Optoelectronic sensor and its transmitting end drive circuit

Abstract

The present application discloses an optoelectronic sensor and its transmitting end drive circuit. The transmitting end drive circuit includes a switching unit, a main control unit, and a transmitting unit. The switching unit is used to control the conduction and cut-off of the clamping element according to the high and low levels of the first interface, and output a corresponding switching signal to the main control unit. The main control unit is used to output a corresponding drive signal to the transmitting unit according to the switching signal. The transmitting unit includes a transmitting drive element and a first triode, a second triode, and a third triode connected in sequence. The transmitting drive element includes a transmitting tube and a receiving tube arranged oppositely. The receiving tube is used to receive the optical pulse signal emitted by the transmitting tube. When the optical pulse signal exceeds a preset threshold, a short circuit occurs to control the second triode and the third triode to cut off, so as to adjust the intensity of the optical pulse signal of the transmitting tube. It can switch the optoelectronic sensor between DC power supply and modulated power supply according to different application scenarios, and reduce the power loss of the transmitting tube.

Description

Technical Field

[0001] This application belongs to the technical field of sensors, and particularly relates to a photoelectric sensor and its transmitter drive circuit. Background Art

[0002] A photoelectric sensor is a key component for photoelectric conversion in various photoelectric detection systems. It usually includes a transmitter and a receiving tube. The receiving tube receives the optical signal emitted by the transmitter, and determines whether there is a target detection object between the transmitter and the receiving tube by detecting the intensity of the optical signal. According to the different propagation and reception paths of light, common photoelectric sensors can be divided into diffuse reflection photoelectric sensors, opposed photoelectric sensors, specular reflection photoelectric sensors, etc.

[0003] Existing photoelectric sensors usually adopt DC power supply or modulated power supply. The optical pulse signal of DC power supply needs to be continuously emitted, and the corresponding receiving tube also needs to receive continuously. This DC power supply method is extremely vulnerable to the influence of optical interference and has a large power loss for the transmitting tube. The modulated power supply can control the emission period and pulse width of the optical pulse signal, so that the transmitting tube of the control transmitting unit only lights up for a certain period of time, and the service life of the transmitting tube will be longer, but the response speed is slow and the frequency is low. Therefore, how to make the photoelectric sensor switch between DC power supply and modulated power supply according to different application scenarios and reduce the power loss of the transmitting tube is an urgent problem to be solved. Summary of the Invention

[0004] This application provides a photoelectric sensor and its transmitter drive circuit, which can make the photoelectric sensor switch between DC power supply and modulated power supply according to different application scenarios and reduce the power loss of the transmitting tube.

[0005] To solve the above technical problems, this application provides a transmitter drive circuit, including a switching unit, a main control unit, and a transmitting unit;

[0006] The switching unit includes a clamping element connected to the first interface, to control the conduction and cut-off of the clamping element according to the high and low levels of the first interface, and output a corresponding switching signal to the main control unit;

[0007] The main control unit is used to output a corresponding drive signal to the transmitting unit according to the switching signal;

[0008] The transmitting unit includes a transmitting drive element and a first triode, a second triode, and a third triode connected in sequence. The transmitting drive element includes a transmitting tube and a receiving tube arranged oppositely. The first triode is used to receive the drive signal, the second triode is connected to the receiving tube, and the third triode is connected to the transmitting end;

[0009] The receiving tube is used to receive the optical pulse signal emitted by the transmitting tube. When the optical pulse signal exceeds a preset threshold, a short circuit occurs to control the second triode and the third triode to cut off, so as to adjust the intensity of the optical pulse signal of the transmitting tube.

[0010] As a further improvement of the present application, the clamping element is a first diode. The cathode of the first diode is connected to the first interface through a first resistor, and the cathode of the first diode is connected to the main control unit through a second resistor to transmit the drive signal to the main control unit. A third resistor is connected between the cathode of the first diode and the second resistor, and the other end of the third resistor is connected to the working voltage;

[0011] To control the conduction and cut-off of the first diode through the high and low levels of the first interface, so that the main control unit outputs a corresponding drive signal to the transmitting unit according to the switching signal; wherein, the switching signal is the high and low levels formed between the second resistor and the main control unit.

[0012] As a further improvement of the present application, when the switching signal is a high level formed between the second resistor and the main control unit, the main control unit outputs a drive signal with a continuously high level to the transmitting unit;

[0013] When the level formed between the second resistor and the main control unit is a low level, the main control unit outputs a drive signal with a periodic change and a duty cycle to the transmitting unit.

[0014] As a further improvement of the present application, the base of the first triode is connected to the main control unit for receiving the drive signal;

[0015] The emitter of the first triode is connected to the emitter of the second triode. The base of the second triode is connected to the receiving tube. The transmitting tube is connected to the collector of the third triode. The collector of the second triode is connected to the base of the third triode. The emitter of the third triode is grounded; the anode of the receiving tube and the base of the second diode are commonly connected and then connected with a pull-down resistor element, and the other end of the pull-down resistor element is grounded.

[0016] Based on the above transmitting end drive circuit, the present application also provides an optical sensor, and the optical sensor further includes a receiving unit and an operational amplifier unit;

[0017] The receiving unit includes a first photosensitive receiving tube and a second photosensitive receiving tube. The first photosensitive receiving tube and the second photosensitive receiving tube are used to receive the optical pulse signal emitted by the transmitting tube and convert the optical pulse signal into two electrical signals;

[0018] The operational amplifier unit includes a first operational amplifier circuit and a second operational amplifier circuit. The first operational amplifier circuit is used to receive the two electrical signals and perform differential amplification on the two electrical signals. The second operational amplifier circuit is used to further amplify the differentially amplified electrical signals and transmit the amplified electrical signals to the main control unit;

[0019] The main control unit is used to compare the electrical signal with a preset voltage threshold value to determine whether there is a target detection object between the transmitting unit and the receiving unit.

[0020] As a further improvement of the present application, a shielding unit is connected between the operational amplifier unit and the main control unit;

[0021] A conducting element is arranged in the shielding unit. One end of the conducting element is connected to the operational amplifier unit, and the other end of the conducting element is connected to the main control unit. The shielding unit is used to control the closing and opening of the conducting element according to the instruction of the main control unit;

[0022] The main control unit is used to control the conducting element to close during the light pulse signal emission period and open during the non-emission period to shield the useless signals obtained by the receiving unit during the non-emission period.

[0023] As a further improvement of the present application, the photoelectric sensor further includes an output protection unit for connecting to a load;

[0024] The output protection unit is used to turn off the output of the photoelectric sensor to the load when the load current exceeds a preset current value and perform self-locking on the output protection unit through a capacitive element until the main control unit restarts the output protection unit.

[0025] As a further improvement of the present application, the output protection unit includes a fourth triode connected to the load and a fifth triode connected to the fourth triode;

[0026] The emitter of the fourth triode is connected to the base of the fifth triode through a fourth resistor. One end of the fourth resistor is commonly connected to the emitter of the fourth triode and then connected to a fifth resistor. The other end of the fifth resistor is grounded. The other end of the fourth resistor is commonly connected to the base of the fifth triode with the capacitive element, and the other end of the capacitive element is grounded;

[0027] The collector of the fifth triode is connected to a sixth triode. The collector of the fifth triode is connected to the base of the sixth triode, the base of the fifth triode is connected to the collector of the sixth triode, and a second diode is connected between the emitter of the sixth triode and the base of the fourth triode;

[0028] When the collector current of the fourth triode exceeds a preset current, the fifth resistor drives the fourth resistor, the fifth triode, and the sixth triode to conduct, so as to pull down the voltage between the base and the emitter of the fourth triode.

