SU966502A1 - Electronic digital scales - Google Patents

Description

The invention relates to a technique for measuring mass and can be used in the construction of accurate weights.

Known off-scale electromagnetic scales, containing a mobile part with a suspension device, a suspension system, a noncompensator converter, the output signal of which is converted into current, voltage, frequency, 4 times a shift, an electrical balancing system, and a digital reading device, as a digital device 13.

Scales of this type are universal, but have limited accuracy.

The closest to the proposed technical essence are the electronic digital files containing the mobile part of the c. a load-carrying device, a series-connected compensation converter, a controlled generator, a frequency counter, a reversible counter, a reading device, as well as a compensator and serially connected code-to-relative converter; the duration of the time interval in the converter is a relative length of time interval into current, the output of which is connected to the adder, to the second input of which the current source of the container is connected, the output of the adder being connected to the compensator, while the code converter in the relative length of the time interval contains an RS flip-flop , reference counter, to the input of which is connected

10 is a reference oscillator, and a coincidence circuit associated with the reference and reversing | 5th C23 counters.

The disadvantage of the device is relatively low accuracy due to

15 ripple compensating current.

The purpose of the invention is to increase the accuracy and speed.

To achieve the goal c. A known code-frequency converter, a 0-flip-flop and a logic switch are introduced, the code-frequency converter inputs are connected to the lower bits of the reversible counter and star1: shmi bits

25 reference counter converter code in the relative duration of the time interval, and direct my. and its inverse outputs are connected to the inputs of the logical switch, others

30 inputs which through the O-trigger and

directly connected to the output of the coincidence circuit, and the output is connected to the R input of the RS flip-flop of the code converter to the relative length of the time interval.

FIG. 1 shows a block diagram of an electronic digital scale; in fig. 2 shows timing charts of signals in a feedback circuit of an electronic digital scale.

Digital scales contain a movable part 1 with a load receptor 2 on which an object 3 is installed with a measured mass fixed on suspensions 4, a noncompensation converter 5 with fixed plates 6 and a movable plate 7 rigidly connected with the movable part 1, a compensator 8 with a constant The magnet 9, in the gap of which is placed the coil 10, is mounted on the movable part 1, the control generator 11 and 12, the subtractor frequency 13, the reversible counter 14 with the younger decade 15 and the senior decade 16, the reading device 17 of the transducer or code analog D8., code-frequency converter 19 with prmlm output 20 and inverse output 21, O-flip-flop 22, logic switch 23, code converter. in the relative length of time interval 24, converter of the relative duration of time interval into current 25. The converter 24 consists of a reference generator 26, a reference counter 27 with lower decades 28 and higher decades 29, a matching circuit of codes 30 and an RS flip-flop 31, and converter 25 contains a key 32 and a current source 33. In addition / there is an adjustable current source of containers 34 and amounts The driving unit 35.

The operation of the device is based on the compensation of the force of the weight of the weighed load by the force created by the compensator 8 and determined by the interaction of the magnetic field of the permanent magnet 9 with the averaged current in the coil 10, defined as

l-ti p

de IP - stabilized current of current source 33;

ac is the duration of the current pulse, the conversion period, determined by yushi: rf by the ratio of the volume of the reference counter 27 to the frequency of the pulses of the reference generator 26;

k is the number of current pulses during the conversion period; readout of the reversing counter 14; reference meter volume.

M The formation of current pulses is carried out by a reversible counter 14 and a reference counter 27..

Electronic digital scales work as follows.

In the initial position, in the absence of the measured object 3 on the load receptor 2, the movable plate 7, rigidly attached to the movable part 1, is in a central position. Moreover, the controlled oscillators 11 and 12 have the same frequencies f and%, and the difference in frequencies at the outputs of the subtractor of frequencies 13 is zero, i.e. ikf f - O, the code combination at the outputs of the reversible counter 14 has the form 0000 and the readout of the reading device 17 is also zero.

In the weighing mode, when setting the object 3 to the load receptor 2, the movable part 1 together with the movable plate 7 moves, the generators 11 and 12 mismatch, and the output of the subtractor frequency 13 shows a difference frequency signal ± f f - f2. The reversible counter 14 counts the pulses that have arrived during the process of balancing the transient process and controls the code-to-analog converter 18.

As the number of pulses grows in the reversible counter 14, the residence time of the flip-flop 31 of the code converter to the relative length of the time interval 24 increases. in the unit state, determined by the difference between the moments of the arrival of overflow pulses from the reference counter 27 of the coincidence circuit of codes 30 through the logic switch 23. This leads to a decrease in the duration of the current pulse ut, -, and consequently an increase in the compensating current I c. The process of changing current I continues until a code combination is typed in the reversing counter 14, proportional to the measured mass of the object. The measured mass t is read by the readout device 17, which is calibrated in units of mass.

Claims (2)

1. Knorring VG, Rukina L.K. A new method of building digital compensation instruments for measuring mechanical quantities. - In Sat. Digital measuring and control devices. L., LPI them. M.I. Kalinina, 1965, 256, p. 3-9. 2. Authors certificate of the USSR 742719, cl. G 01 G 23/36, 1978 5. (Prototype). (t ..- liVV FPL