JP2518279Y2 - Fluid cylinder piston position display unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a piston of a fluid cylinder for displaying the operation of the sensor switch in relation to the sensor switch for detecting and displaying the piston position of the fluid cylinder. Regarding the position display unit.

(Problems to be Solved by the Related Art) There is known a fluid cylinder in which a permanent magnet is inserted in advance in the piston of the fluid cylinder and a reed switch arranged outside the cylinder is driven.

There is known a device for displaying by combining the reed switch with a light emitting element which is a display element.

In the case of using a light emitting diode as a light emitting element, an element in which an inductance and a light emitting diode are connected in series to the reed switch and a protection diode is connected in parallel to the light emitting diode is unitized.

It is possible to prepare a large number of such units, each of which corresponds to a specific position of the cylinder, and when connected in series to the power source, the light emitting diodes are caused to emit light when the pistons of all the cylinders come to the specific position. it can.

However, such a circuit may not be lit, for example, when the circuit itself is inconvenient. Also, in such a circuit, the resistance value of the light emitting diode becomes a problem,
If a large number of them are connected in series, the operation may become unstable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a piston position indicating unit for a fluid cylinder, which solves the above-mentioned problems, enables more stable operation, and allows a large number of units to be connected in series.

(Means for Solving the Problems) In order to achieve the above object, a piston position indicating unit of a fluid cylinder according to the present invention includes a reed switch, a series circuit of a light emitting diode and a constant current diode, and a protection diode in parallel. A plurality of display units which are connected to each other and whose connection terminals are drawn out, and a reed switch so that the light emission of the light emitting diode of each display unit is visually recognized from the outside and is related to the position of the permanent magnet provided in the piston of the corresponding fluid cylinder. Are arranged in each fluid cylinder so that a plurality of the above-mentioned arranged display units are connected in series and connected to a power source, and a light emitting diode of any display unit is a light emitting diode or a lead of another display unit. It is configured to be connected to a power source via a switch.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of a piston position display unit of a fluid cylinder.

FIG. 3 is a view showing a state where the piston position indicating unit of the fluid cylinder is mounted on the air cylinder.

To the reed switch 4, a series circuit of a light emitting diode 3 and a constant current diode 5 is connected in parallel, and a protection diode (surge diode) 7 is connected in parallel.

A choke coil 6 is connected between the positive connection terminal 1 and the cathode of the protection diode 7, and protection is provided when the polarity is mistakenly connected between the anode of the protection diode 7 and the negative connection terminal 2. A protective diode 8 for is connected.

The choke coil 6 is a coil for preventing an inrush current.

As shown in FIG. 3, these circuits are integrated into an integral unit U and arranged at a predetermined position of the cylinder 21 of the air cylinder.

The light emitted from the light emitting diode 3 is the magnetic shield casing 11
The reed switch 4 is fixed to the outside of the cylinder 21 so as to be visually recognized from the outside through the display window 10 provided in the cylinder, and the reed switch 4 is integrated so as to correspond to the position of the permanent magnet 22 provided in the piston 23 of the fluid cylinder. It

FIG. 2 is a schematic diagram showing the structure and symbols of a constant current diode,
FIG. 4 is a graph showing the characteristics of this constant current diode.

The constant current diode 5 is a current adjustment diode CRD (cur
It is also called a rent regulation diode).

As shown in FIG. 2, the constant current diode 5 has an applied voltage of
When a reverse bias is applied to the pn junction, it exhibits constant current characteristics as shown in FIG. The following characteristics are exhibited when the applied voltage is gradually increased.

In the rising region, the current increases due to the silicon specific resistance in the n region.

In the shoulder region, a depletion layer grows on the n side of the p region with respect to the applied voltage, the current passing through the n region is narrowed, an increase in resistance value is suppressed, and finally the depletion layers come into contact with each other to be in a pinch-off state.

The current value in this region is constant regardless of the applied voltage and exhibits constant current characteristics, so this region is used.

Further, in the high voltage region, the voltage applied to the pn junction causes breakdown and the current value remarkably increases.

When the polarity of the applied voltage is reversed, a forward bias is applied to the pn junction and it exhibits the same characteristics as a general diode. In FIG. 4, Ip is a pinch-off current, Vk is a voltage to be 0.8 Ip, Vp is a pinch-off voltage, VB is a breakdown voltage, and IR is a reverse direction allowable current.

Various constant current diodes with different Ip (pinch off current) are manufactured, and an appropriate Ip diode is selected in consideration of the light emission amount.

