CN210899119U - Anti-interference correlation formula photoelectric switch - Google Patents

Abstract

The utility model relates to an interference-proof correlation formula photoelectric switch, including transmitting terminal and receiving terminal, the transmitting terminal is equipped with metal casing, metal casing and transmitting terminal circuit are ground altogether, the receiving terminal is equipped with metal casing, metal casing and receiving terminal circuit are ground altogether. Therefore, various electromagnetic interferences, especially power frequency interferences, in the working environment can be effectively shielded. The metal shell is externally provided with threads, and the photoelectric switch can be installed through the threads.

Description

Anti-interference correlation formula photoelectric switch

Technical Field

The utility model relates to a photoelectric sensor, specifically speaking are correlation formula photoelectric switch.

Background

The opposed photoelectric sensor is a sensor having an optical element and an electronic element as a detection portion. The photoelectric detection technology has the advantages of high precision, high response speed, non-contact type and the like. The sensor ladle is simple and flexible in form. Therefore, photoelectric sensors are widely used in the control and test fields. It can be used to detect non-electricity changes due to changes in light quantity, such as light intensity, radiation temperature, gas composition, etc. It can also measure various physical quantities such as size, displacement, speed, temperature, etc. of an object through transmission, blocking, reflection and interference of light. It is a crucial sensitive device with broad application prospects. When the photoelectric sensor is used, the photoelectric sensor is not directly contacted with a measured object, the beam quality is almost zero, no friction force exists in the measuring process, and no pressure is generated on the measured object. Therefore, photosensors have significant advantages over other sensors in many applications.

The Chinese patent No. (CN 104283543A) is named as a correlation type photoelectric detection switch, and the technology provides a correlation type photoelectric detection switch which comprises a transmitting end control circuit and a receiving end control circuit; the transmitting end circuit comprises a laser diode and a triode connected with the laser diode. The circuit has no effective carrier modulation, and most of external light source interference cannot be avoided.

The Chinese patent number (CN105978545A) is named as 'a correlation type photoelectric switch', and the technical book shows a correlation type photoelectric switch which comprises a light emitter and a light receiver. The illuminator includes the illuminator casing and installs first light source mounting, luminous PCB subassembly and first optical filter in the illuminator casing. The light receptor comprises a light receptor shell, a second light source fixing piece, a receiving PCB assembly and a second filter lens, wherein the second light source fixing piece, the receiving PCB assembly and the second filter lens are installed in the light receptor shell. The receiving PCB assembly detects the optical signal that luminous PCB assembly sent to the detection signal that the output corresponds, have detection distance far away, the interference killing feature is strong, response speed advantage such as fast. However, the design scheme sacrifices the detection precision of the photoelectric switch, and the volume of the object to be detected is limited.

SUMMERY OF THE UTILITY MODEL

The to-be-solved problem of the utility model is to provide an interference-proof correlation formula photoelectric switch.

In order to solve the technical problem, the utility model discloses an anti-interference correlation formula photoelectric switch, including transmitting terminal and receiving terminal, the transmitting terminal is equipped with metal casing, metal casing and transmitting terminal circuit are ground altogether, the receiving terminal is equipped with metal casing, metal casing and receiving terminal circuit are ground altogether. Therefore, various electromagnetic interferences, especially power frequency interferences, in the working environment can be effectively shielded.

The metal shell is externally provided with threads, and the photoelectric switch can be installed through the threads.

One end of the transmitting end is provided with a photoelectric tube, a reflection cavity is arranged on the outer side of the photoelectric tube, and the length of the reflection cavity is one focal length. The scattered infrared light can be made to be incident in parallel with the lens to the maximum extent, the diameter of the opposite beam is reduced to improve the precision, and the intensity of the infrared light is enhanced.

The outer side of the reflection cavity is provided with a lens, a lens outer ring is arranged outside the lens, and the lens outer ring is made of infrared light absorption materials. Therefore, the infrared light can be prevented from being dissipated, and the receiving end is prevented from being triggered by mistake.

