Patent Abstract:
A measurement system comprising modules for receiving analog measurement signals and outputting digital data and a controller for receiving and data processing of these digital data, this measurement system, wherein these modules comprise a A/D converter for converting analog measurement signals to digital data and measuring these data, an output for outputting these digital data, and a controller for controlling the timing of these measurements and the timing of these outputs, and in that the control by the controller is accomplished by outputting during the breaks between multiple measurements.

Full Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a method for measuring analog signals, particularly a method for measuring with a measurement system that transfers measurement data between modules and a controller.  
       DISCUSSION OF THE BACKGROUND ART  
       [0002]     A large number of signals are input in order to be measured by measurement systems that measure the many properties of LSIs, TFT arrays, and other semiconductor devices, and these systems often integrate and analyze the measurement data using an actuator that is divided into modules responsible for analog measurement and analog-digital conversion (ADC) and a controller part that processes and analyzes the digital data obtained from the modules, as in Japanese Kokai [Unexamined] Patent 2001-52,281.  
         [0003]     A typical measurement system having an actuator divided into modules and a controller is described while referring to the structural drawing in  FIG. 4  and the time chart in  FIG. 5 . The system in  FIG. 4  comprises measuring apparatuses  150  and  160 , modules  250  and  260  connected to these measuring apparatuses, and a controller  350  connected to modules  250  and  260 . The solid lines ( 261 ,  264 ) between each structural element in the figure represent the digital signal lines, while the broken lines ( 151 ,  161 ) represent analog signal lines, and the double lines ( 262 ,  361 , etc.) represent data buses of the digital data. Module  250  comprises an analog-digital converter (ADC)  251  that receives analog measurement signals from the measuring apparatus  150 ; an FIFO  253  connected to the output of ADC  251 ; a communications part  254  connected to FIFO  253 ; and a control part  255  that controls ADC  251  and communications part  254 . The internal structure of the other module  260  is the same as that of module  250 ; therefore, it is not illustrated in  FIG. 4 . Moreover, the controller  350  comprises communications parts  355  and  356  that receive output data from modules  250  and  260 , a memory  352  that houses the received data  354 , and a processor  351  that processes these data  354  and finds the measurement and analysis results.  
         [0004]     Next, the operation of the above-mentioned measurement system is described. First, when analog measurement signals are input from measuring apparatus  150 , ADC  251  notifies that data have been input to control part  255  and converts analog measurement signals to digital data. The system in  FIG. 4  is a structure wherein three types of analog measurement signals (represented as a, b, and c in  FIG. 5 ) are output from measuring apparatus  150 ; therefore, ADC  251  converts these three types of data to digital data in succession and accumulates them in FIFO  253 . The same measurement is repeated three times ( 1   a  through  1   c ,  2   a  through  2   c ,  3   a  through  3   c ) and when the measurements are completed, control part  255  sends a command to transfer data to communications part  254 . Thus, communications part  254  transfers the digital data that have accumulated in FIFO  253  to controller  350  in succession. Communications part  355  within controller  350  stores the digital data that have been received in memory  352 . The processor  351  begins data processing when these three data (a, b, c)  354  are received and finds the analysis results.  
         [0005]     There is a data transfer  265  between module  250  and controller  350  such as shown in  FIG. 4 .  
         [0006]     However, when the noise that is generated by the digital data transfer mixes with analog signal lines  151  and  161 , the measurement accuracy deteriorates. Therefore, the data transfer must be performed after analog signal measurement by the measuring apparatus in  FIG. 4 , as is clear from the timing chart in  FIG. 5 . However, when this type of measurement sequence is adopted, it requires time to transfer data after the measurement is completed. In addition, controller  350  can only start processing the data when the data transfer is completed. Therefore, there is a large increase in the time that it takes to obtain measurement results once the measurements are started.  
         [0007]     It is possible to transfer the data between each measurement (between  1   c  and  2   a  and between  2   c  and  3   a ) in order to curtail measurement time, but the control part  255  of module  250  does not know the timing by which analog measurement signals are input from measuring apparatus  150 . There is a chance that the following analog measurement signal may input during the data transfer and the electric noise caused by the data transfer may have an effect on the quality of the analog data. Consequently, data transfer should not be performed during the analog data measurement.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention solves the above-mentioned problems with a measurement system comprising modules that receive analog measurement signals and output digital data and a controller that receives these digital data and processes the data, this measurement system being characterized in that these modules comprise a measuring means that converts analog measurement signals to digital data and measure the data, an output means for outputting these digital data, and a control means for controlling the timing of measurements and the timing of output, and in that control by this control means is accomplished by performing output during the breaks between multiple measurements.  
