Patent Description:
For example, <CIT> discloses a thermogravimetric measurement apparatus that includes a sample plate on which a sample is to be placed, a balance connected to the sample plate, a heating unit adapted to heat the sample, and the like. This thermogravimetric measurement apparatus can measure changes in the weight of the sample placed on the sample plate while the sample is heated.

Such a thermogravimetric measurement apparatus includes a cooling fan to prevent the temperature of the apparatus body from increasing as the sample is heated. However, when the cooling fan rotates and vibrates, the weight measurement value may be different from the actual weight of the sample. That is, in this case, the weight measurement value and the weight waveform, which is the continuous weight measurement value, may include noise.

As for the balance, balances manufactured by the same method may still have mutually different natural frequencies. As for the cooling fan, cooling fans manufactured by the same method may still have mutually different vibration frequencies caused by rotation of a predetermined rotation speed. As such, with the thermogravimetric measurement apparatus, the amount of noise in the weight measurement value may vary from apparatus to apparatus even when the cooling fans are operated under the same conditions.

For these reasons, it is difficult to adjust the amount of noise in the weight measurement value caused by the rotation and vibration of the cooling fan in the thermogravimetric measurement apparatus as described above. Other documents of the prior art are <CIT>, <CIT>, <CIT> and <CIT>.

In view of the foregoing, it is an object of the present invention to provide a thermogravimetric measurement apparatus and a method for setting the same that allow for appropriate determination of the rotation speed in operation of a cooling fan for the individual apparatus.

A first aspect of the invention is a method for setting a thermogravimetric measurement apparatus as defined in claim <NUM>.

A second aspect of the invention is a thermogravimetric measurement apparatus as defined in claim <NUM>.

<FIG> is a schematic cross-sectional view showing an example of the configuration of a thermogravimetric measurement apparatus <NUM> of the present embodiment. The thermogravimetric measurement apparatus <NUM> is an apparatus for measuring changes in the weight of a sample S that occur when the sample S is heated, cooled, or maintained at a constant temperature, and is a concept that encompasses a simultaneous thermogravimetric/differential thermal analysis instrument.

The thermogravimetric measurement apparatus <NUM> may include a measurement unit <NUM>, a heating unit <NUM>, a heat radiation portion <NUM>, and cooling fans <NUM> which are housed inside a housing <NUM>. The housing <NUM> has an exhaust port <NUM> for exhausting air in the housing <NUM>.

The measurement unit <NUM> measures the weight of the sample S. The measurement unit <NUM> is a top-loading thermobalance and thus includes a sample holder 14a and a support member 14b which supports the sample holder 14a. The measurement unit <NUM> can obtain weight measurement values. For example, when the sample S is set on the sample holder 14a as shown in <FIG>, a weight measurement value indicating the weight of the sample S can be obtained.

The measurement unit <NUM> is directly or indirectly attached to the housing <NUM>. For example, the measurement unit <NUM> may be attached to the housing <NUM> through various members for fixing the measurement unit <NUM> to the housing <NUM>.

The heating unit <NUM> is an electrically controllable furnace and heats the sample S. The heating unit <NUM> is arranged above the measurement unit <NUM>. The thermogravimetric measurement apparatus <NUM> also includes an electrically controllable first displacement mechanism (not shown) which displaces the heating unit <NUM>. The heating unit <NUM> can be vertically displaced by this first displacement mechanism.

In the present embodiment, when measuring changes in the weight of the sample S while heating the sample S, for example, the heating unit <NUM> is placed at a position at which the sample S is housed in the heating unit <NUM> as shown in <FIG>. When the sample S is set onto the sample holder 14a and when the sample S is removed from the sample holder 14a, the heating unit <NUM> is placed at a position at which the sample S is not housed in the heating unit <NUM>, that is, at a position indicated by the broken line in <FIG>.

The thermogravimetric measurement apparatus <NUM> includes a general-purpose temperature sensor (not shown), and the temperature of the heating unit <NUM> is controlled based on the temperature signal output from this temperature sensor.

The thermogravimetric measurement apparatus <NUM> also includes an electrically controllable second displacement mechanism (not shown) which displaces a portion of the housing <NUM>. For example, a portion of the housing <NUM> that is lateral to the sample holder 14a can be opened and closed, or is slidable.

