JPS5952919A - Proximity switch - Google Patents

Abstract

PURPOSE:To obtain a proximity switch which does not require an unnecessary initial reset time and operates exactly, by constituting so that an initial reset time attains variable in accordance with a rise speed of oscillation amplitude. CONSTITUTION:When oscillation amplitude is below a detecting level of a voltage comparing circuit 3, a signal of ''L'' level of its output is applied to the base of a transistor 12 of an initial resetting circuit 5', therefore, the transistor 12 is off, and as for an initial reset capacitor C2, charging is started by a current prescribed by the sum of a resistance 14 and 13 connected in series through the first current mirror circuit. In case when the oscillation amplitude reaches the detecting level before the initial resetting circuit 5' goes to time-up, an output of the voltage comparing circuit 3 attains to ''H'' level, therefore, the transistor 12 turns on, and a current flowing in the first current mirror circuit attains approximately a quantity prescribed by a value of the resistance 14, therefore, a current flowing into the initial reset capacitor C2 increases, its charging voltage reaches a threshold level quickly, and the initial reset is released.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency oscillation type proximity switch that detects the presence of a metal object, IR, etc. without contact.

This conventional fin proximity switch generally has a +77J circuit configuration as shown in FIG. In other words, oscillation circuit 1
, the detection circuit 2.11 is connected to the pressure comparison circuit 3, the output circuit 4, the initial reset circuit 5.1:I, and the source stabilization circuit 6 is connected to I.
Proximity sensor circuit 8 that is converted into C and housed in one package
External components are connected to required terminals of each circuit of this proximity/proximity sensor circuit 8.

That is, the detection coil L1, the five-channel capacitor C1, and the operating distance adjustment resistor 1t are connected to each terminal of the oscillation circuit 1, the integrating capacitor (I) is connected to the output 1$111 of the detection circuit, and the initial reset capacitor C2 is connected to the initial reset circuit 5. are connected to each. Here, to explain in detail the configuration and operation of each of the above circuits, the oscillation circuit 1 is a semiconductor circuit including a detection coil and a tuning capacitor C.
When the detected body 9 approaches the detection coil L, the oscillation amplitude of the dragon circuit 1 decreases and the oscillation stops. Then, the output transistor 41 of the output circuit 4 is driven, and the load current is passed through the path of the L output terminal OUT, the output transistor 42, and the circuit ground 1 to drive the load. .

On the other hand, the detected object M is farther away than the detection coil L,
When an object is detected, the output transistor 4 of the output circuit 4 is OFF, and the load ILL is supplied with 11. Flow I
L is not applied, and the load is not driven. By the way, as shown in Fig. 2, circuit II', il east V to 11+', voltage 1
The bow is the positive f of the proximity switch (4, +jF, 4j child e+
When riCIEE is applied, the oscillation amplitude of the oscillator circuit 1 normally rises by a time T1 after the rise of riCIEE.