[0029] As a further improvement of the present application, the main control unit is connected between the sixth triode and the second diode. When the voltage between the base and the emitter of the fourth triode is pulled down, the main control unit charges the capacitive element through the sixth triode and the fifth triode, so that the fourth triode remains in the cut-off state continuously, and the output protection unit is self-locked.

[0030] As a further improvement of the present application, the photoelectric sensor further includes an indication unit, which is connected to the main control unit and includes at least one light-emitting diode;

[0031] The indication unit is used to control the light-emitting state of the light-emitting diode according to whether there is a target detection object between the transmitting unit and the receiving unit.

[0032] The photoelectric sensor and its transmitting-end driving circuit provided by the present application have the following beneficial effects:

[0033] The transmitting-end driving circuit of the present application includes a switching unit, a main control unit, and a transmitting unit. By controlling the conduction and cut-off of the clamping element through the switching unit, the main control unit outputs a corresponding driving signal to the transmitting unit according to the relative switching signal. The transmitting unit is provided with a transmitting tube and a receiving tube. When the optical pulse signal exceeds a preset threshold, a short circuit occurs to control the second triode and the third triode to cut off, so as to adjust the intensity of the optical pulse signal of the transmitting tube. It can switch between DC power supply and modulated power supply according to different application scenarios, reducing the power loss of the transmitting tube; setting the switching unit enables the product to switch between different power supply modes in different scenarios, and can give full play to the advantages of DC power supply and modulated power supply; an output protection unit is provided, which can be self-locked and turn off the output in time when an abnormal situation occurs at the load end, effectively protecting the load output; by controlling the conduction element to close during the optical pulse signal emission period and disconnect during the non-emission period through the shielding unit, the useless signals obtained by the receiving unit during the non-emission period are shielded, so that the photoelectric sensor can be used in a more complex electromagnetic interference environment and a strong light interference environment, with a wide coverage range and high performance. Brief Description of the Drawings

[0034] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only a part of the embodiments of the present application, rather than all the embodiments. For those of ordinary skill in the art, without creative efforts, other drawings obtained based on these drawings all fall within the scope of protection of the present application.

[0035] Figure 1 It is a schematic structural diagram of the transmitter drive circuit provided by the embodiment of the present application;

[0036] Figure 2 It is a circuit schematic diagram of the switching unit in the transmitter drive circuit provided by the embodiment of the present application;

[0037] Figure 3 It is a circuit schematic diagram of the transmitting unit in the transmitter drive circuit provided by the embodiment of the present application;

[0038] Figure 4 It is a schematic structural diagram of the transmitting drive element in the transmitter drive circuit provided by the embodiment of the present application;

[0039] Figure 5 It is a schematic structural diagram of the main control unit in the transmitter drive circuit provided by the embodiment of the present application;

[0040] Figure 6 It is a schematic structural diagram of the photoelectric sensor provided by the embodiment of the present application;

[0041] Figure 7 It is a circuit schematic diagram of the receiving unit in the photoelectric sensor provided by the embodiment of the present application;

[0042] Figure 8 It is a circuit schematic diagram of the operational amplifier unit in the photoelectric sensor provided by the embodiment of the present application;

[0043] Figure 9 It is a circuit schematic diagram of the shielding unit in the photoelectric sensor provided by the embodiment of the present application;

[0044] Figure 10 It is the first embodiment of the output protection unit in the photoelectric sensor provided by the embodiment of the present application;

[0045] Figure 11 It is the second embodiment of the output protection unit in the photoelectric sensor provided by the embodiment of the present application;

[0046] Figure 12 It is a circuit schematic diagram of the indication unit in the photoelectric sensor provided by the embodiment of the present application;

[0047] Figure 13 It is the circuit schematic diagram of the power supply unit in the photoelectric sensor provided by the embodiment of the present application;

[0048] Figure 14 It is the structural schematic diagram of the photoelectric sensor control system provided by the embodiment of the present application;

[0049] Explanation of reference numerals:

[0050] The first diode - D4; the second diode - (D10, D16); the first resistor - R9; the second resistor - R8; the third resistor - R7; the fourth resistor - (R21, R43); the fifth resistors R22, R44;

[0051] The first triode - Q1; the second triode - Q2; the third triode - Q3; the fourth triode - (Q4, Q8); the fifth triode - (Q7, Q13); the sixth triode - (Q6, Q12);

[0052] Capacitor elements - (C9, C24); the first photosensitive receiving tube - PD1; the second photosensitive receiving tube - PD2;

[0053] 1 - Target detection object; 2 - Emission lens; 3 - Receiving lens. Detailed implementation manners

[0054] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0055] In order to make the description of the present disclosure more detailed and complete, the following provides an illustrative description of the implementation manners and specific embodiments of the present application; however, this is not the only form for implementing or applying the specific embodiments of the present application. The implementation manners cover the features of multiple specific embodiments and the method steps and their sequences for constructing and operating these specific embodiments. However, other specific embodiments can also be used to achieve the same or equivalent functions and step sequences. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0056] It should be noted that the terms "first", "second", etc. in the specification, claims and above-mentioned drawings of the present application are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present application described here can be implemented in an order different from those illustrated or described here.

[0057] In the description of the embodiments of the present application, unless otherwise specified, " / " means "or". For example, A / B may mean A or B. "And / or" in the text is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present application, "a plurality of" means two or more than two, and other quantifiers should be understood similarly. The preferred embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application. And without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0058] Please refer to Figures 1 - 12 , the present application provides a photoelectric sensor and its transmitting end driving circuit, which can switch the photoelectric sensor between DC power supply and modulated power supply according to different application scenarios, and reduce the power loss of the transmitting tube.

[0059] Please refer to Figure 1 , which is a schematic structural diagram of the transmitting end driving circuit provided by the embodiments of the present application. The transmitting end driving circuit includes a switching unit, a main control unit, and a transmitting unit. The main control unit is connected to the transmitting unit and the switching unit in a wired or wireless manner.

[0060] As an optional implementation manner, a clamping element connected to the first interface is provided in the switching unit of the present application. The on and off of the clamping element are controlled according to the high and low levels of the first interface, and a corresponding switching signal is further output to the main control unit. The main control unit is used to output a corresponding driving signal corresponding to the switching signal to the transmitting unit according to the switching signal.

[0061] Furthermore, the transmitting unit provided by the present application includes a transmitting driving element and a first triode, a second triode, and a third triode connected in sequence. The transmitting driving element includes a transmitting tube and a receiving tube arranged oppositely. The first triode is connected to the main control unit for receiving the driving signal, the second triode is connected to the receiving tube, and the third triode is connected to the transmitting end.

[0062] The present application receives the optical pulse signal emitted by the transmitting tube through the receiving tube in the transmitting driving element. When the optical pulse signal exceeds a preset threshold, a short circuit occurs to control the second triode and the third triode to turn off, so as to adjust the intensity of the optical pulse signal of the transmitting tube.

[0063] Please refer to Figure 2 , which is the circuit schematic diagram of the switching unit in the transmitting end driving circuit provided by the embodiments of the present application. The above-mentioned first interface corresponds to Figure 2For the interface J4 in [the device], by manually selecting, the first interface is connected to a high level of 24V or a low level of 0V. According to the high and low levels of the first interface, the conduction and cutoff of the clamping element are controlled. Since the clamping element is connected to the main control unit, the level at the end of the clamping element close to the main control unit can be changed by controlling the conduction and cutoff of the clamping element. The conduction and cutoff of the clamping element will change the level at the end of the clamping element close to the main control unit, and the main control unit obtains the switching signal output by the switching unit by detecting the level at the end of the clamping element close to the main control unit.

[0064] It can also be understood that the change in the level at the end of the clamping element close to the main control unit is the switching signal output by the switching unit to the main control unit, that is, the main control unit obtains the switching signal output by the switching unit by detecting the level at the end of the clamping element close to the main control unit.

