGS. 13 and 14 . 
     As shown in  FIGS. 13 and 14 , CPAP apparatus  1 C according to the present embodiment is different from CPAP apparatus  1 A according to the first embodiment described above mainly in construction including a differently constructed humidification unit  200 D. Humidification unit  200 A according to the first embodiment described above is constructed such that water  500  is supplied to heater  250  as the vaporizer by externally pressurizing flexible reservoir  241 , whereas humidification unit  200 D according to the present embodiment instead allows supply of water  500  to heater  250  by making use of elastic resilience of an elastic reservoir  246  itself. 
     Though second housing  210  of humidification unit  200 D of CPAP apparatus  1 D is basically similar in construction to second housing  210  of humidification unit  200 A according to the first embodiment, in the space therein, a space where elastic reservoir  246  is accommodated is not provided as the pressurization chamber but provided simply as accommodation chamber  218 . In other words, accommodation chamber  218  does not necessarily have to hermetically be sealed, and accordingly, a sealing material such as gasket does not have to be provided either between a portion defining opening  212   a  provided in stage surface  212  of second housing  210  and lid  214 . The piezoelectric pump and the electromagnetic valve are not provided in the wall of second housing  210 . 
     A valve  280  is provided in a part of water supply path  230  located in vaporization chamber  217  of second housing  210 . While valve  280  is open, it allows flow of water  500  through water supply path  230 , and while valve  280  is closed, it cuts off flow of water  500  through water supply path  230 . Valve  280  can be driven, for example, by a valve driver  281  implemented by a motor, and valve driver  281  switches valve  280  to any of an open state and a closed state. 
     Elastic reservoir  246  accommodated in accommodation chamber  218  described above is formed from a bag-shaped member where water  500  is stored, and includes a connection port  247  through which stored water  500  can be drained. Elastic reservoir  246  is formed from a member elastically freely deformable without allowing leakage of water  500  stored therein, and accommodated in accommodation chamber  218  described above such that it can be put into and taken out of accommodation chamber  218 . Connection port  247  provided in elastic reservoir  246  can detachably be connected to connection port  231  of water supply path  230 . Elastic reservoir  246  is formed, for example, from a member made of rubber. 
     Elastic reservoir  246  is elastically inflated and deformed by injection of water  500  thereinto. In other words, while external force is not applied, a space inside elastic reservoir  246  is sufficiently small or there is no space provided therein, and elastic reservoir  246  is like a balloon so to speak. 
     Water supply path  230 , elastic reservoir  246 , heater  250 , valve  280 , and valve driver  281  described above mainly correspond to the humidification mechanism that humidifies gas to be humidified sent by blower  140 . The humidification operation by the humidification mechanism is performed by setting valve  280  to the open state (that is, opening the valve) for a prescribed time period. 
     More specifically, by adopting the construction described above, when valve  280  is in the open state, water  500  stored in elastic reservoir  246  is introduced into water supply path  230  through connection ports  247  and  231  owing to elastic resilience of elastic reservoir  246 , thereafter pushed out of water supply path  230  through drain outlet  232 , and supplied to heater  250 . Water supplied to heater  250  is immediately heated and vaporized by heater  250  to become water vapor  501 , and water vapor is provided to air that passes through second flow path  220 . 
     When valve  280  is closed, supply of water  500  to heater  250  is stopped by cut-off of flow of water  500  through water supply path  230  and the humidification operation is accordingly also stopped. 
       FIG. 15  is a flowchart showing an operation of the controller in the first state of use of the CPAP apparatus according to the present embodiment.  FIGS. 16A, 16B, and 16C  are timing charts for illustrating the humidification operation by the CPAP apparatus according to the present embodiment. Details of the humidification operation by CPAP apparatus  1 D according to the present embodiment will now be described with reference to  FIGS. 15 and 16A, 16B, and 16C . 
     As shown in  FIG. 15 , a control flow of controller  130  in CPAP apparatus  1 D according to the present embodiment is in conformity with the control flow shown in  FIG. 8 , and the difference resides only in that valve  280  is opened in step S 11  and valve  280  is closed in step S 14 . Valve  280  is opened and closed by controller  130  providing an operation command to valve driver  281 . 
