JPS6333248B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a photoelectric device for detecting ultra-fine objects, in which the output of the emitter is automatically controlled by the receiver input to the best condition for detecting ultra-fine objects. It is characterized by making it possible.

In a photoelectric device in which a pair of emitter and receiver are installed in correspondence with each other across the passage of the object, the signal level and width of the detection signal are small when detecting ultra-small objects of 1 millimeter (mm) or less, that is, the signal level and width of the detection signal are small. It detects minute signals, and the set distance between the emitter and receiver and the distance to the minute object span a wide range from several centimeters to several tens of meters.In other words, the signal level and width of the detected signal can vary even for the same ultra-minute object. There has been a desire for a photoelectric device that has a function that allows detection even when the values are different.

In response to this, the inventor of the present invention set up a light emitter/receiver and then set the input through a variable resistor (VR) so as to be suitable for detecting ultra-small objects, and also set the input setting automatically. We constructed a prototype using appropriate combinations of a high-frequency amplifier circuit with AGC, a detection circuit, a signal discrimination amplifier circuit, etc., and conducted systematic experiments.

However, it has been found that these devices have disadvantages such as being sensitive to ambient temperature and being prone to malfunction due to static electricity, external noise, etc.
Furthermore, there was a problem that the circuit became complicated and the number of parts increased.

In addition, technological progress in increasing the speed of mechanical devices has been remarkable in recent years, and the relative speed between the ultra-small objects detected by these devices and the light emitter and receiver has also increased.
There is a problem in that the signal level and signal width of the detection signal are further reduced, making it impossible for the above-mentioned device to track the detection signal sufficiently, and malfunctions are likely to occur due to the influence of electrical noise, static electricity, external noise, etc.

Furthermore, in Japanese Patent Publication No. 42-13124, incident light from a light source lamp is detected by a photoelectric detection element, the voltage or current supplied to the light source lamp is controlled according to the detected voltage or current, and the output of the photoelectric detection element is A technique has been shown to always control this constant. This conventional technology merely performs on/off control to determine whether or not there are holes in the punched card, and the light source is subject to variations in lamp warm-up time, dark current of the photoelectric detection element, temperature changes, dust, etc. This conventional technology outputs a constant output by simply applying a negative feedback to stabilize the output.This conventional technology is used when the distance between the emitter and receiver is short, as in the case of punch card reading. This can be done when the size of the object to be detected is constant and always at a predetermined position, but when the object to be detected is extremely small (less than 1 millimeter), and its size and position are not constant, or when it is a foreign object. If the amount of signal is small compared to light, vibration, electrical noise, temperature and humidity, dust, aging, etc., it will not be possible to accurately and reliably detect ultra-small objects no matter how automatically the light intensity of the lamp is adjusted. There was a problem.

The present invention reliably detects a minute signal based on the detection of an ultra-minute detection object of 1 millimeter (mm) or less, and even if the minute signal fluctuates due to changes in the size or position of the ultra-minute object. In addition to reliably detecting, even if an ultra-small object moves at high speed relative to the emitter/receiver and the minute signal becomes even smaller, it can be detected reliably.
The purpose is to enable highly reliable detection of ultra-small objects that is not affected by electrical noise, static electricity, external noise, temperature, humidity, etc.

The photoelectric device for detecting ultra-small objects of the present invention includes a light emitter formed by a light emitting diode, and a light receiver disposed opposite to the emitter, which has a built-in high-frequency amplification circuit for amplifying a carrier component of light received from the emitter. The noise component indicating the peak voltage contained in the signal output from the receiver and the receiver's high-frequency amplifier circuit and wiring connected to the receiver is limited by a diode connected in antiparallel, and the carrier component is tuned by a tuning transformer. A tuned amplifier circuit that is later amplified, a detection circuit that is connected to the tuned amplifier circuit and detects the tuned amplified signal, and a detection circuit that is connected to the detection circuit and amplifies the detected signal to a low frequency and outputs the variation of the detected signal as a low frequency amplified signal. It has a low frequency amplification circuit and a DC amplification circuit connected to the detection circuit to DC amplify the detected signal and output a ripple-free DC voltage for driving the projector. an automatic control power supply circuit that outputs a DC power supply voltage that gradually fluctuates in inverse proportion to the power supply voltage; and an oscillation circuit for a floodlight that is connected to the automatic control power supply circuit and outputs a high-frequency modulated oscillation signal based on the DC power supply voltage. It consists of The photoelectric device for detecting an ultra-small object of the present invention having the above-described configuration reliably detects a small signal based on the detection of an ultra-small object without being affected by noise caused by external or internal factors. It is.
The effects of the device of the present invention will be explained in detail below.

(1) An automatic control power supply circuit having a DC amplifier circuit is installed to automatically control the output of the emitter by making the power supply voltage for the emitter's oscillation circuit vary in direct current in inverse proportion to the output voltage of the detection circuit. This ensures that the receiver always receives the best amount of light, making it possible to always detect ultra-small objects with the highest sensitivity.

