JP3307305B2 - How to judge the quality of capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is good or bad Trial of capacitor
Measuring method, in particular the charging current at the end of charging of the capacitor
And a method of judging the quality of the capacitor .

[0002]

2. Description of the Related Art In general, in order to judge the quality of a capacitor, a DC voltage for measurement is applied to the capacitor, and the leakage current (charging current) of the capacitor after it is sufficiently charged is measured. Methods for measuring resistance are known. Naturally, good products have low leakage current.

Conventionally, as this kind of insulation resistance measuring method, a measuring method specified in JIS-C5102 is known. In this method, it is necessary to measure a current value in a state where the capacitor is sufficiently charged, so that a measurement time of about 60 seconds is required. However, with the demand for cost reduction and reliability improvement of electronic equipment, electronic parts such as capacitors are also required to have improved production capacity and quality.
The conventional measuring method requiring such a long measuring time per capacitor cannot meet such a demand at all.

[0004]

As a method of charging a capacitor, a method of intermittently applying a DC voltage is known in addition to a method of continuously applying a DC voltage.
No. 254,768). This method is a charging method suitable for measuring characteristics using a turntable that is intermittently fed, and has the characteristic that a large number of capacitors supplied from a parts feeder can be continuously measured. Such a method of measuring insulation resistance using a turntable includes a continuous method of measuring insulation resistance one by one for a capacitor that has passed through a plurality of charging regions and has been charged, and a method of measuring a predetermined number of turns on a turntable. After supplying the capacitors, there is a batch method in which the turntable is stopped and charging and insulation resistance measurement are performed simultaneously on multiple capacitors.Both methods require a long time for charging, and work efficiency is low. not really good.

However, the present inventor has conducted intensive studies on the intermittent application of a DC voltage to a capacitor, and as a result,
Even under intermittent application, under certain conditions, it has the same effect as continuous application.In other words, in the case of intermittent application, it has the same charging characteristics as continuous application, even if there is a moment when voltage application is interrupted. Even found that the charging progressed for a short period of time. Based on such facts, if the charging current is measured several times in the initial period of the intermittent application, it is possible to predict the charging current after sufficient charging, and thus the insulation resistance.

The present invention has been made on the basis of the above-described knowledge, and an object of the present invention is to provide a method in which, when a DC voltage is intermittently applied to a capacitor, a point of time when a sufficient charge is obtained from an initial current value of the intermittent application. Predict the current value at the capacitor
To provide a method for determining the quality of a capacitor in a short time .

[0007]

In order to achieve the above object, the invention according to claim 1 includes a step of intermittently applying a DC voltage to a capacitor and a step of applying a DC voltage to each of the plurality of application periods by intermittent application . Measuring the current value;
A plurality of current values, a step of determining a charge current formula for the dielectric polarization component of the capacitor, a step of determining the current value in the charging end of the charging current equation, to the charging end
For judging the quality of a capacitor using the current value of the capacitor
And

For a ceramic capacitor, the change in current value during continuous application and intermittent application is accurately measured,
When the current value and time were plotted on a logarithmic current-logarithmic time coordinate system, it was found that the characteristics shown in FIGS. 1 and 2 were obtained. That is, in the case of continuous application is small period from the application start t ₀ as shown in FIG. 1 is almost constant large current flows, the current rapidly value decreases with subsequent transition period, then, with a certain inclination The current dropped due to the linear charging characteristics. This linear charging characteristic is 1
Minutes to 2 minutes. On the other hand, in the case of intermittent application, the characteristics of the first voltage application, as shown in FIG. 2, are exactly the same as in the case of continuous application. Then, after stopping once the voltage applied at time t _a, the a second time the voltage applied at time t _b, the first is rapidly current value becomes higher as,
Thereafter, the charge rapidly decreases and stabilizes to a linear charging characteristic.
Since the horizontal axis in FIG. 2 is logarithmic time, the characteristic of the top is not clear, but it is actually composed of the same horizontal portion and the same transition period. Further, it was found that the linear charging characteristic was on an extension of the linear charging characteristic when the first voltage was applied. Thereafter, even if the intermittent application of the voltage is repeated, the same characteristics as those described above are repeated, and the characteristic is stabilized on the extension of the linear charging characteristic. The applied voltage was the same for both continuous and intermittent application.

