TWI323347B - Capacitance measuring device and method thereof - Google Patents

Description

1323347 [Summary content]

In view of the above-mentioned invention background, in order to solve the above-mentioned capacitance value judgment and the measurement of the fine money, the present invention provides a measure of the capacitance value, which is mainly a system-by-county adjustment. The cumulative value of the device. When measuring the value of the thundering value, the pulse signal is first divided by the de-listing, the money is charged and discharged for N times, and the counting device is discharged at the time of _ accumulating the frequency of each division, so counting The accumulated value in the device can be averaged to obtain an output value of 1 -, the main purpose of this (4) - to provide a capacitance value measuring device, so that the capacitance value of each measurement is via the counting device Accumulating, so that the measured value can reach the average result, so a stable capacitance value can be measured. The main object of the present invention is to provide a capacitance value position, which can eliminate the interference of the commercial power during measurement by selecting the length and number of cycles of the operation. Still another object of the present invention is to provide a capacitance value measuring device which can provide a fast capacitance value measuring architecture by reducing the resistance of the charging and discharging device and increasing the frequency of the counting pulse wave.

According to the above object, the present invention firstly provides a capacitance value measuring device comprising: a voltage generating device for providing a -first reference voltage and a second reference voltage: a comparing device connected to the voltage generating device; And a discharge device having one end connected to a first reference voltage of the voltage generating device and the other end connected to a second input end of the comparing device; a pulse wave generating device connected to the output end of the comparing device for providing a pulse wave signal; a frequency dividing device connected to the pulse wave generating device, which can divide the pulse wave signal by a set value (Μ); a counting device connected to the frequency dividing device, can discharge in the charging and discharging device Counting during the period; and a control device for controlling the charging and discharging device, the pulse wave generating device and the frequency dividing device, and providing a setting value (Μ) of the frequency dividing device; wherein when the discharging period is entered and the output state of the device is compared When changing, the pulse 6 wave generating device is turned off and the control is restarted by the control device and the number of starts of the placement reaches another set value W, then Charging and discharging means integrated value of the counter. The device does not display the counting device. The invention then provides a method for the t-capacity system, including performing a fine-charging procedure for the tantalum capacitor Cx, and the Cx ray original (four) Ding-discharge procedure is tied to the electricity to be tested. After the program passes =1 to Vrl, the discharge program is then performed; then, the execution-to-count ratio = at the beginning, by a counting device. • Then, the reference voltage is compared with the discharge potential via a comparison device.