(2) The emitter oscillation circuit drives the emitter with a high frequency modulated oscillation signal based on the DC power supply voltage that is inversely proportional to the detection output from the automatic control power supply circuit, and the light receiver receives such high frequency modulated light. This makes it less susceptible to electrical noise and external light than conventional technology that inherently receives direct current light.

(3) The receiver has a built-in high-frequency amplification circuit, so compared to using long lead wires to extract the receiver output, making the lead wires as short as possible prevents electrical noise from being superimposed on the lead wires and In addition to minimizing the influence of light, we also minimized the distributed capacitance of the lead wires.

(4) The tuned amplifier circuit uses a limiter consisting of diodes connected in antiparallel to eliminate ripples and electrical noise contained in the output signal of the optical receiver.
Transient resonance of the tuning transformer is minimized by rapidly stabilizing the bias by limiting the signal change caused by a large object that crosses between the emitter and the receiver to just over ±0.6V using the forward characteristics of the diode. By reducing the size, it is possible to reliably detect minute signals based on ultra-small objects.

The photoelectric device for detecting ultra-fine objects of the present invention is capable of detecting ultra-fine objects of 1 millimeter or less by taking measures against small signals and internal and external noise throughout the entire device and its weight as described above. In addition to making reliable detection possible, the detected minute signal may fluctuate or
It can reliably detect ultra-small objects even when miniaturized, and enables highly reliable detection of ultra-small objects that are not affected by electrical noise, static electricity, external noise, temperature, humidity, etc.

In addition, the device of the present invention allows installation and adjustment to be performed extremely simply and easily, thereby improving productivity. It has the advantage that it is completely unaffected by variations and can maintain its stability even when the light emitting diode and light receiving element change over time.

A photoelectric device for detecting an ultra-small object according to an aspect of the present invention includes:
The low-frequency amplification circuit is equipped with a rapid bias circuit consisting of a diode connected in parallel with a negative feedback resistor, and a large object that does not need to be detected may cross between the emitter and receiver. In the case where an ultra-small object to be detected immediately crosses the path, when the bias of the low-frequency amplification circuit is cut off and the small signal cannot be amplified,
By applying full feedback from the output side to the input side with a negative signal using the diode of the rapid bias circuit and rapidly stabilizing the bias, minute objects can be reliably detected.

Hereinafter, specific embodiments of the present invention will be described using illustrative drawings. This embodiment is applied to an apparatus in which a minute object to be detected may cross immediately after a gigantic object crosses the projector, and belongs to the above-described aspect of the present invention. A is a receiver with a built-in high frequency amplification circuit, B is a tuned amplification circuit with a limiter, C is a double frequency detection circuit, D is an AC amplification circuit with rapid bias stabilization (low frequency amplification circuit), and E is a switch for sensitivity setting. The circuit, F is a constant voltage power supply circuit not shown in FIG. 3, G is an automatic control power supply circuit for the light source, H is an oscillation circuit for a light projector, and I is a light emitting diode light projector. Each of the above circuits is shown in FIG. As shown, the A-B-C circuit and G-H-
Each circuit of I is connected in series, and further a double frequency detection circuit C
An automatic control power supply circuit G for the light projection source is connected to the light projection source, and the automatic control power supply circuit G is connected to an oscillation circuit H for the light projection device. FIG. 3 shows the specific electronic circuit. In the same figure, T
3 is a tuning transformer, which also serves as an output transformer, transistor Tr3 and tuning transformer T3.
etc., and the output is received by the light receiver as the light source of the light emitting diode I, that is, the emitter light source. However, since it contains ripples and electrical noise, this can be oscillated in any way by using the silicon diode forward characteristics of the diode D1 and diode D2. Even large noises are limited to just over ±0.6V, and tuned using a tuning transformer T1 (to minimize the transient resonance characteristic of the tuning coil, making it suitable for ultra-small object detection).

Furthermore, tuning transformer T2 and transistor Tr1
I would like to perform tuned amplification with diodes D3 and D4, and perform double frequency detection with diode D3 and diode D4 to modulate the frequency as high as possible to improve resolution.
Due to the characteristics of
The frequency is set to a little less than 50KHz, and this is smoothed by resistor R2, capacitor C1, and capacitor C2 to obtain a DC voltage according to the input signal, and a low frequency amplification circuit is configured with coupling capacitor C3, CMOS inverter, and feedback resistor R4. However, as shown in Figure 1, a huge object 3
Immediately after returning (within a few milliseconds), the ultra-small object 4
In such a case, as shown in Fig. 5, the bias of the AC amplifier circuit is cut off, making it impossible to amplify minute signals. Therefore, a diode D5 is used to apply full feedback with a negative signal from the output side to the input side to rapidly stabilize the bias and prepare for ultra-small object detection.

The output of the inverter is adjusted with a resistor R5 and a volume R6, and the inverter performs switching to obtain an output signal.