In the thermogravimetric measurement apparatus <NUM>, when an operation reception unit (not shown) receives the first predetermined operation by the user, the first and second displacement mechanisms cooperate to allow the sample S to be set onto or removed from the sample holder 14a.

The heat radiation portion <NUM> is a member that absorbs heat and dissipates heat into the air. The heat radiation portion <NUM> may be a general-purpose heat sink, for example. The heat radiation portion <NUM> is provided around the support member 14b and below the heating unit <NUM>.

The cooling fans <NUM> are electrically controllable axial fans. Each cooling fan <NUM> functions to cool the inside of the housing <NUM> or to cool components of the thermogravimetric measurement apparatus <NUM>.

Also, each cooling fan <NUM> is directly or indirectly attached to the housing <NUM> in the same manner as the measurement unit <NUM>. In other words, the cooling fan <NUM> is physically connected to the measurement unit <NUM>.

The cooling fans <NUM> include a first cooling fan 20a, a second cooling fan 20b, and a third cooling fan 20c.

The first cooling fan 20a cools the inside of the housing <NUM> by discharging the heated air inside the housing <NUM> to the outside of the housing <NUM> through the exhaust port <NUM>. The first cooling fan 20a is always in operation. Thus, while the weight of the sample S is measured, the first cooling fan 20a is in operation.

The second cooling fan 20b cools the heating unit <NUM>. The second cooling fan 20b is stopped while the sample S is heated and is operated as necessary when the sample S is not being heated.

The third cooling fan 20c cools the heat radiation portion <NUM>. The third cooling fan 20c is stopped while the sample S is set onto the sample holder 14a or removed from the sample holder 14a. Also, the third cooling fan 20c is in operation at least while the weight of the sample S is measured.

The cooling fans <NUM> may include fans other than the first cooling fan 20a, the second cooling fan 20b, and the third cooling fan 20c. For example, when the housing <NUM> has an inlet port, the cooling fans <NUM> may include a fan for introducing air into the housing <NUM> from the outside of the housing <NUM> through the inlet port.

The thermogravimetric measurement apparatus <NUM> can measure changes in the weight that occur while the sample S on the sample holder 14a is heated, cooled, or maintained at a constant temperature. It should be noted that the configuration of the thermogravimetric measurement apparatus <NUM> shown in <FIG> is merely an example.

Regarding the thermogravimetric measurement apparatus <NUM>, components other than the measurement unit <NUM> may be provided outside the housing <NUM> as long as they can function as described above. In other words, the thermogravimetric measurement apparatus <NUM> of the present embodiment may have a configuration in which at least the measurement unit <NUM> is provided inside the housing <NUM>.

Also, in the thermogravimetric measurement apparatus <NUM> of the present embodiment, a cooling fan <NUM> may be physically connected to the measurement unit <NUM> without the housing <NUM> interposed therebetween. That is, the cooling fan <NUM> may be directly attached to the measurement unit <NUM> or may be attached to the measurement unit <NUM> through a certain member.

Furthermore, the measurement unit <NUM> of the present embodiment may be a suspension thermobalance or a horizontal thermobalance. The displacement direction of the heating unit <NUM> is set in accordance with the method of thermobalance.

<FIG> is a block diagram showing an example of the electrical configuration of the thermogravimetric measurement apparatus <NUM> of the present embodiment. In addition to the measurement unit <NUM>, for example, the thermogravimetric measurement apparatus <NUM> includes a control circuit <NUM> and a control unit <NUM>.

The control unit <NUM>, the measurement unit <NUM>, the heating unit <NUM>, the control circuit <NUM>, and the like are electrically connected to one another via a circuit <NUM> such as a bus. The control circuit <NUM> is also electrically connected to the first cooling fan 20a, the second cooling fan 20b, and the third cooling fan 20c.

The control circuit <NUM> is a circuit for controlling the operation of each cooling fan <NUM>. The control circuit <NUM> adjusts the control conditions of the cooling fan <NUM>, that is, the parameters that determine the rotation speed of the cooling fan <NUM> according to instructions from the control unit <NUM>. For example, the control circuit <NUM> appropriately adjusts the voltage applied to the cooling fan <NUM> or the pulse signal transmitted to the cooling fan <NUM>.

