CN109115335B - Light detection circuit, device and method - Google Patents
Light detection circuit, device and method Download PDFInfo
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- CN109115335B CN109115335B CN201810836279.5A CN201810836279A CN109115335B CN 109115335 B CN109115335 B CN 109115335B CN 201810836279 A CN201810836279 A CN 201810836279A CN 109115335 B CN109115335 B CN 109115335B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J1/44—Electric circuits
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J2001/4247—Photometry, e.g. photographic exposure meter using electric radiation detectors for testing lamps or other light sources
- G01J2001/4252—Photometry, e.g. photographic exposure meter using electric radiation detectors for testing lamps or other light sources for testing LED's
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Abstract
The embodiment of the invention provides a photodetection circuit, a photodetection device and a photodetection method, wherein the resistance value of a photosensitive device of the photodetection circuit changes along with the change of external light brightness, when the resistance value changes, a voltage/current signal output by the photosensitive device also changes along with the change of the resistance value, a comparison unit compares the voltage/current signal output by a photosensitive resistor with a preset threshold value, when the voltage/current signal changes, a comparison signal output by the comparison unit correspondingly changes, and a control unit generates a corresponding detection signal according to the change of the comparison signal, thereby realizing the detection of the external ambient light brightness. The light detection circuit in the embodiment is applied to circuit board detection, whether the LED indicating lamp of the circuit board to be detected is turned on or not can be detected in real time, automatic detection of the state of the LED indicating lamp on the circuit board of the assembly line is achieved, manpower is saved, and accuracy of circuit board detection is improved.
Description
Technical Field
The present invention relates to the field of detection technologies, and in particular, to a photodetection circuit, a photodetection device, and a photodetection method.
Background
In industrial production, a large number of products manufactured in batch, such as circuit boards (PCBs) in electric meters, circuit boards of mobile phones, computer mainboards and the like, are welded with a large number of components, so that after the circuit boards are welded, an important process is to detect the quality of the boards. The conventional detection method is to test corresponding output signals to judge whether the circuit board is good or bad by electrifying the finished circuit board and applying different signals. For example, for some circuit boards with LED indicators, the quality of the circuit board needs to be judged according to the status of the LED indicators.
At present, aiming at a circuit board with an LED indicating lamp, the state of the LED indicating lamp is judged manually most of the time, and the efficiency is low. Therefore, a detection process for shooting the whole circuit board image through a CCD camera and then judging the state of the LED indicator lamp by adopting an image processing method is provided, although manual detection is avoided, the whole image analysis process is complex in algorithm, the equipment volume is large, the cost is high, and especially some components on the circuit board can shield the LED indicator lamp from the front side, so that the analysis result is inaccurate.
Disclosure of Invention
In view of the above, the present invention has been made to provide a photodetecting circuit, apparatus and method that overcome or at least partially solve the above problems, by the following:
an embodiment of the present invention provides a light detection circuit, including: the device comprises a photosensitive device, a comparison unit and a control unit;
the resistance value of the photosensitive device changes along with the change of external light brightness;
the signal input end of the comparison unit is electrically connected with the output end of the photosensitive device, the voltage/current signal output by the photosensitive device is compared with a preset threshold value, and a comparison signal generated by comparison is transmitted to the control unit;
and the control unit generates and outputs a corresponding detection signal according to the comparison signal.
Optionally, in the photodetection circuit according to the embodiment of the present invention, the photosensitive device is a photoresistor, and the comparing unit includes: the circuit comprises a second resistor, a third resistor, a fourth resistor, a variable resistor and an operational amplifier;
one end of the photoresistor is electrically connected with the positive pole of the power supply, the other end of the photoresistor is simultaneously electrically connected with the positive phase input end of the operational amplifier and one end of the second resistor, and the other end of the second resistor is electrically connected with the negative pole of the power supply; one end of the fourth resistor is electrically connected with the positive electrode of the power supply, the other end of the fourth resistor is electrically connected with the first end of the variable resistor, the adjusting end of the variable resistor is electrically connected with the inverting input end of the operational amplifier, the second end of the variable resistor is electrically connected with one end of the third resistor, and the other end of the third resistor is electrically connected with the negative electrode of the power supply.
