Laser safety protection circuit

Abstract

The utility model provides a laser safety protection circuit. The laser safety protection circuit comprises a laser, a laser driving circuit, a threshold detection circuit and a current sampling circuit. Wherein the current sampling circuit at least comprises a photoelectric sensor and a sampling circuit; one end of the laser driving circuit is connected with the laser and power supply voltage, and is used for triggering the laser to generate laser by a constant-source current generated by the laser driving circuit and irradiating the laser into the photoelectric sensor, so that the photoelectric sensor generates light current; the photoelectric sensor is connected with one end of the sampling circuit and is used for converting light current into light voltage; the other end of the sampling circuit is connected with one end of the threshold detection circuit, the other end of the threshold detection circuit is connected with the other end of the laser driving circuit, and the threshold detection circuit is used for detecting whether the photovoltage exceeds a preset voltage value or not and triggering a circuit switch in the laser driving circuit through the threshold detection circuit if the photovoltage exceeds the preset voltage value. Therefore, the safety of human eyes is protected.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, in particular to a laser safety protection circuit. Background Art

[0002] In order to ensure the safety of lasers to human eyes, in equipment using lasers, it is required that the laser power entering the eye must be less than the safety power specified by regulations. Therefore, it is necessary to make preventive preparations for the laser power entering the eye exceeding the standard to achieve the safety effect of protecting the human eye.

[0003] Therefore, there is an urgent need for a laser safety protection circuit that can detect whether the laser eye power exceeds the standard. Utility Model Content

[0004] Based on the above-mentioned deficiencies of the prior art, the utility model provides a laser safety protection circuit to achieve the purpose of detecting whether the laser eye power exceeds the standard.

[0005] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0006] The first aspect of the utility model provides a laser safety protection circuit, comprising:

[0007] Laser, laser driving circuit, threshold detection circuit and current sampling circuit;

[0008] Wherein, the current sampling circuit at least includes a photoelectric sensor and a sampling circuit;

[0009] One end of the laser driving circuit is connected to the laser and the power supply voltage, and the constant source current generated by the laser driving circuit triggers the laser to generate laser light, and irradiates the laser light to the photoelectric sensor, so that the photoelectric sensor generates photocurrent;

[0010] The photoelectric sensor is connected to one end of the sampling circuit and is used to convert the photocurrent into a photovoltage;

[0011] The other end of the sampling circuit is connected to one end of the threshold detection circuit, and the other end of the threshold detection circuit is connected to the other end of the laser driving circuit, for detecting whether the photovoltage exceeds a preset voltage value.

[0012] Optionally, the laser driving circuit includes: a constant current circuit, a feedback network and a target circuit;

[0013] The first end of the constant current circuit is connected to the laser and the power supply voltage, and the second end of the constant current circuit is respectively connected to the first end of the feedback network, the first end of the target circuit and one end of the threshold detection circuit;

[0014] The second end of the feedback network is connected to the second end of the target circuit.

[0015] Optionally, the constant current circuit includes a first resistor, a first capacitor, a second capacitor, a first MOS tube and a diode;

[0016] The first end of the first capacitor is connected to the power supply voltage and the first end of the second capacitor respectively, and the second end of the first capacitor is grounded;

[0017] The first end of the second capacitor is connected to the positive electrode of the laser and the negative electrode of the diode respectively, and the second end of the second capacitor is connected to the negative electrode of the laser, the positive electrode of the diode and the drain of the first MOS tube respectively;

[0018] The source of the first MOS transistor is connected to one end of the feedback network and the first end of the first resistor, and the gate of the first MOS transistor is connected to the second end of the target circuit;

[0019] A second end of the first resistor is grounded.

[0020] Optionally, the feedback network includes: a first operational amplifier, a second resistor, a third resistor, a fourth resistor and a third capacitor;

[0021] The first end of the second resistor is connected to the source of the first MOS transistor, and the second end of the second resistor is connected to the positive input end of the first operational amplifier;

[0022] The first end of the third resistor is respectively connected to the negative input end of the first operational amplifier and the first end of the fourth resistor, and the second end of the third resistor is grounded;

[0023] The output end of the first operational amplifier is respectively connected to the first end of the target circuit and the second end of the fourth resistor;

[0024] The fourth resistor is connected in parallel with the third capacitor.