[0065] Furthermore, the main control unit outputs a corresponding drive signal to the transmitting unit according to the change in the high and low levels, and controls the optical pulse signal emitted by the transmitting unit through this drive signal.

[0066] In related technologies, the emission drive circuit of a photoelectric sensor usually uses DC power supply or AC power supply. DC power supply requires providing a stable optical pulse signal, and this optical pulse signal needs to be continuously emitted, and the corresponding receiving tube also needs to receive constantly. When there is an object to be detected blocking the transmission of the optical pulse signal between the transmitting end and the receiving tube, the receiving tube can respond immediately. If the circuit delay can be removed, the response speed of the receiving tube can theoretically approach the speed of light at most, but this DC power supply method is also extremely vulnerable to light interference, and the power loss of the transmitting tube is large, and long-distance detection cannot be achieved.

[0067] AC power supply, that is, modulated power supply, can control the emission period and pulse width of the optical pulse signal, and can give the main control unit an optical pulse signal with information type. When the received signal is consistent with the transmitted signal, the main control unit processes according to the received optical pulse signal. Therefore, the modulated power supply has strong anti-electromagnetic interference and anti-environmental interference; on the other hand, the pulse width and period of the modulated power supply can be controlled, so it can be controlled that the transmitting tube of the transmitting unit only lights up for a certain period of time, and it can rest for more time. Therefore, the service life of the transmitting tube will be longer, it can be used for a longer time, and it can achieve detection over a longer distance, but it has disadvantages such as slow response speed and low frequency.

[0068] In the embodiment of the present application, the drive signal is a PWM signal. When the PWM signal is continuously at a high level, the transmitting end continuously emits the corresponding optical pulse signal. When the PWM signal is a periodic rectangular pulse signal, the transmitting end emits the corresponding periodically changing optical pulse signal with a duty cycle according to this PWM signal.

[0069] It can be seen that in the emission driving circuit provided by the present application, the main control unit can output corresponding driving signals to the emission unit according to the high and low levels connected to the first interface, so that the emission tubes in the emission unit emit corresponding optical pulse signals according to the driving signals, so that the photoelectric sensor can be switched between DC power supply and modulated power supply according to different application scenarios, thereby concentrating the advantages of DC power supply and modulated power supply, giving full play to the advantages of various power supply modes, and adapting to different usage scenarios and usage requirements.

[0070] Further, please refer to Figure 4 , which is a schematic structural diagram of the emission driving element in the emission end driving circuit provided by the embodiment of the present application. The emission driving element provided by the present application is a laser tube provided with three pins. An emission tube LD and a receiving tube PD are arranged inside the emission driving element. The emission tube LD is a laser diode for emitting optical pulse signals. The receiving tube PD is integrated in another pin of the laser tube and is used to detect the magnitude of the optical pulse signal emitted by the emission tube LD, and feedback the optical pulse signal to the second triode and the third triode, so as to adjust the optical pulse signal emitted by the emission tube LD by adjusting the on-off states of the second triode and the third triode, and avoid damage to the emission tube LD or fluctuations in the emitted optical pulse signal.

[0071] It should be noted that although the emission tube LD emits in one direction, the optical pulse signal has an emission angle, and as long as the receiving tube PD is arranged within the angle where the optical pulse signal can be received, in principle, the setting position of the receiving tube PD cannot affect the normal reception of the first photosensitive receiving tube PD1 and the second photosensitive receiving tube PD2.

[0072] In practical applications, the receiving tube PD needs to be encapsulated in the laser tube by the shell to avoid it being exposed outside, so that no reflected optical pulse signal will enter the receiving tube PD to cause misjudgment.

[0073] In the embodiment of the present application, the first triode is connected to the main control unit for receiving the PWM signal, the second triode is connected to the receiving tube, the third triode is connected to the emission end, the receiving tube is used to receive the optical pulse signal emitted by the emission tube, and when the optical pulse signal exceeds the preset threshold, a short circuit occurs to control the second triode and the third triode to cut off, so as to adjust the intensity of the optical pulse signal of the emission tube.

[0074] It can be understood that the receiving tube PD is a photodiode, and its internal resistance will change after being irradiated by light, thereby generating a photocurrent. As the intensity of the light irradiation increases, the resistance will become smaller and smaller until it approaches 0. Therefore, when the optical pulse signal exceeds the preset threshold, the internal resistance of the receiving tube PD will become smaller and smaller until it approaches 0, and it can be regarded as a short circuit.

[0075] Under normal circumstances, the optical pulse signal emitted by the transmitting tube LD is controlled within a certain range and will not trigger the receiving tube PD to perform a short-circuit response. Therefore, the second triode is generally default controlled by the first triode. When the optical pulse signal exceeds the preset threshold, it will trigger the receiving tube PD to perform a short-circuit response, pulling up the base voltage of the second triode, thereby turning off the second triode and further turning off the third triode. Since the third triode is connected to the transmitting tube LD, the intensity of the optical pulse signal emitted by the transmitting tube LD can be adjusted to avoid damage.

[0076] Please refer to Figure 3 For the circuit schematic diagram of the transmitting unit in the transmitting-end drive circuit provided by the embodiment of the present application, the above-mentioned first triode corresponds to the triode Q1 in the figure, the second triode corresponds to the triode Q2 in the figure, the third triode corresponds to the triode Q3 in the figure, and the emission driving element corresponds to D5 in the figure. The emission driving element D5 is provided with a transmitting tube LD and a receiving tube PD. When the optical pulse signal exceeds the preset threshold, it will trigger the receiving tube PD to perform a short-circuit response, pulling up the base voltage of the triode Q2, thereby turning off the triode Q2 and further turning off the triode Q3. Since the triode Q3 is connected to the transmitting tube LD, the intensity of the optical pulse signal emitted by the transmitting tube LD can be adjusted.

[0077] As an optional implementation manner, the above-mentioned clamping element is a first diode. The cathode of the first diode is connected to the first interface through a first resistor, and the cathode of the first diode is connected to the main control unit through a second resistor to transmit the drive signal to the main control unit. A third resistor is connected between the cathode of the first diode and the second resistor, and the other end of the third resistor is connected to the working voltage; to control the conduction and cut-off of the first diode through the high and low levels of the first interface, so that the main control unit outputs a corresponding drive signal to the transmitting unit according to the switching signal; wherein, the switching signal is the high and low levels formed between the second resistor and the main control unit.

[0078] Please continue to refer to Figure 3 For the above, the first diode is the diode D4 in the figure, the first resistor is the resistor R9, the second resistor is the resistor R8, the third resistor is the resistor R7, and the first interface is the interface J4. It can be observed that the cathode of the diode D4 is connected to the interface J4 through the resistor R9, the anode of the diode D4 is connected to the Switch pin of the main control unit through the resistor R8, and a resistor R7 is connected between the resistor R8 and the anode of the diode D4. The other end of the resistor R7 is connected to the working voltage V5P0. The main control unit obtains the voltage at one end of the resistor R8 connected to the main control unit through the Switch pin, and this voltage is called the Switch voltage.

[0079] Further, when the level accessed by interface J4 is 24V high level, diode D4 is reversely connected between resistor R9 and resistor R8 and is in a cut-off state. Therefore, diode D4, resistor R9, and interface J4 are in a disconnected state, and the Switch voltage obtained by the main control unit is the working voltage V5P0. When the level accessed by interface J4 is 0V low level, the voltage across diode D4 is clamped at about 0.6V, that is, the Switch voltage is clamped at about 0.6V. At this time, the Switch voltage obtained by the main control unit is the clamped voltage of 0.6V, and the main control unit controls the output PWM signal according to the change of the high and low levels of the above Switch voltage.