When a current value i ₃ at a time point t ₃ after a certain time T from the start of the application was measured, the current value i ₃ was the same both during the continuous application and during the intermittent application. That is, even if the DC voltage is intermittently applied, the OFF time (t
_{If a to} t _b ) is short (for example, several hundred milliseconds or less), the same result as when charging by continuous application is obtained.
According to the experiments of the present inventors, the same result as in the case of continuous application was obtained if the off time of the intermittent application was 500 msec or less for a capacitor having a capacitance value of 0.01 μF or more.

When the charging characteristics were further examined, the following facts were found. That is, the equivalent circuit of the capacitor includes the dielectric polarization component D in addition to the capacitance C ₀ , the internal resistance r, and the insulation resistance R ₀ as shown in FIG.
Dielectric polarization component D is constituted by the capacitance C _1, C ₂ ··· C _n and the resistor _{R 1, R 2 ··· R n} . It has been found that the non-linear charging characteristics in FIGS. 1 and 2 correspond to the charging region of the capacitance C ₀ , whereas the linear charging characteristics correspond to the charging region of the dielectric polarization component D.

Therefore, using the linear charging characteristic 3) at the first time of the intermittent application and the linear charging characteristic 5) at the second time (or the charging characteristic after the third time may be used), the dielectric polarization component D By calculating the current calculation formula for the charging characteristic of, and calculating the current value at the end of charging (for example, after 60 seconds) from the current calculation formula, the insulation resistance of the capacitor can be predicted in a short time. Then, this insulation resistance is used as a reference value.
By comparing, the quality of the capacitor can be easily determined.
You.

According to the present invention, it is not necessary to stop the measuring device (for example, a turntable) for a long time unlike the continuous application method, and the insulation resistance can be measured while the capacitor is intermittently conveyed. There is an advantage that can be.

Various methods are conceivable as a method for obtaining the above-mentioned charging current calculation formula. For example, a current value at each time point in two application periods due to intermittent application is measured, and a charging current calculation formula log i = a · lo is obtained from the two measured current values.
There is a method of determining the gradient a of g t + b and the intercept b. In this case, the measurement time depends on the linear characteristic part in intermittent application,
It is necessary to be.

The above-described charging current calculation formula is a linear approximation formula, but if it cannot be approximated by a linear approximation formula, a logarithmic approximation formula may be used. The charge current calculation formula in this case is log (log
i) = a · log t + b.

As another method for obtaining the charging current calculation formula, there is a method using an equivalent circuit of a capacitor. In the case of this method, first, a charging current calculation formula is initially set based on an equivalent circuit, and a measured current value m (t) in a plurality of application periods by intermittent application and a calculation current value i obtained by using the above charging current calculation formula. as (t) and matches, resistance capacitance C _1, C ₂ ··· C _n is the dielectric polarization component D of the equivalent circuit R _1, R ₂
... to determine the R _n, it may be modified charging current formula. Also in this case, the measured current value m (t) may be measured at a linear characteristic portion in intermittent application.

Incidentally, the charging current flowing through the capacitor at the time of intermittent application is determined to be 50 mA according to JIS. However, when the charging current is larger than 50 mA, the time of the initial characteristics (, in FIG. 2) becomes shorter, and the linear characteristics become longer. Therefore, when the charging current is increased, the responsiveness of the charging is improved, and the charging can be performed even when the voltage application time is short, so that the equipment processing capacity can be increased.

[0017]

FIG. 4 shows an example of a current measuring device for carrying out the method of the present invention. This measuring device has been proposed by the present applicant in Japanese Patent Application No. 7-293442. This measuring device comprises a DC measuring power supply 10, a switch 1
1. Capacitor 12 to be measured, limiting resistor 13, logarithmic amplifier 14, measuring amplifier 15, A / D converter 16,
And an arithmetic processing circuit (CPU) 17. At the beginning of charging, the current value is measured by the measuring amplifier 15 and switched to the logarithmic amplifier 14 at a predetermined threshold.
In step 4, the current value is measured. This measuring device uses a capacitor 1
Since the measurement can be performed accurately even if the charging current of No. 2 changes in a wide range, the current value from the initial stage to the end of charging, which is difficult to measure with the conventional measuring device, can be continuously measured.