[0025] Optionally, the target circuit includes: a fifth resistor, a sixth resistor, a seventh resistor, a second operational amplifier and a fourth capacitor;

[0026] The first end of the fourth capacitor is connected to the negative input end of the second operational amplifier, and the second end of the fourth capacitor is connected to the output end of the second operational amplifier respectively;

[0027] A first end of the fifth resistor is connected to the negative input end of the second operational amplifier, and a second end of the fifth resistor is connected to the output end of the first operational amplifier;

[0028] A first end of the sixth resistor is connected to the positive input end of the second operational amplifier, and a second end of the sixth resistor is connected to a voltage input port or a voltage follower circuit;

[0029] A first end of the seventh resistor is connected to the output end of the second operational amplifier, and a second end of the seventh resistor is connected to the gate of the first MOS transistor.

[0030] Optionally, the voltage follower circuit includes: a fifth operational amplifier, a sixth capacitor, a seventh capacitor and an eighteenth resistor;

[0031] The positive input terminal of the fifth operational amplifier is respectively connected to the first terminal of the sixth capacitor and the voltage input port, the negative input terminal of the fifth operational amplifier is connected to the first terminal of the eighteenth resistor, and the output terminal of the fifth operational amplifier is respectively connected to the second terminal of the eighteenth resistor and the second terminal of the sixth resistor in the target circuit;

[0032] The second end of the sixth capacitor is grounded;

[0033] The seventh capacitor is connected in parallel with the eighteenth resistor.

[0034] Optionally, the sampling circuit includes: a fifth capacitor, an eighth resistor, a ninth resistor and a third operational amplifier;

[0035] The positive input terminal of the third operational amplifier is connected to the first end of the ninth resistor and the photoelectric sensor respectively, the negative input terminal of the third operational amplifier is connected to the first end of the eighth resistor, and the output terminal of the third operational amplifier is connected to one end of the threshold detection circuit;

[0036] The fifth capacitor is connected in parallel with the eighth resistor, and a second end of the ninth resistor is grounded.

[0037] Optionally, the threshold detection circuit includes: a threshold comparator, a third MOS tube and a twelfth resistor;

[0038] The gate of the third MOS tube is respectively connected to the threshold comparator and the first end of the twelfth resistor, the drain of the third MOS tube is connected to the gate of the first MOS tube in the laser driving circuit, and the source of the third MOS tube is grounded.

[0039] Optionally, the threshold detection circuit further includes: a second MOS tube, a tenth resistor, an eleventh resistor and a thirteenth resistor;

[0040] The drain of the second MOS tube is connected to the gate of the first MOS tube in the laser driving circuit, and the source of the second MOS tube is grounded; the gate of the second MOS tube is respectively connected to the first end of the tenth resistor, the first end of the eleventh resistor, and the first end of the thirteenth resistor; the first end of the eleventh resistor is also connected to the gate of the third MOS tube;

[0041] The second end of the tenth resistor is connected to the power supply voltage and the second end of the eleventh resistor respectively.

[0042] Optionally, the threshold comparator includes: a target diode, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor and a fourth operational amplifier;

[0043] The cathode of the target diode is connected to the first end of the fourteenth resistor and the output end of the third operational amplifier in the sampling circuit respectively, and the anode of the target diode is grounded;

[0044] The positive input terminal of the fourth operational amplifier is respectively connected to the second end of the fourteenth resistor and the first end of the seventeenth resistor, the negative input terminal of the fourth operational amplifier is connected to the first end of the fifteenth resistor, and the output terminal of the fourth operational amplifier is respectively connected to the first end of the sixteenth resistor and the second end of the seventeenth resistor;

[0045] The first end of the sixteenth resistor is connected to the second end of the seventeenth resistor, and the second end of the sixteenth resistor is connected to the gate of the third MOS tube;

[0046] The second end of the fifteenth resistor is connected to the threshold voltage setting port.