Optionally, in the light detection circuit according to the embodiment of the present invention, the control unit includes: the circuit comprises a sixth resistor, a seventh resistor, a capacitor, a diode, a triode and a relay;
one end of the sixth resistor is electrically connected with the output end of the operational amplifier, the other end of the sixth resistor is simultaneously electrically connected with one end of the seventh resistor, the positive end of the capacitor and the base electrode of the triode, the other end of the seventh resistor, the negative end of the capacitor and the emitting electrode of the triode are electrically connected with the negative electrode of the power supply, the collecting electrode of the triode is electrically connected with the positive electrode of the diode, the negative electrode of the diode is electrically connected with the positive electrode of the power supply, the coil end of the relay is connected with the diode in parallel, two normally open contacts of the relay are electrically connected with the IO port of the programmable logic controller at the far end, and the normally open contacts are the detection signal output port of the control unit.
On the other hand, an embodiment of the present invention further provides a light detection apparatus, including:
the above-mentioned photodetection circuit;
the light detection circuit comprises a pressing plate, a light guide plate and a light detection circuit, wherein a plurality of light shields are arranged on the pressing plate, each light shield corresponds to an LED indicating lamp on a circuit board to be detected, one end of each light shield, facing the LED indicating lamp, is opened, and after the pressing plate moves downwards to a preset detection position, the light shields enable the corresponding LED indicating lamps to be arranged in light shielding spaces surrounded by the top surfaces and the side surfaces of the light shields through the openings, and the light detection circuit is arranged in the top surfaces of the light shields;
and the control mechanism controls the light detection circuit to be electrified before the corresponding circuit board to be detected and controls the lifting mechanism to move up or down the pressing plate.
Optionally, in the light detection device according to the embodiment of the present invention, the light shield is made of an elastic material.
Optionally, in the light detection device according to the embodiment of the present invention, a gap in a preset shape is formed at a position of the pressing plate corresponding to the LED indicator, a plurality of columns are disposed around the gap, the light-shielding covers are fixed to the gap, and each light-shielding cover corresponds to one LED indicator.
On the other hand, an embodiment of the present invention further provides a light detection method, which detects a circuit board to be detected by using the light detection device, and specifically includes:
placing a circuit board to be detected at a position to be detected of a detection table;
controlling the lifting mechanism to push the pressing plate to move downwards to a preset detection position;
controlling the light detection circuit to be electrified before the corresponding circuit board to be detected;
and outputting a detection signal of the light detection circuit.
Optionally, in the light detection method according to the embodiment of the present invention, the controlling the lifting mechanism to push the pressing plate to move downward to a preset detection position includes:
determining a preset time length according to the initial position of the pressing plate, the preset detection position and the downward moving speed of the pressing plate;
and timing when the pressure plate starts to move downwards, and controlling the lifting mechanism to stop moving downwards and keep static after the preset time length.
Optionally, the light detection method according to the embodiment of the present invention, controlling the light detection circuit to be powered on before the corresponding circuit board to be detected is powered on includes:
after the preset time, controlling the light detection circuit to be powered on;
and after the optical detection circuit is electrified, controlling the circuit board to be detected to be electrified.
Optionally, the light detection method according to the embodiment of the present invention further includes:
judging whether the circuit board to be detected is qualified or not according to the detection signal;
and moving the circuit board to be detected out of the detection table and placing the circuit board to be detected in a classified mode based on the detection result.
In the light detection circuit in the embodiment of the invention, the resistance value of the photosensitive device changes along with the change of external light brightness, when the resistance value changes, the voltage/current signal output by the photosensitive device also changes, the comparison unit compares the voltage/current signal output by the photosensitive resistor with the preset threshold value, when the voltage/current signal changes, the comparison signal output by the comparison unit changes correspondingly, and the control unit generates a corresponding detection signal according to the change of the comparison signal, thereby realizing the real-time detection of the external environment light brightness. The light detection circuit in the embodiment is applied to circuit board detection, whether the LED indicating lamp of the circuit board to be detected is turned on or not can be detected in real time, automatic detection of the state of the LED indicating lamp on the circuit board of the assembly line is achieved, manpower is saved, and accuracy of circuit board detection is improved.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 is a schematic block diagram of one embodiment of a light detection circuit in an embodiment of the present invention;
FIG. 2 is a circuit schematic of an embodiment of a light detection circuit in an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of an embodiment of a light detection device according to the present invention;
FIG. 4 is a schematic structural view showing one embodiment of a platen in the embodiment of the present invention;
fig. 5 is a flowchart of a specific example of the light detection method in the embodiment of the present invention.
