JPH0356829A - Electromagnetic balance type balance - Google Patents

Abstract

PURPOSE:To obtain a balanced state fast and to suppress fluctuations of a display in an imbalance state by controlling the gain of an amplifier with the high-frequency component of an imbalance output. CONSTITUTION:A photosensor 7 detects the movement of a slit 6 by the rotation of a lever 5 and a differential amplifier 8 outputs the imbalance output; and a frequency separating circuit 11 separates the high-frequency component which varies according to the imbalance state in the imbalance output and the gain of the amplifier 14 which amplifies the output of a PID control circuit 12 supplied with the low-frequency component from the circuit 11 through a rectifier 13 is controlled. Then the gain of the amplifier 14 is made larger and larger as the degree of the imbalance is larger and larger and a coil 10 is controlled with the output of the amplifier 14 to obtain an electromagnet balanced state. Therefore, the balanced state is entered speedily and the display fluctuations of a display device 18 due to the output of the amplifier 14 is suppressed because the gain of the amplifier 14 decreases in the balanced state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic balance, particularly an electromagnetic balance type balance.

[Prior Art] A conventional electromagnetic balance type balance is constructed as shown in FIG.

The weighing plate holder engages with a roberval mechanism 2 for preventing overturning, and the force applied to the weighing plate 1 is applied to the lever 5 via the force point 3. Then, the lever 5 rotates around the fulcrum 4,
The slit 6 at the end moves, and electric signals are generated in two photosensors 7 that detect the amount and direction of movement of the slit 6. This signal is passed through the differential amplifier 8 to the P-D control circuit 1.
2, a current flows from the control circuit 12 to the coil 1.0 so that the lever 5 returns to its original balanced position, that is, so that the output of the differential amplifier 8 becomes zero. Returned to equilibrium position. This current is simultaneously applied to amplifier l5
, MPU (Micro Pr
(UniL) circuit 17 and is converted into a load value, and the load value is displayed on the display 18.

At this time, the output of the differential amplifier 8 becomes as shown in FIG.

In other words, in an equilibrium state where the load on the weighing pan is stable,
As shown in Figure 4 (a), many high-frequency components with a frequency equal to the natural vibration frequency of the feedback system are generated, and when the load on the weighing pan is gradually increasing, such as when loading an object to be weighed, the As shown in FIG. 4(b), the high frequency components decrease.

Furthermore, in a state where the load on the weighing pan increases significantly and the differential output is saturated, the result is as shown in FIG. 4(C), and the high frequency component further decreases.

[Problem to be solved by the invention] With conventional electromagnetic balance type balances, it takes about 2 to 3 seconds until the lever reaches a balanced state, so it is difficult to use electromagnetic force balance type balances on production lines etc. In practice, it is difficult to obtain an equilibrium state within one second and measure precise quality and quantity.

Further, even in an equilibrium state where the load is stable as shown in FIG. 4(a), display fluctuations occur due to disturbances such as high frequency components.

The present invention was devised to eliminate the above-mentioned drawbacks of the prior art, and aims to quickly obtain an equilibrium state and suppress display flickering in the equilibrium state.

[Means for Solving the Problem] In order to achieve the above object, the electromagnetic force balance type balance according to the present invention generates many high frequency components in the unbalanced output when it is balanced as shown in Fig. 4, and the load increases. The gain is controlled by a frequency separation circuit that separates the load unbalanced output into a low frequency component and a high frequency component, and the high frequency component from the frequency separation circuit. It has an amplifier.

Also, in order to balance the equilibrium point, other embodiments include a PID control circuit controlled by the high frequency component from the frequency separation circuit.

[Function] In the electromagnetic force balance type balance configured as described above, the load unbalanced output from the sensor (is inputted to a two-frequency separation circuit and separated into a high frequency component and a low frequency component, and the low frequency component is sent to the control circuit, The high frequency component is input to the coil via the amplifier, and the amplification degree of the amplifier is controlled by the high frequency component.

In another embodiment, the low frequency component is input to the PID control circuit, and the high frequency component is input to the PID control circuit. I. The distribution of D is changed.