Γ , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , The pulse signal is sent to a frequency dividing device' and the frequency dividing device divides the pulse signal by a set value M and then executes the cumulative program by a counting device. [Embodiment] The device discussed in the present invention is a device with a capacitance value and a method for measuring the same. In particular, an average voltage trough measurement can be achieved by accumulating the frequency dividing device and the counting device. value. In order to fully understand the present invention, the detailed steps and the composition of the circuit will be presented in the following description. Obviously, the application wire of the present invention is limited to the specific details familiar to those skilled in the art of capacitance measuring devices. On the other hand, the well-known capacitance value detecting means or measuring step, etc., is not described in detail to avoid unnecessarily limiting the present invention. The preferred embodiments of the present invention are described in detail below, but the present invention may be widely practiced in other embodiments, and the scope of the present invention is not limited by the scope of the following patents. . First, please refer to Fig. 1, which is a functional block diagram of the capacitance value measuring device of the present invention. As shown in FIG. 1 and #, the capacitance value measuring device of the present invention includes the following I main parts: a reference power generating device 30 for providing a first reference voltage (5) and a second reference power M (Vr2). '··Electrical and discharge device 40, one end of which is connected to the first reference voltage (Vrl) of the reference power generating device 30, and a comparison device 5〇 whose first input terminal is connected to the second reference voltage (Vr2) And the second input terminal is connected to the charging and discharging device 40; a pulse wave generating device connected to the output end of the comparing device 5〇 for providing a pulse wave (4); ^ %, the pulse wave domain _ - Jian Jian value (M); - Tibetan removal shot. Post-device 8 〇 ' can be counted in the charging and discharging device 40; the money control device 10 is used to control The charging and discharging device 4〇, the pulse wave generating device 6〇 and the frequency dividing device 7〇, and providing a set value (M) of the 7G in addition to the county; and then accumulating each of the discharging cycles by the __ counting device (9) The frequency. In order to further explain the detailed operation of the capacitance value measuring device of the present invention, please refer to FIG. The second embodiment of the present invention relates to the charging and discharging device and the pulse wave generating device. As shown in Fig. 2, the charging and discharging cracking includes resistors R1 to R3, opening (four) S1 and S2, and measuring capacitance Cx, where ri is a variable resistance of an adjustable resistance value, and switches S1 and S2 are controlled. The device (1) is controlled. The reference voltage generator 30 is used to generate stable reference potentials Vrl and Vr2', wherein the reference potential Vr>2 can also directly provide a voltage value by the reference voltage generating device, which can also be supplied via a fraction. The voltage device 2 turns the reference potential Vrl into a reference voltage Vr2 by a voltage dividing circuit, for example, the resistance RQR5 in FIG. When performing the capacitance measurement, the control device 1〇t drives the switch S1 in the charging and discharging device 4〇 to start (ON), and turns off the switch S2 (〇FF), at which time the charging and discharging device 40 enters a test. The charging program of the capacitor Cx is charged by the reference potential Vrl (four) switch si and the resistor R3 of the reference voltage generating device 3 to charge the capacitor, so that the capacitor 3x to be tested is charged to the potential equal to the reference potential Vrl, it is emphasized that In order to enable the capacitor Cx to be charged to be quickly charged to the level of the reference potential Vrl, a resistor is usually used for the resistor. At this time, the voltage of the first input terminal of the comparison device 50 is thinner than the reference potential, and the voltage of the second input terminal of the comparison device 50 is the potential Vex of the capacitor Cx to be measured after being charged, and the capacitance Cx to be measured is at this time. The charging potential is greater than the reference potential. Next, the control device 10 drives the charging and discharging device 4A to turn on (4) turn off () and the switch S2 to turn on (ON). At this time, the charging and discharging device 4〇 enters a discharge cycle. The discharge procedure is performed by the capacitor Cx to be tested via the switch S2 and the resistor R1 and the terminal connected to the reference potential Vr3. In the embodiment of the present invention, the reference potential end point is a ground point. At this time, the potential Vex of the capacitor will continuously decrease the voltage value with the discharge _, wherein FU and R2 are used as the discharge resistor of the capacitor Cx, and the discharge resistor can be adjusted by the varistor of the resistor, thereby changing the discharge. Rate ^ During the period of discharge, the comparing means 50 continues to compare the potential Vcx of the capacitor Cx to be measured with the magnitude of the reference potential. However, while the control device 10 drives the charging and discharging device 4 to enter the discharge cycle, it also drives the ON (4) S3 start so that the pulse wave generating device 6 can send a pulse signal ck to the frequency dividing device 7〇 and then divide The frequency device 7〇 divides the pulse signal ck into an appropriate pulse signal by using a set value Μ provided by the control device 1〇 as a divisor, that is, 'dividing the frequency fck of the pulse signal ck by frequency division After the device is divided into frequency cells (i.e., fck/M-fckl 'where fck, fcki are the frequencies of ck and cgl, respectively), the frequency fdd is sent to the counting device 80 for accumulation. Therefore, Μ S3 can be controlled by the output logic of the comparison device 50. In this discharge operation, the comparing means 50 continues to compare the magnitude of the potential Vcx of the capacitor Cx to be measured with the reference potential Vr2. When the Vex potential of the capacitor to be tested is less than the reference potential Vr2, the output logic of the comparison device 5〇 will change, and the off S3 will be turned off (〇FF), and the pulse transposition 6() will stop. It also causes the counting device 80 to stop counting. Then, the control device 1 再次 again drives the charging and discharging device 40 to enter the charging program and the discharging program of the capacitor Cx to be tested another time, and the process is the same as the above process _, the straight (four) axis-set of her N, then _ special # β魏钱定4G times reached

The capacitance value of Cx, "The g-value added in the #8 device 8G is the capacitance to be tested.