((:=L detected' proboscis M is) Fn No. 15', I6''
! Although it is farther than the output distance piii, the detection Iton 1'ii6 vicinity 1
In the three-phase case, the pressure rises (it rises with a further delay).In other words, during the time period 1 for this oscillation output to reach the detection level, which is a predetermined V), the detected object M
Since the oscillation J plane is small as well as detecting the
Even though the protruding object M approaches the detection coil L and C does not exist, the proximity switch detects 4 to the detection coil L.Similarly, each circuit after the oscillation circuit 1 is detected by the proximity switch. 4 is t
Since there was a risk that μ would occur when generating lb and output from output circuit 4, in order to prevent this from ft'fl, the oscillation 4Jr4 'l':;f until it reaches a predetermined detection level At the time of , the output signal from the output circuit 4 is sent to the output circuit 4 by the first time 11!5, which transmits the output signal tH from the output circuit 4 in a strong 11i1J manner. However, during the generation of the initial reset signal of the reset circuit 5 (referred to as the initial reset time), the oscillation amplitude is limited to a predetermined value because the output from the output circuit b'h is prohibited. There is a necessary step that continues for more than 1ffl until it reaches the exit level of 1, and since this initial reset time is fixed, the oscillation 1
1i'li tube quickly goes to the detection level to the proximity switch;
! Despite this, there was a drawback that the output times 1r and 3 operated in a short period of time (i:) and wasted operation.The present invention was developed in view of the above.
Depending on the rising speed of the 1'iis, the reset time is always the necessary and sufficient initial 1tJ.
) Make sure that the set time is even 1, so that the initial 1υ] reset time is set without any damage, and! i
This is a proof of a proximity switch that actually works. Hereinafter, part 1'7 of the present invention, but ii Ipl+, will be explained in detail with reference to FIGS. In this figure, the same circuit parts as in figure 1 are omitted in Figure 3, and the modified W set circuit 5' and output circuit 4, which are the essential parts of the present invention, are omitted.
′ is shown below. In other words, the configuration of the initial reset circuit 5' of the present invention is shown in FIG. Based on this, transistors 15 and 1 send out a photoelectric current of 1 to capacitor 0 for regulating the initial reset time.
．． The first tlfl flow mirror circuit formed by 4↑II in 6 and the first r (charge T'+
i', a second box consisting of transistors 19 and 20 for detecting when the initial reset capacitor q and the charge of the initial reset capacitor reach a constant voltage (total pressure) J1, connected in series with the mirror circuit; Transistor 1.7.18
It is composed of a detection circuit consisting of. Furthermore, Ail
Charging capacitor C7 during initial reset! +', '+:
(The amount of current flowing in is determined by the value of the resistor 14°13. 4' is an output circuit, and the transistor 22 operates based on the signal of the second current mirror circuit of the initial reset circuit 5'. The third current mirror circuit composed of ゜23 and the mirror city of this 30th
, an output transistor 25 driven by +IIC;
The transistor 24, whose collector is connected to the base of the output transistor 25, is configured as follows.

Next, the operation will be explained. Circuit '1. ii, the source V is applied to the source stabilizing circuit 6 through the four terminals 1, 2, 3, and 4 from the source stabilizing circuit 6 to the proximity sensor circuit 8. Voltage is supplied to 4°5.

Therefore, the oscillation circuit 1 including the detection coil 1 starts oscillating with the amplitude waveform shown in FIG. It will be delayed by 111. And this oscillation amplitude is 1
1't, EE comparison circuit 11 each: The output of F below the detection level of 3 is "L" level, and this "L" level signal is sent to output circuit 4' (7), tl (resistance). 21 to the base of the transistor 24, the transistor 24 is 01i"I-. On the other hand, the signal of the °L" level of the Nip IE comparator circuit 3 is applied to the base of the transistor 24 through the initial reset circuit 5'.
is also applied to the base of the transistor 12 of the transistor 12, so that the transistor 12 is also OFl'', and therefore the initial reset capacitor 0 is connected to the resistor 14 (!:13) connected in series via the first current mirror circuit. Charging is started with a current defined by the sum of the resistance values, but at this initial 1υ], the ri3. Since the detection level (threshold value) specified by the transistors 19 and 20 of the circuit has not been reached, the current force does not flow through the mirror circuit through the 23rd'[1.Therefore, the output transistor of the output circuit 4'Pace'distance is not applied to 25 and it is 0F
7 and the load ILL is Hjl
The output amount h':S4' remains unchanged due to the initial reset, and no output signal is sent from the output circuit power when the oscillation circuit 1 is unstable at the start of the light 1 cycle. The initial reset circuit 5' operates in this manner.

When a predetermined period of time has elapsed and the charging voltage of the initial reset capacitor (-) reaches the threshold determined by the transistors 17 and 18 and the transistors 1.9 and 20 of the second current mirror circuit, the initial reset capacitor is activated. a2ov charge 11i: rtt IIE does not exceed the threshold ((a), and the mirror '11 of the first current mirror circuit
All 5 streams are transistors 17, 18, and the second i'1
．． flows into the mirror circuit.