     As controller  130  operates in accordance with a series of control flows shown in  FIG. 15 , a duration for which valve  280  is open is appropriately controlled so that water  500  in an amount necessary for humidification is supplied to heater  250 . The humidification operation as shown in  FIGS. 16A, 16B, and 16C  are thus performed. 
     Therefore, CPAP apparatus  1 D constructed as described above can also obtain an effect similar to the effect described in the first embodiment above and a compact CPAP apparatus capable of efficient humidification can be provided. 
     Though an example in which accommodation chamber  218  where elastic reservoir  246  is accommodated is provided in second housing  210  is illustrated in the present embodiment, accommodation chamber  218  does not have to be provided and elastic reservoir  246  may externally be attached to second housing  210 . According to such a construction, humidification unit  200 D as a whole including elastic reservoir  246  can significantly be reduced in size, and furthermore, while the apparatus is not used, elastic reservoir  246  not filled with water  500  is also foldable and portable. Therefore, a highly convenient CPAP apparatus can be provided. 
     Fifth Embodiment 
       FIG. 17  is a schematic cross-sectional view in the first state of use of a CPAP apparatus according to a fifth embodiment of the present disclosure and  FIG. 18  is a diagram showing a configuration of a functional block in the first state of use of the CPAP apparatus. A CPAP apparatus  1 E according to the present embodiment will be described below with reference to  FIGS. 17 and 18 . 
     As shown in  FIGS. 17 and 18 , CPAP apparatus  1 E according to the present embodiment is different from CPAP apparatus  1 A according to the first embodiment described above mainly in construction including a differently constructed humidification unit  200 E. 
     Specifically, pressurization chamber  216  as the accommodation portion provided in second housing  210  of humidification unit  200 E is provided with a pressure sensor  290  as the pressure sensing portion. More specifically, pressure sensor  290  is arranged in a space outside flexible reservoir  241  and inside pressurization chamber  216  so as to sense a pressure in pressurization chamber  216 . The pressure sensed by pressure sensor  290  is provided to controller  130  and mainly used for the humidification operation by the humidification mechanism. 
     In CPAP apparatus  1 E according to the present embodiment, unlike CPAP apparatus  1 A according to the first embodiment described above, an amount of humidification by the humidification mechanism is adjusted by control by controller  130 , of drive of piezoelectric pump  260  (for example, control of a duration of drive) based on the pressure in pressurization chamber  216  sensed by pressure sensor  290  described above. 
     In CPAP apparatus  1 E according to the present embodiment, flexible reservoir  241  accommodated in pressurization chamber  216  is compressed by driving piezoelectric pump  260 , so that some of water  500  stored in flexible reservoir  241  is supplied to heater  250  through water supply path  230 . Therefore, the pressure in pressurization chamber  216  establishes prescribed correlation with an amount of water  500  (that is, an amount of humidification) pushed out of flexible reservoir  241 . 
     Therefore, under feedback control by controller  130 , while the pressure in pressurization chamber  216  is sensed, piezoelectric pump  260  is appropriately driven based on the sensed pressure, so that flexible reservoir  241  is appropriately pressurized and consequently the amount of humidification by the humidification mechanism can be adjusted. 
     In humidification unit  200 E, an orifice  233  smaller in flow path cross-sectional area than another portion of water supply path  230  having connection port  231  as one end connected to flexible reservoir  241  and having drain outlet  232  as the other end connected to heater  250  is provided at a position in the middle of water supply path  230 . Orifice  233  is provided at a position in the middle of water supply path  230  for forming a portion higher in flow path resistance than other portions. 
     By thus providing orifice  233  at the position in the middle of water supply path  230 , an amount of water  500  supplied to heater  250  through water supply path  230  can further be smaller. As orifice  233  functions as a high flow path resistance portion, a ratio of an amount of supply of water  500  to heater  250  against increase in pressure in pressurization chamber  216  can be lowered, and consequently water  500  can be supplied to heater  250  at a low flow rate in a stable manner. 