The transmitting terminal includes transmitting terminal circuit, the receiving terminal includes receiving terminal circuit, the receiving terminal circuit includes the frequency discrimination circuit, the frequency discrimination circuit is equipped with frequency signal output interface, frequency signal output interface connection transmitting terminal circuit, the pulse signal of frequency signal output interface output introduce transmitting terminal circuit, drives the work of photoelectric emission pipe after handling.

The transmitting end circuit is not provided with a special signal generating circuit, and the modulating signal of the transmitting end circuit is provided by the self-excited oscillation frequency feedback of the frequency discrimination circuit of the receiving end. Through the design of frequency following, the circuit structure is simplified, the circuit and debugging work are simplified, the problem of frequency deviation is effectively avoided, the difference of receiving and transmitting frequencies caused by the change of the surrounding environment and the change of element parameters is prevented, the synchronous automatic tracking of photoelectric transmitting and receiving working frequencies is realized, and the stability and the anti-interference capability of the circuit are greatly enhanced.

The receiving end circuit is provided with a multi-stage filter circuit.

The receiving end circuit comprises a first-stage amplifying circuit, a second-stage amplifying circuit and a level control circuit, wherein a first-stage low-pass filter circuit is arranged at the input end of the first-stage amplifying circuit, a second-stage high-pass filter circuit is arranged at the input end of the second-stage amplifying circuit, and a third-stage filter circuit is arranged at the output end of the level control circuit.

After the signal reaches a receiving end circuit through a photoelectric receiving tube, the signal is processed through a secondary negative feedback amplifying circuit, a plurality of signal nodes are filtered through a multi-stage decoupling filter circuit in the process, and finally the signal enters a frequency discrimination circuit to carry out frequency selection and demodulation of modulation frequency and carry out level control output. The utility model discloses all carried out the processing of decoupling at whole circuit each grade, the filtering effect is better.

The frequency discrimination circuit is an LM567 chip, and the frequency signal output interfaces are a pin 5 and a pin 6 of the LM567 chip.

The transmitting end circuit modulates a signal introduced by pins 5 and 6 of the LM567 chip, and the signal is the phase-locked central frequency of the phase-locked audio decoder LM 567.

After adopting such structure, the utility model discloses the creative design of following of having carried out the frequency has both simplified circuit structure, and the effectual problem of avoiding frequency deviation again makes this sensor when having the advantage that the detection precision is high, can adapt to the violent adverse operating condition of environmental change again. The utility model discloses optimize the output waveform by a wide margin, all carried out the processing of decoupling at whole circuit each grade, made the filtering effect better. In the aspect of structural design, the utility model relates to a metal shielding shell to with the circuit common ground, the effectual various electromagnetic interference who shields among its operational environment. By these means, the utility model discloses a photoelectric switch its output waveform ripple peak-to-peak value can be controlled within 100mv, and in some occasions strict to the output waveform requirement, their sensor needs additionally to increase the cost of making an uproar that falls. The photoelectric tube is driven by adopting modulation frequency, so that the anti-interference capability of the photoelectric switch is effectively enhanced, and the defect that the response frequency of the sensor is influenced due to the lower modulation frequency is effectively overcome.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Fig. 1 is a diagram illustrating an overall circuit structure according to the present invention.

Fig. 2 is a circuit diagram of a transmitting end of the present invention.

Fig. 3 is a circuit diagram of the receiving end of the present invention.

Fig. 4 is a functional block diagram of LM 567.

Fig. 5 is a cross-sectional view of the emitting terminal of the correlation photoelectric switch of the present invention.

Fig. 6 is a waveform diagram of the transmission of the photocell.

Fig. 7 is a photo switch level output diagram.

Fig. 8 is a general photoelectric switch output waveform ripple.

Fig. 9 shows the output ripple of the photoelectric switch of the present invention.

Reference numerals: pencil 1, operating condition pilot lamp 2, LED lamp lid 3, metal casing 4, circuit board arrangement 5, photoelectric tube arrangement 6, photoelectric tube draw-in groove 7, reflection chamber 8, lens 9, lens outer loop 10.

