Abstract:
A thermal analyzer is capable of separating a baseline component, a convex peak component and a concave peak component. During concave peak separation, arithmetic symbol inversion is performed by an arithmetic symbol inverter and separation into basic peaks is performed by basic peak optimization. Arithmetic symbol inversion is performed after separation by a second arithmetic symbol inverter. During convex peak separation, no arithmetic symbol inversion is performed.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to thermal analysis apparatuses. 
     In thermal analysis, analysis in which individual peaks are extracted from data having a plurality of peaks overlapped therein has been conventionally made. In a known method, parameters are sequentially varied in a plurality of basic peak model functions given by a curve-fitting method, or a Gaussian function, or the like, in a spectrum analysis such as spectroscopy, to optimize a spectrum measured. 
     It is satisfactory in every spectrum analysis to analyze data above a baseline, i.e. convex-formed peaks. However, there are often cases encountered in techniques of thermal analysis (DSC or DTA) in which convex-formed peaks and concave-formed peaks exist in the same data. 
     In such case it has been a conventional practice to cut out only convex-formed peaks to separate peaks or give up separation itself. 
     The above problem that the present invention is intended to solve, is solved by providing a thermal analysis apparatus that can separate respective peaks into basic peaks even where convex-formed peaks and concave-formed peaks exist in the same data. 
     SUMMARY OF THE INVENTION 
     The present invention has been developed in order to solve the above problem, and has constituent components comprising temperature control means, temperature measuring means, physical amount measuring means, thermal analysis data, baseline separation means, basic peak separation means and output means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing an embodiment of the present invention. 
     FIG. 2 is an explanatory view of a heat generation peak, heat absorption peak and baseline of the present invention. 
     FIG. 3 is an output example in the embodiment of the present invention. 
     FIG. 4 is a concave-formed peak component partial magnifying view in the output example of the embodiment of the present invention. 
     FIG. 5 is a block diagram showing another embodiment of the present invention. 
    