[0080] As an optional implementation manner, when the switching signal is a high level formed between the second resistor and the main control unit, the main control unit outputs a driving signal with a continuously high level to the transmitting unit. When the level formed between the second resistor and the main control unit is a low level, the main control unit outputs a driving signal with a periodic change and a duty cycle to the transmitting unit.

[0081] In the embodiment of the present application, please refer to Figure 5 , which is a schematic structural diagram of the main control unit in the transmitting end driving circuit provided by the embodiment of the present application. When the Switch voltage obtained by the main control unit is the working voltage V5P0, it can be considered that the level formed between the second resistor and the main control unit is a high level, and the main control unit outputs a PWM signal with a continuously high level to the transmitting unit to achieve DC power supply. When the Switch voltage obtained by the main control unit is the clamped voltage of 0.6V, it can be considered that the level formed between the second resistor and the main control unit is a low level, and the main control unit outputs a PWM signal with a periodic change and a duty cycle to the transmitting unit to achieve modulated power supply, so as to realize the switching between DC power supply and modulated power supply according to the change of the high and low levels of the first interface.

[0082] As an optional implementation manner, the base of the first triode is connected to the main control unit for receiving the driving signal. The emitter of the first triode is connected to the emitter of the second triode. The base of the second triode is connected to the receiving tube. The transmitting tube is connected to the collector of the third triode. The collector of the second triode is connected to the base of the third triode. The emitter of the third triode is grounded. The anode of the receiving tube is commonly connected to the base of the second diode and then connected with a pull-down resistor element, and the other end of the pull-down resistor element is grounded.

[0083] Please further refer to Figure 3 , the pull-down resistor element corresponds to Figure 3For the resistors R13 and R17 therein, it can be observed that the base of the triode Q1 is connected to the main control unit for receiving the PWM signal. The emitter of the triode Q1 is connected to the emitter of the triode Q2. The base of the triode Q2 is connected to the receiving tube PD. The transmitting tube LD is connected to the collector of the triode Q3. The collector of the triode Q2 is connected to the base of the triode Q3. The emitter of the triode Q3 is grounded. The anode of the receiving tube PD and the base of the diode Q2 are commonly connected and then connected with the resistors R13 and R17. The other end of the resistor R17 is grounded.

[0084] In the embodiment of the present application, when the PWM signal is a continuous high-level signal, the triodes Q1 and Q2 are always turned on. The voltages across the resistors R13 and R17 are limited to about 4V. By adjusting the resistance values of the resistors R13 and R17, the current across the receiving tube PD can be controlled, so that the receiving tube PD controls the triode Q2. When the optical pulse signal received by the receiving tube PD is very strong, its internal resistance will change and become smaller and smaller. Therefore, the receiving tube PD can be approximately regarded as a short circuit, pulling the voltages across the resistors R13 and R17 to 5V, raising the base voltage of the triode Q2, thereby turning off the triode Q2 and further turning off the triode Q3. Since the triode Q3 is connected to the transmitting tube LD, the intensity of the optical pulse signal emitted by the transmitting tube LD can be adjusted.

[0085] It can be understood that when the intensity of the optical pulse signal emitted by the transmitting tube LD is usually controlled within a certain range, the short-circuit response of the receiving tube PD will not be triggered. Therefore, generally by default, the triode Q1 controls the triode Q2, further controls the triode Q3 and the transmitting tube LD. Only when the intensity of the optical pulse signal received by the receiving tube PD exceeds the preset threshold will the triodes Q2 and Q3 be turned off to adjust the optical pulse signal of the transmitting tube LD.

[0086] When the PWM signal is a periodically changing signal with a duty cycle, since the PWM signal is periodic and has a certain duty cycle, the triode Q1 will be periodically controlled to conduct, further controlling the triode Q2 and the triode Q3 to conduct, so that the transmitting tube LD periodically emits optical pulse signals.

[0087] Please continue to refer to Figure 3 , a resistor R10 is also connected between the base of the triode Q1 and the PWM pin of the main control unit. The collector of the triode Q1 is connected to the working voltage V5P0. A resistor R11 is connected between the emitter of the triode Q1 and the emitter of the triode Q2. A zener diode D7 is also connected between the resistor R11 and the emitter of the triode Q2. The other end of the zener diode D7 is grounded.

[0088] Further, a capacitor C6 is connected to the collector of the triode Q2, and the other end of the capacitor C6 is grounded. The base of the triode Q3 is connected to the collector of the triode Q2 and the capacitor C6 through a resistor R14. A resistor R16 is connected between the resistor R14 and the base of the triode Q3, and the other end of the resistor R16 is grounded. The emitter of the triode Q3 is grounded.

[0089] It can be observed that a resistor R12 is connected between the collector of the triode Q3 and the cathode of the emitting tube LD. The receiving tube PD is disposed opposite to the emitting tube LD. The anode of the receiving tube PD is connected to the base of the triode Q2. A resistor R13 and a resistor R17 are connected between the anode of the receiving tube PD and the base of the triode Q2. The other end of the resistor R17 is grounded. The anode of the emitting tube LD and the cathode of the receiving tube PD are commonly connected and then connected to a resistor R6. The other end of the resistor R6 is connected to the operating voltage V5P0. A capacitor C4 is connected between the resistor R6 and the emission driving element D5. A capacitor C5 is connected in parallel across the two ends of the capacitor C4. The capacitor C4 and the capacitor C5 are commonly connected and then grounded. A voltage stabilizing diode D6 is also connected in parallel across the two ends of the receiving tube PD.

[0090] Among them, the above-mentioned resistor R12 is a current limiting resistor, which can be used to control the intensity of the optical pulse signal of the emitting tube LD. The voltage stabilizing diodes D6 and D7 are used to protect the corresponding devices and prevent damage caused by excessive voltage at both ends.

[0091] Exemplarily, the above-mentioned triode Q1 and triode Q3 can be in the form of NPN transistors, and the triode Q2 can be in the form of a PNP transistor.

[0092] The present application realizes the adjustment of the intensity of the emitted optical signal through the above-mentioned emission driving circuit, and switches the PWM signal between DC power supply and modulation power supply, so as to avoid damage to the emitting tube due to excessive emission intensity.

[0093] Based on the above-mentioned emission driving circuit, the present application further provides an optical sensor. Please refer to Figure 6 , which is a schematic structural diagram of the optical sensor provided by the embodiment of the present application. The optical sensor further includes a receiving unit and an operational amplifier unit.

[0094] As an optional implementation manner, the receiving unit includes a first photosensitive receiving tube and a second photosensitive receiving tube. The first photosensitive receiving tube and the second photosensitive receiving tube are used to receive the optical pulse signal emitted by the emitting tube and convert the optical pulse signal into two electrical signals.

[0095] The operational amplifier unit includes a first operational amplifier circuit and a second operational amplifier circuit. The first operational amplifier circuit is used to receive two electrical signals and perform differential amplification processing on the two electrical signals. The second operational amplifier circuit is used to further amplify the differentially amplified electrical signals and transmit the amplified electrical signals to the main control unit;

[0096] The main control unit is used to compare the electrical signal with a preset voltage threshold to determine whether there is a target detection object between the transmitting unit and the receiving unit.

[0097] In the embodiment of the present application, please refer to Figure 7 , which is the circuit schematic diagram of the receiving unit in the photoelectric sensor provided in the embodiment of the present application. The receiving unit includes a first photosensitive receiving tube D12 and a second photosensitive receiving tube D13. The cathode of the first photosensitive receiving tube D12 is connected to the working voltage V5P0 through a resistor R23, and the anode of the first photosensitive receiving tube D12 is grounded through a resistor R31. It can be observed that a capacitor C11 is connected between the cathode of the first photosensitive receiving tube D12 and the resistor R23, and the other end of the capacitor C11 is grounded.