The control unit <NUM> performs the overall control of the thermogravimetric measurement apparatus <NUM>. The control unit <NUM> includes a central processing unit (CPU) <NUM>. The control unit <NUM> also includes a random access memory (RAM) <NUM> and a storage unit <NUM>, which can be directly accessed by the CPU <NUM>.

The RAM <NUM> is used as a work area and a buffer area for the CPU <NUM>. A non-volatile memory such as a hard disc drive (HDD) or a solid state drive (SSD) is used as the storage unit <NUM>.

The storage unit <NUM> stores a program (control program) for controlling the operation of the thermogravimetric measurement apparatus <NUM>, data required for executing the control program (execution data), and the like. The storage unit <NUM> may also be configured to include the RAM <NUM>.

In the thermogravimetric measurement apparatus <NUM>, the measurement unit <NUM> and the cooling fans <NUM> are physically connected, and the vibration caused by the rotation of the cooling fans <NUM> thus propagates to the measurement unit <NUM>. This may cause the weight measurement value to be different from the actual weight of the sample S. That is, the weight measurement value and the continuous weight measurement value (weight waveform) may include noise.

As for the measurement unit <NUM>, measurement units that are manufactured by the same method may still be susceptible to mutually different vibration frequencies, that is, may have mutually different natural frequencies. As for the cooling fans <NUM>, cooling fans that are manufactured by the same method may still have mutually different vibration frequencies with respect to the rotation speed.

As such, as for the thermogravimetric measurement apparatus <NUM>, the amount of noise in the weight measurement value may vary from apparatus to apparatus even when the cooling fans <NUM> are operated under the same conditions. For example, in the thermogravimetric measurement apparatus <NUM>, the rotation speed of the cooling fan <NUM> with which the amount of noise in the weight measurement value is considered the smallest may vary from apparatus to apparatus.

Thus, with the thermogravimetric measurement apparatus <NUM>, it is difficult to adjust the amount of noise in the weight measurement value caused by the rotation and vibration of the cooling fans <NUM>.

For this reason, the thermogravimetric measurement apparatus <NUM> is configured to be capable of performing a rotation speed setting process at any given time. The rotation speed setting process identifies the relationship between the rotation speed of the cooling fan <NUM> and the amount of noise in the weight measurement value caused by the vibration of the cooling fan <NUM> and then sets a rotation speed in operation of the cooling fan <NUM>.

Here, the cooling fan <NUM> in operation refers to that the cooling fan <NUM> is in operation other than the rotation speed setting process. As such, the rotation speed in operation of the cooling fan <NUM> includes, for example, the rotation speed of the cooling fan <NUM> in a situation in which the sample S on the sample holder 14a is heated, cooled, or maintained at a constant temperature while changes in the weight of the sample S are measured.

Also, determining the control conditions of the cooling fan <NUM> determines the rotation speed of the cooling fan <NUM>. As such, the rotation speed of the cooling fan <NUM> may also be considered as a control condition of the cooling fan <NUM>. In this respect, the rotation speed in operation of the cooling fan <NUM> may be considered as a control condition of the cooling fan <NUM> in operation.

The parameter that determines the control conditions of the cooling fan <NUM> may be the voltage applied to the cooling fan <NUM> or the pulse signal transmitted to the cooling fan <NUM> as described above.

The rotation speed setting process is automatically executed before the weight of the sample S is measured, for example when the power of the thermogravimetric measurement apparatus <NUM> is switched from off to on. The rotation speed setting process may also be performed when the thermogravimetric measurement apparatus <NUM> receives the second predetermined operation by the user at the above-mentioned operation reception unit.

In the present embodiment, when the rotation speed setting process starts, the rotation speed determination step is performed one or more times.

The rotation speed determination step monitors changes in the weight measurement value at the measurement unit <NUM> while altering the rotation speed of a cooling fan <NUM>, and determines the rotation speed in operation of the cooling fan <NUM> based on the changes in the weight measurement value.

The beating caused by vibrations of the multiple cooling fans <NUM> can be ignored because the natural frequency of the measurement unit <NUM> does not change. Furthermore, when multiple cooling fans <NUM> are operated, it is difficult to identify the cooling fan <NUM> that affects the weight measurement value.