    
     EXPLANATION OF THE REFERENCE NUMERALS AND SYMBOLS 
       1  Temperature sensor 
       2  Sample 
       3  Heater/cooler 
       4  Physical amount sensor 
       5  Computer a 
       6  Temperature adjust means 
       7  Physical amount fetch means 
       8  Temperature fetch means 
       9  Baseline separation means a 
       10  Arithmetic symbol inverter A 
       11  Basic peak model function generation means 
       12  Basic peak optimizing means a 
       13  Arithmetic symbol inverter B 
       14  Combining means 
       15  Output means 
       16  Heat generation peak 
       17  Baseline 
       18  Heat absorption peak 
       19  Computer b 
       20  Baseline separation means b 
       21  Basic peak model function generation means for convex-formed peak components 
       22  Basic peak optimizing means b 
       23  Basic peak model function generation means for concave-formed peak components 
     DESCRIPTION OF THE INVENTION 
     Hereunder, one embodiment of this invention will be explained based on the drawings. 
     FIG. 1 is a block diagram in the embodiment of the present invention. In FIG. 1 a computer  5  is a personal computer, workstation or the like provided with a user interface, such as a key board, mouse and CRT. This computer  5  has hardware and software to realize temperature adjusting means  6 , physical amount acquisition means  7 , temperature acquisition means  8 , baseline separation means  9 , first arithmetic symbol inverter  10 , basic peak model function generation means  11 , basic peak optimizing means  12 , second arithmetic symbol inverter  13 , combining means  14 , and output means  15 . 
     Temperature control means is realized by a heater/cooler  3  and temperature adjusting means  6 . Similarly, temperature measuring means is realized by a temperature sensor  1  and temperature acquisition means  8 , physical amount measuring means is realized by a physical sensor  4  and physical amount acquisition means  7 , basic peak separation means is realized by first arithmetic symbol inverter  10  and basic peak model function generation means  11  and basic peak optimizing means  12  and second arithmetic symbol inverter  13 , and combining output means by a combining means  14  and an output means  15 . 
     First, a utilizer places a sample  2  in the heater/cooler  3 . The utilizer interacts with the computer  5  to deliver a proper temperature program to the temperature adjusting means  6 . The temperature adjusting means  6  controls the heater/cooler  3  to make a desired temperature change. The temperature sensor  1  measures a temperature of the sample  2  or around the sample  2 , and a result thereof is fetched by the temperature acquisition means  8 . The physical amount sensor  4  measures a change in a physical amount on the sample  2  due to temperature change or time, and a result thereof is fetched by the physical amount acquisition means  7 . The physical amount sensor  4 , if DSC, measures a change of a heat amount flowing into/out of the sample  2 , if TC, a weight change of the sample  2 , and, if TMA, a shape change of the sample  2 . The physical amount and temperature fetched by the temperature acquisition means  8  and physical amount acquisition means  7  are made into thermal analysis data having a physical amount as a temperature or time function to be sent to the baseline separation mans  9 . 
     In the baseline separation means  9 , the thermal analysis data is separated into a baseline component and a peak component. 
     In conventional thermal analysis, a baseline is taken by a succession of dots on a temperature or time axis where a physical amount change is in a steady state, a data departure from which is taken as a peak. In the case of DSC, a base line is taken by a succession of dots where a change of heat flowing into/out of the sample with respect to a reference substance is in a steady-state. Assuming that data increases greater than the baseline when heat flows out of the sample, data decreases less than the baseline when heat flows into the sample. In the case of fixing a rule of data increase and decrease with the baseline in this manner, a reaction of heat of from a steady state to a sample heat generation and again to the steady state is recorded as a convex-formed peak on the baseline  17  in the thermal analysis data as in a heat generation peak  16  in FIG.  2 . Also, a reaction of heat of from the steady state to sample heat absorption and again to a steady state is recorded as a concave-formed peak on the baseline  17  as in a heat absorption peak  18  in FIG.  2 . 
     The baseline separation means  9  is used to separate the thermal analysis data into a baseline component, a convex-formed peak component and a concave-formed peak component, respectively. The convex-formed peak component and the concave-formed peak component are subtracted physical amount data of the baseline component from the physical amount data of the thermal analysis data. Due to this, the physical amount of the concave-formed peak component assumes a negative value. Also, it is assumed that the baseline is properly set from a sample, measurement technique and measurement conditions. The setting method for a baseline may be conducted by any of the following. 
     (1) The utilizer provides curve fitting. The method includes a method of designating respective ends of a peak component on the measurement data by straight lines, a method of designating points on the measurement data and making a approximation between the dots by a spline function, a method of freely drawing a baseline irrespective of measurement data, and so on. 
     (2) Automatic setting is made by software. Measurement data is retrieved to extract data-stabilized points. The dots are functionally approximated to be set as a baseline. Also, a method may be used that data-stable points are used directly as a baseline and data-unstable, or peak component, regions are functionally approximated. 
     (3) The data measured on a sample that is thermally stable without change is directly used as a baseline. 
     The baseline component separated by the baseline separation means  9  is sent to the combining means  14 . The concave-formed peak component is sent to the first arithmetic symbol inverter  10  and the convex-formed peak component to the basic peak optimizing means  12 . 
     The first arithmetic symbol inverter  10  inverts the arithmetic symbol of a physical amount of the concave-formed peak component and supplies a result thereof to the basic peak optimizing means  12 . In general, the basic peak model functions representing basic peaks, such as a Gauss function or Lorenz function, generates only a positive value of a function value. Due to this, the concave-formed peak component cannot be adapted for optimization to a basic peak model function. Accordingly, the concave-formed peak component in physical value is converted to a positive value by the first arithmetic symbol inverter  10  whereby the basic peak model function can be optimized into a concave-formed peak component. 
     The basic peak model function generation means  11  is a basic peak generation means. A basic peak is generated by providing parameters to the basic peak model function, such as the Gauss function or Lorenz function. The parameters, if for a Gauss function, are three parameters of peak position, peak height and width at half maximum. By handling these parameters an arbitrary-formed basic peak can be generated. Also, it is possible to select different basic peak model functions for respective basic peaks. 
     The basic peak optimizing means  12  separates the sent convex-formed peak component and arithmetic-symbol-inverted concave-formed peak component into a plurality of basic peaks. The method for separation is conducted by sequentially varying parameters of a plurality of basic peaks generated by the basic peak model function generation means  11 , optimizing the peak component. The method for optimization uses a generally-known Davidon Fletcher Powell method, Simplex method, Gauss-Newton method or the like. In order to enhance optimization, devising may be used in this means that intrinsic components in the peak component are removed and the intrinsic components are added after optimization. The intrinsic components include fixed values, high-order functions, etc. The optimized plurality of basic peaks are sent to the second arithmetic symbol inverter  12  where the original peak component is in a concave form, or to the combining means  14  where the original peak component is in a convex form. 
     The second arithmetic symbol inverter  13  performs arithmetic symbol inversion on the sent basic peak. Due this, the basic peak turns into a concave form similar to the original concave-formed-peak component. After arithmetic symbol inversion, the basic peak is sent to the combining means  14 . 
     The combining means  14  is used to combine the basic peak with a baseline component. The method for combining may be by any one or all of the followings. 
     (1) Addition of each basic peak and a baseline. 
     (2) The basic peak is synthesized on a basis of a calculation-source peak component and further added with the baseline. 
     A result of combining is sent the output means  15 . 
     The output means  15  is used to visualize or record the combining result. All the combined results may be output or an addition result of one basic peak with a baseline may be output. 
     Output examples in the above embodiment are shown in FIG.  3  and FIG.  4 . FIG. 3 is a simultaneous separation example of a convex-formed peak and a concave-formed peak. FIG. 4 is a magnified figure of a concave-formed peak portion in the same example. In the figures, the solid line is thermal analysis data, and the one-dot chain line is an addition of each basic peak and a base line and the basic peak is synthesized on a basis of a peak component as a calculation source, and further added with the baseline. 
     Next, another embodiment of the present invention will be explained. 
     FIG. 5 is a block diagram of another embodiment according to the invention. In FIG. 5 a temperature sensor  1 , a sample  2 , a heater/cooler  3 , a physical amount fetch means  4 , temperature adjust means  6 , physical amount fetch means  7 , temperature fetch means  8 , combining means  14 , output means  15 , are the same as those of FIG.  1 . 
     A computer  19  is a similar computer to the computer  5  in FIG. 1, but differs from the computer  5  with respect to a connection destination of an incorporated baseline separation means and in a method of realizing a peak separation means. 
     A baseline separation means  20  has the same function as the baseline separation means  9  but is different in a peak component result output destination. The baseline separation means  20  merely outputs a peak component to the basic peak optimizing means  22 , but does not change an output destination depending on a peak shape unlike the baseline separation means  9 . 
     In FIG. 5, the method of making possible separation of a concave-formed peak component into a basic peak does not perform arithmetic symbol inversion as made in FIG. 1, and is provided as a basic peak generation means a basic peak model function generation means  21  for convex-formed peak components and a basic peak model function generation means  23  for concave-formed peak components. 
     The basic peak model function generation means  21  for convex-formed peak components is similar in function to the basic peak model function generation means  11  in FIG. 1, and generates a positive function value. 
     A basic peak model function generation means  23  for concave-formed peak components is similar in function to the basic peak model function generation means  11 , but generates a value inverted in arithmetic symbol, or negative function value. Specifically, for a Gauss function for example, the basic peak model function generation means  21  for convex-formed peak components generates a function value by the following formula. 
     