The switch 11 is turned on / off at predetermined intervals by the CPU 17, and a DC voltage is intermittently applied to the capacitor 12. Switch 11 ON / OFF
It is not necessary that the time interval be constant. For example, the second ON time may be longer than the first ON time, or the first ON time may be longer than the second ON time. When applying more than three times, turn on each time
You may change the time. The method of the present invention does not require the use of the measuring device of FIG. 4, and any other measuring device may be used as long as the voltage application to the capacitor can be intermittently performed.

Next, a first embodiment of a method for predicting a charging current according to the present invention will be described with reference to FIG. First, a DC voltage is intermittently applied to the capacitor (step S0).
1). Next, each time point t of the two application periods due to the intermittent application
The current values i ₁ , i ₂ at ₁ , ₁ and t ₂ are measured (step S0).
2). The measurement time points t ₁ and t ₂ need to be within the charged area 3) 5) of the dielectric polarization component D as shown in FIG.
It is desirable to measure the current value in the charging area at the beginning of the intermittent application (for example, the first or second time) because the measurement time can be reduced. Subsequently, a linear approximation formula (lo) of the charged region of the dielectric polarization component D of the capacitor is obtained from the measured current values i ₁ and i _2.
The gradient a and the intercept b of g i = a · log t + b) are obtained (step S03). The gradient a and the intercept b are calculated by the following equations. a = (log i ₂ −log t ₁ ) / (log t ₂ −log t ₁ ) b = (log i ₁ · log t ₂ −log i ₂ · log t ₁ ) / (log t ₂ −log t ₁ ) Next, a linear approximation formula log i = a that is obtained from the gradient a and the intercept b
If the last charging time t ₃ (for example, 60 seconds) is substituted for log t + b, the current value i ₃ during charging can be obtained by calculation (step S04). From this current value i ₃ can know the insulation resistance of the capacitor.

FIG. 6 shows the linear approximation formula (shown by a broken line) and the measured value (shown by a solid line) obtained as described above.
A multilayer ceramic capacitor was used as the capacitor to be measured, and the charging current was 50 mA. Specific data for obtaining the linear approximation formula is as follows. t _a = 30 ms, t _b = 70 ms, t _c = 100 ms t ₁ = 30 ms, i ₁ = 1.0 μA t ₂ = 100 ms, i ₂ = 0.3 μA a = −0.97, b = 3.5 × 10 ⁻⁸ t ₃ = 60 seconds Calculated value i ₃ = 1.05 nA, measured value i ₃ = 1.01 nA As described above, the error between the calculated value i ₃ and the measured value i ₃ is 3.9.
6%. This proved that the above method was a highly accurate measurement method. The measured value in FIG.
It was determined by continuous application up to 0 seconds. The calculated value is 0
It was determined by two intermittent applications of 〜30 ms, 70 ms to 100 ms.

[0021] In the above embodiment, the predicted current value i ₃ at time t ₃ using linear approximation in the logarithmic coordinates (log i = a · log t + b), the charging of the dielectric polarization component D depending on the type of capacitor The characteristics may not always be linear. In that case, the logarithmic approximation (log (log
The current value i ₃ may be obtained using i) = a · log t + b). In this case, the gradient a and the intercept b are obtained as follows.

[0022]

(Equation 1)

(Equation 2)

Next, the principle of a third embodiment of the method for predicting a charging current according to the present invention will be described. First, it has already been described that the equivalent circuit of the capacitor is shown in FIG. Here, the capacitance C ₁ , which is the dielectric polarization component D of the equivalent circuit shown in FIG.
The C ₂ ··· C _n and the resistor _{R 1, R 2 ··· R n} , placed in relationship geometric progression as shown below. C _k = p ^k−1 C ₁ , R _k = q ^k−1 R ₁ where k = 1, 2,..., N, C ₁ , R ₁ , p, and q are constants. The current equation flowing through the equivalent circuit is as follows.

[0024]

(Equation 3) Here, E is the voltage applied to the capacitor, t is time, and R ₀ is the insulation resistance.

In the equation (1), the first term is the insulation resistance R ₀
And the second term is the current flowing through the dielectric polarization component D. In the initial stage of charging, a current also flows in a series circuit of the capacitance C ₀ and the internal resistance r, but this is omitted because the charging current calculation formula in the present invention has no linear relationship.

