Abstract:
To improve an incubator. In an incubator for incubating a culture medium accommodated in an incubation space defined in a storage. A heater to control a temperature of the water stored in a water storing structure which is in the bottom side of the storage, and to keep the temperature of the water a predetermined temperature. A water supplier to supply the water to the water storing structure when the water has been decreased. In the incubator when the water supplier supplies the water during the culture medium is incubated, the water supplier decreases the amount of water supplied per an unit time than the amount of water supplied during the culture medium is not incubated.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to an incubator such as a CO 2  incubator in which a humidifying water dish portion is provided with the water level detecting device using a self-heating type thermistor. 
         [0002]    As shown in Japanese Patent No. 3197696, in an incubator such as a CO 2  incubator, humidifying water is accommodated in a bottom portion of a storeroom to maintain a predetermined high humidity of the storeroom and the water is heated by a heater. 
         [0003]    In addition, as shown in Japanese Patent No. 3670876, in such an incubator, the humidifying water is irradiated and sterilized by ultraviolet rays by the use of an ultraviolet lamp to suppress the propagation of bacteria. 
         [0004]    When the humidifying water is evaporated, the humidity in the storeroom is lowered and thus a culture medium is affected. For this reason, it is considered to provide a water level detecting device for detecting a water level of the humidifying water. When the water level detecting device is a float type device, the cleaning and the like are troublesome. 
         [0005]    As the water level detecting device, a water level detecting device using a self-heating type thermistor has been proposed (see Japanese Patent Application Laid-Open No. 2001-159556 and Japanese Patent Application Laid-Open No. 7-260547). 
       SUMMARY OF THE INVENTION 
       [0006]    The invention relates to the improvement of an incubator. 
         [0007]    In a first aspect of the invention, in an incubator incubating a culture medium accommodated in an incubation space defined in a storage comprising a heater to control a temperature of the water stored in a water storing structure which is in the bottom side of the storage, and to keep the temperature of the water a predetermined temperature; and a water supplier to supply the water to the water storing structure when the water has been decreased. In the incubator when the water supplier supplies the water during the culture medium is incubated, the water supplier decreases the amount of water supplied per unit time than the amount of water supplied during the culture medium is not incubated. 
         [0008]    In a second aspect of the invention, in an incubator including the water supplier supplies the water intermittently. 
         [0009]    In a third aspect of the invention, in an incubator, the heating operation performed by the heater is stopped or weakened when the water supplier is supplying the water. 
         [0010]    In a fourth aspect of the invention, in an incubator including a notification means to notify that the water level fell down than the predetermined water level during incubation. 
         [0011]    In a fifth aspect of the invention, in an incubator, the notification means further stores and notifies that a history of the notification. 
         [0012]    In a sixth aspect of the invention, in an incubator further comprising an ultraviolet rays radiation means to radiate ultraviolet rays for sterilizing the water and a temperature sensor to measure a temperature of the water, which is protected from the ultraviolet rays by a tube. 
         [0013]    In a seventh aspect of the invention, in an incubator, the temperature sensor comprising a first self-heating type thermistor and a second self-heating type thermistor which amount of self-heating is less than that of the first self-heating type thermistor, the thermistors are provided at a position corresponds to a predetermined water level of the water storing structure. The incubator further comprising a power source to supply power to the thermistors intermittently and a judging means comparing the voltages correspond to the temperatures measured by the thermistors, and judging the water level of the water storing structure fell down than the predetermined water level when the voltage of the first self-heating type thermistor is less than the voltage of the second self-heating type thermistor having less amount of self-heating. 
         [0014]    According to the invention described in a first aspect of the invention, in an incubator incubating a culture medium accommodated in an incubation space defined in a storage comprising a heater ( 17 ) to control a temperature of the water stored in a water storing structure ( 30 ) which is in the bottom side of the storage, and to keep the temperature of the water a predetermined temperature; and a water supplier ( 16 ) to supply the water to the water storing structure when the water has been decreased. In the incubator when the water supplier ( 16 ) supplies the water during the culture medium is incubated, the water supplier decreases the amount of water supplied per unit time than the amount of water supplied during the culture medium is not incubated. That is, when the incubation is not performed, it doesn&#39;t matter if a temperature and a humidity vary and thus the water is supplied to shorten the amount of time. However, during the incubation, the water is slowly supplied to suppress the variation in temperature and humidity. 