       
           y=h· exp (−ln (2)·( x−xc ){circumflex over ( )}2/ w {circumflex over ( )}2) 
       
     
     y: function value (physical amount) 
     h: peak height (physical amount) 
     x: individual variable (temperature or time) 
     xc: peak position (temperature or time) 
     w: width at half maximum (temperature or time) 
     Similarly, for the Gauss function, the basic peak model function generation means  23  for concave-formed peak components generates a function value by the following formula. 
     
       
           y=−h· exp (−ln (2)·( x−xc ){circumflex over ( )}2/ w {circumflex over ( )}2) 
       
     
     y: function value (physical amount) 
     h: peak height (physical amount) 
     x: individual variable (temperature or time) 
     xc: peak position (temperature or time) 
     w: width at half maximum (temperature or time) 
     The basic peak optimizing means b 22  selectively use the basic peak model function generation means  21  for convex-formed peak components and the basic peak model function generation means  23  for concave-formed peak components according to a form of a peak component sent from the baseline separation means b 20 , and performs optimization similarly to the basic peak optimizing means a 12  and sends a result thereof to the combining means  14 . 
     Using the above function, the other embodiment of FIG. 5 can realize a thermal analysis apparatus having a similar effect to the embodiment of FIG.  1 . 
     The present invention is structured using separation means to separate a convex-formed peak and a concave-formed peak. Accordingly, even where a convex-formed peak and a concave-formed peak exist in same data, the respective peak can be separated into basic peaks.