[0047] The utility model provides a laser safety protection circuit, which includes: a laser, a laser driving circuit, a threshold detection circuit and a current sampling circuit, wherein the current sampling circuit at least includes a photoelectric sensor and a sampling circuit, one end of the laser driving circuit is connected to the laser and the power supply voltage, and the constant source current generated by the laser driving circuit triggers the laser to generate laser light, and irradiates the photoelectric sensor, so that the photoelectric sensor generates a photocurrent, the photoelectric sensor is connected to one end of the sampling circuit, and is used to convert the photocurrent into a photovoltage, the other end of the sampling circuit is connected to one end of the threshold detection circuit, and the other end of the threshold detection circuit is connected to the other end of the laser driving circuit, and is used to detect whether the photovoltage exceeds a preset voltage value, and if the photovoltage exceeds the preset voltage value, the circuit switch in the laser driving circuit is triggered by the threshold detection circuit to turn off the laser. The utility model can complete the rapid shutdown of the laser through a hardware circuit, which not only improves the safety of human eyes, but also improves the accuracy of control and reduces industrial costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0049] Figure 1 A schematic diagram of the structure of a laser safety protection circuit provided by an embodiment of the utility model;

[0050] Figure 2 A first structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model;

[0051] Figure 3 A second structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model;

[0052] Figure 4 A third structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model;

[0053] Figure 5 A fourth structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model;

[0054] Figure 6 A fifth structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model;

[0055] Figure 7 A sixth structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model;

[0056] Figure 8 A seventh structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model;

[0057] Fig. 9 An eighth structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model;

[0058] Fig.10 A flow chart of a photovoltage detection method provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0060] In the present invention, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0061] As can be seen from the background technology, in equipment using lasers, in order to ensure the safety of the laser to human eyes, it is necessary to make preventive preparations for excessive laser power.

[0062] Therefore, an embodiment of the utility model provides a laser safety protection circuit, including: a laser, a laser driving circuit, a threshold detection circuit and a current sampling circuit. The laser power generated by the laser is safely detected by the laser driving circuit, the threshold detection circuit and the current sampling circuit. If the laser power exceeds the safety threshold, it will trigger the controllable switch circuit inside the laser driving circuit to shut down, thereby achieving the purpose of shutting down the laser.

[0063] So see Figure 1 , shows a schematic diagram of the structure of a laser safety protection circuit provided in an embodiment of the utility model, wherein the laser safety protection circuit includes a laser 101, a laser driving circuit 102, a threshold detection circuit 103 and a current sampling circuit 104.

[0064] The current sampling circuit 104 may include a photoelectric sensor ( Figure 1 D1 in ) and sampling circuit 105.

[0065] It should be noted that, in the present invention, the photoelectric sensor (D1) is used as a photoelectric conversion device. The stronger the laser power generated by the laser 101, the greater the photocurrent generated by the photoelectric sensor (D1).

[0066] In some embodiments, the photosensor (D1) may be a PD, an APD, an MPPC, or the like.

[0067] One end of the laser driving circuit 102 is connected to the laser 101 and the power supply voltage ( Figure 1 The laser driving circuit 102 generates a constant source current which triggers the laser 101 to generate laser light and irradiates the laser light to the photoelectric sensor (D1), so that the photoelectric sensor (D1) generates a photocurrent.

[0068] It should be emphasized that the laser driving circuit 102 is a stable laser driving source, which can make the laser 101 work stably, and the laser driving circuit 102 also includes a controllable switch (Q1) of the laser 101. Specifically, when the power supply voltage inputs the corresponding voltage to the laser driving circuit 102, the laser 101 generates laser, and then uses a split light path to irradiate part of the laser onto the photoelectric sensor (D1), so that the photoelectric sensor (D1) generates a photocurrent.

