JP3302467B2 - Electronic scales - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measured value detector, a control and electronic evaluation circuit, an indicator for weighing results, and a motor drive for avoiding damage to the measured value detector when transferring the balance. Power supply-powered electronic balance having a locking device.

[0002] The present invention also relates to a power distribution-powered electronic balance, comprising a measured value detector, a control and electronic evaluation circuit, an indicator for the weighing result, and a motor-driven weighing circuit.

[0003]

2. Description of the Related Art A motor-driven locking device of this kind and / or
Alternatively, an electronic balance for a distribution power supply having a motor-driven weighing circuit is generally known. Under the concept of a "weighing circuit" in this case, a replacement weighing circuit (as is known from analytical weighing circuits) and a calibrating weighing circuit (by which one or more calibration weights of the measuring value detectors are measured) Placed on the value detector)
It is also to be understood. A weigher with such a calibrated weighing circuit is disclosed, for example, in DE 38 38
No. 15626.

A disadvantage of this known embodiment is that in the event of an abrupt interruption of the power supply voltage or an unexpected disconnection of the connection to the power supply, it is no longer possible to change the locking operation or the weighing circuit state. It is. For this purpose, manual operation and / or corresponding alarm instructions must additionally be included in the service manual. Nevertheless, the following cannot be avoided. That is, when the weigher attempts to move the weigher to another location, the user simply pulls out the power plug and lifts the weigher out, so that the weigher is unlocked and / or (vibrated during transportation). It is unavoidable to be transported in the state of a (unprotected) weighing circuit.

[0005]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electronic weigher of the type mentioned at the outset in which the weigher is automatically locked during the transfer or the weighing circuit is automatically transferred. The improvement is to make a transition to the protection state (lock position).

[0006]

SUMMARY OF THE INVENTION The object is achieved according to the invention in that the locking device is driven by a DC electric motor,
The control and electronic evaluation circuit sends a lock command to the electric motor in the event of a supply voltage interruption, the electric motor being provided with a capacitor, the capacity of which can be adjusted without further energy supply. The problem is solved by a configuration that is selected so that energy can be supplied to the electric motor until the end of the operation.

[0007] The object is also achieved according to the invention in that the weighing circuit is configured to be driven by a DC electric motor, and the control and electronic evaluation circuit section interrupts the supply voltage. A command to shift the weighing circuit to the locked position is sent to the weighing circuit motor, and a capacitor is assigned to the electric motor, and the capacity of the capacitor reaches the locked position without further energy supply. The problem is solved by a configuration that is selected so that energy can be supplied to the electric motor until the power is supplied.

The above two means according to the present invention may be used independently of each other for a balance having both a motor-driven locking device and a motor-driven weighing circuit. However, in a preferred embodiment, one common DC electric motor is used.

According to another advantageous embodiment of the invention, the capacitor is sufficiently charged in order to prevent the voltage supply of the scale from remaining in the unlocked state even for a very short time. Only afterwards can the motor for unlocking or adjusting the weighing circuit be released from the locked position. This can be implemented in a simple manner using appropriately selected delay elements, for example correspondingly configured electronic monitoring devices.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings.

The electronic balance shown in FIG. 1 comprises a device support 1 fixed to a casing. The load receiver 2 is vertically movably fixed to the device support 1 via two connecting portions 4 and 5 having a bearing 6.
The load receiving portion 2 supports a load receiving tray 3 for receiving a measurement object at an upper portion thereof. The load receiving part 2 transmits a force corresponding to the mass to be loaded to the load arm of the transmission lever 7 via the coupling element 9. The transmission lever 7 is supported on the device support 1 by a cruciform spring hinge 8. The coil 1 is provided in the compensation arm of the transmission lever 7.
1 is fixed. This coil 11
Is provided in the gap of the permanent magnet system 10 and generates a compensating force. In this case, the magnitude of the compensation current through the coil 11 is determined in a known manner by the position
Is controlled as follows. That is, control is performed so that the mass of the object to be measured is balanced with the compensation force generated electromagnetically. The compensation current produces a measuring voltage at the measuring resistor 15. This measured voltage is supplied to the analog / digital converter 17. The digitally converted result is received by the digital signal processing unit 18 and is digitally displayed on the indicator 19. Further, a temperature sensor 26 is provided.
6 converts the temperature of the measured value detector into a digital signal and supplies it to the digital signal processing unit 18 via the line 31. Thereby, the digital signal processing unit 18
Compensate for temperature errors in the measurement detector.