Zunawaji 2nd Tit; The mirror'it flow that flows into the current mirror circuit is the current flowing in the first 'IL7JIC mirror circuit, which is approximately the same size as the current flowing through the current, and this Bi4. '(, 2 Tj7. Output line of the mirror circuit (first lυ] recessor l-signal + group) 5a' is the output circuit 4'
Nonaru 3 111. γfIC mirror circuit receives one pulse,
Applicable? II+ of t\3, flowing into the υ luminar circuit"111
! i), so that the current flows through the emitter-collector of the transistor 23 to the base of the output transistor 25.
5 is turned ON. Zunawachi,
If the object to be detected N1 is sufficiently far away from the detection coil and the oscillation circuit does not cause any change in the oscillation Bcr)ζ, the oscillation system width remains 1 for a predetermined time. "+ (When the detection level is reached, the output of the voltage comparator circuit 3 becomes the "l-I" level by the output signal 8 through the side circuit 2, and this signal is sent to the output circuit 4' (via the coal mine 21). transistor 2
4 and turns on the transistor 24, the mirror current of the mirror circuit flows to the ground via this transistor 24, and the transistor 25 becomes O1i'l- and conducts.・r'+
By the way, in the present invention, the oscillation cycle i is set before the time-up (vJI) after the reset +jiJ) of the re-hit circuit 5'.
When the excavation class 1 width of 1'31 reaches the detection level, the output of the pressure comparator circuit 3 will naturally be at the "I" level, so the signals at the "I-V" level will be respectively (
Since the voltage is applied to the bases of the transistors 12 and 24 through the coal mines 11 and 21, the transistors 12 and 24 are turned on.Looking at the output circuit 4', since the transistor 24 is turned on, the transistors 12 and 24 are turned on. Marked on the base of 25) ``city to be rivered, +% of stables i Koka/Hawara 1
6. The transistor 25 is OFF. Also, since the transistor 12 is □N, the first Tj vifi mirror 1F"J::'R is ZMC'ed, and the current is Ti constant at the value of approximately 1+1 anti-14. As the current becomes 1-,
Iic bifi flowing into the initial reset capacitor Q
increases, and quickly the light weight and 'l pressure increase as transistor 1
7,18°, 2nd (7) Ifi', +'+Ir,
Miller cycle: The threshold value determined by the value of transistor 19.20 of C'+'+ is reached at 5p. Therefore, the second I11'
The current mirror circuit, the third 50' IC, and the mirror circuit 1 also operate in response to this, and 1 is applied to the base of the output transistor 25.
11; The flow is made into supply circular r, t, 5. Then, as the object M approaches the detection coil, the output to the pressure detection circuit Tlr becomes the J, I+ level, and the transistor 24 becomes OFlρ, and the transistor 24 becomes the base'! L
j: It flows and turns ON, output 11J4 child 01J'l
'I ((i: 11 (11) 4 - quickly) 1 (the moving thing is present. The above] IU) according to the present invention, the oscillation is oscillated. A box that detects '!i'+ and adds it to the initial reset capacitor for the first time of initial reset.', m.

Because we controlled the time (ilil (increase or decrease)) and the time amplifier time (to make it wider or longer), we could detect nearby switches.
11 works are sure, 7,) One silent jk initial reset time can be eliminated, and it is easy to use for large scale JK (and response characteristics are also 1'□(1) Near 42 switch flea-4 is provided) I was able to do that.

4. Figure-+n70) Hr3 Description Figure 1 is a block circuit diagram of a near-dark switch with a conventional initial reset circuit.

FIG. 21 is a diagram showing the relationship between the voltage applied to the 7 nearby switches and the oscillation output amount of each oscillation circuit.

FIG. 3 is a block diagram showing the circuit configuration of the main part of the near-back switch of the present invention.

l Oscillation circuit, 3 boxes, positive ratio 1 bit circuit, 5.5' initial reset circuit, 4,4' output circuit, RL/negative 11
1 piece・

Claims (1)

[Claims] Turn on the load based on the strength of the oscillation amplitude of the oscillation circuit, OFi
! In a proximity switch that drives an output circuit, the previous output circuit is forcibly kept inactive until the Q oscillation amplitude of the oscillation circuit reaches a predetermined level when no object is detected. An initial reset circuit is provided, and the initial reset circuit performs a switching operation based on the output signal when the oscillation amplitude of the oscillation circuit reaches a predetermined level, and the initial reset circuit performs a switching operation based on the output signal when the oscillation amplitude of the oscillation circuit reaches a predetermined level.
11. A switching circuit is provided to control the current flowing into the upper setton capacitor, and the initial reset time is set according to the rising speed of the oscillation amplitude of the oscillation circuit.11. A proximity switch featuring +fi capability.