The calculated current value i (t) set as described above
And the actually measured current value m (t) measured by the current measuring device of FIG.
So that the parameters C ₁ , R ₁ , p,
Determine q. Note that the measurement time of the actually measured current value m (t) needs to be at the time point within the charged region of the dielectric polarization component D (see FIG. 2), but the initial time (for example, the first time, the second time, etc.) in the intermittent application. It is desirable to use a charging area.

The calculated current value i (t) and the actually measured current value m (t)
Is evaluated in the following manner. First, the evaluation function n (t) is set as follows. n (t) = log (m (t))-log (i (t)) The evaluation function n (t) obtained by the above equation is linearly approximated. The approximate expression is represented by a linear expression y = ax + b, and it is determined that the closer the slope a and the intercept b of this expression are to 0, the higher the degree of coincidence. By correcting the calculation formula (1) using the parameter having a high degree of coincidence and substituting the time at the end of charging (for example, 60 seconds) into the corrected calculation formula (1), the current at the end of charging is calculated. The value can be determined.

Next, the charging current prediction method in the third embodiment
A specific example of the method will be described. First, a multilayer ceramic capacitor was used as a capacitor to be measured, and parameters C ₁ , R ₁ , p, and q were initially set to the following values. C ₁ = 210 × 10 ⁻¹² R ₁ = 0.1 × 10 ⁶ p = 1.07 q = 2.1

FIG. 7 shows the calculated value i (t) and the actually measured value m (t) obtained from such initial setting values. The linear approximation equation obtained from the initial setting value has a slope a as shown in the equation in FIG.
= 5.37, intercept b = 0.044, and both are not close to 0. Therefore, for example, it can be seen that the calculated value i (t) after 60 seconds does not match the actually measured value m (t). In addition,
In FIG. 7, the measured values and the calculated values were obtained in the same manner as in FIG.

Next, the parameters C ₁ , R are set using the method as shown in FIG. 8 so that the slope a and the intercept b are close to 0.
₁ , p and q were modified. First, the parameters C ₁ , R ₁ ,
Initially, p and q are set (step S1). Next, the calculated current value i (t) in the charged region (see FIG. 2) of the dielectric polarization component D is obtained by the calculation formula (1) using the initially set parameters (step S2). Subsequently, the measured value m (t) at the same point is measured, and the measured value m (t)
An evaluation function n (t) is obtained from the difference between the calculated value and the calculated value i (t) (step S3). Next, the evaluation function n (t) is linearly approximated (step S4). Next, it is determined whether or not the absolute value of the intercept b of the approximate expression y = ax + b is smaller than a predetermined value β (step S5). This step determines whether or not the intercept b is close to zero. In step S5, | b
| In the case of ≧ beta is the number of approximation calculations is equal to or less than a predetermined number N ₁ (step S6). This is a process for avoiding an infinite loop. Number of approximate calculations is N
If more than _once, a C ₁ is increased or decreased by a fixed value by the sign of b (step S7). If the number of approximate calculations becomes N ₁ or more, it means that the intercept b does not approach 0 with the correction of C ₁ , so that q and / or R ₁
Is increased or decreased by a constant value depending on the sign of b (step S8). In step S7 or S8, C ₁ or q, after modifying the R _1, step S2~S3~S4
To S5 are repeated. When | b | <β is satisfied in step S5, it is determined whether the absolute value of the gradient a of the approximate expression is smaller than a predetermined value α (step S9). Step S
In 9, | a | in the case of ≧ alpha is the number of approximation calculations is equal to or less than a predetermined number N ₂ (step S10).
This is also a process for avoiding an infinite loop. If the number of approximate calculations is N ₂ or less, p is increased or decreased by a constant value depending on the sign of a (step S1).
1). If the number of approximation calculations is more than _two times N, the inclination a is the modification of p is meant that not approach 0, is increased or decreased by a fixed value q and / or R ₁ by the sign of a (step S12 ). In step S11 or S12, after modifying the p or q and / or R _1, repeat steps S2~S3~S4~S5~S9, | b | when a <α, | a | <and in β It is determined that the matching has been completed (step S13). That is, the parameters C ₁ , R ₁ , p, and q are finally determined.