         [0015]    According to the invention described in a second aspect of the invention, the water supplier ( 16 ) supplies the water intermittently. In this manner, when the water is supplied, it is easier to control a valve to be completely opened and completely closed than to control the fastening amount of the valve in order to slowly supply the water. 
         [0016]    According to the invention described in a third aspect of the invention, in an incubator, the heating operation performed by the heater ( 17 ) is stopped or weakened when the water supplier is supplying the water. In this manner, no-water heating is prevented. 
         [0017]    According to the invention described in a fourth aspect of the invention, in an incubator including a notification means ( 12 ,  13 ,  14 ) to notify that the water level fell down than the predetermined water level during incubation. 
         [0018]    According to the invention described in a fifth aspect of the invention, in an incubator, the notification means (display portion  12 ) further stores and notifies that a history of the notification. 
         [0019]    According to the invention described in a sixth aspect of the invention, in an incubator further comprising an ultraviolet rays radiation means to radiate ultraviolet rays for sterilizing the water and a temperature sensor ( 2 ,  3 ) to measure a temperature of the water, which is protected from the ultraviolet rays by a tube ( 2 C). 
         [0020]    According to the invention described in a seventh aspect of the invention, in an incubator, the temperature sensor comprising a first self-heating type thermistor ( 2 ) and a second self-heating type thermistor ( 3 ) which amount of self-heating is less than that of the first self-heating type thermistor ( 2 ), the thermistors are provided at a position corresponds to a predetermined water level of the water storing structure. The incubator further comprising a power source to supply power to the thermistors intermittently and a judging means comparing the voltages correspond to the temperatures measured by the thermistors, and judging the water level of the water storing structure fell down than the predetermined water level when the voltage of the first self-heating type thermistor ( 2 ) is less than the voltage of the second self-heating type thermistor ( 3 ) having less amount of self-heating. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a schematic circuit diagram of a first embodiment of an incubator according to the invention; 
           [0022]      FIG. 2  is a diagram for illustrating output voltage values in accordance with temperatures of thermistors of the first embodiment; 
           [0023]      FIG. 3  is a diagram of the thermistor which is a temperature sensor of the first embodiment; 
           [0024]      FIG. 4  is a partially fractured perspective view for illustrating the case where the thermistors of the first embodiment are attached to the humidifying dish; and 
           [0025]      FIG. 5  is a timing chart for illustrating intermittent driving of the thermistor of the first embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
       [0026]    A first embodiment of the invention will be described with reference to  FIGS. 1 to 5 . 
         [0027]    The first embodiment is an incubator employing a water level detecting device according to the invention.  FIG. 1  is a schematic circuit diagram of the incubator.  FIG. 2  is a diagram for illustrating output voltage values in accordance with temperatures of thermistors.  FIG. 3  is a diagram of the thermistor which is a temperature sensor.  FIG. 4  is a partially fractured perspective view for illustrating the case where the thermistors are attached to the humidifying dish portion.  FIG. 5  is a timing chart for illustrating intermittent driving of the thermistor. 
         [0028]    In  FIG. 1 , reference numeral  1  is a water level sensor. The water level sensor  1  is provided in the humidifying dish portion  30  (water storing structure) on an inner bottom surface of an incubator for incubating a culture medium accommodated in an incubation space defined in a storage to detect water in the humidifying dish portion  30 . Reference numeral  2  is a detection thermistor (first self-heating type thermistor) and reference numeral  3  is a standard thermistor (second self-heating type thermistor). Reference numeral  4  is a power supply voltage and reference numeral  5  is a switch for intermittent energization. Reference numeral R 1  is a current limit resistance for the detection thermistor  2 . Reference numerals R 2  and R 3  are current limit resistances for the standard thermistor  3 . Reference numeral  9  is a differential amplifier circuit for amplifying the output voltage of the detection thermistor  2  and the output voltage of the standard thermistor. Reference numeral  10  is a waveform shaping circuit for converting the output of the differential amplifier circuit  9  into “1” or “0”. Reference numeral  11  is a microcomputer (1-chip microcomputer). Reference numeral  12  is a display portion, reference numeral  13  is a buzzer, reference numeral  14  is a communication portion, reference numeral  15  is a memory, and reference numeral  16  is a feed-water valve to supply water (humidifying water) to the humidifying dish portion  30 . Reference numeral  17  is a heater (humidifying heater) for heating the inner bottom surface (humidifying dish portion  30 ) of the incubator. Reference numeral  18  is a heater provided in an area other than the inner bottom surface of the incubator for heating the inside. 