         [0009]     This invention makes it possible for the modules to control the timings of when to allow the analog measurement, and when to transfer the digital data to the controller. Digital data is transferred successfully to the controller between measurements without interfering with the analog data input quality.  
         [0010]     The measuring method of the present invention makes high-speed measurement possible while preventing a deterioration of measurement precision by the electrical noise that is generated during the data transfer by means of modules and a system. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a schematic drawing of the measurement system of an embodiment of the present invention.  
         [0012]      FIG. 2  is a time chart of the measurement system of an embodiment of the present invention.  
         [0013]      FIG. 3  is an example of the control program of an embodiment of the present invention.  
         [0014]      FIG. 4  is a schematic drawing of a measurement system of the prior art.  
         [0015]      FIG. 5  is a time chart of a measurement system of the prior art.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]     A preferred embodiment of the measurement system of the present invention is described in detail while referring to the drawings.  
         [0017]      FIG. 1  is a general structural diagram of a TFT array substrate measurement system, which is the measurement system of the present invention. This system comprises measurement modules  200  and  220  connected to a measuring apparatus  100 , and a controller  300  connected to modules  200  and  220 . The solid lines ( 211 ,  215 , etc.) between each of the structural elements in the figure are the digital signal lines, while the broken lines ( 101 ,  102 ) are the analog signal lines, and the double lines ( 210 ,  311 , etc.) are data buses of the digital data.  
         [0018]     Measuring apparatus  100  is a measuring apparatus with a TFT array substrate. Analog signals of electric current, voltage, charge, and the like flowing to the array substrate at multiple measurement points are the output from the apparatus. Measuring apparatus  100  is not limited to a voltmeter, ammeter, and the like, and can be an optical sensor, piezoelectric element, and the like. The number of measuring apparatuses is not limited to one. There can be multiple apparatuses.  
         [0019]     Module  200  comprises an analog-digital converter (ADC)  201 , which is a measuring means that performs analog-digital conversion when it receives analog measurement signals from the measuring apparatus  100 ; a processor  202 , which is a processing means connected by data bus  210  to the output of ADC  201 ; an FIFO  203 , which is connected to processor  202  by data bus  212 ; a communications part  204 , which is the output means connected to the output of FIFO  203  by the data bus  213 ; and a control part  205 , which is the control means connected to ADC  201  and communications part  204  by control signal lines  211  and  214 . Control part  205  has a memory that can be rewritten so that it can house a control program  206 . The internal structure of the other module  220  is the same as that of module  200 ; therefore, it is not shown in  FIG. 1 . The structure is not necessarily limited to two modules; the present invention may also have one module or three or more modules.  
         [0020]     The controller  300  comprises communications parts  305  and  306  that receive output data from modules  200  and  220 ; a memory  302  connected to the communications part  305  by data buses  312  and  313 ; and a processor  301  connected to a memory  302  by the data bus  311 . Data transfer between module  200  and controller  300  employs a serial data transferring system that includes 8B/10B conversion (for instance, the conversion technology cited in JP (Kokai) 59[1984]-010,056); therefore, the data can be transferred using small number of data lines  215  and  216 . Data  304  received from module  200 , module  220  and a control program  303  are housed inside memory  302 .  
         [0021]     The operation of this system is described while referring to the structural drawing in  FIG. 1  and the time chart in  FIG. 2 . It should be noted that the system of the present working example is a measurement system for evaluating the quality of a TFT array. The electric current flowing through the TFT array is measured for each element and the relationship between the brightness or defects, and the electric current flow is measured at module  200 . Moreover, module  200  or  220  can measure an electric conductivity in order to evaluate the quality of the connection between each element, and controller  300  finds the coefficient of compensation for each element and the quality of the TFT array based on the results from the each module.  
         [0022]     When an operator selects a program that measures a TFT array substrate from multiple control programs  303  housed in memory  302  of controller  300 , the selected program is transferred by the communications part  305  inside of controller  300  through the communications part  204  inside of module  200  and stored inside control part  205  of module  200 . As shown in detail in  FIG. 3 , the control program  206  records over time the procedure that module  200  is performing, that is, receiving of analog signals from the measuring apparatus (data uptake), transfer of digital data to the controller  300  (data transfer), or no operation (stand-by), and the control part  205  executes the details of the control program  206  in succession in accordance with the internal clock.  
         [0023]     Control part  205  implements controls based on an initial data uptake order  400  such that analog measurement signals are received at ADC  201  from measuring apparatus  200 . ADC  201  converts electric current values (analog measurement signals) corresponding to the first brightness of the first element to digital data and transfers these data to processor  202  (data  1   a  in  FIG. 2 ). Processor  202  is designed such that when digital data (a, b, c) corresponding to three types of brightness are input, the relationship between the brightness of the element and the current is found. However, only data corresponding to the first brightness are input at this time; therefore, the data processing is not performed at this point, and the input digital data is stored.  