[0069] The photoelectric sensor (D1) is connected to one end of the sampling circuit 105 and is used to convert the photocurrent into a photovoltage.

[0070] It can be understood that in the present invention, the photocurrent generated by the photoelectric sensor (D1) is converted into a photovoltage through the sampling circuit 105. If the photocurrent is larger, the converted voltage signal will be larger. Therefore, it is necessary to perform safety detection on the converted voltage signal to avoid exceeding the preset safety voltage standard, thereby damaging human eyes.

[0071] The other end of the sampling circuit 105 is connected to one end of the threshold detection circuit 103 , and the other end of the threshold detection circuit 103 is connected to the other end of the laser driving circuit 102 .

[0072] It should be emphasized that the threshold detection circuit 103 is responsible for making a safety judgment on the converted photovoltage, that is, detecting whether the photovoltage exceeds the preset voltage value. If the photovoltage exceeds the preset voltage value, the controllable switch Q1 in the laser driving circuit 102 will be triggered to be closed through the threshold detection circuit 103 to turn off the laser 101.

[0073] Optionally, if the photovoltage does not exceed the preset voltage value, the threshold detection circuit 103 will remain in the on state to continuously detect the converted photovoltage.

[0074] In an embodiment of the utility model, the laser safety protection circuit includes a laser driving circuit, a current sampling circuit and a threshold detection circuit, and detects the safety threshold of the converted photovoltage to achieve the function of protecting human eyes.

[0075] In some specific embodiments, in combination Figure 1, see Figure 2 , shows a first structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model, the laser driving circuit 102 includes: a constant current circuit 201, a feedback network 202 and a target circuit 203.

[0076] The first end of the constant current circuit 201 is connected to the laser 101 and the power supply voltage, and the second end of the constant current circuit 201 is respectively connected to the first end of the feedback network 202, the first end of the target circuit 203 and one end of the threshold detection circuit 103.

[0077] A second terminal of the feedback network 202 is connected to a second terminal of the target circuit 203 .

[0078] It should be noted that the constant current circuit 201, the feedback network 202 and the target circuit 203 form a constant current source circuit, namely, the laser driving circuit 102. During the application process, when the laser 101 is connected to the constant current source circuit, the constant current source circuit will pull down the internal laser signal, and then the power supply voltage will input the corresponding voltage to control the output voltage of the constant current source circuit, triggering the laser 101 to emit laser so that it shines on the photoelectric sensor (D1), so as to subsequently know whether the laser at this time will endanger the safety of human eyes.

[0079] In a specific embodiment, in combination Figure 1 and Figure 2 , see Figure 3 , shows a second structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model, the constant current circuit 201 includes a first resistor (R8), a first capacitor (C2), a second capacitor (C5), a first MOS tube (Q1) and a diode (D2).

[0080] The first end of the first capacitor (C2) is respectively connected to the power supply voltage and the first end of the second capacitor (C5), and the second end of the first capacitor (C2) is grounded.

[0081] The first end of the second capacitor (C5) is respectively connected to the positive electrode of the laser 101 and the negative electrode of the diode (D2), and the second end of the second capacitor (C5) is respectively connected to the negative electrode of the laser 101, the positive electrode of the diode (D2) and the drain of the first MOS tube (the second end of Q1).

[0082] The source of the first MOS transistor (the third end of Q1 ) is connected to one end of the feedback network 202 and the first end of the first resistor ( R8 ), and the gate of the first MOS transistor (the first end of Q1 ) is connected to the second end of the target circuit 203 .

[0083] A second end of the first resistor (R8) is grounded.

[0084] In some specific embodiments, the diode (D2) is a rectifier diode, and the first resistor (R8) is a current limiting resistor, which can provide a stable DC power supply for the constant current circuit 201.

[0085] It can be seen from the above content that when the laser 101 emits laser, the first resistor (R8), the first capacitor (C2), the second capacitor (C5), the first MOS tube (Q1) and the diode (D2) in the constant current circuit 201 will form a voltage stabilizing circuit for protecting and stabilizing the function of the laser 101, and the key is to provide a stable working current.