To detect ultra-small objects with high precision and sensitivity,
As shown in Figure 4A, it is preferable to always keep the voltage one step before the saturation point, and the receiver output is preferably about ±0.5V, one step short of just over ±0.6V, for noise isolation. The gist of this embodiment is to always maintain the best conditions in this way, and the power supply voltage of the oscillator is of a floating type, and it is varied appropriately to obtain the best conditions at all times as described above. The oscillator power supply voltage is gradually varied in inverse proportion to the detection output voltage (b).
Therefore, the resistor R3 is connected to the smoothing capacitor C4, the DC amplifier circuit consisting of a CMOS inverter and the resistor R7, the smoothing capacitor C5, the transistor Tr2, and the smoothing capacitor C6 to obtain a DC voltage that does not contain any ripples. min 1 mV or less). It is desirable that this time constant be 100 to 1000 times the object signal width.

Although a CMOS inverter is used in the above embodiment, it is used because it has high input impedance, low output impedance, and low current consumption, and is not limited to this. Of course, other elements such as transistors and FETs may also be used. The emitter 1 is a light-emitting diode, and the receiver 2 uses a solar cell as its light-receiving element 5. It also has a built-in amplifier to improve the signal-to-noise ratio, and has a low output impedance (approximately 600Ω) of over 60db. There is a gain, and a two-wire circuit has been devised to prevent lead wire troubles, but detailed explanation thereof will be omitted.

However, in a photoelectric device having such an electronic circuit, as shown in FIG. In this case, the waveform deformation occurs at points A, B, C, and D of the circuit in FIG. 3 as shown in FIG. 4, and the control signal (detection signal ) can be obtained. For reference, Figure 5 shows the waveform in the case where a minute object crosses immediately after a huge object crosses, and there is no bias quick stabilization diode D5 in the device of this embodiment, and the input point of the oscillator (Figure 3 FIG. 6 shows voltage waveforms when the power supply voltage is fixed and there is no diode D5 in (middle E).

As described above, the photoelectric device of the present invention has the advantage that it can be made smaller and lighter due to the simplified circuit configuration of the light emitter/receiver circuit. It can be used in weft inserting devices, weft insertion devices (center fork or side fork), dropper devices, etc., and can fully respond to recent technological advances in speeding up, high efficiency, and high precision. In addition, the results of experiments and implementation tests show that even spun yarn of 15 denier (approximately 0.02 mm [mm] in thickness) can be reliably detected at speeds up to 12 m/s.
It has been demonstrated that it is not affected by static electricity, electrical spike noise, changes in ambient temperature, etc., and we can expect a significant improvement in performance compared to conventional products.

[Brief explanation of the drawing]

1 to 6 are diagrams for explaining an embodiment of the present invention, in which FIG. 1 is a sketch of the detection section, FIG. 2 is a block diagram of the embodiment device, and FIG. 3 is a detailed diagram of the device. Electronic circuit diagram, Figure 4 is a voltage waveform diagram at points A, B, C, and D in Figure 3 when an object passes between the emitter and receiver, and Figure 5 is the waveform when diode D5 is not present. 6 are voltage waveform diagrams when the output of the projector is not equipped with an automatic control function. A...Receiver, B...Tuned amplifier circuit, C...Double frequency detection circuit, D...AC amplifier circuit, E...Switching circuit, F...Constant voltage power supply circuit, G...Automatic control of light emitting source Power supply circuit, H...Oscillation circuit, I...Light emitter, C1, C2, C3...Capacitor, D1, D2, D3...Diode, T
1, T2, T3...Tuning transformer, Tr1, Tr
2, Tr3...transistor, R1, R2, R
3...Resistor,,,...Inverter, 1...
... Emitter, 2... Light receiver, 3... Huge object, 4...
...Ultra-micro object, 5... Light receiving element (solar cell).

Claims (1)

[Scope of Claims] 1. A light projector formed by a light emitting diode; a light receiver disposed opposite to the light projector, which includes a built-in high-frequency amplification circuit for amplifying a carrier component received from the light projector; and a light receiver. The noise component representing the peak voltage contained in the signal connected to the receiver's high-frequency amplification circuit and the wiring is limited by antiparallel-connected diodes, and the carrier component is tuned by a tuning transformer and then amplified. an amplifier circuit, a detection circuit connected to the tuned amplifier circuit to detect the tuned amplified signal, and a low frequency amplifier circuit connected to the detector circuit to amplify the detected signal to a low frequency and output the variation of the detected signal as a low frequency amplified signal. and a DC amplification circuit connected to the detection circuit to DC amplify the detection signal and output ripple-free DC voltage for driving the projector. An ultra-microscopic system consisting of an automatic control power supply circuit that outputs a DC power supply voltage that varies gradually in proportion, and a floodlight oscillation circuit that is connected to the automatic control power supply circuit and outputs a high-frequency modulated oscillation signal based on the DC power supply voltage. Photoelectric device for object detection. 2. The photoelectric device for ultra-small object detection according to claim 1, wherein the low-frequency amplification circuit includes a rapid bias circuit constituted by a diode connected in parallel with a negative feedback resistor. .