The Cx's electric command value 'finally displays this accumulated value in the display. Obviously, the capacitor of the present invention is used to adjust the accumulation of the counting device 8〇. ♦ If a frequency-dividing device signal is used, the signal is removed from the county, and the battery is set to 2,; The post-counting device 80 accumulates the number ckl that has been removed every time the frequency-dividing device 70 is removed during the (fourth) input of the demining period of the N times, so the accumulated value formed in the counting device 8〇 The average effect can be achieved and a stable output value can be obtained. Then, please refer to Fig. 4, which is the capacitance value of the present invention _ step, the potential of the capacitor and the voltage in the figure. ...Qing, the residual value measuring device will first reset the sample device 80, such as the program, and the weaving device will drive the charging device into the charging program, such as the program 2〇〇, at this time, the switch is illusory n, and Switch s2 (10), so the capacitance Cx to be tested will be charged to the potential of Vrl, and then controlled by the control device i () to cause the charging and discharging device 40 to enter the discharge program 'as in program 3 (8), at this time switch S2 / S3 〇 n, and switch Si OFF 'The capacitor Cx to be tested starts to pass through w, and discharges to the terminal. At this time, the pulse wave generating device 60 will also The pulse signal ek starts to be sent to the frequency dividing device, and the counting device 8〇 will also start counting 'as in the program 400. During the discharging process, the absolute value of the capacitance of the capacitor & will continue to decrease, when it falls to When it is less than Vr2, the comparison device 5〇 sends out a minus switch S3 〇FF after the output state is changed, so the counting split (10) also stops counting until the end of the discharging process. Next, the control device 1 Continue and repeat the above charging and discharging procedures, such as the procedure 5〇〇, where CNT is used to count the number of charging/discharging in the current measurement process, and \ represents the process of one measurement. The number of charge/discharge cycles expected to be operated, so each time the charge/discharge process is completed, the value of CNT is incremented by one until the value of CNT is equal to n. ~ Counting device during discharge process of capacitor Cx to be tested 80 will continue to accumulate 'The fifth circle is the potential of the capacitor to be tested Μ with the charging and discharging procedures _; _ _ 5th towel COUNTING refers to the S3 is activated (ON) Time of the lion' * The outline is also the pulse wave signal after frequency division. The time period (4) of the feed device (10) is sent to the ground, and the COUNTING is started from the time of entering the discharge program until the 丨Vex丨 is less than 丨Vf2丨. Will change the number, at this time the switch S3 〇 FF ' and the COUNTING of the counting device 80 will also stop. In the actual measurement, when the capacitance of the capacitor Cx to be measured is larger, it is discharged by Vrl

The longer it takes for Vr2. The following explains the secret of the capacitor's hard discharge time. The formula for the charge/discharge of the capacitor versus time: V(t)= Vi + (Vf - Vi) * (1 - e^) t== RC * Ln(Vf - Vi / V(t). yf) -- ------(1) In the above formula, Vi is the initial value of the capacitor potential, vf is the final value of the capacitor potential, and t is the time elapsed since the capacitor potential is charged/discharged to v(1). For the discharge period of the present invention, the potential of the capacitor to be tested is discharged from Vrl to Vr3. Therefore, in the formula (1), Vi is vh, Vf is Vr3, and R is (R1+R2) 'If Cx is discharged from Vrl to Vr2 The required time is τ, where V(T) is vr2, and the above is substituted into (1), then τ can be expressed by the following equation: T = (R1+R2) * Cx * Ln[(Vr3-Vrl) / (Vr2-Vr3)] ---------(2) In the formula (2), Vrl, Vr2, and Vr3 are all fixed values, so Ln[(Vr3-VrlXVr2_Vi3" is a fixed constant, in addition, R2 is also a fixed value, and R1 needs to be fine-tuned except for correction. Otherwise, it is also a certain value, so (R1+R2)* Ln[(Vr3-Vrl)/(Vr2_Vr3^ is a constant K, then (2) The formula can be further simplified as: 11 (3) T = K * Cx -------------