However, it is necessary to use the one having substantially the same pinch-off current Ip when used in series connection described later.

Since the light emitting diode 3 is connected in series with the constant current diode 5, a pinch-off voltage is applied to the constant current diode 5.
As long as a voltage equal to or higher than Vp and equal to or lower than the breakdown voltage VB is supplied, a substantially constant current is always supplied.

In the unit U on the right side of FIG. 3, the reed switch 4 is closed corresponding to the permanent magnet 22, and it is in a state where it is detected that the piston 23 has returned to the right side.

At this time, both ends of the series circuit of the light emitting diode 3 and the constant current diode 5 are short-circuited, and the light emitting diode 3 is turned off.

In the unit U on the left side of FIG. 3, since the reed switch 4 is not associated with the permanent magnet 22, a constant current is supplied to the light emitting diode 3 in the open state and the light is turned on.

FIG. 5 is a circuit diagram showing an example of serial connection of the embodiment of the piston position indicating unit of the fluid cylinder according to the present invention.

For example, ten cylinders shown in FIG. 3 are prepared and ten right side units U1 to U10 are connected in series.

Only one choke coil 6 needs to be used.

When the pistons of all the cylinders return to the right side, all the reed switches 4 are closed. As a result, a series circuit of 10 reed switches 4 is formed, and it is possible to drive another circuit by utilizing this series circuit.

In the circuit, the light emitting diode 3 corresponding to the cylinder whose piston has not returned is supplied with a constant current and is lit, so that it is possible to know which cylinder's piston has not returned.

The VB of the constant current diode is VB> 10Vp. The inventors connected 10 units U in series as described above,
Checking the operation of 10 AND logic.

Further, since a constant current is supplied to each light emitting diode, there is no inconvenience that the brightness changes depending on the number of lights.

(Effect of the Invention) As described in detail above, the piston position display unit of the fluid cylinder according to the present invention has the reed switch, the series circuit of the light emitting diode and the constant current diode, and the protection diode connected in parallel and the connection terminal. The plurality of display units that are pulled out, and the light emission of the light emitting diode of each display unit is visually recognized from the outside, and the reed switch is arranged so as to be related to the position of the permanent magnet provided on the piston of the corresponding fluid cylinder. The display unit is arranged in a fluid cylinder, and a plurality of the arranged display units are connected in series to be connected to a power source, and a light emitting diode of any display unit is connected to a power source through a light emitting diode of another display unit or a reed switch. It is configured to be.

Since the reed switch and the light emitting diode are connected in parallel, and the circuit is connected when the reed switch is turned off, the light emitting diode does not affect the closed circuit of the reed switch. Therefore, another device can be driven by the series connection circuit of the reed switches.

All the problems of the conventional circuit in which the reed switch and the light emitting diode are connected in series have been solved.

Also, in the voltage range within the use range of the constant current diode, the brightness of the light emitting diode can be kept constant even if the applied voltage changes, and the number of lights can be increased even when multiple LEDs are connected in series. There is no problem that the brightness changes due to.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of a piston position display unit of a fluid cylinder. FIG. 2 is a schematic diagram showing the structure and symbols of a constant current diode. FIG. 3 is a view showing a state where the piston position indicating unit of the fluid cylinder is mounted on the air cylinder. FIG. 4 is a graph showing the characteristics of the constant current diode. FIG. 5 is a circuit diagram showing an example of serial connection of the embodiment of the piston position indicating unit of the fluid cylinder according to the present invention. 1,2 ... Drawout terminal 4 ... Reed switch 5 ... Constant current diode 6 ... Choke coil 7,8 ... Protection diode 10 ... Display window 11 ... Magnetic shield casing 20 ... Piston rod 21 ... Cylinder 22 ... Permanent magnet 23 ... Piston U, U1 to U10 ... Display unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography Sho 60-37803 (JP, U) Rikai 57-54007 (JP, U) Rikai 57-115404 (JP, U)

Claims (1)

(57) [Scope of utility model registration request] 1. A plurality of display units in which a reed switch, a series circuit of a light emitting diode and a constant current diode, and a protective diode are connected in parallel and a connection terminal is drawn out, and each of the display units has a light emitting diode which emits light. Arranged on each fluid cylinder so that the reed switch is arranged so as to be visually recognized from the outside and associated with the position of the permanent magnet provided on the piston of the corresponding fluid cylinder. A piston position display unit for a fluid cylinder which is configured to be connected to a power source by connecting to a power source, and the light emitting diode of any display unit is connected to the power source through a light emitting diode of another display unit or a reed switch.