Detailed Description

The utility model discloses a correlation formula photoelectric switch, including transmitting terminal and receiving terminal, the transmitting terminal includes transmitting terminal circuit, and the receiving terminal includes receiving terminal circuit, and the receiving terminal circuit includes the frequency discrimination circuit, and the frequency discrimination circuit is equipped with frequency signal output interface, and frequency signal output interface connects the transmitting terminal circuit, and the pulse signal of frequency signal output interface output introduces the transmitting terminal circuit, drives the photoelectric emission pipe work after handling. The frequency discrimination circuit is selected as an LM567 chip, and the frequency signal output interfaces are the 5 pin and the 6 pin of the LM567 chip. The transmitting end circuit modulates a signal introduced by pins 5 and 6 of the LM567 chip, and the signal is the phase-locked central frequency of the phase-locked audio decoder LM 567.

Fig. 4 is a functional schematic diagram of the structure of the LM567 chip, which is shown in the figure, and includes two phase detectors, i.e., PD1 and PD2 in fig. 4, and further includes a voltage amplifier AMP and a voltage controlled oscillator VOD. When the input signal is in the range of hundreds of millivolts, the phase-locked loop circuit (i.e. at the Frequency following in fig. 3) composed of the oscillator VCD can be made to output a triangular oscillating wave of 10KHZ to 50KHZ by configuring the resistor RT and the capacitor CT in fig. 4 (i.e. R9 and C6 in fig. 3).

The 10KHZ-50KHZ triangular oscillation wave output by the phase-locked loop circuit has two functions. The first is the reference frequency f0 with the most frequency discrimination, the input signal and the output signal of the phase-locked loop circuit are subjected to phase discrimination, the obtained phase difference signal is filtered, and then the output frequency f0 of the phase-locked loop circuit is controlled to track the input frequency again. If the input signal frequency falls within the capture band of the phase-locked loop circuit, the loop locks. At this time, the output frequency f0 of the phase-locked loop circuit is consistent with the frequency of the input signal, so that the frequency discrimination function is realized.

Secondly, the phase-locked loop circuit is used as a generating circuit of a modulation wave, and the output frequency f0 of the phase-locked loop circuit is used as the modulation frequency of the photoelectric emission tube, is filtered by an amplifying circuit based on LM386, and then directly drives the photoelectric emission tube to work. Because the utility model discloses the photoelectric tube of well adoption can be by triangle wave direct drive to can not influence its transmission waveform, so need not extra rectifier circuit.

When the frequency discrimination reference frequency f0 fluctuates due to the change of the external uncontrollable factors, the modulation frequency of the photoelectric emission tube changes along with the fluctuation, and the anti-interference performance and the accuracy of the photoelectric switch are improved.

The transmitting end circuit is not provided with a special signal generating circuit, and the modulating signal of the transmitting end circuit is provided by the self-excited oscillation frequency feedback of the frequency discrimination circuit of the receiving end. And after power amplification and filtering processing is carried out at the receiving end, the photoelectric emission tube is driven to work.

Through the design of frequency following, the circuit structure is simplified, the circuit and debugging work are simplified, the problem of frequency deviation is effectively avoided, the difference of receiving and transmitting frequencies caused by the change of the surrounding environment and the change of element parameters is prevented, the synchronous automatic tracking of photoelectric transmitting and receiving working frequencies is realized, and the stability and the anti-interference capability of the circuit are greatly enhanced.

The sensor has the advantage of high detection precision, and can adapt to severe working conditions with severe environmental changes. (note: when the frequency deviation is caused by environmental changes, such as temperature, humidity, illumination intensity and the like, the design avoids the frequency discrimination failure of the photoelectric switch by synchronously changing the input quantity and the output quantity.)