Cx= T/K (Farad)-------- (4) From equation (3), the 'discharge time T is related to the capacitance to be measured c. This linear relationship can be proportional to the sixth, and is a linear threshold. Different capacitors: C1 and C2, #其八^明° Figure 6 shows that the two capacitors are discharged by the potential of === please, the electric and b1 are T1 and T2. Then, the ratio of T1 to T2 will be the ratio of the capacitance values of C1 and C2, that is, C1/C2 = T1/T2. In addition, the unit in the formula (4) is Farad. When the capacitance measuring device of the present invention is required to have a capacitance value of nF or pF, the numerical value can be _, and the outline can be expressed as: (5)

Cx=(T/K)* 109(nF) Further, if the value divided by the frequency dividing device 70 is M, the value counted by the counting device 80 during the discharge time τ is: T*fck/ M, and since the counting device 8 累 is accumulated N times, the total value of the accumulation is ···******* It can be seen from equation (5) that in the fabrication of the circuit, an appropriate K value is taken to make the following relationship true:

Cx= (T/K)* 109 = N*T*fck/M ----------------------- (6) Then K=(N/M)* 109/fck=(Rl+R2)*Ln[(Vr3-Vrl)/(Vr2-Vr3)]-一(7) 12 1323347 To make (7) hold, it can be achieved by selecting the appropriate illusion, w, 、, state. The error of R2, W, Vr2, Vr3 itself and the error caused by the comparator can be corrected by the varistor R1. That is, the actual compensation of the present invention can be applied to the reference voltage generating device 〇 charge and discharge device 40 and The error that may be generated by the comparison device 50 provides the function of the chick. In the formula (6), the correction method can send a known capacitance value by the correction device __ (not shown in the figure), and adjust the variable discharge resistance IU to adjust the size of the capacitor discharge time T, thus counting The value of device 80 will also be changed to the final adjustment to the value of 8G and the known capacitance value - the calibration can be completed. Obviously, the amount of change in this tuning φ process can be observed through the display device 90. In addition, in another embodiment of the present invention, the connection relationship between the frequency dividing device 7A and the counting device 80 may be mutually adjusted, as shown in FIG. 7, that is, while entering the discharging cycle, the counting device 80 will first start the cumulative pulse wave generating device 6 〇 the number of pulse signal ck sent, after the accumulation of N cycles, and then a dividing device 75 to set the value accumulated by the counting device f80. The results obtained in this way can also approximate the capacitance value of an average value. For both embodiments, the embodiments of the present invention are not limited thereto. φ Next, an embodiment in which the capacitance measuring device of the present invention is used in combination with a universal meter having an automatic judgment type of the object to be tested is further disclosed, wherein the measuring device having the type of automatically determining the object to be tested is already in another The patent application is filed in the specification. Therefore, in the embodiment of the present invention, only the part related to the capacitance measurement during the operation of the multimeter is described. FIG. 8 is a functional block diagram of a multimeter having an automatic judgment of the type of the object to be tested. 'Includes control unit (CONTROLLER) 110, switching unit (SWITCH) 120, TYPE DETECTOR 130, analog/digital conversion circuit (A/f) CONVERTER 140, data processing circuit (DATAPROCESSING CIRCUIT) 13 1323347 15 〇, display device (DISpLAY) 16〇, short-circuit detection unit (SH0RT DETECT〇R), 170, buzzer (BUZZER) 180 and gear control circuit (RANGE control CIRCUIT) 190 and so on. As shown in FIG. 8, the universal meter for automatically determining the type of the object to be tested in the embodiment is controlled by a control unit no to first perform a detection mode (detectm〇de) and sequentially provide the same. The plurality of scan messages are sent to the switching unit 120, and the switching unit 12 依 sequentially performs the switching action according to the plurality of scan messages provided by the control unit 110, in order to sequentially A plurality of test circuits are connected to the input terminal; for example, when the control unit 110 provides a diode scan signal, it first provides a diode positive bias scan signal (P-DI〇_CHK), and then Then, a negative bias scan signal (n_dio_chk) of the diode is provided. When the switching unit 120 receives the p_di〇_chk signal transmitted by the control unit 110, the switching unit 120 performs a switching action to connect the input terminal to the circuit configuration in FIG. At this point, the terminal T2 in the circuit configuration is connected to the positive bias VDD, for example: VDD-3V, and the terminal T3 is connected to the ground point (gnd), and the terminal T2 can also be connected to the detecting unit m. The comparator (not shown) is connected to extract the potential of the input terminal, wherein R1 is a large resistance, rptc is a dust separation resistor, and R1>>RpTC, in a preferred embodiment The heart is a thermistor that can be used to protect the circuit. At this time, if the input terminal is connected to a forward (forward e〇nnecti〇n) diode, as shown in the figure, the potential of the terminal T2 (ie VT2) will be clamped in the diode. The conduction potential 'for example: VT2 = 0.7V » At this time, the potential will fall within the range of, 0V,, and, +Vr" where +Vr is - a potential less than yj^D. At this time, If the diode of the input terminal is connected to the reverse (reverse eGnneetiGii), as shown in Figure 9b, since the diode is not turned on, the VT2 potential at this time is the result of the partial pressure of RpT々R1. Therefore, when the voltage dividing resistor is made into Rl»RPTe, the t bit of 贞彳VT2 will be close to the positive bias VDD.