Reference numerals
1-a light detection circuit; 2-pressing a plate; 3-a control mechanism; 4-a lifting mechanism; 11-a photosensitive device; 12-a comparison unit; 13-a control unit; 21-a light shield; 22-a gap; 23-cylindrical body.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
Photosensitive devices, such as the more common photoresistors, are special resistors made of semiconductor materials such as sulfide or selenide, and the working principle of the photosensitive devices is based on the internal photoelectric effect. The stronger the illumination is, the lower the resistance value is, and the resistance value is rapidly reduced along with the increase of the illumination intensity, and the bright resistance value can be reduced to below 1K omega. The photoresistor is very sensitive to light, and is in a high-resistance state in the absence of illumination, and the dark resistance can generally reach 1.5M omega. The inventor of the application develops a light detection circuit based on the special performance of the photoresistor, and the light detection circuit can detect the change of the brightness of the surrounding environment in time.
As shown in fig. 1, a light detection circuit in the present embodiment includes: a photosensor 11, a comparing unit 12, and a control unit 13;
a photosensor 11 whose resistance value changes with a change in external light brightness; in application, the photosensitive device can be a photoresistor.
A comparison unit 12, the signal input end of which is electrically connected with the output end of the photosensitive device 11, compares the voltage/current signal output by the photosensitive device 11 with a preset threshold value, and transmits a comparison signal generated by the comparison to the control unit 13;
and a control unit 13 for generating and outputting a corresponding detection signal according to the comparison signal.
In the light detection circuit in this embodiment, the resistance value of the photosensitive device changes with the change of the external light brightness, and when the resistance value changes, the voltage/current signal output by the photosensitive device also changes, the comparison unit compares the voltage/current signal output by the photosensitive resistor with a preset threshold, when the voltage/current signal changes, the comparison signal output by the comparison unit changes correspondingly, and the control unit generates a corresponding detection signal according to the change of the comparison signal, thereby realizing the real-time detection of the external ambient light brightness. The light detection circuit in the embodiment is applied to circuit board detection, whether the LED indicating lamp of the circuit board to be detected is turned on or not can be detected in real time, automatic detection of the state of the LED indicating lamp on the circuit board of the assembly line is achieved, manpower is saved, and accuracy of circuit board detection is improved.
Alternatively, in the light detection circuit of the present embodiment, as shown in fig. 2, the photosensor 11 is a photoresistor R1, and the comparison unit 12 includes: a second resistor R2, a third resistor R3, a fourth resistor R4, a variable resistor R5 and an operational amplifier U1A;
one end of the photosensitive resistor R1 is electrically connected with the positive pole of the power supply, the other end of the photosensitive resistor R1 is simultaneously and electrically connected with the non-inverting input end of the operational amplifier U1A and one end of the second resistor R2, and the other end of the second resistor R2 is electrically connected with the negative pole of the power supply; one end of the fourth resistor R4 is electrically connected with the positive pole of the power supply, the other end is electrically connected with the first end of the variable resistor R5, the adjusting end of the variable resistor R5 is electrically connected with the inverting input end of the operational amplifier U1A, the second end of the variable resistor R5 is electrically connected with one end of the third resistor R3, and the other end of the third resistor R3 is electrically connected with the negative pole of the power supply.
