JPS59122906A - Zero adjusting device for level - Google Patents

Abstract

PURPOSE:To perform zero adjustment accurately at any place, by obtaining the average value of detected level signals in positive/negative directions, and displaying the average value as a correcting quantity for a zero adjusting device. CONSTITUTION:At first, a receiving table 2a is mounted on the side of a rail 4a. A mode switch SW is switched to the side K, and then a power switch PS is turned ON. Thereafter a push button switch PBa is turned ON, and a detected level signal Cxp in the positive direction is obtained. Then, the detected level signal Cxp in the positive direction including an error component before zero adjustment is inputted to a sample hold amplifier 13 and held. Thereafter, the receiving table 2a is mounted on the side of a rail 4b in order to get a detected level signal Cxn in the reverse direction, a push button PBb is depressed, and the detected level signal Cxn in the reverse direction including errors is held by a sample hold amplifier 15. Then, the average value signal of the two signals Cxp and Cxn is computed by an operation amplifier 18, and the value is displayed on a display device 20 together with positive and negative sign. The value indicates the correcting quantity for a zero adjusting device 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zero adjustment device for a spirit level for measuring the inclination of rails or various structures.

2. Description of the Related Art Conventionally, there is a spirit level shown in FIG. 1 for measuring the inclination of, for example, a rail. That is, two pedestals 2a connected by the inspection par 1.

A level detection sensor 3 is installed inside one of the pedestals 2a of 2b.
With the two pedestals 2a and 2b placed on the rails 4a+4b, a voltage signal corresponding to the level between the rails 4a and 4b is taken out from the level detection sensor 3, and this voltage signal is sent to the connectors 5a, 5b and the cable. The level measurement value is input to the level main body 7 via the level gauge 6, and is digitally displayed as a level measurement value (including positive and negative signs) on the display 8.

By the way, various types of measuring instruments are equipped with a zero adjuster in order to eliminate measurement errors due to aging of components such as circuit elements, and the above-mentioned level is also equipped with a similar zero adjuster. ing.

However, since the zero adjuster of the conventional level gauge described above is configured by simply turning the zero adjustment knob 9, accurate zero adjustment can only be performed in maintenance areas where reference rails are installed. The drawback was that it couldn't be done.

The present invention has been made to solve these drawbacks, and an object of the present invention is to provide a level gauge zero adjustment device that can perform accurate zero adjustment at any location.

To avoid this, the present invention provides an operational amplifier that obtains an average value signal of the level measurement signals in the forward direction and the reverse direction, displays this average value signal as a correction amount for the zero adjuster, and uses this displayed value to adjust the zero adjuster. It is configured to adjust the

Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 2 is a circuit diagram showing an embodiment of a spirit level to which the present invention is applied, and FIG. 3 is an external view of the main body 7.

In FIG. 2, the voltage signal obtained by the level detection sensor 3 is inputted to a differential amplifier 11 after high frequency noise components are removed by a low noise filter (LPF) 10. An output signal from a zero adjuster 12 made up of a variable resistor is input to one input of the differential amplifier 11.

The output signal of the differential amplifier 11 is input to a resistor 14 via a push button switch PBa and a sample hold amplifier 13, and is also input to a resistor 16 via a push button switch PBb and a sample hold amplifier 15. Further, the output signal of the differential amplifier 11 is converted to an analog-to-digital converter (ADC) by a mode changeover switch SW.
) 17 is configured to be selectively input.

The pushbutton switch PBa displays the level measurement value in the positive direction (i.e.
It is turned on when measuring the measured value when the pedestal 2a is placed on the side of the rail 4a in Fig. 1.
The other push button switch PBb is turned on when measuring the level measurement value in the opposite direction (the measurement value when the pedestal 2a is placed on the side of the rail 4b).
located on the operating surface of the

On the other hand, the output signals of resistors 14 and 16 are output to operational amplifier 1.
8 is entered. This operational amplifier 18 (d is the average value signal of the level detection signal C in the positive direction and the level detection signal CXn in the opposite direction ((Cxp + CXn)/
2), and its output signal can be selectively input to the ADC 17 via a mode changeover switch SW.

The ADC 17 converts the input signal into a digital signal according to its level, and the output signal is decoded by the decoder 19 and then displayed on the display 20 as a digital signal.

In the level gauge configured in this way, the zero adjustment operation is performed as follows.

First, in order to obtain the level measurement signal C in the positive direction, place the xp pedestal 2a on the side of the rail 4a, and then switch the mode changeover switch SW to the 'to' side, and then turn the power switch P.
S is turned on. Next, the push button switch PBa is turned on. Then, the positive level detection signal C including the error component before zero adjustment is input to the sample p-hold amplifier 13 and held there.

Next, in order to obtain the level measurement signal C in the opposite direction, after placing the pedestal 2a on the side of the rail 4b, the push button switch PBb is turned on. Then, the water rate measurement signal C in the opposite direction including the error component before zero adjustment is input to the sample and hold amplifier 15 and held there.

Then, in the operational amplifier 18, an average value signal of the two level detection signals C and C is calculated.

xp xn This average value signal is displayed dinotally on the display 20 including positive and negative signs. The average value of the level detection signals C and C displayed in diagonal represents the correction amount k of the zero adjuster xp xn 12.

Therefore, next, switch the mode changeover switch SW to the "M" side, take out the level measurement signal C in the forward direction (yet xp is the level measurement signal CXn in the reverse direction), and display it on the display 20 as a disotal. . Assuming that the displayed value at this time is C, the zero adjuster 12 is adjusted so that the displayed value C becomes C-Cx-. As a result, the zero regulator 12
is set exactly to the zero adjustment position.

In this way, in the present invention, the average value of the level detection signals in both the positive and negative directions is determined, and this average value is displayed as the correction amount of the zero adjuster. Therefore, if it is applied not only to a level for rails but also to a level for membrane structures, there is no need for a reference level point for zero adjustment, making it extremely easy to handle. It has effects such as convenience.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of a conventional spirit level, FIG. 2 is a diagram showing an embodiment of the present invention, and FIG. 3 is a diagram showing the appearance of the main body. DESCRIPTION OF SYMBOLS 1... Inspection bar, 2a, 2b... Rest, 3... Level detection sensor, 7... Level body, 11... Differential amplifier, 12... Zero adjuster, 18 ...Operation amplifier, 2
0... Display k, SW... Mode changeover switch. Patent applicant: Shibaura Seisakusho Co., Ltd.

Claims (1)

[Claims] A differential amplifier that corrects the output signal of the level detection sensor by a zero regulator output signal, and a display that digitally displays the output signal of the differential amplifier as a level measurement value. The level device includes first and second storage circuits that receive the output signal of the differential amplifier and store positive and reverse water detection signals in the detection target, respectively; an operational amplifier that outputs an average value signal of the water turbine inspection signal; and a display changeover switch that selectively displays the output signal of the differential amplifier and the output signal of the operational amplifier on the display; A level gauge zero adjustment device that displays an output signal as a correction amount of a zero adjuster, and adjusts the zero adjuster based on the displayed value.