For this reason, when there are multiple cooling fans <NUM>, the rotation speed determination step monitors changes in the weight measurement value at the measurement unit <NUM> while altering the rotation speed of one of the multiple cooling fans <NUM> with the other cooling fans <NUM> stopped. In this case, the rotation speed determination step is repeatedly performed while switching the target cooling fan <NUM>.

The present embodiment can also obtain a negative weight measurement value because the measurement unit <NUM> is a thermobalance. As such, the rotation speed determination step is performed in a state in which the sample S is not set on the sample holder 14a.

On the other hand, since the weight of the measurement unit <NUM> itself is substantially greater than the weight of the sample S, the presence or absence of the sample S does not affect the amount of noise in the weight measurement value. As such, the rotation speed determination step may also be performed with the sample S set on the sample holder 14a.

When the rotation speed determination step is performed in a state in which the sample S is not set on the sample holder 14a, the weight measurement value itself corresponds to the amount of noise. That is, in this case, the amount of noise in the weight measurement value can be easily identified. The rotation speed determination step is therefore preferably performed in a state in which the sample S is not set on the sample holder 14a.

Also, the rotation speed determination step alters the rotation speed of the cooling fan <NUM> in ascending order. However, the rotation speed determination step may alter the rotation speed of the cooling fan <NUM> in descending order. There is no limitation to the range of alteration of the rotation speed of the cooling fan <NUM> in the rotation speed determination step.

<FIG> is a schematic diagram showing an example of a weight waveform in the rotation speed determination step of the present embodiment. In the present embodiment, each cooling fan <NUM> is an electrically controllable component, and a response time T1 is needed between when the cooling fan <NUM> is controlled to alter its rotation speed and when the rotation speed of the cooling fan <NUM> becomes stable.

Thus, the response time T1 is needed between when the cooling fan <NUM> is controlled to alter its rotation speed and when a weight measurement value is obtained in a state in which the rotation speed of the cooling fan <NUM> is stable.

As such, if the rotation speed of the cooling fan <NUM> is continuously altered, it is difficult to identify the weight measurement value corresponding to the rotation speed, and a weight measurement value in a state in which the rotation speed of the cooling fan <NUM> is stable is not obtained.

For this reason, the rotation speed determination step monitors changes in the weight measurement value at the measurement unit <NUM> while altering the rotation speed of the cooling fan <NUM> in a stepwise manner.

When the rotation speed of the cooling fan <NUM> is altered in a stepwise manner, the rotation speed of the cooling fan <NUM> is altered each time a rotation speed maintaining time T2 elapses. To obtain a weight measurement value in a state in which the rotation speed of the cooling fan <NUM> is stable, the rotation speed maintaining time T2 is preferably longer than the response time T1. For example, in the rotation speed determination step, the rotation speed of the cooling fan <NUM> is altered every minute.

In the rotation speed determination step, when changes in the weight measurement value at the measurement unit <NUM> are monitored, the rotation speed in operation of the cooling fan <NUM> is determined based on the magnitude of the weight measurement value in a reference period P2 within a period P1 in which the rotation speed of the cooling fan <NUM> is maintained (rotation speed maintaining period).

The rotation speed maintaining period P1 is a period corresponding to a rotation speed maintaining time T2. The maximum of the reference period P2 is the same as the rotation speed maintaining period P1. The reference period P2 is preferably a period after the response time T1 in the rotation speed maintaining period P1 has elapsed, that is, a period after the rotation speed of the cooling fan <NUM> becomes stable.

Specifically, the rotation speed determination step refers to the magnitude of the weight measurement value in the reference period P2 for each rotation speed maintaining period P1, that is, for each rotation speed. In other words, the rotation speed determination step refers to a peak-to-peak value of the weight waveform within the reference period P2 for each rotation speed. The peak-to-peak value refers to the difference (divergence amount) between the maximum value and the minimum value of the weight waveform.

The magnitude of the peak-to-peak value of the weight waveform is proportional to the amount of noise in the weight waveform. Thus, when the accuracy of the weight measurement value is given a high priority, the step may refer to the peak-to-peak value of the weight waveform for each rotation speed, and determine, as the rotation speed in operation of the cooling fan <NUM>, the rotation speed with which the amount of noise in the weight measurement value is considered the smallest. In the example shown in <FIG>, rotation speed R1 may be determined as the rotation speed in operation of the cooling fan <NUM>.