The working principle is as follows: the sum of the voltages at the two ends of the photoresistor R1 and the second resistor R2 is a power supply voltage value, when the external light value changes, the resistance value of the photoresistor R1 changes, so that the voltages distributed on the photoresistor R1 and the second resistor R2 also change, because the positive phase input end of the operational amplifier U1A is electrically connected with one end of the second resistor R2, namely the input end of the positive phase input end of the operational amplifier U1A is the voltage value distributed on the second resistor R2; since one end of the fourth resistor R4 is electrically connected to the positive electrode of the power supply, the other end is electrically connected to the first end of the variable resistor R5, the adjustment end of the variable resistor R5 is electrically connected to the inverting input end of the operational amplifier U1A, the second end of the variable resistor R5 is electrically connected to one end of the third resistor R3, and the other end of the third resistor R3 is electrically connected to the negative electrode of the power supply, it can be known that by adjusting the adjustment end of the variable resistor R5, the voltage signal inputted from the inverting input end of the operational amplifier U1A can be adjusted to a preset voltage threshold as a comparison signal (for example, the adjustment end of the variable resistor R5 is placed at a middle position of the resistance), since the larger the external brightness value is, the smaller the resistance of the photoresistor R1 is smaller, and accordingly, the larger the voltage value is the voltage value of the two ends of the second resistor R2 is, that is the larger, that is the voltage value inputted from the non-inverting input end of the operational, according to the working principle of the operational amplifier, the output is high level, otherwise, the output is low level, and the high level or the low level is amplified and then output. The light detection circuit in the embodiment can know the change of the external light brightness through the comparison signal of high and low levels output by the operational amplifier, and has quick and accurate response.
Fig. 2 shows an example of the output voltage signal of the photosensitive device, and in practical applications, the non-inverting input terminal and the inverting input terminal of the operational amplifier may also collect the current signal for comparison.
Alternatively, in the light detection circuit of the present embodiment, as shown in fig. 2, the control unit 13 includes: a sixth resistor R6, a seventh resistor R7, a capacitor C1, a diode D1, a triode Q1 and a relay K1;
one end of a sixth resistor R6 is electrically connected to the output end of the operational amplifier U1A, the other end of the sixth resistor R6 is electrically connected to one end of a seventh resistor R7, the positive end of a capacitor C1 and the base of a transistor Q1, the other end of the seventh resistor R7, the negative end of a capacitor C1 and the emitter of the transistor Q1 are electrically connected to the negative electrode of a power supply, the collector of the transistor Q1 is electrically connected to the positive electrode of a diode D1, the negative electrode of the diode D1 is electrically connected to the positive electrode of the power supply, the coil end of a relay K1 is connected in parallel to the diode D1, two normally open contacts of the relay K1 are electrically connected to the IO port of the remote programmable logic controller, and the normally open contacts are the detection signal.
The working principle is as follows: when the operational amplifier U1A outputs a high level, the transistor Q1 is turned on, and at this time, a current forms a loop through the positive terminal of the power supply, the coil terminal of the relay K1, the transistor Q1, and the negative terminal of the power supply, and the coil terminal of the relay K1 has a current flowing in and generates magnetism to attract the normally open contact, and the normally open contact is the detection signal output port of the control unit 13, so that the remote programmable logic controller can detect the signal of the attracted normally open contact, that is, can judge that the LED indicator lamp is bright. And the seventh resistor R7 is electrically connected to the base of the transistor Q1, which is equivalent to providing a bias voltage to the transistor Q1, so that no signal distortion occurs and a large current is prevented from flowing into the transistor Q1 directly. The capacitor C1 is beneficial to the voltage stabilization of the base electrode of the triode Q1 through charging and discharging. The diode D1 can play a role in preventing reverse connection.
Optionally, this embodiment further provides a light detection apparatus, as shown in fig. 3, including:
the photodetection circuit 1 described above;
the pressing plate 2 is provided with a plurality of light shields 21, each light shield 21 corresponds to an LED indicating lamp on the circuit board to be detected, one end of each light shield 21, facing the LED indicating lamp, is opened, after the pressing plate 2 is moved downwards to a preset detection position, the light shields 21 surround the corresponding LED indicating lamp on the top surfaces and the side surfaces of the LED indicating lamps through the openings, and the light detection circuit 1 is arranged on the top surfaces of the light shields 21;
and the control mechanism 3 controls the light detection circuit 1 to be electrified before the corresponding circuit board to be detected and controls the lifting mechanism 4 to move up or down the pressing plate 2. In application, the control mechanism may be a programmable logic controller, and the lifting mechanism may be an existing lifting mechanism, which is not limited in this embodiment.