Claims (1)

0. A method for measuring a capacitance value, comprising: to be sequenced by a first reference voltage through a charging and discharging device to perform a one-single-electricity program, in which the charging program charges the capacitance to be tested The measuring capacitor is then subjected to the discharging process via the charging and discharging device, and the absolute value of the potential of the measuring capacitor is continuously decreased with the discharging time; h ^ line - counting program is started at the beginning of the discharging process When the power is compared with the program, the second reference voltage is compared with the potential of the power to be tested through a comparison device and a determination is made; when the second reference voltage is greater than the system The electric power of the capacitor (4) is continuously performed by the counting program. When the second reference voltage is less than the potential of the capacitor, the counting procedure is stopped; and (4) the accumulating procedure of charging and discharging is to perform the charging procedure and the discharging After entering the <7 cumulative 'straight dragon cumulative value __ set number of times, then stop, and display a measured value; wherein a pulse signal is provided to the frequency dividing device in the discharging program, and the frequency dividing device is installed The pulse signal by dividing - the set value of [mu], execution of the program by a cumulative counting means. For example, the capacitance value measuring method described in claim 10, wherein the resetting (R£set) procedure of the counting device can be performed first before the discharging process. 12. The method of measuring a capacitance value according to claim 1G, wherein the charging procedure, the discharging procedure, and the counting procedure are performed by a control device. 13. As described in claim 1 The capacitance value measuring method, wherein the second reference voltage is generated by a voltage dividing device. M. The capacitance value measurement method described in the patent detail item H) can further provide a calibration procedure. 15. A measuring device having an automatic determining device type to be tested, comprising: 25 a control unit to sequentially provide a plurality of scanning messages; a switching unit consisting of a plurality of test circuits, a first The terminal is connected to the input end connected to the component to be tested, and the second end is connected to the control unit, and the switching action is sequentially performed according to the plurality of scan messages, and the plurality of test circuits are sequentially connected thereto. The input terminal is connected; a detecting unit, a first end thereof is connected to the third end of the switching unit, and the voltage of the input terminal is sequentially compared by a comparison circuit, and the result of the comparison is determined by a first The two ends are sent back to the control unit, so that the control unit determines the type of the component to be tested according to the comparison result; and a measuring unit is connected with the control unit and selects a corresponding one according to the judgment result of the control unit. The measuring circuit measures the component to be tested, and displays the result of the measurement on a display device; wherein the measuring unit comprises a capacitance value measuring circuit, and the capacitance value The measuring circuit comprises: a voltage generating device for providing a first reference voltage and a second reference voltage; a comparing device, a first input end is connected to the second reference voltage; and a charging and discharging device is at one end Connected to the voltage generating device, and the other end is connected to a second input end of the comparing device; a pulse wave generating device 'connects with the output end of the comparing device and provides a pulse wave signal; Connecting to the pulse wave generating device, and dividing the pulse wave signal by a first set value; and a counting device connected to the frequency dividing device and counting during discharging of the charging and discharging device; wherein the controlling The device may further control the charging and discharging device, the pulse wave generating device and the frequency dividing device, and provide the first setting value of the frequency dividing device; and when the first input end and the second input of the comparator When the voltage of the terminal is the same, the pulse wave generating device is turned off and the charging and discharging device is restarted by the control device until the charging and discharging device 26 1323347 When the number reaches a second movable set value, by a display device showing the cumulative value of the counting means. The measuring device of claim 15 further comprising a short circuit detecting unit, the first end of which is connected to the third end of the switching unit, and the second end of which is connected to the control unit . Π·As claimed in the patent application scope of the IM6 handle measuring device, wherein the short circuit extraction unit can be further connected to a single sounding device. 