     Therefore, according to such a construction, variation in amount of supply of water  500  due to variation in pressure can be suppressed and an amount of humidification by the humidification mechanism can highly accurately be adjusted. Orifice  233  does not necessarily have to be provided at the position in the middle of water supply path  230  but may be provided at an end on a side of connection port  231  or on a side of drain outlet  232  of water supply path  230 . 
     CPAP apparatus  1 E constructed as described above can also obtain an effect similar to the effect described in the first embodiment above and a compact CPAP apparatus capable of efficient humidification can be provided. 
     (Other Forms) 
     Though an example in which the present disclosure is applied to the CPAP apparatus as the humidification and blowing apparatus for respiratory organs is described by way of example in the first to fifth embodiments above, the present disclosure is applicable also to a steam inhaler or an oxygen inhaler other than the CPAP apparatus. The present disclosure is applicable to any apparatus so long as the apparatus includes the humidification apparatus and naturally applicable also to an apparatus other than the humidification and blowing apparatus for respiratory organs. Furthermore, the present disclosure is effectively applicable also to the humidification apparatus used alone. 
     Though an example in which the heater as the vaporizer that heats water is employed is described by way of example in the first to fifth embodiments above, the vaporizer does not necessarily have to be constructed as such, and any component capable of vaporizing water can be employed as the vaporizer. When an atomizer (for example, an ultrasonic vibrator) is provided instead of the vaporizer, the apparatus can be made use of as an atomization apparatus. Examples of the atomization apparatus include a nebulizer as an atomization apparatus for respiratory organs. 
     Though an example in which the piezoelectric pump as the ambient air introduction source is employed as the pressurization source is described by way of example in the first to third and fifth embodiments above, the pressurization source that pressurizes the pressurization chamber does not necessarily have to include the ambient air introduction source that introduces ambient air into the pressurization chamber. When the pressurization source includes the ambient air introduction source as well, the ambient air introduction source does not necessarily have to include the piezoelectric pump, and any component capable of delivering ambient air can be employed as the ambient air introduction source. 
     Though an example in which a component formed from a low-profile sack-shaped member is provided as the flexible reservoir and the elastic reservoir is described by way of example in the first to fifth embodiments above, the shape of the flexible reservoir and the elastic reservoir is not particularly restricted, and the reservoir may be formed from a sack-shaped member which is not of a low profile (for example, like a ball or a rod) or a sack-shaped member in a special shape such as bellows. 
     Characteristic features disclosed in the first to fifth embodiments described above can be combined with one another unless they depart from the gist of the present disclosure. 
     The embodiments disclosed herein are thus illustrative and non-restrictive in every respect. The technical scope of the present disclosure is defined by the terms of the claims and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. 
     REFERENCE SIGNS LIST 
       1 A to  1 E CPAP apparatus;  100  blowing unit;  110  first housing;  111  operation surface;  112  placement surface;  113  first connection surface;  114  bulkhead;  115  wide portion;  116  narrow portion;  117  blower chamber;  118  carrier surface;  120  first flow path;  120 A upstream flow path portion;  120 B downstream flow path portion;  121  first inlet;  122  first outlet;  130  controller;  131  operation portion;  132  temperature and humidity sensor;  133  flow rate sensor;  134  pressure sensor;  135  power consumption sensor;  140  blower;  141  impeller;  142  casing;  143  suction port;  144  emission port;  150  silencer;  160  hose;  170  filter;  171  filter cover;  200 A to  200 E humidification unit;  210  second housing;  211  tube connection surface;  212  stage surface;  212   a  opening;  213  second connection surface;  214  lid;  215  partition wall;  216  pressurization chamber;  217  vaporization chamber;  218  accommodation chamber;  219  placement surface;  220  second flow path;  221  second inlet;  222  second outlet;  230  water supply path;  231  connection port;  232  drain outlet;  233  orifice;  234 A check valve;  234 B to  234 D nozzle;  240  two-ply bag;  241  flexible reservoir;  242  connection port;  243  bag-shaped member;  244  connection port;  245  pressurization space;  246  elastic reservoir;  247  connection port;  250  heater;  251  temperature sensor;  260  piezoelectric pump;  270  electromagnetic valve;  280  valve;  281  valve driver;  290  pressure sensor;  300  air tube;  400  mask;  500  water;  501  water vapor