[0086] In a specific embodiment, in combination Figure 1 , Figure 2 as well as Figure 3 , see Figure 4 , showing a third structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model, the feedback network 202 includes: a first operational amplifier (U1B), a second resistor (R6), a third resistor (R7), a fourth resistor (R9) and a third capacitor (C6).

[0087] The first end of the second resistor (R6) is connected to the source of the first MOS tube (the third end of Q1), and the second end of the second resistor (R6) is connected to the positive input end of the first operational amplifier (U1B).

[0088] The first end of the third resistor (R7) is respectively connected to the negative input end of the first operational amplifier (U1B) and the first end of the fourth resistor (R9), and the second end of the third resistor (R7) is grounded.

[0089] The output terminal of the first operational amplifier (U1B) is connected to the first terminal of the target circuit 203 and the second terminal of the fourth resistor (R9) respectively.

[0090] The fourth resistor (R9) is connected in parallel with the third capacitor (C6).

[0091] It should be noted that the first operational amplifier (U1B) plays a role in adjusting the amplification ratio in the feedback network 202 .

[0092] In the embodiment of the utility model, the feedback network includes a first operational amplifier, a second resistor, a third resistor, a fourth resistor and a third capacitor, wherein the first operational amplifier is one of the core components of the feedback network, responsible for amplifying the signal and controlling the operating state of the entire circuit. The second resistor, the third resistor, the fourth resistor and the third capacitor are used to adjust the gain, frequency characteristics and stability of the feedback network. By reasonably selecting and configuring the values ​​of these components, the performance of the amplifier circuit can be accurately adjusted and controlled.

[0093] In a specific embodiment, in combination Figure 1 , Figure 2 , Figure 3 as well as Figure 4 , see Figure 5 , showing a fourth structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model, the target circuit 203 includes: a fifth resistor (R4), a sixth resistor (R2), a seventh resistor (R3), a second operational amplifier (U1C) and a fourth capacitor (C3).

[0094] A first end of the fourth capacitor (C3) is connected to the negative input end of the second operational amplifier (U1C), and a second end of the fourth capacitor (C3) is connected to the output end of the second operational amplifier (U1C).

[0095] A first end of the fifth resistor (R4) is connected to the negative input end of the second operational amplifier (U1C), and a second end of the fifth resistor (R4) is connected to the output end of the first operational amplifier (U1B).

[0096] A first end of the sixth resistor (R2) is connected to the positive input end of the second operational amplifier (U1C), and a second end of the sixth resistor (R2) is connected to the voltage input port (con interface).

[0097] A first end of the seventh resistor (R3) is connected to the output end of the second operational amplifier (U1C), and a second end of the seventh resistor (R3) is connected to the gate (the first end of Q1) of the first MOS tube.

[0098] In a specific embodiment, in combination Figure 1 , Figure 2 , Figure 3 , Figure 4 as well as Figure 5 , see Figure 6 , shows a fifth structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model, the sampling circuit 105 includes: a fifth capacitor (C7), an eighth resistor (R12), a ninth resistor (R15) and a third operational amplifier (U1D).

[0099] The positive input terminal of the third operational amplifier (U1D) is respectively connected to the first end of the ninth resistor (R15) and the photoelectric sensor (D1), the negative input terminal of the third operational amplifier (U1D) is connected to the first end of the eighth resistor, the output terminal of the third operational amplifier (U1D) and the second end of the eighth resistor (R12) are connected to one end of the threshold detection circuit 103, and the second end of the ninth resistor (R15) is grounded.

[0100] The fifth capacitor (C7) is connected in parallel with the eighth resistor (R12).

[0101] In some specific embodiments, the ninth resistor (R15) is a sampling resistor, which can be used to set sampling parameters, specifically expressed as:

[0102] OV =I Sensor R15

[0103] Among them, O V is the photovoltage converted by the sampling circuit 105, I Sensor is the photocurrent output by the photosensor (D1).