[0098] Correspondingly, the cathode of the second photosensitive receiving tube D13 is connected to the working voltage V5P0 through a resistor R24, and the anode of the first photosensitive receiving tube D13 is grounded through a resistor R32. It can be observed that a capacitor C12 is connected between the cathode of the first photosensitive receiving tube D13 and the resistor R24, and the other end of the capacitor C12 is grounded.

[0099] The above resistors R23 and R24 are current-limiting resistors, and the capacitors C11 and C12 are used as energy storage capacitors to briefly provide a 5V power supply for the receiving unit when the working voltage power supply is stopped, and as decoupling capacitors, they can filter out high-frequency noise in the working voltage. The resistors R31 and R32 are respectively used as the resistors of the first photosensitive receiving tube D12 and the second photosensitive receiving tube D12, and convert the optical pulse signals received by the first photosensitive receiving tube D12 and the second photosensitive receiving tube D12 into two electrical signals, corresponding to the PD1_signa signal and the PD2_signal signal in the figure.

[0100] As an alternative embodiment, please refer to Figure 8 , which is the circuit schematic diagram of the operational amplifier unit in the photoelectric sensor provided in the embodiment of the present application. The above operational amplifier unit includes a first operational amplifier circuit and a second operational amplifier circuit. The first operational amplifier circuit is used to receive two electrical signals and perform differential amplification processing on the two electrical signals. The second operational amplifier circuit is used to further amplify the differentially amplified electrical signals and transmit the amplified electrical signals to the main control unit.

[0101] It can be observed that the operational amplifier unit includes operational amplifier U3A and operational amplifier U3B. The above PD1_signa signal and PD2_signal signal are respectively connected to the inverting input terminal and non-inverting input terminal of operational amplifier U3A through capacitor C14 and capacitor C15. A resistor R26 is connected between the inverting input terminal and the output terminal of the operational amplifier U3A, and a capacitor C10 is connected in parallel at both ends of the resistor R26.

[0102] Furthermore, a resistor R30 and a capacitor C22 are connected between the non-inverting input terminal of the operational amplifier U3A and the capacitor C15. The other end of the capacitor C22 is grounded. A capacitor C18 and a resistor R29 are connected to the VCC terminal of the operational amplifier U3A. The capacitor C18 is grounded, the other end of the resistor R29 is connected to the working voltage V5P0, and the VCC terminal of the operational amplifier U3A is connected between the capacitor C18 and the resistor R29.

[0103] In the embodiment of the present application, a capacitor C23 is connected to the non-inverting input terminal of the operational amplifier U3B. A resistor R45 is connected in parallel at both ends of the capacitor C23. A resistor R36 and a resistor R40 are connected between the resistor R45 and the resistor R29. The connection node between the resistor R36 and the resistor R40 is connected to the connection between the resistor R30 and the capacitor C22.

[0104] Furthermore, the output terminal of the operational amplifier U3A is connected to the inverting input terminal of the operational amplifier U3B through a resistor R33 and a capacitor C17. A resistor R28 is connected between the inverting input terminal of the operational amplifier U3B and the output terminal of the operational amplifier U3B. A capacitor C13 is connected in parallel at both ends of the resistor R28. A resistor R26 and a diode D14 are connected in parallel at both ends of the capacitor C13. The output of the operational amplifier U3B forms an AMP_OUPUT signal through a resistor R37 and is transmitted to the main control unit or transmitted to the shielding unit.

[0105] It can be observed that the two electrical signals PD1_signa and PD2_signal formed by the receiving unit, through the coupling effect of capacitor C14 and capacitor C15, filter out the DC components in the two electrical signals and only retain the AC components. The AC components pass through the operational amplifier U3A and the operational amplifier U3B and then form an AMP_OUPUT signal and are transmitted to the main control unit or connected to the shielding unit.

[0106] In the embodiment of the present application, the first operational amplifier circuit is a differential inverting differentiating circuit, and its amplification factor formula is:

[0107]

[0108] Wherein, U O1(t) is the instantaneous voltage of resistor R33 and resistor R25 at time t, U REF1 is the voltage across capacitor C22, which can also be understood as the voltage to ground between resistor R30 and capacitor C15. However, the resistance value of resistor R30 is generally several hundred K, and the current on it can be almost ignored. Therefore, it is generally defaulted to the voltage across capacitor C22; u PD1_signal (t) refers to the voltage value of signal PD1_signa at time t; u PD2_s i gnal (t) refers to the voltage value of signal PD2_signa at time t. The above formula is based on the condition that capacitor C14 is equal to capacitor C15 and resistor R25 is equal to resistor R30.

[0109] The second operational amplifier circuit is also called an inverting differentiator circuit. The difference from the first operational amplifier circuit is that it lacks differential processing. Its amplification factor formula is:

[0110]

[0111] Among them, U O2 (t) refers to the instantaneous voltage of resistor R37 and resistor R28 at time t, U REF2 refers to the voltage across capacitor C23. The above formula is based on the condition that the resistance value of resistor R33 is very small.

[0112] In the first operational amplifier circuit, the function of capacitor C16 is to filter out the noise in the working voltage V5P0. Resistor R29 is a voltage-dividing resistor. When a high current appears in the working voltage V5P0, it plays a voltage-dividing role through resistor R29 to protect the operational amplifier U3A; the functions of resistor R36, resistor R40, and resistor R45 are to provide DC reference voltages for operational amplifier U3A and operational amplifier U3B respectively.

[0113] Capacitors C22 and C23 are bypass capacitors for these two DC reference voltages, filtering out the high-frequency signal components in these two voltages. Resistor R30 is a matching resistor, and its resistance value is equal to that of resistor R25, so that the static resistance to ground of the in-phase input terminal and the anti-phase input terminal of operational amplifier U3A remains balanced. Resistor R25 is the amplification feedback resistor of the first-stage operational amplifier. Capacitor C10 is added to feedback resistor R25 to play a role in phase compensation, suppressing self-oscillation, reducing noise, and improving the rejection ratio.

[0114] In the second operational amplifier circuit, the resistor R33 and the capacitor C17 form the input impedance of the operational amplifier U3B. The resistor R28, the capacitor C13, the resistor R16, and the diode D14 form the feedback loop of the second-stage operational amplifier. The resistor R28 is the amplification feedback resistor of the second-stage operational amplifier, and the capacitor C13 is added to the feedback resistor R28 to play a phase compensation role and suppress self-oscillation. The resistor R16 and the diode D14 form a clamping circuit to limit the peak voltage of the output waveform of the operational amplifier and clamp it at a certain voltage to make the operational amplifier more stable. At the same time, the output signal forms an AMP_OUPUT signal after being filtered by the resistor R37 and the capacitor C20 and is transmitted to the main control unit or the shielding unit.

[0115] As an alternative embodiment, a shielding unit is connected between the above-mentioned operational amplifier unit and the main control unit. A conducting element is provided in the shielding unit. One end of the conducting element is connected to the operational amplifier unit, and the other end of the conducting element is connected to the main control unit. The shielding unit is used to control the closing and opening of the conducting element according to the instructions of the main control unit. The main control unit is used to control the conducting element to close during the optical pulse signal emission period and open during the non-emission period to shield the useless signals obtained by the receiving unit during the non-emission period.

[0116] Please refer to Figure 9 , which is the circuit schematic diagram of the shielding unit in the photoelectric sensor provided by the embodiment of the present application. A controller U4 is provided in the shielding unit provided by the present application. The main controller U4 is provided with a conducting element, which can be understood in the form of a control switch. It can be observed that one end of the conducting element is connected to the operational amplifier unit to receive the AMP_OUPUT signal provided by the operational amplifier unit. The other end of the conducting element is connected to the Receiver pin of the main control unit to transmit the Receiver signal to the main control unit. The input end of the conducting element is also connected to the Doors pin of the main control unit. A resistor R35 is connected between the Doors pin of the main control unit and the input end of the controller U4, and the other end of the resistor R35 is grounded.