When a permissible amount of noise in the weight measurement value is predetermined, one of the rotation speeds with which the amounts of noise in the weight measurement values are less than or equal to the permissible amount may be determined as the rotation speed in operation of the cooling fan <NUM>.

For example, when the cooling efficiency of the thermogravimetric measurement apparatus <NUM> is given a high priority, the highest rotation speed of the rotation speeds with which the amounts of noise in the weight measurement values are less than or equal to the permissible amount may be determined as the rotation speed in operation of the cooling fan <NUM>.

Furthermore, instead of the peak-to-peak value of the weight waveform, the amplitude of the weight waveform, specifically, the difference between the maximum absolute value of the weight waveform and a reference value B may be referred to. Here, the reference value B is a weight measurement value indicating the weight of the sample S when the sample S is set on the sample holder 14a, and is <NUM> when the sample S is not set on the sample holder 14a.

Also, in the rotation speed determination step, when changes in the weight measurement value at the measurement unit <NUM> are monitored, the rotation speed in operation of the cooling fan <NUM> may be determined based on the average value of the weight measurement values in the reference period P2 within the rotation speed maintaining period P1.

Specifically, in this case, the rotation speed determination step refers to the average value of the weight measurement values in the reference period P2 for each rotation speed maintaining period P1, that is, for each rotation speed. In other words, the rotation speed determination step refers to the average value of the weight waveform in the reference period P2 for each rotation speed.

The difference between the average value of the weight waveform and the reference value B is proportional to the amount of noise in the weight waveform. As such, when the accuracy of the weight measurement value is given a high priority, the step may refer to the difference between the average value of the weight waveform for each rotation speed and the reference value B, and determine, as the rotation speed in operation of the cooling fan <NUM>, the rotation speed with which the amount of noise in the weight measurement value is considered the smallest.

In this case, as described above, when the permissible amount of noise in the weight measurement value is predetermined, any one of the rotation speeds with which the amounts of noise in the weight measurement values are within the permissible range may be determined as the rotation speed in operation of the cooling fan <NUM>.

In other words, when the cooling efficiency of the thermogravimetric measurement apparatus <NUM> is given a high priority, the highest rotation speed of the rotation speeds with which the amounts of noise in the weight measurement values are less than or equal to the permissible amount may be determined as the rotation speed in operation of the cooling fan <NUM> in the same manner.

When the rotation speed determination step determines the rotation speed in operation of the cooling fan <NUM> in this manner, the storage unit <NUM> stores rotation speed information indicating this rotation speed as data. When multiple cooling fans <NUM> are present, each piece of rotation speed information includes identification information that enables the identification of the associated cooling fan <NUM>. A specific operation flow of the thermogravimetric measurement apparatus <NUM> is described below, using as an example a situation in which the rotation speed determination step is performed for the first cooling fan 20a.

In the present embodiment, when the rotation speed determination step is performed for the first cooling fan 20a, the second and third cooling fans 20b and 20c are stopped, and the rotation speed of the first cooling fan 20a is increased in a stepwise manner. While the rotation speed of the first cooling fan 20a is increased in a stepwise manner, changes in the weight measurement value at the measurement unit <NUM> are monitored.

When the monitoring of the weight measurement value at the measurement unit <NUM> is completed, the magnitude or average value of the weight measurement values in the reference period P2 is referred to for each rotation speed. The rotation speed with which the amount of noise in the weight measurement value is considered the smallest is determined as the rotation speed in operation of the first cooling fan 20a, for example.

When the rotation speed in operation of the first cooling fan 20a is determined in this manner, the storage unit <NUM> stores rotation speed information indicating this rotation speed as data. Also, in this case, the rotation speed information includes identification information indicating that this rotation speed information is associated with the first cooling fan 20a.

The thermogravimetric measurement apparatus <NUM> of the present embodiment refers to the rotation speed information when a rotation speed setting process is not in progress. In other words, in the thermogravimetric measurement apparatus <NUM> of the present embodiment, each cooling fan <NUM> rotates at the rotation speed determined in the rotation speed determination step, when the sample S is heated, cooled, or maintained at a constant temperature while changes in the weight of the sample S are measured.