[0104] In an embodiment of the utility model, the sampling circuit includes a fifth capacitor, an eighth resistor, a ninth resistor and a third operational amplifier. The photocurrent generated by the photoelectric sensor (D1) is converted into a photovoltage through the components in the sampling circuit, which can better adapt to the characteristics and requirements of the laser safety protection circuit, thereby facilitating improving the efficiency and reliability of signal processing.

[0105] In a specific embodiment, in combination Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 as well as Figure 6 , see Figure 7 , shows a sixth structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model, the threshold detection circuit 103 includes: a threshold comparator 701, a third MOS tube (Q3), a tenth resistor (R10), an eleventh resistor (R11), a twelfth resistor (R14), a thirteenth resistor (R13) and a second MOS tube (Q2).

[0106] The gate of the third MOS tube (the G end of Q3) is respectively connected to the threshold comparator 701, the first end of the twelfth resistor (R14) and the first end of the eleventh resistor (R11), the drain of the third MOS tube (the D end of Q3) and the drain of the second MOS tube (the D end of Q2) are connected to the gate of the first MOS tube (the first end of Q1) in the laser driving circuit 102, and the source of the third MOS tube (the S end of Q3) and the source of the second MOS tube (the S end of Q2) are grounded. When the output power of the laser 101 is too large, so that the output voltage of the sampling circuit is greater than the set threshold voltage, the threshold comparator 701 will output a high level to turn on the source and drain of the third MOS tube (Q3), so that the gate of the first MOS tube (Q1) is grounded, thereby turning off the source and drain of the first MOS tube (Q1), realizing the turning off of the constant current source, and then controlling the turning off of the laser 101.

[0107] The second end of the thirteenth resistor (R13) is connected to the second control signal, and the first end of the thirteenth resistor (R13) is respectively connected to the gate of the second MOS tube (G end of Q2) and the first end of the tenth resistor (R10).

[0108] The second end of the tenth resistor (R10) is connected to the power supply voltage and the second end of the eleventh resistor (R11) respectively.

[0109] The second end of the twelfth resistor (R14) is connected to the first control signal.

[0110] In some specific embodiments, the second MOS tube (Q2) and the third MOS tube (Q3) are controlled devices, the first control signal is a laser state signal (Laser_State), and the second control signal is a laser external control enable signal (Laser_EN_N), which controls the switch of the second MOS tube (Q2). There will be a Laser_State pin in the laser safety protection circuit, which is used to reflect the state of the third MOS tube (Q3). When Laser_State is detected to be at a high level, that is, the source and drain of the third MOS tube (Q3) are turned on, then Laser_EN_N is pulled high, so that the source and drain of the second MOS tube (Q2) are turned on, so as to further ensure that the gate of the first MOS tube (Q1) is grounded, thereby closing the source and drain of the first MOS tube (Q1), realizing the closing of the constant current source, and then controlling the closing of the laser 101.

[0111] It should be noted that, since the sampling circuit 105 is connected to the threshold comparator 701 in the threshold detection circuit 103, when the converted voltage is input into the threshold comparator 701, the threshold comparator 701 sets the upper voltage and the lower voltage of the threshold comparator 701 through the internal port. When the converted light voltage is greater than the preset upper threshold voltage, the threshold comparator 701 outputs a high level, quickly controls the third MOS tube (Q3) to turn on, thereby pulling down the gate of the first MOS tube (the first end of Q1), turning off the first MOS tube (Q1), and thus turning off the laser 101.

[0112] In an embodiment of the utility model, the threshold detection circuit includes a threshold comparator, a third MOS tube, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor and a second MOS tube, so that the threshold comparator, the third MOS tube and other components in the threshold detection circuit can realize safety monitoring and protection of the laser, thereby ensuring the safety of equipment and personnel.

[0113] In a specific embodiment, in combination Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 as well as Figure 7 , see Figure 8, shows the seventh structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model, the threshold comparator 701 includes: a target diode (D3), a fourteenth resistor (R18), a fifteenth resistor (R19), a sixteenth resistor (R16), a seventeenth resistor (R17) and a fourth operational amplifier (U2).