The parameters finally determined are as follows. C ₁ = 198.3 × 10 ⁻¹² R ₁ = 0.1 × 10 ⁶ p = 1.093 q = 2.1

FIG. 9 is a comparison diagram between the calculated value (t) obtained using the corrected parameters and the actually measured value m (t). In this case, the linear approximation formula is as follows: slope a = 2 × 10 ⁻⁵ , intercept b =
−6 × 10 ⁻⁶ , and both are close to 0. As is clear from FIG. 9, the calculated value i (t) and the actually measured value m (t) match very well even at the end of charging (for example, after 60 seconds), and the method of the present invention has extremely high accuracy. It proved to be a prediction method. Note that, in FIG. 9, measured values and calculated values were obtained in the same manner as in FIG. 6.

In the above embodiment, the parameters C ₁ , R ₁ , p, and q are modified by linear approximation. However, the parameters may be modified by using quadratic curve approximation in addition to linear approximation. . That is, as shown in FIG. 10, when the difference n (t) between the actually measured value and the calculated value is approximated by a straight line y = ax + b, both the slope a and the intercept b become values close to 0, and the straight line approximation is performed. Will be high. However, the measured values and the approximate straight line do not completely match. Therefore, the calculated value and the measured value at the end of charging greatly differ from each other. In such a case, 2
By using the following curve approximation together, the degree of coincidence can be evaluated with high accuracy.

When performing quadratic curve approximation, the evaluation function n
When the approximate expression of (t) is y = dx ² + ex + f, and the secondary coefficient d is close to 0 and (−e / 2d) is a value within the section time for comparing the degree of coincidence, the degree of coincidence Is determined to be high. As this section time, for example, 5 to 20 m
Seconds are desirable. If the degree of coincidence is low, the value of R _{0 in} equation (1) is changed. As described above, if the parameters are corrected so that the degree of coincidence between the linear approximation formula and the quadratic curve approximation formula becomes high, and then the current value is obtained by the calculation formula (1) using the corrected parameters, a more accurate calculation can be performed. Value can be obtained.

FIG. 11 is a diagram showing a parameter determination method using both the linear approximation method and the quadratic curve approximation method. First,
Current value m at the beginning of charging (for example, 5 to 20 msec)
(T) is measured (step S14). Next, the insulation resistance R ₀ is determined. A sufficiently large value is set as the initial value of R ₀ (step S15). Next, the parameters C ₁ , R ₁ ,
p and q are determined (step S16). The initial values of these parameters may be empirically known values, similarly to step S1 in FIG. Next, a calculated current value i (t) is obtained by the calculation formula (1) using the determined parameters (step S17). Next, an evaluation function n (t) is obtained from the difference between the actually measured current value m (t) and the calculated current value i (t) (step S18). Next, the evaluation function n (t) is linearly approximated (step S19). Next, it is determined whether or not the degree of coincidence by the linear approximation is high (step S20). The determination method is based on whether both the slope a and the intercept b in FIG. 8 are close to 0. If the degree of coincidence is low, the parameters C ₁ , R ₁ , p, and q are corrected, and the processing from step S16 is repeated. If the degree of coincidence in the linear approximation is high, then the evaluation function n (t) is approximated by a quadratic curve (step S21). Subsequently, it is determined whether or not the degree of coincidence by the quadratic curve approximation is high (step S22). This determination method determines whether or not the quadratic coefficient d of the quadratic curve approximation equation is close to 0 and (-e / 2d) is a value within the section time for comparing the degree of coincidence. If the degree of coincidence is low, the parameter _R0 is corrected, and the processing from step S15 is repeated. If it is determined that the degree of coincidence in the quadratic curve approximation is high, the parameters R ₀ and C ₁ , R ₁ , p, and q are finally determined (step S23).

In the above embodiment, the capacitances C ₁ , C ₂ ... C _n and the resistances R ₁ , R _2.
··· R _n is set to a geometric progression, but may be set to a relationship other than a geometric progression. In any case, the capacitances C ₁ , C ₂ ... C _n and the resistances R ₁ , R ₂ ... R _n are determined from the degree of coincidence between the measured current value m (t) and the calculated current value i (t). Any method that can be used can be used. Also, the measured current value m (t)
Although linear approximation or quadratic curve approximation was performed to evaluate the degree of coincidence between the calculated current value i (t) and the calculated current value i (t), it is a matter of course that other known approximation methods may be used.

In the above embodiment, the charging current flowing to the capacitor is limited to 50 mA determined by JIS by the limiting resistor 13 (see FIG. 4).
When the charging current is increased by lowering the resistance value of FIG.
As shown in FIG. 2, it has been found that the response of charging is faster.
The solid line in FIG. 12 is the case where the charging current is 50 mA, and the two-dot chain line is the case where the charging current is 100 mA.