18. The measuring device of claim 15, wherein the plurality of scanning messages provided by the control circuit are in the order of a diode, followed by a capacitor, and then a resistor. 19. The measuring device of claim 18, wherein the broom information of the diode is further divided into a diode for a forward connection or a reverse connection. 20. The measuring device according to claim 15, wherein the test circuit in the switching unit comprises a diode positive bias test circuit configuration, a diode negative bias test circuit configuration, and a Capacitor charging test circuit configuration, a capacitor discharge test circuit configuration and an open circuit test circuit configuration. 21. The measuring device according to claim 15, wherein the control unit compares the comparison result with a set table by a look-up table (LOOK-UPTABLE) and judges the device to be tested The type. 22. The measuring device of claim 20, wherein the diode positive bias test circuit configuration in the switching unit comprises: an input end of the device to be tested; a first end point, via a a second resistor is connected to the input end of the device to be tested; a second terminal is connected to the input end of the device to be tested via a bias resistor; and a second terminal is connected to the second resistor via the first resistor The input end of the component is connected; wherein the first end point is floating. The second end point is connected to the comparator in the side element and the third end point is connected to the ground point. The measuring device of claim 20, wherein the diode negative bias test circuit configuration in the switching unit comprises: an input end of the device to be tested; a first end point Connected to the input end of the device to be tested via a second resistor; a second terminal connected to the input end of the device to be tested via a bias resistor; and a third terminal via the first resistor The input end of the device to be tested is connected; wherein the first end point is suspended, the second end point is connected to a negative bias voltage and a comparator in the detecting element, and the third end point is connected to the ground point. 24. The measuring device of claim 20, wherein the capacitive charging test circuit configuration in the switching unit comprises: an input end of the device to be tested; a first end point, via a second resistor The input end of the device to be tested is connected; a second terminal is connected to the input end of the device to be tested via a bias resistor, and a third terminal 'passes the first-resistance and the input to be tested The terminal is connected to a comparator in the device to be tested, the second terminal is connected to a negative pressure, and the third terminal is suspended. , The measuring device of claim 20, wherein the capacitor discharge test circuit configuration in the switching unit comprises: - an input end of the component to be tested; : a - end point 'via - a second resistor The input end of the device to be tested is connected to the two terminals 'connected to the input end of the device to be tested via a furnace resistance; and: the third end point is connected via the input end of the -first-to-be-test element; = The first meaning is connected to the lying point, and the comparator is connected to the side of the two side wipers and the third end point is suspended. The measurement device of claim 20, wherein the cut test circuit configuration comprises: T 28 an input end of the device to be tested; a first end point, via the second resistor The input end of the measuring component is connected; the second end is connected to the input end of the device to be tested via a bias resistor; and a second end is connected to the input end of the device to be tested via a first resistor; The first end point is connected to a comparator in the detecting component, the second end point is suspended, and the third end point is connected to a reference voltage. • Work 27 • The measuring device described in claim 23, wherein the table of settings is – a built-in logic table. Μ 28. If the measuring device described in claim 15 is open, when the input is judged to be open, the scanning process is continued without performing the measuring procedure. 