The light detection device in this embodiment may be applied to detection of a circuit board, and is exemplified by taking the circuit board to be detected in fig. 3 as an example, a plurality of small function units are divided on the circuit board to be detected, each small function unit is a small module to be detected, and an LED indicator lamp is installed on the small module to be detected, so that a plurality of light shields corresponding to the positions of each small function unit are also installed on a corresponding pressing plate (only 1 light shield is exemplarily drawn in fig. 3). In application, because the light shield is very small in diameter and thin in thickness, the light shield can be covered in the light shielding space of the LED indicator lamp through the gap of the element on the circuit board to be detected, so that the influence of ambient illumination is reduced as much as possible. During detection, the control mechanism controls the lifting mechanism to move downwards, so that the pressing plate is driven to move downwards to a preset detection position, optionally, at the preset detection position, the light shield is just contacted with the circuit board to be detected or has a small gap so as to block the influence of ambient light and other LED indicating lamps on a detection result. In order to achieve accurate position control, the time length required for moving the pressure plate downwards to the preset detection position can be calculated in advance according to the downward moving speed and the initial position of the pressure plate, the time is counted from the downward moving time of the lifting mechanism, and the lifting mechanism is controlled to stop moving downwards after the pressure plate moves downwards to the preset detection position. In order to make the detection result more accurate, the control mechanism can control the light detection circuit to be electrified firstly and then control the circuit board to be detected to be electrified, so that the condition that the LED indicator lamp on the circuit board to be detected is lighted but the LED indicator lamp is not detected because the light detection circuit is not electrified can be avoided.
Alternatively, in the light detection device in the present embodiment, the light shield 21 is made of an elastic material.
In the application, the lens hood can adopt elastic material, and when pushing down to waiting to detect the circuit board, the clamp plate pushes down the contact pin that makes to detect the circuit board and wait to detect the jack connection circular telegram of position, because the lens hood is elastic material and makes, can make the lens hood with wait to detect the better contact of circuit board and be difficult for causing the damage of circuit board. Optionally, in the light detection device in this embodiment, as shown in fig. 4, a gap 22 with a preset shape is formed at a position of the pressing plate 2 corresponding to the LED indicator, a plurality of columns 23 are disposed around the gap 22, the light shielding covers 21 are fixed on the gap 22, and each light shielding cover 21 corresponds to one LED indicator.
In application, the shade depth of the light shield can be determined according to the specific situation of the circuit board to be detected, and can be higher than the columnar body, or lower than or equal to the columnar body, which is not limited in this embodiment. After the pressing plate moves downwards to the preset detection position, the circuit board to be detected can be pressed downwards, and the contact pin on the circuit board to be detected is connected with the jack at the position to be detected and powered on. In order to electrify the light detection circuit before the circuit board to be detected, the control mechanism controls the light detection circuit to be electrified before the pressing plate moves downwards to the preset detection position.
Optionally, an embodiment of the present invention further provides a light detection method, as shown in fig. 5, the detecting of the circuit board to be detected by using the light detection device specifically includes:
placing a circuit board to be detected at a position to be detected of a detection table;
controlling the lifting mechanism 4 to push the pressing plate 2 to move downwards to a preset detection position;
controlling the light detection circuit 1 to be electrified before the corresponding circuit board to be detected is electrified;
the detection signal of the photodetection circuit 1 is output.
In the light detection method in this embodiment, after the circuit board to be detected is placed at the position to be detected of the detection table, the lifting mechanism 4 is controlled to push the pressing plate 2 to move downward to the preset detection position, and the light detection circuit 1 is controlled to be powered on before the corresponding circuit board to be detected is powered on, so as to output the detection signal of the light detection circuit 1 finally. At the preset detection position, because the light shield just contacts with the circuit board to be detected or has a minimum gap, the influence of ambient light and other LED indicating lamps on the detection result can be obstructed. And the light detection circuit is controlled to be electrified firstly, and then the circuit board to be detected is controlled to be electrified, so that the condition that the LED indicator lamp on the circuit board to be detected is lighted but is not detected because the light detection circuit is not electrified can be avoided.
Optionally, in the light detection method in this embodiment, the controlling the lifting mechanism 4 to push the pressing plate 2 to move downward to the preset detection position includes:
determining a preset time length according to the initial position of the pressing plate 2, a preset detection position and the downward moving speed of the pressing plate 2;
and timing when the pressure plate 2 starts to move downwards, and controlling the lifting mechanism 4 to stop moving downwards and keep still after a preset time length.