<FIG> is a functional block diagram showing a specific example of the electrical configuration of the thermogravimetric measurement apparatus <NUM> of the present embodiment. In <FIG>, illustration of the RAM <NUM> and the like is omitted.

The storage unit <NUM> stores measurement data <NUM>, rotation speed data <NUM>, and the like. The measurement data <NUM> is data corresponding to weight measurement values. The measurement data <NUM> also corresponds to weight waveform.

The rotation speed data <NUM> is rotation speed information in a data format. The storage unit <NUM> may store multiple pieces of rotation speed data <NUM>. The rotation speed data <NUM> may include data format identification information. Although illustration is omitted, the storage unit <NUM> also stores the control program, execution data, and the like as described above.

When the CPU <NUM> (see <FIG>) runs the control program, the thermogravimetric measurement apparatus <NUM> may function as a measurement process unit <NUM>, a rotation speed determination process unit <NUM>, a storage process unit <NUM>, and an operation process unit <NUM>.

The measurement process unit <NUM> causes the storage unit <NUM> to store the weight measurement values obtained by the measurement unit <NUM> as measurement data <NUM>.

The rotation speed determination process unit <NUM> functions to perform the rotation speed determination step. As such, the rotation speed determination process unit <NUM> monitors changes in the weight measurement value at the measurement unit <NUM> by referring to the measurement data <NUM> while altering the rotation speed of the cooling fan <NUM>, and determines the rotation speed in operation of the cooling fan <NUM> based on the changes in the weight measurement value.

Specifically, the rotation speed determination process unit <NUM> monitors changes in the weight measurement value at the measurement unit <NUM> while altering the rotation speed of the cooling fan <NUM> in a stepwise manner.

Specifically, the rotation speed determination process unit <NUM> determines the rotation speed in operation of the cooling fan <NUM> based on the magnitude of the weight measurement values in the reference period P2 within the rotation speed maintaining period P1.

The rotation speed determination process unit <NUM> may also determine the rotation speed in operation of the cooling fan <NUM> based on the average value of the weight measurement values in the reference period P2 within the rotation speed maintaining period P1.

The storage process unit <NUM> causes the storage unit <NUM> to store the rotation speed determined by the rotation speed determination process unit <NUM> as rotation speed data <NUM>.

When the rotation speed setting process is not in progress, the operation process unit <NUM> refers to the rotation speed data <NUM> as necessary and rotates the cooling fan <NUM> at the rotation speed indicated by the rotation speed data <NUM>.

<FIG> is a flowchart showing an example of rotation speed setting process of the thermogravimetric measurement apparatus <NUM> of the present embodiment. The rotation speed setting process may start at any given time as described above.

Step S1 monitors changes in the weight measurement value at the measurement unit <NUM> while altering the rotation speed of a cooling fan <NUM> and determines the rotation speed in operation of the cooling fan <NUM> based on the changes in the weight measurement value.

Specifically, step S1 monitors changes in the weight measurement value at the measurement unit <NUM> while increasing or decreasing the rotation speed of one of the multiple cooling fans <NUM> in a stepwise manner with the other cooling fans <NUM> stopped, and determines the rotation speed in operation of the cooling fan <NUM> based on the magnitude or average value of the weight measurement values in the reference period P2 within the rotation speed maintaining period P1.

Step S2 causes the storage unit <NUM> to store information on the rotation speed determined at step S1 as rotation speed information indicating the rotation speed in operation of the cooling fan <NUM>.

Claim 1:
A method for setting a thermogravimetric measurement apparatus (<NUM>) comprising a measurement unit (<NUM>) adapted to measure a weight of a sample, a heating unit (<NUM>) adapted to heat the sample, and a cooling fan (<NUM>) physically connected to the measurement unit (<NUM>), the method characterized in that it comprises:
a rotation speed determination step comprising monitoring changes in a weight measurement value at the measurement unit (<NUM>) while altering a rotation speed of the cooling fan (<NUM>), wherein such monitoring changes in the weight measurement value at the measurement unit are performed in a state in which the sample is not set on the measurement unit (<NUM>),
identifing the relationship between the rotation speed of the cooling fan (<NUM>) and an amount of noise in the weight measurement value caused by the vibration of the cooling fan (<NUM>),
and determining a rotation speed in operation of the cooling fan (<NUM>) based on the changes in the weight measurement value.