The receiving end circuit is provided with a multi-stage filter circuit. The receiving end circuit comprises a first-stage amplifying circuit, a second-stage amplifying circuit and a level control circuit, wherein a first-stage second-order low-pass filter circuit (A in figure 3) is arranged at the input end of the first-stage amplifying circuit, and signals higher than 1.1f0 are filtered out (f0 is the central frequency of the frequency discrimination circuit). The input end of the second-stage amplifying circuit is provided with a second-stage second-order high-pass filter circuit (B in figure 3) for filtering signals lower than 0.9f 0. The two stages of filtering may optimize the input signal to the frequency discrimination circuit. The output of the level control circuit is provided with a third stage of filtering circuit (C in fig. 3), where the filtering reduction is aimed at outputting level ripple.

After the signal reaches a receiving end circuit through a photoelectric receiving tube, the signal is processed through a secondary negative feedback amplifying circuit, a plurality of signal nodes are filtered through a multi-stage decoupling filter circuit in the process, finally the signal enters a frequency discrimination circuit to carry out frequency selection and demodulation of modulation frequency and carry out level control output, and the output waveform is shown in figure 7.

Decoupling processing is carried out on each stage of the whole circuit, and the filtering effect is better.

With present correlation photoelectric switch only in the output design filter circuit different, the utility model discloses decoupling processing has all been carried out at whole circuit each grade, makes the filtering effect better. Because multistage filtering can make the frequency band too narrow and the frequency selection effect that leads to is not good, for avoiding this kind of condition, general receiving terminal circuit design can't adopt multistage filtering, and the utility model discloses a receiving terminal circuit does not exist this problem owing to the design that adopts the frequency to follow.

The photoelectric tube is driven by adopting modulation frequency, so that the anti-interference capability (other light sources) of the photoelectric switch is effectively enhanced. The utility model discloses an excellent high frequency characteristic of phototube makes photoelectric switch have higher frequency response (the utility model discloses a TSAL6200 transmitting tube and TSOP98260 receiver tube are as the transmitting terminal and the receiving terminal of sensor), than other photoelectric switch (modulation frequency is generally lower, influenced by the phototube), the utility model discloses a modulation frequency is between 20KHz to 60KHz (see figure 6), the effectual drawback of influencing sensor response frequency because of modulation frequency is lower of having avoided.

The utility model discloses in adopt TSAL6200 as the photoemissive tube, it is a high-efficient infrared emitting diode, adopts GAAlAS technique, and the coloured plastic package of transparent blue grey becomes in the mould pressing. Compared with a photoelectric transmitting tube under the traditional GAAS standard, the TSAL6200 can achieve high-power carrier transmission of 5-60 Khz. The wavelength was 940 mm. The photoelectric receiving tube TSOP98260 is a micro-sensor for receiving a modulated signal of an infrared remote control system.

Some production lines in industry originally used diffuse reflection photoelectric sensors for detecting the number of cans on the can production line, package the cans when sending a certain number, but often the case of missing detection occurs during boxing, the automatic effect which is originally desired to be realized is not achieved, and workers need to be arranged additionally for detection.

And a high-precision correlation type photoelectric sensor is used because the photoelectric switch includes a transmitter and a receiver which are structurally separated from each other and whose optical axes are disposed opposite to each other, and light emitted from the transmitter directly enters the receiver. When the detected object passes between the transmitter and the receiver and blocks light, the photoelectric switch generates a switching signal. The correlation type photoelectric switch is the most reliable detection mode when the detection object is opaque. By utilizing the characteristic of the photoelectric switch, the leakage detection or piece counting on an industrial production line can be realized.

The utility model discloses except the improvement on control circuit, still improved on the structure of correlation formula photoelectric switch.

The transmitting end and the receiving end are both provided with metal shells 4, and the metal shells 4 are grounded with the control circuit. Therefore, various electromagnetic interferences, especially power frequency interferences, in the working environment can be effectively shielded.

Through metal casing 4 and control circuit these means of being in common place and multistage filtering, the utility model discloses an its output waveform ripple peak-to-peak value of photoelectric switch is steerable within 100mv, see fig. 9, and its ripple of present most ordinary photoelectric switch is about 200mv, see fig. 8, and in some occasions strict to the output waveform requirement, their sensor needs additionally to increase the cost of making an uproar that falls.