In the light detection method in this embodiment, to achieve accurate position control, a time period required for moving down to the preset detection position is calculated in advance according to the moving down speed and the initial position of the pressing plate, and the lifting mechanism is controlled to stop moving down after the lifting mechanism starts timing when moving down and moves down to the preset time period, so as to control the pressing plate to move down to the preset detection position.
Optionally, in the light detection method in this embodiment, controlling the light detection circuit 1 to be powered on before the corresponding circuit board to be detected is powered on includes:
after the preset time length, controlling the light detection circuit 1 to be powered on;
after the light detection circuit 1 is powered on, the circuit board to be detected is controlled to be powered on.
Optionally, the light detection method in this embodiment further includes:
judging whether the circuit board to be detected is qualified or not according to the detection signal;
and moving the circuit board to be detected out of the detection table and placing the circuit board in a classified manner based on the detection result.
In the light detection method in the embodiment, in the application, timing is started when the air cylinder in the lifting mechanism starts to push the pressing plate to move, after a certain time (generally, when the pressing plate is just in contact with the circuit board to be detected), the light detection circuit starts to be electrified to continuously detect whether light exists, and the circuit board to be detected is further pressed down, so that the contact pin on the circuit board to be detected is connected with the jack at the position to be detected and electrified. After the LED indicator light is turned on, the resistance value of the photosensitive resistor of the light detection circuit is reduced, so that the voltage of a positive phase input end of an operational amplifier in the circuit is higher than that of a negative phase input end, the operational amplifier outputs high level, a triode in the circuit is further conducted, and at the moment, current flows through a coil of a relay to generate a magnetic attraction normally-open contact; if the LED indicator light is not bright, the resistance value of the photoresistor is not changed, correspondingly, the voltage of the positive phase input end of the operational amplifier in the circuit is lower than the voltage of the negative phase input end, the operational amplifier outputs low level, no current flows through a coil of the relay at the moment, and the normally open contact is disconnected, so that signals 0 and 1 can be transmitted to the PLC through the optical detection circuit, and the PLC can classify and mark the PCB to be detected according to the received signals; when the cylinder begins to drive the pressing plate to move upwards, the optical detection circuit is powered off, the detection process is stopped continuously, the detection box is used for detecting whether other functions of the PCB are normal or not, the PCB with problems is marked, and one-time detection is completed.
The above are merely examples of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (10)
1. A light detection device, comprising:
a photodetection circuit (1);
the light detection circuit comprises a pressing plate (2), wherein a plurality of light shields (21) are arranged on the pressing plate, each light shield (21) corresponds to an LED indicating lamp on a circuit board to be detected, the light shields (21) face an opening at one end of the LED indicating lamp, the pressing plate (2) moves downwards to a preset detection position, the light shields (21) enable the corresponding LED indicating lamps to be arranged in a light shielding space surrounded by the top surfaces and the side surfaces of the light shields through the openings, and the light detection circuit (1) is arranged in the top surface of the light shields (21);
the control mechanism (3) controls the optical detection circuit (1) to be electrified before the corresponding circuit board to be detected and controls the lifting mechanism (4) to move up or down the pressing plate (2);
wherein, control elevating system (4) move down clamp plate (2) specifically include:
and calculating the time length required for moving the pressure plate downwards to the preset detection position in advance according to the downward moving speed and the initial position of the pressure plate, starting timing when the lifting mechanism moves downwards, and controlling the lifting mechanism to stop moving downwards after moving downwards to the preset time length so as to control the pressure plate to move downwards to the preset detection position.
2. A light detection arrangement as claimed in claim 1, wherein the light shield (21) is made of an elastic material.
3. The light detection device according to claim 1 or 2, wherein a gap (22) having a preset shape is formed at a position of the pressing plate (2) corresponding to the LED indicator, a plurality of columns (23) are disposed around the gap (22), the light shielding covers (21) are fixed to the gap (22), and each light shielding cover (21) corresponds to one LED indicator.