The load arm of the transmission lever 7 is
(12), and protrudes further toward a portion (hereinafter referred to as a crank-shaped portion) 22 which is bent downward in a crank shape. This crank-shaped part 22
, Three centering pins that are vertically upright are fixed. FIG. 1 shows only two pins 24 and 25 of the three centering pins.
These centering pins support the calibration weight 13. This calibration weight 13 has a hole 29 with an opening below.
have. This hole 29 extends towards the conical surface 23. This hole passes exactly through the center of gravity of the calibration weight 13 so that the conical surface 23 is perpendicular to the center of gravity of the calibration weight.

FIG. 1 shows a lift device for a calibration weight. This device comprises a needle bar 20. The needle bar 20 is vertically movably guided in a sleeve 21 fixed to the casing. The device for moving the needle bar 20 is shown only by the eccentric 28 and the electric motor. The needle bar 20 passes through the hole 27 in the crank-shaped part 22 and reaches into the hole 29 in the calibration weight 13. The calibration weight 13 is placed on the centering pin and thus the transmission lever 7 /
In the illustrated state mounted on 12/22, the needle bar 2
The 0 conical tip terminates just below the conical surface 23. Here, when the needle bar 20 is lifted by the eccentric plate 28, the needle bar 20 comes into contact with the conical surface 23, the calibration weight 13 is released from the transmission lever, and comes into contact with the stopper 39 fixed to the casing. This is the normal position of the calibration weight (weighing position and lock position). In contrast, the lowered position as shown in FIG. 1 is a position that is only taken for the calibration process. The center of gravity of the calibration weight 13 can be slightly shifted by the screw 38. This allows fine tuning to be achieved.

After operation of a calibration key, not shown, the digital signal processing unit 18 activates the calibration control 40 via the line 36. The calibration control unit 40 starts the electric motor 41. After the calibration weight 13 is placed on the transmission lever 7/12/22, the signal processing unit 18 waits until the measured value of the balance is settled (to a stationary state). When the measurement value is received (by the signal processing unit 18), the calculation is performed, the new calibration coefficient is stored, and the calibration weight 1 is supplied to the motor 41 via the calibration control unit 40.
3 is again lifted to the weighing position.

The weighing parts described thus far are known in the prior art, and their structure and function are therefore only outlined.

The calibration controller 40 has the capacitor 30 as an energy storage. This capacitor 30 is always kept charged. This capacitor does not work as long as the supply voltage is available without interruption. Only in the following cases, namely when the supply voltage is interrupted during metering (for example, this is also the case when the power outlet is unplugged), and at the moment of this interruption, the calibration weight circuit part is in the calibration state or The capacitor 30 functions only in the transition state, and supplies the energy necessary to operate the motor (DC electric motor) 41 again to the metering position and the lock position. The instructions for this operation are received by the calibration control unit 40 by a voltage monitoring circuit within the microprocessor 18 or by a separate voltage monitoring circuit.

FIG. 2 shows an example of a circuit for controlling the motor 41. Capacitor 30 (eg, having a capacitance of one farad) is charged via diode D1.
In this case, the internal resistance limits the charging current at the supply voltage. When the voltage at the capacitor 30 reaches the threshold voltage of the Zener diodes ZPD3,6, the transistor T1 conducts and furthermore the input 50 of the gate IC 1.1.
At the H-level. As a result, the microprocessor 18 makes the gate IC 1.1 conductively connected via the line 36 and the transistor T5, and furthermore, the diode D
2. The DC electric motor 41 can be started via the resistors R4 and R5 and the transistor T2. In this case, the resistor R5 is used for limiting the current to the motor 41.

The circuit portion 55 enclosed by a broken line is a monitoring circuit. This monitoring circuit only allows the motor 41 to start when the minimum voltage has been reached at the capacitor 30. Thereby, after the supply connection of the supply voltage, the motor 41 can be started after the energy stored in the capacitor 30 has reached a sufficient level (to return the motor 41 to its initial state again). Becomes

The motor now (as described with reference to FIG. 1) uses the calibration weight 13 for the calibration of the lever 7 for calibration.
On the / 12/12/22. The achievement of the calibration position is signaled to microprocessor 18 via line 51 by opening switch S2. Microprocessor 18 then stops motor 41 via line 36. In this case, the transistor T3 acts as a short-circuit brake. In this case, a relatively slight rotation of the motor 41 does not become an obstacle. This is because the eccentric plate 28 approaches its gentle minimum deviation point. After the balance has come to a standstill and the calibration result has been accepted by the microprocessor 18, the microprocessor 18 starts the motor 41 again, and the motor 41 continues to rotate until it reaches the weighing position. This measurement position is notified to the microprocessor 18 via the line 52 by opening the switch S. Thereby, the microprocessor 18 stops the motor 41.