[0114] The cathode of the target diode (D3) is connected to the first end of the fourteenth resistor (R18) and the output end of the third operational amplifier (U1D) in the sampling circuit 105, respectively, and the anode of the target diode (D3) is grounded.

[0115] The positive input terminal of the fourth operational amplifier (U2) is respectively connected to the second end of the fourteenth resistor (R18) and the first end of the seventeenth resistor (R17), the negative input terminal of the fourth operational amplifier (U2) is connected to the first end of the fifteenth resistor (R19), and the output terminal of the fourth operational amplifier (U2) is connected to the first end of the sixteenth resistor (R16).

[0116] The first end of the sixteenth resistor (R16) is connected to the second end of the seventeenth resistor (R17), and the second end of the sixteenth resistor (R16) is connected to the gate of the third MOS tube (G end of Q3).

[0117] The second end of the fifteenth resistor (R19) is connected to the threshold voltage setting port. Specifically, the threshold voltage setting port may be a Comparer_Set port.

[0118] In some specific embodiments, the target diode (D3) is a voltage-stabilizing diode, which is used to achieve functions such as voltage stabilization, regulation, and protection in laser safety protection.

[0119] In the embodiment of the utility model, when the photovoltage is input into the threshold comparator, the threshold comparator can set the upper voltage and lower voltage of the threshold comparator through the internal Comparer_Set port. By comparing whether the photovoltage exceeds the upper voltage in the threshold comparator, if it exceeds the upper voltage, the laser is turned off through the controlled device, thereby ensuring the safety of human eyes.

[0120] In some specific embodiments, the laser safety protection circuit further includes: a voltage follower circuit 901 .

[0121] One end of the voltage follower circuit 901 is connected to the target circuit 203 in the laser driving circuit 102, and the other end of the voltage follower circuit 901 is connected to the voltage input port. Specifically, the voltage input port includes but is not limited to a con interface, a digital-to-analog converter (DAC) and an adjustable resistor, which are used to stabilize the voltage of the laser driving circuit 102.

[0122] It should be noted that, since the voltage follower circuit 901 usually includes a voltage stabilizer or other stabilizing elements, it can provide voltage stability to a certain extent, ensuring that the output voltage will not change significantly with the fluctuation of the input voltage. This stabilizing effect helps to prevent the impact of voltage fluctuations on subsequent circuits or devices, and improve the stability and reliability of the system. In addition, the voltage follower circuit 901 can also be used for signal transmission and amplification, amplifying the input signal and changing it with the change of the input signal, thereby achieving front-to-back isolation and enhancement of the signal.

[0123] In a specific embodiment, in combination Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 ,as well as Figure 8 , see Fig. 9 , shows an eighth structural schematic diagram of a laser safety protection circuit provided by an embodiment of the utility model, the voltage follower circuit 901 includes: a fifth operational amplifier (U1A), a sixth capacitor (C1), a seventh capacitor (C4) and an eighteenth resistor (R5).

[0124] The positive input terminal of the fifth operational amplifier (U1A) is respectively connected to the first end of the sixth capacitor (C1) and the Con port, the negative input terminal of the fifth operational amplifier (U1A) is connected to the first end of the eighteenth resistor (R5), and the output terminal of the fifth operational amplifier (U1A) is respectively connected to the second end of the eighteenth resistor (R5) and the second end of the sixth resistor (R2) in the target circuit 203.

[0125] A second terminal of the sixth capacitor (C1) is grounded.

[0126] The seventh capacitor (C4) is connected in parallel with the eighteenth resistor (R5).

[0127] In the embodiment of the utility model, the voltage follower circuit uses components such as operational amplifiers to achieve front and rear isolation. Through the operation and control of these components, the input voltage can be followed and the output voltage can be kept at the same level as the input voltage. Thus, an isolated stable environment is established between the front and rear circuits to ensure that the output voltage is always consistent with the input voltage.