4. The light detection arrangement according to claim 1, wherein the light detection circuit (1) comprises: a photosensor (11), a comparison unit (12) and a control unit (13);
the resistance value of the photosensitive device (11) changes along with the change of external light brightness;
the signal input end of the comparison unit (12) is electrically connected with the output end of the photosensitive device (11), the voltage/current signal output by the photosensitive device (11) is compared with a preset threshold value, and a comparison signal generated by comparison is transmitted to the control unit (13);
and the control unit (13) generates and outputs a corresponding detection signal according to the comparison signal.
5. A light detecting arrangement according to claim 4, characterized in that the light sensitive device (11) is a photo resistor (R1) and the comparing unit (12) comprises: a second resistor (R2), a third resistor (R3), a fourth resistor (R4), a variable resistor (R5), and an operational amplifier (U1A);
one end of the photosensitive resistor (R1) is electrically connected with the positive pole of a power supply, the other end of the photosensitive resistor is simultaneously and electrically connected with the positive-phase input end of the operational amplifier (U1A) and one end of the second resistor (R2), and the other end of the second resistor (R2) is electrically connected with the negative pole of the power supply; one end of the fourth resistor (R4) is electrically connected with the positive electrode of the power supply, the other end of the fourth resistor is electrically connected with the first end of the variable resistor (R5), the adjusting end of the variable resistor (R5) is electrically connected with the inverting input end of the operational amplifier (U1A), the second end of the variable resistor (R5) is electrically connected with one end of the third resistor (R3), and the other end of the third resistor (R3) is electrically connected with the negative electrode of the power supply.
6. A light detection arrangement as claimed in claim 5, characterized in that the control unit (13) comprises: the circuit comprises a sixth resistor (R6), a seventh resistor (R7), a capacitor (C1), a diode (D1), a triode (Q1) and a relay (K1);
one end of the sixth resistor (R6) is electrically connected with the output end of the operational amplifier (U1A), the other end of the sixth resistor (R6) is simultaneously electrically connected with one end of the seventh resistor (R7), the positive end of the capacitor (C1) and the base electrode of the triode (Q1), the other end of the seventh resistor (R7), the negative terminal of the capacitor (C1) and the emitter of the triode (Q1) are all electrically connected with the negative terminal of the power supply, the collector of the triode (Q1) is electrically connected with the anode of the diode (D1), the negative electrode of the diode (D1) is electrically connected with the positive electrode of the power supply, the coil end of the relay (K1) is connected with the diode (D1) in parallel, two normally open contacts of the relay (K1) are electrically connected with the IO port of the remote programmable logic controller, and the normally open contact is a detection signal output port of the control unit (13).
7. A method for detecting light, which is characterized in that the light detection device according to any one of claims 1 to 6 is used for detecting a circuit board to be detected, and comprises the following steps:
placing a circuit board to be detected at a position to be detected of a detection table;
controlling the lifting mechanism (4) to push the pressing plate (2) to move downwards to a preset detection position;
controlling the light detection circuit (1) to be electrified before the corresponding circuit board to be detected is electrified;
outputting the detection signal of the light detection circuit (1).
8. A light detection method according to claim 7, wherein said controlling the lifting mechanism (4) to push the pressing plate (2) to move downward to a preset detection position comprises:
determining a preset time length according to the initial position of the pressing plate (2), the preset detection position and the downward moving speed of the pressing plate (2);
timing when the pressure plate (2) starts to move downwards, and controlling the lifting mechanism (4) to stop moving downwards and keep static after the preset time length.
9. A light detection method according to claim 8, wherein controlling the light detection circuit (1) to power on prior to its corresponding board to be detected comprises:
after the preset time, controlling the light detection circuit (1) to be powered on;
and after the optical detection circuit (1) is powered on, controlling the circuit board to be detected to be powered on.
10. A light detection method as defined in any one of claims 7-9, wherein the method further comprises:
judging whether the circuit board to be detected is qualified or not according to the detection signal;
and moving the circuit board to be detected out of the detection table and placing the circuit board to be detected in a classified mode based on the detection result.
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| CN201810836279.5A CN109115335B (en) | 2018-07-26 | 2018-07-26 | Light detection circuit, device and method |
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| CN201810836279.5A CN109115335B (en) | 2018-07-26 | 2018-07-26 | Light detection circuit, device and method |
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| CN109115335B true CN109115335B (en) | 2021-07-06 |
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