Here, when the supply voltage is interrupted, the input side of the gate IC 1.4 falls to L-level.
If switch S1 is then open (i.e. since the calibration weighing circuit is in its weighing position-in this case the same as the locked position), no problem occurs. However, when the switch S1 is closed (that is, the motor 41 rotates and shifts to the calibration position or enters the calibration state).
The input side 54 of the gate IC 1.3 is also at the L level, and the gate IC 1.2 controls the motor 41 via D3, R4, R6, T2, and also supplies current via D3, R4, R6, T2. Is done. The motor 41 is rotated or started anew, and stops only after the switch S1 is opened. Gates IC1.1 to IC1.4 receive operating voltage Vo directly from capacitor 30. In addition, these gates are of the type that operates at relatively low operating voltages. Therefore, their functions are guaranteed until the motor 41 reaches the end position even when the capacitor 30 is discharged.

Even if the balance is not controlled by the microprocessor, the control of the motor 41 can be realized by other circuits. For example, this can be done by a relay. In that case, these relays are connected and configured as follows. That is, when all the relays return to the stationary state, the motor 41 is connected so that the capacitor 30 receives the current until the motor 41 reaches the metering position or the lock position.

FIG. 3 shows a second embodiment of the electronic balance. In this case, it is an analytical balance equipped with a motor-driven locking device or a micro balance. This scale is a casing 61
Consists of The casing 61 surrounds a weighing space 62, a space 63 for the measured value detector, and a space 64 for the electronic device. The measured value detector operates again according to the electromagnetic force compensation method. This measurement value detector is
Consists of The bar 65 is rotatably supported by a spring hinge on a base 66 fixed to the casing. A movable intermediate member 60 is hung on a relatively short lever arm of the bar 65. The intermediate member 60 supports the weighing pan frame 69 and the original weighing pan 70 in the lower region 68. A coil 71 is fixed to a relatively long lever arm of the bar 65. The coil 71 is provided in the magnetic field of the permanent magnet system 72. Electronic device section 64
1 shows only a control circuit 73 for locking and an associated capacitor 74. Otherwise, an indicator 75 for the weighing result is identified.

For transport, the scale according to FIG. 3 has a locking device. The locking device includes two levers 76 and 77 for fixing the bar 65 and two levers 76 and 77 for fixing the movable intermediate member 60.
It consists of two pressing members 78 and 79. The lock levers 76 and 77 are supported on one side of the fixed points 80 and 81 of the casing 61, and are eccentric plates 82 and 8 when locked.
3 is pressed against the bar 65 at the other end to fix the bar. The eccentric plate is driven by a DC electric motor (not shown) and is controlled by a control circuit 73. This control circuit 73 functions as described above in connection with FIGS. 1 and 2 and automatically controls the lock circuit when the supply voltage of the scale is interrupted. Similarly movable intermediate member 6
In the case of transfer, 0 is also fixed using pressing members 78 and 79, eccentric plates 84 and 85 belonging to the pressing members 78 and 79, and a DC electric motor (not shown).

FIG. 4 shows a third embodiment of the electronic balance provided with the displacement type weighing circuit. The same parts as those in FIG. 3 are denoted by the same reference numerals, and the description thereof will not be repeated. The displacement weighing circuit comprises a weight support 90. The weight support 90 is fixed to a movable intermediate member 91, and supports a plurality of weights 92. FIG. 4 illustrates only two of the plurality of weights. The weight 92 is lifted from the weight support 90 by a hook 93 (which is mounted to be secured to the casing at the member 94) and is fixed in this raised position. The transfer position is a state where all weights have been lifted. In FIG. 4, all weights are lowered and rest on the weight support 90. This state is the zero position.
The hook 93 is moved by the eccentric plate 95. Eccentric plate 9
5 is driven by a DC electric motor, also not shown. The electronic control unit 96 controls the DC electric motor.
Done by The electronic control unit 96 is provided for the weighing pan 7.
Depending on the load on zero, more or less weight 92 is placed on weight support 90 until a substantially balanced condition occurs at bar 65 and the remaining weight difference can be compensated by the electromagnetic force compensation coil. Place or lift from the weight support. When the supply voltage is interrupted, the electronic control unit 96 controls the DC electric motor again so that all of the weights are lifted (= transfer position) and the energy required for this is taken from the condenser 74.