         [0024]     Similarly, a second data uptake command  401  and a third data uptake command  402  are issued, and analog current values corresponding to the second and third brightnesses are converted to digital data by ADC  201  and sent to the processor  202  (data  1   b ,  1   c  in  FIG. 2 ). The processor  202  finds the slope of the electric current values to the brightness of the first pixel by first order approximation from the three data sets ( 1   a ,  1   b ,  1   c ) when the third data set has been input. As a result, the amount of data from the measurement findings is reduced from the data for three brightnesses to data for one slope, and the amount of data transferred between module  200  and controller  300  can be reduced to ⅓. The slope data that is calculated is transferred to FIFO  203 .  
         [0025]     Next, a data transfer command  404  is given. Communications part  204  receives data with the slope of the first pixel from FIFO  203 , and it performs 8B/10B conversion, parallel to serial conversion, and outputs the data of controller  300 . The serial to parallel conversion, extension treatment, and the like are performed, digital data are regenerated, and the slope of the first pixel data is stored in memory  302 . By means of the present working example, the amount of transferred data can become smaller, because of using the processor  202  as a method of data compression. The data transfer time is shorter when compared to the data transfer without using the processor by the prior art shown in  FIG. 4 .  
         [0026]     Measuring apparatus  100  can pursue several measuring process depend on user&#39;s application. One example of the processing is the following. Electrical continuity of the first pixel wire is measured by module  220  as module  200  is measuring the relationship between the brightness of the first pixel and the current and the received measurement data  304  stored in memory. Processor  301  evaluates the quality of the first pixel and calculates the compensation data from the gradient data from module  200  and from electrical continuity data obtained by parallel measurement by module  220 .  
         [0027]     Similarly, module  200  measures the brightness and the current of the second pixel ( 2   a ,  2   b ,  2   c ) by the group of commands  405  of the sixth to the tenth commands, finds the relationship between the brightness and the current, and transfers this to controller  300 . Moreover, controller  300  assesses the electrical continuity data of the second pixel measured by module  200  and evaluates the quality of the second pixel.  
         [0028]     Measuring apparatus  100  of the present working example processes and transfers data while changing the measured pixel from the measurement of the first pixel to the measurement of the second pixel. Control program  206  can be designed so that when the time used to change the measured pixel is too short for the data transfer, only the data processing is conducted and the data is stored in FIFO  203 . When the measurement interval is long enough for the data transfer, the data housed in FIFO  203  is transferred to the controller. The processing function of processor  202  is not limited to finding the relationship of the acquired data as described above and should also include processing to reduce the amount of data, such as averaging of multiple groups of data and condensing data. Furthermore, by means of the present working example, the same measurement is performed in succession for the first and second elements, but the “multiple measurements” of the present invention include not only the case where the same measurement is repeated multiple times, but also the case where different measurements are conducted in succession.  
         [0029]     Here&#39;s another example of the measuring process. The Electric characteristics of the first pixel are measured by the module  200 . The pixel data ( 1   a ,  1   b ,  1   c  of  FIG. 2 ) from the module is processed by the processor  202  and transferred to the controller memory  304 . The processor  301  then evaluates the quality of the first pixel by analyzing the data in memory  304 . When the measurement of the first pixel is completed, the controller  205  uses a group of commands  405  in  FIG. 3 . to instruct the module  200  to measure the next pixel. ( 2   a ,  2   b ,  2   c ), and performs similar tasks which was done for the first pixel. The module  220  measures a different pixel in parallel to the module  200 . When pixel data from each module is transferred to the controller memory  304 , the processor  301  can perform an analysis for the entire TFT array based on the each pixel information.  
         [0030]     The processes disclosed above are examples of the measuring process. The claimed invention is not limited to the above processes. This invention can be applied to other measuring processes.  
         [0031]     As is clear from a comparison of  FIG. 2 , which is a time chart of the present working example, and  FIG. 5 , which is a time chart of the prior art, by means of the present measurement system, each module “knows” the measurement sequence from the control program; therefore, it is possible to efficiently process and transfer data while in between measurements of analog measurement signals. As a result, it is possible to minimize the noise that accompanies during the digital data transfer that affect the analog measurement quality, to maintain a high measurement precision, and to reduce the time needed for the overall measurement operation. Moreover, controlling ADC  201  and communications part  204  by means of software simplify the structure of the hardware, and the measurement sequence can easily be changed using centrally managed software with memory  303  of controller  300 .

Technology Classification (CPC): 6