[Example] An example will be described with reference to FIGS. 1 and 2. Note that 1 to 10 are the same as those in the prior art shown in FIG. 3, so their explanation will be omitted.

In FIG. 1, the output of the differential amplifier 8 is input to a frequency separation circuit 11, where it is separated into a low frequency component and a high frequency component. Then, the low frequency component of the frequency separation circuit 1 is PI
The control current from the PID control circuit 2 is input to the D control circuit 2, and the high frequency component from the frequency separation circuit 11 controls the gain of the amplifier 14 via the rectifier circuit 13. The output of the amplifier 4 is fed back to the coil 10 to return the lever 5 to its equilibrium position, and is also input to the MPU circuit 17 via the amplifier 15 and AD converter 16, and the load value is displayed on the display 18. .

As a result, in an unbalanced state where there are few high frequency components as shown in FIG. 4(b) or (C), the amplification degree of the amplifier 14 is large, and the balanced state can be approached more quickly than in the case where only a PID circuit is used. becomes possible. Furthermore, in a balanced state where there are many high frequency components as shown in FIG. 4(a), the amplification degree of the amplifier 14 is reduced, and unnecessary hunting etc. can be suppressed.

In the embodiment shown in FIG. 2, the low frequency component from the frequency separation circuit l1 is input to the PID control circuit 12, and the high frequency component from the frequency separation circuit 1↓ is input to the rectifier circuit 1.
3 to the control circuit 19. Then, the amplifier 20 of the P■D control circuit 12 is controlled by the control circuit 19. For example, when there are few high frequency components as shown in FIG. 4(b) or (c), P is made stronger and When there are many high-frequency components, as in the case of can.

[Effects of the Invention] Since the present invention is constructed as described above, the balanced state of the electromagnetic balance type balance can be quickly achieved, and the fluctuation of the display section due to disturbance can be suppressed.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the structure of an electromagnetic balance type balance according to the present invention, Fig. 2 is a diagram showing another embodiment of the present invention, and Fig. 3 is a diagram showing a conventional electromagnetic force balance type balance. 4 is a waveform diagram showing the load unbalanced output of the electromagnetic force balanced type balance of FIG. 3. {... Weighing pan, 2... Roberval mechanism, 3... Force point, 4... Fulcrum, 5...
...Lever 6...Slit, 7...
・Photo sensor, 8...Differential amplifier, 9...
... Magnet, 10... Coil, 11-...
...Frequency separation circuit, 12...PID control circuit, 13... Rectifier circuit, 14...Amplifier, 1-5...Amplifier, l6... ...AD converter, 17...MPU, 18...Display, 19...Control circuit, 20...Amplifier 1st and 2nd times

Claims (2)

[Claims] (1) By holding a movable wire that interlocks with the weighing pan in a static magnetic field, and supplying the movable wire with a load balancing current necessary to generate an electromagnetic force that cancels out the load applied to the weighing pan. In an electromagnetic force balanced balance that holds the weighing pan in a predetermined balanced position and calculates and displays the value of the load from the value of the load balanced current at this time, a frequency separation circuit to which a load unbalanced output is input; It is characterized by having a control circuit into which the low frequency component output from the frequency separation circuit is input, and an amplifier into which the load balance current from the control circuit is input and whose gain is controlled by the high frequency component output from the frequency separation circuit. Electromagnetic balance type balance. (2) By holding a movable wire that interlocks with the weighing pan in a static magnetic field, and supplying the movable wire with a load balancing current necessary to generate an electromagnetic force that cancels out the load applied to the weighing pan. In an electromagnetic force balanced balance that holds the weighing pan in a predetermined balanced position and calculates and displays the value of the load from the value of the load balanced current at this time, a frequency separation circuit to which a load unbalanced output is input; It is characterized by having a PID control circuit which receives the low frequency component output from the frequency separation circuit and outputs a load balance current, and a circuit which controls the operation of the PID control circuit by the high frequency component output from the frequency separation circuit. Electromagnetic balance type balance.