Although all mechanical components are shown only schematically in the drawings as they are merely an aid to the original considerations of the present invention, those skilled in the art will readily understand from such drawings. The configuration means can be derived.

In a weigher having a lock device and a weighing circuit, a DC electric motor for a separate lock device and a weighing circuit may be provided. In this case, a special capacitor for storing energy may be provided for each motor. However, this 2
One motor is supplied with energy from only one capacitor. However, it is also possible to use only one DC electric motor for the two functions and to drive the locking device and / or the weighing circuit by means of an additional coupling device.

[0027]

According to the present invention, the lock is automatically performed at the time of transfer, or the weighing circuit is shifted to the transfer protection state (lock position).

[Brief description of the drawings]

FIG. 1 is a diagram showing a saucer weigher provided with a weighing circuit.

FIG. 2 is a diagram showing an electronic circuit belonging to the scale of FIG. 1;

FIG. 3 is a diagram showing a cross section of an analytical balance or a micro balance provided with a lock device.

FIG. 4 is a diagram showing an analytical balance or a micro balance equipped with a weighing circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Apparatus support 2 Load receiving part 3 Load receiving tray 4 Connecting part 5 Connecting part 6 Bearing part 7 Transmission lever 8 Cross-shaped spring hinge 9 Connection element 10 Permanent magnet system 11 Coil 12 Transmission lever 13 Calibration weight 14 Control amplifier 15 Measurement resistance 16 Position sensor 17 A / D converter 18 Signal processing unit 19 Indicator 20 Needle bar 21 Sleeve 22 Transmission lever 23 Conical surface 24 Centering pin 25 Centering pin 27 Hole 28 Eccentric plate 29 Hole 38 Screw 39 Stopper 40 Calibration controller 41 Electric Motor 60 intermediate member 61 casing 65 bar 66 table 67 spring hinge 69 weighing pan frame 73 control circuit 78 pressing member 79 pressing member 84 eccentric plate 85 eccentric plate 74 capacitor 90 weight support 91 intermediate member 92 weight 93 hook 95 eccentric Board

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Heinrich Feldotte Göttingen Waldweg, Germany 17 (56) Reference US Patent 4932487 (US, A) (58) Field of Study (Int. Cl. ⁷ , DB name) ) G01G 23/02

Claims (5)

(57) [Claims] 1. A measuring value detector, a control and electronic evaluation circuit, an indicator for the weighing result and a motor-driven locking device for avoiding damage to the measuring value detector during the transfer of the balance. , A power supply-powered electronic balance, a lock device (76, 77, 78, 79, 82, 83, 8).
4, 85) are driven by a DC electric motor, and the control and electronic evaluation circuit (73) sends a lock command to the electric motor when the supply voltage is interrupted, and the electric motor has a capacitor. (74) is assigned,
An electronic balance, characterized in that the capacity of the capacitor is selected so that energy can be supplied to the electric motor until the end of the locking process without further supply of energy. 2. A distribution-powered electronic balance having a measured value detector, a control and electronic evaluation circuit, an indicator for a weighing result, and a motor-driven weighing circuit, wherein the weighing circuit is a DC electric motor (41). ), And a control and electronic evaluation circuit unit (1).
8, 40, 96) issue a command to shift the weighing circuit to the locked position when the supply voltage is interrupted.
1), the electric motor (41) is assigned a capacitor (30, 74) whose capacity is increased until the lock position is reached without further energy supply. An electronic balance characterized by being selected so that it can supply energy to the electronic balance. 3. The electronic balance according to claim 1, wherein the single DC electric motor drives both the locking device and a weighing circuit. 4. An electronic monitoring device (55) is additionally provided, said electronic monitoring device (55) comprising a capacitor (3).
0, 74), and furthermore only after sufficient energy has been stored in the capacitors (30, 74) after the supply voltage is switched on, the DC electric motor (41).
And the lock position is again reached when the supply voltage is interrupted.
Electronic balance as described. 5. An additional time delay element, which triggers said DC electric motor (41) only after a predetermined period of time after the supply voltage is switched on. An electronic balance according to any one of claims 1 to 3.