That is, the current value of the charging area by the capacitance C ₀ was increased, and the time was shortened. On the other hand, the charging curve of the charged region of the dielectric polarization component D did not change at all, and the starting point of the charged region became faster. That is, the charging region of the linear dielectric polarization component D is extended. Therefore, the times t ₁ and t ₂ for measuring the current values i ₁ and i ₂ in the first embodiment.
Also, the time at which the evaluation and correction of the formula (1) are performed can be reduced. That is, it has become possible to measure the insulation resistance faster and more accurately.

FIG. 13 shows a specific example of a characteristic measuring / selecting / taping apparatus using the method of the present invention. In the figure, 2
Reference numeral 0 denotes a turntable, and the turntable 20 rotates intermittently by one pitch in the direction of the arrow. Around the turntable 20, a plurality of holding parts 21 capable of holding one chip type capacitor as an object to be measured are provided at equal pitch intervals. Around the turntable 20, a supply unit 22 for supplying a capacitor to the turntable 20, a capacity measuring unit 23, two charging IR measuring units 24a and 24b in which the present invention is implemented, a defective product discharging unit 25, and a non-defective product extracting unit 26
The supply unit 22 is provided with a supply device 27 such as a parts feeder that feeds the capacitors to the turntable 20 one by one.

A taping device 28 is arranged corresponding to the non-defective product take-out section 26. The taping device 28 intermittently drives the base tape 29 for accommodating the capacitor in the direction of the arrow one pitch at a time.
9a, non-defective capacitors are stored one by one from the non-defective portion 26. After storing the capacitor in the storage section 29a,
The taping device 28 adheres a cover tape (not shown) to the base tape 29 as is well known.

In the conventional case, since the capacitor must be charged on the turntable for a long time, the capacitor cannot be synchronized with the taping device. A predetermined number is stored, and condensers are taken out of the take-out container one by one again using a parts feeder or the like and supplied to a taping device. Therefore, the operation speed from the characteristic measurement to the packaging is extremely slow, which has led to an increase in size of the equipment and an increase in cost.

On the other hand, when the method of the present invention is used, the current at the time of charging the capacitor, that is, the insulation resistance, can be instantaneously obtained by the charging IR measuring units 24a and 24b. Alternatively, the insulation resistance measurement can be completed during the suspension period, and the charging IR measurement unit 2
4a and 24b can be composed of at least two sections. Therefore, the turntable 20 and the taping device 28 can be easily synchronized, and the capacitor whose characteristics have been measured can be directly transferred from the turntable 22 to the taping device 2.
8 can be sent. As a result, not only the work speed is remarkably improved as compared with the conventional one, but also the downsizing of the equipment and the cost reduction can be realized.

FIG. 14 shows another specific example of the characteristic measuring / sorting / taping apparatus. In this device, a supply device 27 such as a parts feeder is arranged on both sides of a single turntable 20 and two taping devices 28 are arranged. The two tapes 29 are sent in opposite directions. In the case of this device, the working speed can be further improved and efficiency can be improved as compared with the device of FIG.

FIG. 15 shows a specific example of an apparatus for measuring, sorting, and filling a bulk case. In this device, the non-defective capacitor taken out through the parts feeder 27 and the turntable 20 is packed from the turntable 20 into the bulk case 31 by the bulk case packing device 30. A predetermined number of capacitors can be stored in the bulk case 31, and after a certain number of capacitors are stored, the bulk case 31 is driven in the direction of the arrow. In this case, the same effect as in FIG. 13 is obtained.

It should be noted that the present invention is not limited to ceramic capacitors, and any capacitor having a dielectric polarization component, such as an electrolytic capacitor or a film capacitor, can be measured.

[0046]

As is apparent from the above description, according to the present invention, a DC voltage is intermittently applied to a capacitor, and the current value at each time point within a plurality of application periods due to the intermittent application is measured.
Then, the charging current calculation formula for the dielectric polarization component of the capacitor is obtained from the measured current value, and the current value at the end of charging is obtained from the charging current calculation formula, so that the final current value (for example, the current after one minute) is obtained. Value) can be accurately predicted. That
Therefore, the quality of the capacitor can be accurately determined in a short time from the current value . Further, in the present invention, since it is not necessary to continuously apply a voltage to the capacitor, it is possible to determine the quality of the capacitor while intermittently transporting the capacitor using a turntable or the like. Since the stop period during intermittent conveyance can be reduced to about several tens of milliseconds, there is an effect that the determination ability can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a charge characteristic diagram when a DC voltage is continuously applied to a capacitor.