         [0029]    In the incubator, for example, 24 volts as the power supply voltage  4  passes through the switch  5  and the current limit resistances R 1 , R 2  and R 3  to be applied to the detection thermistor  2  and the standard thermistor  3  of the water level sensor  1 . 
         [0030]    A resistance of an NTC thermistor is reduced as an ambient temperature thereof increases. Output voltages Vt and Va from the detection thermistor  2  and the standard thermistor  3  have characteristics depending on the ambient temperature and the presence/absence of water, as shown in  FIG. 2 . A multipurpose current flows to the detection thermistor  2  to purposely self-heat the detection thermistor. Thus the amount of self-heating of the standard thermistor  3  is less than the amount of self-heating of the detection thermistor  2 . When the detection thermistor  2  is present in the water, its discharge characteristic is excellent as compared with when the detection thermistor is present in the air (drought state). Accordingly, the temperature becomes low, the resistance value becomes high and the output voltage Vt becomes high. The standard thermistor  3  has a general characteristic suppressing self-heating and has little variation in accordance with the output voltages in the air and water. 
         [0031]    The two output voltages are input to the waveform shaping circuit  10  via the differential amplifier  9 . When the output voltage Vt is lower than the output voltage Va, that is, when the water level sensor  1  is present in the air, the waveform shaping circuit  10  outputs output “0” to a port A of the microcomputer  11 . When the output voltage Vt is higher than the output voltage Va, that is, when the water level sensor  1  is present in the water, the waveform shaper  10  outputs output “1” to the port A of the microcomputer  11 . 
         [0032]    Based on the input of the port A, the microcomputer  11  determines that there is no water in the humidifying dish portion  30  in case of the output “0”, and that there is the water in the humidifying dish portion  30  in case of the output “1”. 
         [0033]    The output voltage Va is directly input from a port B of the microcomputer  11  to measure a value thereof by an A/D converter  6  and thus the ambient temperature (water temperature, when there is the water) of the standard thermistor  3  is determined. In addition, data from a storeroom temperature sensor (not shown) for measuring a temperature of a storeroom of the incubator is also input to the microcomputer  11 . The microcomputer  11  calculates the humidity (relative humidity) of the storeroom based on the water temperature data and storeroom temperature data and controls energization rates of the humidifying heater  17  and the heater  18  so as to obtain a preliminarily set temperature and humidity. 
         [0034]    In this first embodiment, the water level sensor  1  is configured so as to detect the water by using the standard thermistor  3  and the detection thermistor  2 . However, only the detection thermistor  2  may be used. In this case, it is preferable that the output voltage Vt of the detection thermistor  2  is read by the A/D converter of the microcomputer and a memory in which the value of the output voltage Vt obtained by the temperature in the storeroom and the presence/absence of the water is written is provided to perform the determination operation based on the value of the memory, the value of the output voltage Vt and the value of the temperature in the storeroom. 
         [0035]    Returning to the first embodiment, the incubator will be described.  FIG. 3  is a diagram for illustrating the thermistor  2 . In  FIG. 3 , reference numeral  2   a  is a lead wire. Reference numeral  2   b  is a temperature sensor. Reference numeral  2   c  is a protective tube for protecting the periphery of a thermistor element  2   d  in the temperature sensor  2   b . The thermistor element  2   d  is soldered  2   f  to the lead wire  2   a . A buffer  2   i  is disposed at the periphery of the thermistor element  2   d  and a filler  2   h  is disposed around the lead wire  2   a . The thermistor  3  has the same configuration as above. 
         [0036]    The protective tube  2   c  is made of metal which is resistant to ultraviolet radiation, such as a stainless material (SUS316). The protective tube  2   c  is provided to protect the thermistor from ultraviolet rays. That is, as described in the above Japanese Patent No. 3670876, there is also an incubator of a type in which a storeroom is irradiated by ultraviolet rays. Accordingly, the protective tube  2   c  prevents the deterioration of the performance of the thermistor, which occurs by the ultraviolet rays. 
