JPS59174020A - Proximity switch sensor - Google Patents

Abstract

PURPOSE:To miniaturize a proximity switch sensor by connecting a chip capacitor to a metallic film formed on the rear side of the core of the switch sensor. CONSTITUTION:A detection coil 4 is buried into a circular groove of a core 12 of a coil case 11, and metallic vapor deposition is applied on the rear side of the core 12. Thus the inside of a sensor 1 is shielded electrostatically from the coil 4. An end 50a of a chip capacitor 50 and a reed frame 14 are connected to the metal vapor-deposited film 13. The hot end side at an end of the coil 4 is wound around the other end 50b of the capacitor 50 and fixed there, and a core wire 3a of a coaxial cable 3 is soldered to an end part 50b. The cold end side of the coil 4 is wound around an end of the frame 14, and the other end of the frame 14 is connected to a mesh wire part 3b of the cable 3. Thus the sensor 1 can be miniaturized since no connection terminal is separately needed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a proximity switch sensor used in a high frequency oscillation type proximity switch in which a sensor having a detection coil and a detection circuit section are separated.

Background of the Invention In high frequency oscillation type proximity switches, in order to detect metal objects in narrow areas, a separate structure is adopted in which the sensor and detection circuit are separated and connected using a connecting cable such as a coaxial cable. There are many. In recent years, as the range of use of proximity switches has expanded, there has also been a demand for smaller sensors. By the way, the smaller the sensor is, the thinner the lead wire of the detection coil is used. Therefore, it is not possible to directly connect the detection coil and the coaxial cable, but it is necessary to use some kind of terminal inside the sensor to connect the coaxial cable and the detection coil. In order to make the sensor smaller, it is desirable to make these terminals as small as possible. In addition, the capacitors that make up the sensor's detection coil and resonant circuit are often installed in the detection circuit to keep the sensor small, but in order to avoid the effects of the direct current resistance of the coaxial cable and temperature changes, as well as a decrease in the Q of the resonant circuit. It is preferable to provide a capacitor on the sensor side.

Purpose of the Invention The present invention has been made in view of the characteristics of such a proximity switch sensor, and contributes to miniaturization of the sensor and can omit terminal parts for connecting the end of the coil and the coaxial cable. The present invention aims to provide a proximity switch sensor.

Structure and Effects of the Invention The present invention is a proximity switch sensor that includes a detection coil embedded in the core and is separated from the detection circuit section via a connecting cable. A chip capacitor, one end of which is connected to a metal film provided on the back surface, one end of a detection coil fixed to the other end, and one end of a connection cable connected to this end, and a metal film on the back surface of the core. and a connection line connected via the connection line at the end of the cable.

According to the present invention having such characteristics, since the sensor is provided with a capacitor, it is possible to reduce the effects of direct current resistance and temperature changes of the coaxial cable connecting the sensor and the detection circuit section. In addition, a chip capacitor is used as the capacitor, and since the chip capacitor is connected to the metal film provided on the back of the core, there is no need to provide other connection terminals, and the sensor itself can be miniaturized. can. Furthermore, since it does not have a connecting terminal, assembly time can be reduced and work efficiency can be improved.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a block diagram showing a general sensor-separated type proximity switch. In this figure, sensor 1 and detection circuit section 2
is connected with coaxial cable 3. A detection coil 4 is provided in front of the sensor 1, and a capacitor 5 connected in parallel with the detection coil 4 may be provided on the sensor 1 side as shown in the figure, or may be provided on the detection circuit section 2 side. However, in either case, a resonant circuit is formed together with the detection coil 4. On the detection circuit section 2 side, the coaxial cable 3
An oscillator 6 whose oscillation frequency is the resonant frequency of this resonant circuit is connected to the end of the resonant circuit. While the proximity switch is in operation, this oscillator 6 oscillates, and when the object 7 to be detected approaches, the oscillation level decreases. The output of the oscillator 6 is given to a detection/level discriminator 8, and this level change is read to obtain an object detection signal. This signal is outputted to the external gB via the output section 9. The power supply circuit 10 supplies power to each part.

FIG. 2 is a diagram showing the structure of the proximity switch sensor 1' according to the present invention. In this figure, the detection coil 4 is embedded in an annular groove of a core 12 provided at the tip of a coil case 11. Metal vapor deposition is performed on the back surface of the core 12, and the sensor 1
The inside of the sensor is electrostatically shielded from the detection coil 4.

Now, in the present invention, one end 50a of the chip capacitor 50 and the lead frame 14 are connected to the metal vapor deposited film 13. The chip capacitor 50 is used as an internal circuit component of a hybrid IC or the like, and is a capacitor before being molded as an individual component. One end of the detection coil 4 on the hot end side is wound and fixed around the other end 50b of the chip capacitor 50, and the core wire 3a of the coaxial cable 3 is connected to the end 50b of the chip capacitor by soldering. Further, the cold end side of the detection coil 4 is wound around and fixed to one end of a lead frame 14, and the other end of the lead frame 14 is connected to the mesh wire portion 3b of the coaxial cable 3. Note that the cold end side of the detection coil 4 is connected to the metal vapor deposited film 1 on the back surface of the core 12.
3, or may be connected by winding it around the end 50a of the chip capacitor 50. In this way, the chip capacitor 50 is used as a terminal block for the detection coil 4 to form a parallel resonant circuit and to be connected to a coaxial cable. After that, the coil case 11 is embedded in the case 15 of the sensor 1 and fixed. Note that the gaps in the sensor 1 are filled with epoxy resin or the like to fix each part.

In this way, if you wrap the terminal of the detection coil directly around one end of the chip-type capacitor and use it as a connection terminal,
There is no need to provide additional connection terminals, and the sensor itself can be miniaturized.

In this embodiment, a metal vapor deposition film may be connected to the back surface of the core 12 for shielding, or a printed circuit board with copper foil may be attached to the front surface of the core 12, or another metal plate may be attached to the front surface. Furthermore, the cold end of the detection coil 4 may be connected to this metal film without being connected to the lead frame.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a general sensor-separated proximity switch, and FIG. 2 is a W1 side view showing the structure of the sensor portion of the proximity switch according to the present invention. 1------・-Sensor 2------Detection circuit section
3------One coaxial cable 4---Detection coil
5------Capacitor 50---Chip capacitor 6Oscillator 12---Core 13------
-Metal deposited film 14--Lead frame 15-
=Case patent applicant Tateishi Electric Co., Ltd. agent Patent attorney Kanki Okamoto (and one other person)

Claims (1)

[Claims] (1) In a proximity switch sensor that includes a detection coil embedded in the core and is separated from the detection circuit section via a connecting cable, a capacitor that forms a resonant circuit with the coil and is located on the back surface of the core. a chip capacitor, one end of which is connected to the provided metal film, one end of the detection coil wound around and fixed to the other end, and one end of the connection cable connected to the other end; A proximity switch sensor comprising a metal film on the back surface and a connection line connecting the other end of the connection cable.