JPH01259228A - Pressure sensor - Google Patents

Abstract

PURPOSE:To detect pressure with good stability by applying a reference AC signal to a serial circuit of a serial or parallel circuit of a core-containing coil and a capacitor, and a resistance, and varying the resonance frequency mechanically. CONSTITUTION:An AC signal of 455kHz is obtained by a CMOS oscillation circuit which uses a ceramic oscillator X1. This is applied to the series reso nance circuit of a capacitor C3, a coil L, and a resistance R2. When the core is not inserted into the coil L, the resonance frequency is close to 455kHz and the voltage drop across the resistance R2 is large. When the core is inserted, the resonance frequency varies away from 455kHz and the voltage drop across the resistance R2 is small. An AC signal generated at the R2 is rectified by a rectifier D1, its DC voltage is amplified by a transistor(TR) Q1 and led to a terminal OUT, and the position of the core insertion appears as variation in output voltage E. Then the mechanism of the coil L is constituted as shown in a figure using a coil spring 3 and then this is used as the pressure sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is used in a chuck part of an industrial robot, and detects the pressure of gripping an object and also performs positioning.

It also detects vibrations at low frequencies and is also used to measure heavy loads.

[Prior Art] Conventionally, semiconductor diffusion pressure sensors exist, which have high accuracy but have a small stroke, are easily damaged, and are expensive.

There are also devices using conductive rubber, but these have large permanent deformation and large hysteresis, so they have the drawback of poor repeatability.

Means for Solving Problems] The position sensor of the present invention applies an AC signal from an oscillation circuit including a ceramic oscillator to a resonant circuit consisting of a coil containing a core and a resistor, and adjusts the voltage depending on the insertion position of the core into the coil. The drop becomes small, and as a result, the alternating current signal generated in the resistor is rectified, and the resulting direct current voltage is amplified by a transistor and appears as a change in output voltage, making the core act as a position sensor. - By attaching a coil spring to this position sensor, it can function as a pressure sensor.

[Example] CMO3 using ceramic oscillator x 1 in Fig. 1
An AC signal of 455KII7 is obtained by the oscillation circuit. This is added to the series resonant circuit of capacitor 03, coil, and resistor R2.

When no core is inserted into the coil, the resonant frequency is 4
55KII2, and the voltage drop occurring across resistor R2 is large. When the core is inserted, 455 is in a direction farther away than R2, and the voltage drop across resistor R2 becomes smaller.

In this circuit, the AC signal generated in R2 is rectified by a rectifier D1, and the DC voltage is amplified by a transistor Q1 and guided to the OUT terminal, so that the core insertion position appears as a change in the output voltage.

The variable resistor VR1 adjusts the voltage applied to the base of the transistor Q1 and adjusts the sensitivity.

This core is then used as a contact part of a position sensor. In this circuit, the resistor R2 is 10Ω,
Since the resistance is high, the Q of the transistor is low, so a stable output can be obtained.

By arranging the mechanism of the coil L as shown in FIG. 2, it can be used as a pressure sensor.

[Effects of the Invention] Since the position sensor and pressure sensor of the present invention have the above configuration, the cost is much lower than that of the conventional semiconductor diffusion type, and the oscillation frequency is obtained from the ceramic oscillator, so it is stable. When a pressure sensor using a coil spring is used as a pressure sensor for the industrial robot 1, since the stroke is large, it can be cushioned and objects can be transported.

Since changes in pressure are output as changes in DC voltage, they can be converted from analog to digital and processed by a computer.

Since the phase-to-phase relationship of low-frequency vibrations can be output correctly,
Effective for detecting vibration isolators.・

[Brief explanation of the drawing]

Figure 1 is a circuit diagram. Figure 2 is a diagram of the pressure sensor mechanism. TCI...Transmission circuit IC2...Low voltage stabilization circuit x 1...Ceramic resonator Dl...Rectifier Ql...Transistor R...
...Resistance VRl...Variable resistance C...Capacitor L...Coilt...Core 2...Coil 3...Coil spring 4...Pressure sensor contact part 5 ...Cover 6 ...Coil bobbin patent applicant Fuji Rubber Co., Ltd. Agent Patent attorney
Matsu 1) Ministry amendment to incorrect procedure (voluntary) July 8th, 1986

Claims (2)

[Claims] (1) Add a reference AC signal to a series or parallel circuit of a coil with a core, a capacitor, and a resistor connected in series. A position sensor that generates a voltage change across a resistor by mechanically varying either or both of the capacitances, and outputs that voltage. (2) A pressure sensor in which a coil spring is attached to the mechanically variable part of the position sensor according to claim (1).