         [0037]      FIG. 4  is a perspective view of an example of the attachment of the water level sensor  1 . As illustrated in  FIG. 4 , holes are defined at the height corresponding to a water level position to be detected and the thermistors  2  and  3  of the water level sensor  1  of a humidifying water dish portion  30  disposed in the bottom portion in the storeroom of the incubator are inserted to the holes from the outside. Then, O-rings (not shown) or the like are used to waterproof gaps and fix the thermistors. In this manner, in the humidifying dish portion  30  in the storeroom, only the temperature sensor  2   b  of the thermistor protrudes so as to suppress the bad effects occurring by ultraviolet rays and the deterioration of maintenance such as cleaning. 
         [0038]    Next, automatic water feeding of the first embodiment will be described with reference to  FIG. 5 . 
         [0039]    In an automatic water feeding function of the microcomputer  11 , the water is intermittently detected. That is, since the detection thermistor  2  of the water level sensor  1  purposely increases a self-heating value thereof, a lifetime thereof may be affected when the thermistor is continuously energized under a high-temperature environment. Accordingly, the thermistor is intermittently driven at time intervals so as not to interfere with the detection of a water level. That is, the microcomputer  11  of  FIG. 1  intermittently turns on the switch  5  to apply a power supply voltage of 24 V to the detection thermistor  2  via the resistance R 1 . In this manner, energization is performed. When the output voltage Vt of the detection thermistor  2  is balanced by the energization, the water detection is performed. In this first embodiment, the ON state is maintained for 2 minutes and the water detection is performed. After that, the ON state is switched to the OFF state and the OFF state is maintained for 8 minutes and then switched to the ON state again. This operation is repeated. 
         [0040]    As described above, the microcomputer  11  turns on the switch  5  and counts 2 minutes. When the 2 minutes are counted, at this time, the presence/absence of the water and the water temperature are detected by the output of the water level sensor  1  and the temperature in the storeroom is detected from the storeroom temperature sensor. 
         [0041]    When there is the water, the switch  5  is turned off for 8 minutes, and as described above, the humidifying heater  17  and the heater  18  are controlled so that the humidity and the temperature in the storeroom is adjusted to a predetermined humidity and temperature. 
         [0042]    At this time, when there is no water, an automatic water feeding mode is applied. That is, the microcomputer  11  opens the feed-water valve  16  for a predetermined period of time to supply a predetermined amount of water to the humidifying dish portion  30 . Herein, when the humidifying dish portion  30  is continuously replenished with the water at one time, the temperature and the humidity in the incubator may vary largely. 
         [0043]    Accordingly, in the first embodiment, the humidifying dish portion  30  is replenished with the water by intermittently opening the feed-water valve  16 . For example, in this first embodiment 1, when the feed-water valve  16  is opened for 2 minutes and a predetermined amount of water is thereby replenished, the feed-water valve  16  is not continuously opened for 2 minutes. A cycle in which the valve is opened for 1 second and then closed for 4 seconds is repeated 120 times. 
         [0044]    when the feed-water valve  16  supplies the water to the humidifying dish portion  30  during the culture medium is incubated, the feed-water valve  16  decreases the amount of water supplied per unit time than the amount of water supplied during the culture medium is not incubated. That is, when the incubation is not performed, it doesn&#39;t matter if a temperature and a humidity vary and thus the water is supplied to shorten the amount of time. However, during the incubation, the water is slowly supplied to suppress the variation in temperature and humidity. 
         [0045]    Further, during the intermittent supply of the water, the heater (other than humidifying heater) in the storeroom of the incubator is controlled as normal. The humidifying heater is controlled to be stopped to prevent no-water heating. Then, during the intermittent supply, the humidifying heater in the storeroom is controlled again. 
         [0046]    Moreover, during the supply of the water, the drought in the humidifying dish portion  30  (accurately, there is no water at the height of water level sensor) is displayed by the display portion  12 , notified by the buzzer, or notified to the outside (mobile phone, outside organization, other room) by the communication portion with the use of an E-mail. In addition, even after the supply of the water is ended, the display portion displays the history (number of times, time) of the drought state. 
         [0047]    In this first embodiment, the example of performing the automatic water feeding when the drought is detected is shown. However, the present application can be employed for other incubators without the automatic water feeding function. In this case, when the drought is detected, the microcomputer  11  notifies the drought and stops (or weakens) the heating operation performed by the humidifying heater to prevent no-water heating. In addition, the microcomputer  11  causes the display portion to display the history (number of times, time) of the drought state even after the manual supply of the water is ended by a user. This drought history data is important as compared with the case of the incubator with the automatic water feeding function.