JPS624018B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an average current measurement conversion circuit.

For example, when measuring the current of a watch, the average current within one period of the output signal is measured, but since the period of the output signal differs depending on the type of watch, one ammeter can measure the current of all types of watches. It is difficult to make measurements. The one currently in use uses a V-F converter, and its gate time is 0.25, 0.5,
It can be switched to 8 types, 1.0, 2.0 seconds, and 10 times each, and can measure output signal periods if they are any of the above, but cannot measure anything else.

In recent years, many watches with decorative pendulums, so-called pseudopendulums, that are driven independently of the clock have been commercialized, and there are various pendulum periods, and even within the same product, there are variations. Therefore, it was impossible to measure it with the above-mentioned measuring device.

Therefore, the present invention makes it possible to measure the average value of an input signal of any period by automatically changing the reference voltage of a double integration type A-D conversion circuit according to the period of the input signal. It is something.

An embodiment of the present invention will be described below based on the drawings. In Fig. 1, A is a pseudo-pendulum drive circuit;
_OP1 to _OP5 are operational amplifiers, and _OP4 and _OP5 operate as comparators. S ₁ to _{S 4} are analog switches, and analog switch S ₂ constitutes a control circuit. _F1 to _F3 are flip-flop circuits,
W is a one-shot pulse generator, G ₁ and G ₂ are gate circuits, and CT is a counting circuit. C ₁ and C ₂ are capacitors, R ₀ to _{R 4} are resistors, D is a Zener diode, and E is a battery. A first integrating circuit is formed by a capacitor C ₁ , a resistor R ₁ and an operational amplifier OP ₂ , and a capacitor C ₂ , a resistor R ₂ and an operational amplifier
OP ₃ constitutes a second integration circuit.

Next, the operation will be explained. If the driving current of the vibrator with period T generated from the vibrating circuit A is i,
The output e ₁ of the operational amplifier OP ₁ becomes e ₁ =i _RO , and this output voltage is generated with a period T as shown in FIG. 2a.
This output voltage is determined by a comparator as shown in Figure 2b.
The waveform is shaped by OP ₄ , and the output of flip-flop circuit F ₂ is inverted to "1" as shown in FIG. 2C, and analog switches S ₁ and S ₃ are turned on.

Therefore, the first integrator circuit integrates the output voltage from terminal a, resulting in the voltage shown in _FIG . The reference voltage ES obtained is integrated, and the voltage shown in Fig. 2h is generated at its output.

Therefore, looking at the voltage e ₀ after one period T of the first integrating circuit, it is expressed as e ₀ = 1/R ₁ C ₁ ∫ ^T ₀ e ₁ dt = −R ₀ /R ₁ C ₁ ∫ ^T ₀ idt It can be done. However, it is assumed that the bias current and offset voltage of operational amplifiers OP ₁ and OP ₂ are zero.

On the other hand, the output voltage e' ₀ of the second integrating circuit after one period T is expressed as e' ₀ =-1/R ₂ C ₂ ∫ ^T ₀ es dt. Since the reference voltage es is constant, it is expressed as e′ ₀ =−Tes/R ₂ C ₂ (1).

Then, when one period T ends, the output of the flip-flop circuit _F3 is inverted to "0", and the gate circuit
Flip-flop circuits F ₁ , F ₂ by the output of G ₁
is reset and analog switches S ₁ and S ₃ are closed. On the other hand, since the output Q of the flip-flop circuit _F3 is inverted to "1" as shown in FIG. 2d, the analog switch _S2 is turned on. Therefore, the output voltage e′ ₀ of the second integration circuit integrates the first integration circuit in the opposite direction to the above, and the output voltage e ₀ becomes 0V.
_{If the time} ^taken _{for _ _ _} ^_ _{_} /R ₁ C ₁・Tes/R ₂ C ₂ −R ₀ /R ₁ C ₁ ∫ ^T ₀ idt=0 tT/R ₂ C ₂・es=R ₀ ∫ ^T ₀ idt...(2).

Now, the average current found in this example is expressed as = 1/T∫ ^T ₀ idt, so from the above formula (2), it is expressed as = 1/T∫ ^T ₀ idt=es/R ₀ R ₂ C ₂・t. It can be done. In this equation, since R ₀ , R ₂ , C ₂ , and es are constants, the average current within one period T can be determined by measuring time t as follows.

When the output voltage of the first integrating circuit becomes 0V, the output of the operational amplifier _OP5 is inverted to "0" as shown in Fig. 2f, and the one-shot pulse generator W is triggered, and its output Q is changed to Fig. 2g. One pulse is generated as shown below. The flip-flop circuit _F3 is reset by this rising edge. Therefore, from the output Q of the flip-flop circuit _F3 , a pulse having a width equal to the above-mentioned time t is generated as shown in FIG. 2d, thereby opening the gate circuit _G2 . By supplying a clock pulse to the terminal P of the gate circuit _G2 , the time t is counted by the counting circuit CT.

Note that the present invention is not limited to the above-mentioned embodiments, but can be applied to various methods such as periodic average voltage measurement.

As described above, according to the present invention, the average value of an input signal of any period can be accurately measured. Therefore, it is particularly effective when there are variations in the period of the input signal, such as when measuring the average driving current of a pseudopendulum of a watch.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing an embodiment of the present invention, and FIG. 2 is a voltage waveform diagram for explaining the operation. OP ₂ , OP ₃ ... operational amplifier, C ₁ , C ₂ ... capacitor, R ₁ , R ₂ ... resistor, CT ... counting circuit, S ₂ ... control circuit.

Claims (1)

[Claims] 1. A first integrating circuit that integrates a periodic input signal for one period, a second integrating circuit that integrates a reference signal for one period, and a second integrating circuit that integrates a periodic input signal for one period. A control circuit that integrates the output in the opposite direction with a first integrating circuit, and a time period from when the first integrating circuit starts integrating the output of the second integrating circuit until the output of the first integrating circuit reaches the initial value. An average current measurement circuit consisting of a counting circuit that performs counting.