If fig. 5 is the utility model discloses a section view of correlation formula photoelectric switch's transmitting terminal, the one end of metal casing 4 of transmitting terminal and receiving terminal is equipped with LED lamp lid 3, set up operating condition pilot lamp 2 on the LED lamp lid 3, connecting wire harness 1 (including the power cord, signal line and feedback line), the other end that is equipped with circuit board arrangement 5 metal casing 4 through two upper and lower draw-in grooves are fixed in metal casing 4 is equipped with photoelectric tube arrangement 6 and annular photoelectric tube draw-in groove 7 of installation photoelectric tube, the photoelectric tube draw-in groove can be guaranteed that the photoelectric tube is fixed in lens focus department. The photoelectric tube outside is equipped with reflection chamber 8, the reflection chamber 8 outside is equipped with lens 9, lens 9 passes through draw-in groove 7 installation, 8 length in reflection chamber are a focus of lens 9, that is to say the photoelectric tube is on the focus of lens, reflection chamber 8 is inside to encircle to cover by the material that infrared light reflective ability is strong that disposes certain camber according to the infrared wave band of photoelectric tube, can make scattered infrared light furthest be on a parallel with the lens and penetrate, reduce the diameter of correlation light beam in order to improve the precision to the intensity of reinforcing infrared light. The lens outer 9 is provided with a lens outer ring 10, and the lens outer ring 10 is made of infrared light absorption material. Therefore, the infrared light can be prevented from being dissipated, and the receiving end is prevented from being triggered by mistake.

The receiving end is similar in structure to the transmitting end except that the receiving end is not provided with a reflective cavity 8.

The metal casing outside is equipped with the screw thread, can install this photoelectric switch through the screw thread.

The utility model discloses a photoelectric switch's part operating parameter:

Claims (9)

1. the utility model provides an interference-proof correlation formula photoelectric switch, includes transmitting terminal and receiving terminal, its characterized in that: the transmitting terminal is provided with a metal shell, the metal shell and the transmitting terminal circuit are grounded, the receiving terminal is provided with a metal shell, and the metal shell and the receiving terminal circuit are grounded.

2. The interference rejection opposed-type photoelectric switch according to claim 1, wherein: and threads are arranged outside the metal shell.

3. The interference rejection opposed-type photoelectric switch according to claim 1, wherein: one end of the transmitting end is provided with a photoelectric tube, and the outer side of the photoelectric tube is provided with a reflecting cavity.

4. The interference rejection opposed-type photoelectric switch according to claim 3, wherein: and a lens is arranged outside the reflection cavity, and the length of the reflection cavity is the focal length of the lens.

5. The interference rejection opposed-type photoelectric switch according to claim 4, wherein: and a lens outer ring is arranged outside the lens and is made of an infrared light absorption material.

6. The interference rejection opposed-type photoelectric switch according to claim 1, wherein: the transmitting terminal includes transmitting terminal circuit, the receiving terminal includes receiving terminal circuit, the receiving terminal circuit includes the frequency discrimination circuit, the frequency discrimination circuit is equipped with frequency signal output interface, frequency signal output interface connection transmitting terminal circuit, the pulse signal of frequency signal output interface output introduce transmitting terminal circuit, drives the work of photoelectric emission pipe after handling.

7. The interference rejection opposed-type photoelectric switch according to claim 6, wherein: the receiving end circuit is provided with a multi-stage filter circuit.

8. The interference rejection opposed-type photoelectric switch according to claim 7, wherein: the receiving end circuit comprises a first-stage amplifying circuit, a second-stage amplifying circuit and a level control circuit, wherein a first-stage low-pass filter circuit is arranged at the input end of the first-stage amplifying circuit, a second-stage high-pass filter circuit is arranged at the input end of the second-stage amplifying circuit, and a third-stage filter circuit is arranged at the output end of the level control circuit.

9. The interference rejection opposed-type photoelectric switch according to claim 6, wherein: the frequency discrimination circuit is an LM567 chip, and the frequency signal output interfaces are a pin 5 and a pin 6 of the LM567 chip.

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