29. A universal meter having a display device for displaying a plurality of measurement modes and measuring values, and a switching device for providing a plurality of switching selection modes for performing a specific signal system' - for the input switch, characterized in that the plurality of measurement modes include at least one capacitance value measuring device, and the capacitance value measuring device comprises: a reference power generating device, which has provided the __first reference voltage and a second reference voltage; a comparison device having a first input connected to the second reference voltage; - a charging and discharging device having a terminal connected to the voltage generating device and the other end being associated with the comparing device The second input terminal is connected; the pulse wave generating device is connected to the output end of the comparing device and provides a pulse signal; the frequency dividing device is connected to the pulse wave generating device, and the pulse signal is divided by a first a set value (Μ); a juice number device connected to the frequency dividing device and counting during discharge of the charging and discharging device; and a control device for controlling the charging and discharging device The pulse wave generating device and the frequency dividing device, and providing the first set value (Μ) of the frequency dividing device; 29 丄 to W47, wherein when the voltage of the second input terminal of the comparing device is less than the first When the voltage of the terminal is input, the pulse wave generating device is turned off, and the charging device and the charging device are again hosted until the starting slot of the charging and discharging device reaches the second set value (8), and then a display is performed. The device displays the cumulative value of the counting device. 30. The universal meter of claim 29, wherein the charging and discharging device in the capacitance measuring device controls charging and discharging by using an H-off device and a second switching device, and The first switching device and the second switching device are controlled by the control device. M. The universal meter of claim 29, wherein the discharge circuit of the charging and discharging device in the capacitance measuring device comprises at least one variable resistor. 32. The universal meter as claimed in claim 5, wherein the variable resistor is used as a calibration resistor of the capacitance value measuring device. 33. A capacitance value measuring device, comprising: a reference voltage generating device, wherein a first reference voltage and a second reference voltage are provided; and a comparing device, a first input end of which is connected to the second reference voltage; a charging and discharging device having its end connected to the voltage generating device and the other end connected to a second input of the comparing device; - a pulse generating device 'connecting to the output of the comparing device and providing - a pulse signal; a counting device is connected to the pulse wave generating device, and the charging and discharging device performs counting of the pulse wave signal during discharge; a dividing device is connected to the counting device, and the counting device counts The pulse signal is divided by a first set value (M); and - a control device S for controlling the "electric and discharge device, the pulse wave generating device and the frequency dividing device, and providing the frequency dividing device a first set value (M); wherein when the voltage of the second input terminal of the comparing device is less than the voltage of the first input terminal, the pulse wave generating device is turned off, and the charging device is restarted by the control device And the discharge device 30 1323347 is set until the number of starts of the charging and discharging device reaches a second set value (N), and the integrated value of the counting device is displayed by a display device. 34. The capacitance value measuring device according to claim 33, wherein the charging and discharging device controls charging and discharging by a first switching device and a second switching device, and the first switching device And the second switching device is controlled by the control device. 35. The capacitance value measuring device of claim 33, wherein the discharge circuit in the charging and discharging device comprises at least one variable resistor. The capacitance value measuring device according to claim 35, wherein the variable resistor is used as a calibration resistor of the capacitance value measuring device.