[0117] In the embodiment of the present application, high-level and low-level signals are given to the Doors pin by the main control unit to control when the AMP_OUPUT signal is conducted to the Receiver signal pin. It can also be understood that the second pin and the first pin in the controller U4 are controlled through the fourth pin, that is, the conduction of the second pin and the first pin is controlled by the high and low levels of the fourth pin. During the optical pulse signal emission period, the AMP_OUPUT signal is transmitted to the main control unit through the Receiver pin and is disconnected during the non-emission period to shield the useless signals obtained by the receiving unit during the non-emission period.

[0118] Through the setting of the shielding unit, the present application can shield the useless signals emitted during the non-transmission period, avoid the interference of the useless signals on the control of the main control unit, and effectively avoid optical interference and electromagnetic interference.

[0119] As an optional implementation manner, the present application is further provided with an output protection unit for connecting a load. The output protection unit is used to turn off the output of the photoelectric sensor to the load when the load current exceeds a preset current value, and self-lock the output protection unit through a capacitive element until the main control unit restarts the output protection unit.

[0120] The output protection unit includes a fourth triode connected to the load and a fifth triode connected to the fourth triode; the emitter of the fourth triode is connected to the base of the fifth triode through a fourth resistor. One end of the fourth resistor is commonly connected to the emitter of the fourth triode and then connected to a fifth resistor, the other end of the fifth resistor is grounded, the other end of the fourth resistor is commonly connected to the base of the fifth triode with the capacitive element, and the other end of the capacitive element is grounded;

[0121] The collector of the fifth triode is connected to a sixth triode. The collector of the fifth triode is connected to the base of the sixth triode, the base of the fifth triode is connected to the collector of the sixth triode, and a second diode is connected between the emitter of the sixth triode and the base of the fourth triode;

[0122] When the collector current of the fourth triode exceeds the preset current, the fifth resistor drives the fourth resistor, the fifth triode, and the sixth triode to conduct, so as to pull down the voltage between the base and the emitter of the fourth triode.

[0123] Further, please refer to Figure 10 , which is the first embodiment of the output protection unit in the photoelectric sensor provided by the embodiment of the present application. The present application is provided with an NPN-type output protection unit. The above-mentioned fourth triode is triode Q4, the fifth triode is triode Q7, the sixth triode is triode Q6, the capacitive element is C9, the fourth resistor is R21, the fifth resistor is R22, and the second diode is D10. It can be observed that the bases of triode Q4 and triode Q7 are connected through resistor R21. One end of resistor R21 is commonly connected to the emitter of triode Q4 and then connected to resistor R22, and the other end of this resistor R22 is grounded.

[0124] The other end of the resistor R21 is connected to the base of the triode Q7 and then connected with a capacitor C9. The other end of the capacitor C9 is grounded. The collector of the triode Q7 is connected to the base of the triode Q6, and the base of the triode Q7 is connected to the collector of the triode Q6. And a diode D10 is connected between the emitter of the triode Q6 and the base of the triode Q4.

[0125] When the collector current of the triode Q4 exceeds the preset current value, the resistor R22 drives the resistor R21, the triode Q7 and the triode Q6 to conduct, so as to pull down the voltage between the base and the emitter of the triode Q4, thereby achieving the purpose of turning off.

[0126] In the embodiment of the present application, please further refer to the figure. It can be observed that the collector of the triode Q4 is connected with an interface L1 through a diode D9, and is further connected to an external load through the interface L1. A bidirectional breakdown diode D11 is also connected between the diode D9 and the interface L1. The other end of the bidirectional breakdown diode D11 is grounded. A bidirectional breakdown diode D8 is also connected to the cathode of the diode D9. A resistor D15 is connected in parallel at both ends of the bidirectional breakdown diode D8. After the resistor D15 and the bidirectional breakdown diode D8 are connected, they are jointly connected to the VCC_IN input voltage.

[0127] In the present application, a resistor R19 is also connected between the cathode of the diode D10 and the base of the triode Q4. A capacitor C8 is connected in parallel at both ends of the resistor R19. The other end where the resistor R19 and the capacitor C8 are commonly connected is grounded.

[0128] When the current of the external load is too large and the collector current of the triode Q4 exceeds the preset current, the resistor R22 becomes larger as the collector current of the triode Q4 increases, and the voltage difference across it also increases. When the voltage across the resistor R22 rises to 0.6V, through the loop of the resistor R22 - resistor R21 - the Ube of the triode Q7, the triode Q7 is turned on. Since the triode Q7 is turned on, the triode Q6 satisfies the conduction condition of the PNP transistor, and then the triode Q6 is also turned on. The voltage at the emitter of the triode Q6 is pulled down from 1.1V to about 0.6V. After the voltage at the emitter of the triode Q6 is pulled down to 0.6V, about 0.4V of voltage division is carried out through the diode D10. At this time, the Ube of the triode Q4 and the voltage across the resistor R22 are 0.2V. Obviously, the triode Q4 does not meet the conduction condition, so the function of turning off the output load is achieved.

[0129] As an alternative implementation, please refer to Figure 11, which is the second embodiment of the output protection unit in the optoelectronic sensor provided by the embodiments of the present application. The present application also provides an NPN-type output protection unit. The above-mentioned fourth triode is triode Q8, the fifth triode is triode Q13, the sixth triode is triode Q12, the capacitive element is C24, the fourth resistor is R43, the fifth resistor is R44, and the second diode is D16. It can be observed that there is a connection between the emitter of triode Q8 and the base of triode Q13 through resistor R43. One end of resistor R43 is connected to the emitter of triode Q8 and then connected to resistor R44, and the other end of this resistor R44 is connected to the VCC_IN input voltage.

[0130] The other end of resistor R43 is connected to the base of triode Q13 and then connected to capacitor C24, and the other end of this capacitor C24 is connected to the VCC_IN input voltage. Connect the collector of triode Q13 to the base of triode Q12, connect the base of triode Q13 to the collector of triode Q12, and a diode D16 is connected between the emitter of triode Q12 and the base of triode Q8.

[0131] When the collector current of triode Q8 exceeds the preset current value, resistor R44 drives resistor R43, triode Q13, and triode Q12 to conduct, so as to lower the voltage between the base and emitter of triode Q8, thereby achieving the purpose of turning off.

[0132] In the embodiments of the present application, please further refer to Figure 10 , it can be observed that the collector of triode Q8 is connected to interface L1 through diode D15, and further connected to an external load through interface L1. A bidirectional breakdown diode D17 is also connected between diode D15 and interface L1, and the other end of the bidirectional breakdown diode D17 is connected to the VCC_IN input voltage.

[0133] The present application also connects a resistor R34 between the cathode of diode D16 and the base of triode Q8, and a capacitor C18 is connected in parallel at both ends of resistor R34. The other end where resistor R34 and capacitor C18 are commonly connected is connected to the VCC_IN input voltage.

[0134] When the current of the external load is too large, causing the collector current of the triode Q8 to exceed the preset current, the resistance R44 increases as the collector current of the triode Q8 increases, and the voltage difference across it also increases. When the voltage across the resistance R44 rises to 0.6V, through the loop of the resistance R44 - resistance R43 - the Ube of the triode Q13, the triode Q13 is turned on. Since the triode Q13 is turned on, the triode Q12 meets the conduction condition of the PNP transistor, and then the triode Q12 is also turned on, pulling the voltage of the emitter of the triode Q12 from 1.1V to about 0.6V. After the voltage of the emitter of the triode Q12 is pulled down to 0.6V, a voltage division of about 0.4V is carried out through the diode D16. At this time, the Ube of the triode Q8 and the voltage across the resistance R44 are 0.2V. Obviously, the triode Q8 does not meet the conduction condition, so the function of turning off the output load is achieved.