FIG. 2 is a charge characteristic diagram when a DC voltage is intermittently applied to a capacitor.

FIG. 3 is a circuit diagram of another example of an equivalent circuit of a capacitor.

FIG. 4 is a circuit diagram of an example of a charging current measuring device.

FIG. 5 is a flowchart of a first embodiment of a charging current measuring method.

FIG. 6 is a comparison diagram between a current calculation formula according to the present invention and an actually measured value.

FIG. 7 is a comparison diagram between a calculated value of a current calculation formula according to the present invention before correction and an actually measured value.

FIG. 8 is a flowchart illustrating a method for determining parameters using a linear approximation method.

FIG. 9 is a comparison diagram between a calculated value of a current calculation formula according to the present invention after correction and an actually measured value.

FIG. 10 is a diagram in a case where approximation by a linear approximation formula cannot be performed.

FIG. 11 is a flowchart illustrating a parameter determination method when both linear approximation and quadratic curve approximation are used.

FIG. 12 is a diagram illustrating charging characteristics of a capacitor when a charging current is increased.

FIG. 13 is a plan view of an example of a characteristic measuring / sorting / taping apparatus using the method of the present invention.

FIG. 14 is a plan view of another example of the characteristic measuring / sorting / taping apparatus using the method of the present invention.

FIG. 15 is a plan view of an example of an apparatus for measuring, sorting, and packing a bulk case using the method of the present invention.

[Explanation of symbols]

 Reference Signs List 10 DC measurement power supply 12 Capacitor 13 Resistance 14 Logarithmic amplifier 15 Measurement amplifier 16, 18 A / D converter 17 CPU 20 Turntable 24a, 24b Charge IR measurement unit 27 Parts feeder 28 Taping device

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsuru Kitagawa 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. (56) References JP-A-9-113545 (JP, A) JP-A Sho 62-123367 (JP, A) JP-A-57-39360 (JP, A) JP-A-11-83926 (JP, A) JP-A-10-221396 (JP, A) JP-A-10-239368 (JP, A A) Patent 3127574 (JP, B2) Patent 3293540 (JP, B2) Patent 3293541 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/00 G01R 31/02 G01R 27 / 00-27/32 H01G 13/00

Claims (5)

(57) [Claims] A step of intermittently applying a DC voltage to a capacitor; a step of measuring a current value at each point in time during a plurality of application periods by intermittent application; A step of obtaining a charging current calculation formula of the dielectric polarization component; a step of obtaining a current value at the end of charging from the charging current calculation formula; and a step of determining the quality of the capacitor using the current value at the end of charging. Pass / fail judgment method. 2. The step of calculating the charging current calculation formula includes the steps of: measuring current values i ₁ and i ₂ at time points t ₁ and t ₂ of two application periods by intermittent application; from the current value i _1, i _2, the quality of the capacitor of claim 1 comprising the steps of determining the gradient a and the intercept b of the charging current equation log i = a · log t + b
Judgment method . 3. The step of obtaining the charging current calculation formula includes the steps of measuring current values i ₁ and i ₂ at time points t ₁ and t ₂ of two application periods by intermittent application. _{2. The} method of claim 1, further comprising: determining a gradient a and an intercept b of a charging current calculation formula log (log i) = a · log t + b from the current values i ₁ and i ₂ . 4. The step of obtaining the charging current calculation formula includes the steps of: initializing the current calculation formula using an equivalent circuit of a capacitor; and measuring the measured current value m (t) in a plurality of application periods by intermittent application and the charging current. The calculated current value i (t) obtained using the current calculation formula
As bets are matched, the capacitance C ₁ is the dielectric polarization component of the equivalent circuit, C ₂ ··· C _n and the resistor R _1, R ₂ ··· determine a R _n, modifies the charging current formula 2. The method of claim 1, further comprising the steps of: 5. A quality determination method of a capacitor according to any one of claims 1 to 4, characterized in that the maximum charging current flowing to the capacitor by the intermittent application of the DC voltage of greater than 50 mA.