JPH0118364B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is a scale that measures weight by balancing a loaded weight with an opposing control force, such as a spring scale or a balance, by measuring the vibration of the measurement system based on the fluctuation of the loaded weight itself based on the displayed weight value. This relates to a device that removes the effects of

Generally, when measuring weight with an automatic digital scale, the weight is detected analogously using a potentiometer scale, a load cell, an electromagnetic balance scale, etc.
-D conversion and digital display to reduce the risk of misreading due to the scale plate and pointer, and to prevent small fluctuations within the tolerance of the displayed value from being displayed.

However, with this method, at the moment when a large change in load weight occurs, large amplitude vibrations occur in the measuring mechanism due to the time delay in balancing the control force and the lack of braking force. Until this happens, stable display cannot be obtained even with digital display.

As a means of stabilizing this display value, a method has been proposed in which the analog weight value is held after a certain period of time has elapsed after a new weight is loaded, and the analog weight value is converted to a digital value and displayed. Even if it is effective for objects that do not move on their own, in living organisms, if a part of the body moves even after a load is applied, the balance between body weight and control force will be disrupted, so the displayed value will randomly oscillate, making accurate weight measurement impossible. .

Especially these days, the weight measurement of a living body is also printed as a digital value on printed paper, so if the digital display value is unstable, the printout may become unclear or an abnormal value may be printed twice, making it difficult to accurately measure the body's weight. Since the value of is unknown, it is first desired to improve the stability of the analog value, but in this case, the influence of randomly occurring vibrations as in the case of measuring the body weight cannot be ignored.

In view of the above, this invention holds the weight value and converts it to a digital value and displays it only when the measuring system of the scale is not vibrating, thereby ensuring stable and accurate weight display under any circumstances. The company provides an automatic digital scale that does the following:

In other words, a control circuit is installed that separates only the alternating current component from the electrical signal coming from the weight detector, and does not issue a weight value hold signal while this alternating signal is being output, and only outputs a weight value hold signal when the scale no longer vibrates. If the weight value is analog, the held analog value is converted to a digital value and displayed, thereby making it possible to avoid duplicate display of different weight values, unclear display, etc.

Next, embodiments of the present invention will be described. In FIG. 1, 1 is a DC component removal circuit, 2 is a measurement set circuit, 3 is a differential shaping circuit, 4 is a sawtooth wave generation circuit, 5 is a one shot that operates with the output signal of 4,
Multivibrator, 6 is a one-shot multivibrator that operates with 3 outputs, 7 is 2, 5,
AND circuit that operates with 6 output signals,
8 is a display device operated by the output signal of 7, 9 is a weight detector, 10 is an AD converter, and 11 is a control device according to the present invention.

Figure 2 shows the output signal waveforms of each circuit shown in Figure 1, where A is the weight measurement value signal, and each waveform from 2 to 6 is the output waveform of the circuit with the same number in Figure 1. B is the output signal waveform of the circuit 7, which is a hold command pulse of the weight analog value. Second
In the timing chart shown in the figure, when weight is first applied to the scale, the analog value indicating the weight increases from zero value as shown in A, passes the expected value (value when not vibrating), and begins to vibrate. . This vibration waveform including the vibration component (AC component) and the expected value (DC component) is divided and first enters the second measurement set circuit.
Reference numeral 2 denotes a gate circuit that is open for a certain period of time t ₁ after the arrival of the weight analog signal, and this open (1) signal puts the display device in a displayable state. Second, the vibration waveform from which the DC component has been removed by the DC component removal circuit 1 enters the differential shaping circuit 3. In the circuit No. 3, one pulse is output for each period of the vibration waveform. This pulse signal is guided to a one-shot multivibrator 6 to create a negative rectangular wave at 6 in FIG. On the other hand, the output of circuit 3 is guided to circuit 4, but circuit 4 is a sawtooth wave generation circuit, and when there is no pulse input from circuit 3, a threshold level (threshold value) is generated every fixed time _t2 . The sawtooth wave is self-oscillated, rising at a slope that reaches the threshold value (lth in Figure 2), but when there is a pulse input from the circuit 3, the sawtooth wave is reset. The output waveform of the circuit No. 4 is guided to the circuit No. 5, and when the peak value of the sawtooth waveform No. 4 is close to the threshold value, the one-shot multivibrator No. 5 generates the rectangular wave shown in Fig. 2, No. 5. do. The output waveforms of 2, 5, and 6 are combined by the AND circuit of 7, and only when the output of the weight detector 9 is not in a vibration state, it becomes the hold signal B of the weight analog value, and the digital display of the weight value is switched to A-D of 10. Instruct the converter. Incidentally, in the weight analog signal of FIG. 2A, the vibration a occurs immediately after a load is applied, and in the case of an inanimate object, vibrations such as b generally do not occur. When a living body is subjected to a load, the living body itself oscillates even after the load is applied, disrupting the balance of forces within the living body, so there is a risk that vibrations like b will occur repeatedly at irregular intervals.