[0135] As an alternative implementation, the above main control unit is connected between the sixth triode and the second diode. When the voltage between the base and the emitter of the fourth triode is pulled down, the main control unit charges the capacitive element through the sixth triode and the fifth triode, so that the fourth triode remains in the cut-off state and self-locks the output protection unit.

[0136] Please continue to refer to Figure 11 In the above NPN-type output protection unit, a triode Q5 is also provided. The collector of the triode D5 is connected between the emitter of the triode Q6 and the second diode D10. The emitter of the triode Q5 is grounded. The base of the triode Q5 is connected with a resistance R20, and the other end of the resistance R20 is grounded. A capacitor C7 is also connected between the triode Q5 and the resistance R20 in this application. The other end of the capacitor C7 is connected to the resistance R18 and then connected to the working voltage V5P0.

[0137] In the above NPN-type output protection unit, the signal pin of the main control unit is connected between the emitter of the triode Q6 and the second diode D10. After the capacitor C9 is charged for the first time, since the resistance values of the resistance R21 and the resistance R22 are relatively small, the discharge current of the capacitor C9 is slow. And the power supply is provided by the signal pin of the main control unit, and the signal pin will keep charging the capacitor C9, that is, the triode Q6 and the triode Q7 are always in the on state. Therefore, the triode Q4 is always in the off state. At this time, it doesn't matter whether the load returns to normal or not. It must be triggered again through the main control unit to change the signal level, or power on again to restart the output mode. Therefore, the output protection unit can achieve the purpose of self-locking. The diode D9 is set to prevent reverse connection and prevent large voltage from flowing out of the output loop of L1.

[0138] Please continue to refer toFigure 11 , a triode Q9, a triode Q10, and a triode Q11 are further provided in the above NPN-type output protection unit. The collector of the triode 19 is connected between the emitter of the triode Q12 and the cathode of the diode D16 through a resistor R39. The base of the triode Q9 is connected to the collector of the triode Q11. The emitter of the triode Q9 is connected to the base of the triode Q11. A resistor R42 is also connected between the base and the emitter of the triode Q11. After the resistor R42 and the emitter of the triode Q11 are commonly connected, they are grounded.

[0139] Further, the collector of the triode Q10 is connected between the collector of the triode Q10 and the base of the triode Q9. The emitter of the triode Q10 is grounded. A resistor R46 is connected to the base of the triode Q10. The other end of the resistor R46 is grounded. A capacitor C21 is also connected after the base of the triode Q10 and the resistor R46 are commonly connected. The capacitor C21 is connected to the resistor R38 and then connected to the working voltage V5P0.

[0140] In the above PNP-type output protection unit, the signal pin of the main control unit is connected between the collector of the triode Q10 and the base of the triode Q9.

[0141] After the capacitor C24 is charged for the first time, since the resistance values of the resistor R43 and the resistor R44 are relatively small, the discharge current on the capacitor C24 is slow. And the power supply is provided by the signal pin of the main control unit. The signal pin will keep charging the capacitor C24 all the time, that is, the triode Q12 and the triode Q13 are always in the conducting state. Therefore, the triode Q5 is always in the off state. At this time, it doesn't matter whether the load returns to normal or not. It must be triggered by the main control unit again to change the signal level, or power on again to restart the output mode. Therefore, the output protection unit can achieve the purpose of self-locking. The diode D15 is set to prevent reverse connection and prevent large voltage from flowing out from the output loop of L1.

[0142] In the embodiment of the present application, the triode Q11, the triode Q9, and the resistor R42 form a constant current to control the current in the resistor R39 loop and keep it at a basically stable current value. The loop of V5P0, the resistor R38, the capacitor C21, the capacitor C46, and the triode Q10 constitutes a power-on protection output circuit to prevent the generation of interference signals at the moment of power-on.

[0143] As an optional implementation manner, the above photoelectric sensor further includes an indication unit, and the indication unit is connected to the main control unit and includes at least one light-emitting diode.

[0144] The indication unit is configured to control the light-emitting state of the light-emitting diode according to whether there is a target detection object between the transmitting unit and the receiving unit.

[0145] Please refer to Figure 12 , which is the circuit schematic diagram of the indication unit in the optoelectronic sensor provided by the embodiment of the present application. The indication unit includes a first light-emitting diode D5 and a second light-emitting diode D6. The cathode of the first light-emitting diode D5 is grounded, and the anode of the first light-emitting diode D5 is connected to the LED1 pin of the main control unit through a resistor R30. The cathode of the second light-emitting diode D6 is also grounded, and the anode of the second light-emitting diode D6 is connected to the LED2 pin of the main control unit through a resistor R31.

[0146] In an alternative embodiment, the presence or absence of a target detection object between the transmitting unit and the receiving unit can be indicated by the light-emitting states of the first light-emitting diode D5 and the second light-emitting diode D6. Alternatively, one of the first light-emitting diode D5 and the second light-emitting diode D6 can be set to indicate the presence or absence of a target detection object between the transmitting unit and the receiving unit, and the other light-emitting diode can indicate the power supply state of the optoelectronic sensor. The present application does not further limit the specific number of light-emitting diodes in the above indication unit and the states indicated by the light-emitting diodes, and corresponding adjustments can be made according to actual needs. Those skilled in the art should be aware of this.

[0147] As an alternative implementation, please refer to Figure 13 , which is the circuit schematic diagram of the power supply unit in the optoelectronic sensor provided by the embodiment of the present application. The input voltage VCC_IN is converted into the working voltage V5P0 through the power supply unit. As for the specific circuit of the power supply unit, the present application will not elaborate too much here. In principle, it only needs to satisfy the conversion of the input voltage into a 5V working voltage, and the present application does not impose any restrictions on this.

[0148] Based on the above optoelectronic sensor, the present application also provides an optoelectronic sensor control system. Please refer to Figure 14 , the control system includes a switching unit, a main control unit, a transmitting unit, a receiving unit, an operational amplifier unit, a shielding unit, a power supply unit, and an indication unit;

[0149] Among them, the switching unit includes a clamping element connected to the first interface to control the conduction and cut-off of the clamping element according to the high and low levels of the first interface, and output a corresponding switching signal to the main control unit;

[0150] The main control unit is configured to output a corresponding driving signal to the transmitting unit according to the switching signal;

[0151] The transmitting unit includes a transmitting driving element, a first triode, a second triode, and a third triode connected in sequence. The transmitting driving element includes a transmitting tube and a receiving tube arranged opposite to each other. The first triode is used to receive the driving signal. The second triode is connected to the receiving tube. The third triode is connected to the transmitting end;

[0152] The receiving tube is used to receive the optical pulse signal emitted by the transmitting tube. When the optical pulse signal exceeds a preset threshold, it is short-circuited to control the second triode and the third triode to cut off, so as to adjust the intensity of the optical pulse signal of the transmitting tube.

[0153] The receiving unit includes a first photosensitive receiving tube and a second photosensitive receiving tube. The first photosensitive receiving tube and the second photosensitive receiving tube are used to receive the optical pulse signal emitted by the transmitting tube and convert the optical pulse signal into two electric signals;

[0154] The operational amplifier unit includes a first operational amplifier circuit and a second operational amplifier circuit. The first operational amplifier circuit is used to receive the two electric signals and perform differential amplification processing on the two electric signals. The second operational amplifier circuit is used to amplify the differentially amplified electric signals again and transmit the amplified electric signals to the main control unit;

[0155] The main control unit is used to compare the electric signal with a preset voltage threshold to judge whether there is a target detection object between the transmitting unit and the receiving unit.

[0156] A conducting element is arranged in the shielding unit. One end of the conducting element is connected to the operational amplifier unit, and the other end of the conducting element is connected to the main control unit. The shielding unit is used to control the closing and opening of the conducting element according to the instruction of the main control unit;

[0157] The main control unit is used to control the conducting element to close during the optical pulse signal emission period and open during the non-emission period, so as to shield the useless signals obtained by the receiving unit during the non-emission period.

[0158] The output protection unit is used to turn off the output of the optoelectronic sensor to the load when the load current exceeds a preset current value and perform self-locking on the output protection unit through a capacitive element until the main control unit restarts the output protection unit.

[0159] The indicating unit is used to control the lighting state of the light-emitting diode according to whether there is a target detection object between the transmitting unit and the receiving unit.

[0160] For other details of how each unit in the above control system implements the above technical solution, reference may be made to the descriptions of the transmitter drive circuit and the photoelectric sensor provided in the embodiments of the above application, which will not be elaborated here.

[0161] The photoelectric sensor and its transmitter drive circuit provided by this application. The transmitter drive circuit includes a switching unit, a main control unit, and a transmitting unit. The switching unit controls the on and off of the clamping element, so that the main control unit outputs corresponding drive signals to the transmitting unit according to the relative switching signals. A transmitting tube and a receiving tube are arranged in the transmitting unit. When the optical pulse signal exceeds the preset threshold, a short circuit occurs to control the second triode and the third triode to turn off, so as to adjust the intensity of the optical pulse signal of the transmitting tube. It can switch the photoelectric sensor between DC power supply and modulated power supply according to different application scenarios, reducing the power loss of the transmitting tube; setting the switching unit enables the product to switch between different power supply modes in different scenarios, and can give full play to the advantages of DC power supply and modulated power supply; an output protection unit is provided, which can self-lock and turn off the output in time when an abnormal situation occurs at the load end, effectively protecting the load output; the shielding unit controls the conducting element to close during the optical pulse signal emission period and disconnect during the non-emission period, so as to shield the useless signals obtained by the receiving unit during the non-emission period, enabling the photoelectric sensor to be used in a more complex electromagnetic interference environment and a strong light interference environment, with a wide coverage range and high performance.

[0162] The above-described embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

[0163] In summary, although the present invention has been disclosed above with preferred embodiments, the above preferred embodiments are not used to limit the present invention. The description method of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A transmitter driving circuit, characterized in that, It includes a switching unit, a main control unit, and a transmitting unit; The switching unit includes a clamping element connected to the first interface to control the conduction and cut-off of the clamping element according to the high and low levels of the first interface, and output a corresponding switching signal to the main control unit; The main control unit is used to output a corresponding driving signal to the transmitting unit according to the switching signal; The transmitting unit includes a transmitting driving element and a first triode, a second triode, and a third triode connected in sequence. The transmitting driving element includes a transmitting tube and a receiving tube arranged oppositely. The base of the first triode is connected to the main control unit to receive the driving signal; The emitter of the first triode is connected to the emitter of the second triode. The base of the second triode is connected to the receiving tube. The transmitting tube is connected to the collector of the third triode. The collector of the second triode is connected to the base of the third triode. The emitter of the third triode is grounded; The receiving tube is used to receive the optical pulse signal emitted by the transmitting tube. When the optical pulse signal exceeds a preset threshold, a short circuit occurs to control the cut-off of the second triode and the third triode to adjust the intensity of the optical pulse signal of the transmitting tube.

2. The transmitting end driving circuit according to claim 1, wherein The clamping element is a first diode. The cathode of the first diode is connected to the first interface through a first resistor. The anode of the first diode is connected to the main control unit through a second resistor to transmit the driving signal to the main control unit. A third resistor is connected between the anode of the first diode and the second resistor, and the other end of the third resistor is connected to the working voltage; To control the conduction and cut-off of the first diode according to the high and low levels of the first interface, so that the main control unit outputs a corresponding driving signal to the transmitting unit according to the switching signal; wherein, the switching signal is the high and low level formed between the second resistor and the main control unit.

3. The transmitting end driving circuit according to claim 2, wherein When the switching signal is the high level formed between the second resistor and the main control unit, the main control unit outputs a driving signal with a continuously high level to the transmitting unit; When the level formed between the second resistor and the main control unit is low, the main control unit outputs a driving signal with a periodic change and a duty cycle to the transmitting unit.

4. The transmitting end driving circuit according to claim 1, wherein The anode of the receiving tube and the base of the second triode are commonly connected and then connected with a pull-down resistor element, and the other end of the pull-down resistor element is grounded.

5. An optoelectronic sensor, comprising the transmitting end driving circuit according to any one of claims 1-4, characterized in that, The photoelectric sensor further includes a receiving unit and an operational amplifier unit; The receiving unit includes a first photosensitive receiving tube and a second photosensitive receiving tube. The first photosensitive receiving tube and the second photosensitive receiving tube are used to receive the optical pulse signal emitted by the transmitting tube and convert the optical pulse signal into two electrical signals; The operational amplifier unit includes a first operational amplifier circuit and a second operational amplifier circuit. The first operational amplifier circuit is used to receive the two electrical signals and perform differential amplification processing on the two electrical signals. The second operational amplifier circuit is used to further amplify the differentially amplified electrical signals and transmit the amplified electrical signals to the main control unit; The main control unit is configured to compare the electrical signal with a preset voltage threshold to determine whether there is a target detection object between the transmitting unit and the receiving unit.

6. The optoelectronic sensor according to claim 5, characterized in that, A shielding unit is connected between the operational amplifier unit and the main control unit; A conducting element is provided in the shielding unit. One end of the conducting element is connected to the operational amplifier unit, and the other end of the conducting element is connected to the main control unit. The shielding unit is configured to control the closing and opening of the conducting element according to an instruction from the main control unit; The main control unit is configured to control the conducting element to close during the optical pulse signal emission period and open during the non-emission period, so as to shield the useless signals acquired by the receiving unit during the non-emission period.

7. The optoelectronic sensor according to claim 5, characterized in that, The photoelectric sensor further includes an output protection unit for connecting to a load; The output protection unit is configured to turn off the output of the photoelectric sensor to the load when the load current exceeds a preset current value, and perform self-locking on the output protection unit through a capacitive element until the main control unit restarts the output protection unit.

8. The optoelectronic sensor according to claim 7, characterized in that, The output protection unit includes a fourth triode connected to the load and a fifth triode connected to the fourth triode; The emitter of the fourth triode is connected to the base of the fifth triode through a fourth resistor. One end of the fourth resistor is commonly connected to the emitter of the fourth triode and then connected to a fifth resistor. The other end of the fifth resistor is grounded. The other end of the fourth resistor and the base of the fifth triode are commonly connected with the capacitive element, and the other end of the capacitive element is grounded; The collector of the fifth triode is connected to a sixth triode. The collector of the fifth triode is connected to the base of the sixth triode. The base of the fifth triode is connected to the collector of the sixth triode. A second diode is connected between the emitter of the sixth triode and the base of the fourth triode; When the collector current of the fourth triode exceeds a preset current, the fifth resistor drives the fourth resistor, the fifth triode and the sixth triode to conduct, so as to pull down the voltage between the base and the emitter of the fourth triode.

9. The optoelectronic sensor according to claim 8, wherein, The main control unit is connected between the sixth triode and the second diode. When the voltage between the base and the emitter of the fourth triode is pulled down, the main control unit charges the capacitive element through the sixth triode and the fifth triode, so that the fourth triode remains in the cut-off state continuously, and performs self-locking on the output protection unit.

10. The optoelectronic sensor according to claim 5, characterized in that, The photoelectric sensor further includes an indication unit connected to the main control unit and including at least one light-emitting diode; The indication unit is configured to control the light-emitting state of the light-emitting diode according to whether there is a target detection object between the transmitting unit and the receiving unit.

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