As a result of the above, the period during which gate circuit 2 is open is t ₁
Otherwise, the weight analog value hold command signal will not be issued, but the fundamental wave of the weight analog value hold command signal B as shown in waveform 5 is generated by a sawtooth wave whose period is t ₂ shorter than t ₁ . c, d, e, f
Make a pulse. In this case, since the two pulses c and d are emitted at the start of vibration, they cannot be the fundamental wave of B, and must be canceled as a result. In other words, when 2, 5, and 6 are combined in the AND circuit of 7, the positive (1) pulse of c and d is canceled by the negative pulse (0) of 6, and only the e pulse of 5 during period _t1 . becomes B's hold command signal. In this case, the time T from when the vibration of a in the waveform A is attenuated until the vibration of b arrives is indefinite, but T≦ _t2 . When T and _t2 are close, there is a risk that pulses similar to e and f will occur, such as c and d, but as a result, they are eliminated by the negative pulse of 6 in the AND circuit of 7. be.

As described in detail above, the present invention waits for the vibrations of the measuring mechanism to decay when a heavy object to be measured is loaded onto a weight measuring device, obtains a stable digital indication in a relatively short period of time, and calculates the weight of the living body. Even when there is a risk of vibration occurring irregularly many times after a weight is loaded, as in the case of measurement, the displayed value is held only when the vibration has stopped, so the displayed value is always stable and reliable. becomes.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the present invention, Figure 2 is a block diagram showing the configuration of the present invention.
The figure is a timing chart showing the output waveforms of each circuit shown in FIG. Explanation of symbols: 1: DC component removal circuit, 2: Measurement set circuit, 3: Differential shaping circuit, 4: Sawtooth wave generation circuit, 5: Multivibrator (), 6: Multivibrator (), 7: AND (AND ) circuit, 8: display device, 9: weight detector, 10: A-
D converter, 11: control device, A: weight measurement value signal, B: output signal of 7 (hold command pulse),
a: initial load vibration of weight value A, b: intermediate irregular vibration of weight value A, _t1 : measurement set period, _t2 : sawtooth wave threshold reset period, T: non-vibration period of A,
lth: Threshold value of sawtooth wave, c, d: Pulse based on reset caused by the start of vibration of A,
e,t: Pulse based on reset caused by reaching sawtooth threshold.

Claims (1)

[Claims] 1. A differential shaping circuit that differentiates the output of a detector that detects the load weight in a device that balances the force or displacement of the load weight using gravity or elasticity and converts and displays the force or displacement required for the balance into a digital quantity; A hold signal generation circuit is provided, which includes a sawtooth wave generation circuit that is reset by the output of the differential shaping circuit, and a circuit that generates an output signal when the output of the sawtooth wave generation circuit reaches a predetermined threshold. An automatic digital scale characterized in that the output of the detector is held by the output signal from the hold signal generation circuit, and the output is converted into a digital quantity and displayed.