[0128] Corresponding to a laser safety protection circuit provided by the above-mentioned embodiment of the utility model, see Fig.10 The embodiment of the utility model further provides a flow chart of a method for detecting a photovoltage. The method for detecting a photovoltage is applicable to the laser safety protection circuit mentioned in the embodiment of the utility model. The method for detecting a photovoltage includes:

[0129] Step S1001: obtaining the photocurrent generated by the laser in the laser driving circuit through a current sampling circuit.

[0130] Step S1002: converting the photocurrent into photovoltage.

[0131] Step S1003: determining whether the photovoltage is greater than a preset safety voltage through a threshold detection circuit.

[0132] Specifically, if the photovoltage is greater than the preset safety voltage, step S1004 is executed.

[0133] Optionally, if the photovoltage is less than a preset safety voltage, the laser continues to be turned on.

[0134] Step S1004: Turn off the laser.

[0135] It should be noted that for the specific contents of the laser driving circuit, the current sampling circuit and the threshold detection circuit, please refer to the above-mentioned embodiment of the present invention. Figures 1 to 9 It should also be noted that the photovoltage detection method is only implemented by the circuit, and the laser can be quickly turned off without the assistance of software or control chip.

[0136] In an embodiment of the utility model, the photocurrent of the laser is obtained, and whether the laser light generated by the laser at this time will endanger the safety of human eyes is determined according to the photocurrent of the laser. If so, the laser is immediately turned off, thereby achieving the purpose of protecting human eyes.

[0137] In summary, the embodiment of the utility model provides a laser safety protection circuit, which includes: a laser, a laser driving circuit, a threshold detection circuit and a current sampling circuit, wherein the current sampling circuit includes at least a photoelectric sensor and a sampling circuit, one end of the laser driving circuit is connected to the laser and the power supply voltage, and the constant source current generated by the laser driving circuit triggers the laser to generate laser light, and irradiates the photoelectric sensor, so that the photoelectric sensor generates a photocurrent, and the photoelectric sensor is connected to one end of the sampling circuit, which is used to convert the photocurrent into a photovoltage, and the other end of the sampling circuit is connected to one end of the threshold detection circuit, and the other end of the threshold detection circuit is connected to the other end of the laser driving circuit, which is used to detect whether the photovoltage exceeds a preset voltage value. If the photovoltage exceeds the preset voltage value, the threshold detection circuit triggers the circuit switch in the laser driving circuit to turn off the laser. This protects the safety of human eyes.

[0138] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present utility model.

[0139] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A laser safety protection circuit, characterized in that: The laser safety protection circuit comprises: Laser, laser driving circuit, threshold detection circuit and current sampling circuit; Wherein, the current sampling circuit at least includes a photoelectric sensor and a sampling circuit; One end of the laser driving circuit is connected to the laser and the power supply voltage, and the constant source current generated by the laser driving circuit triggers the laser to generate laser light, and irradiates the laser light to the photoelectric sensor, so that the photoelectric sensor generates photocurrent; The photoelectric sensor is connected to one end of the sampling circuit and is used to convert the photocurrent into a photovoltage; The other end of the sampling circuit is connected to one end of the threshold detection circuit, and the other end of the threshold detection circuit is connected to the other end of the laser driving circuit, for detecting whether the photovoltage exceeds a preset voltage value.

2. The laser safety protection circuit according to claim 1, characterized in that: The laser driving circuit comprises: a constant current circuit, a feedback network and a target circuit; The first end of the constant current circuit is connected to the laser and the power supply voltage, and the second end of the constant current circuit is respectively connected to the first end of the feedback network, the first end of the target circuit and one end of the threshold detection circuit; The second end of the feedback network is connected to the second end of the target circuit.

3. The laser safety protection circuit according to claim 2, characterized in that: The constant current circuit comprises a first resistor, a first capacitor, a second capacitor, a first MOS tube and a diode; The first end of the first capacitor is connected to the power supply voltage and the first end of the second capacitor respectively, and the second end of the first capacitor is grounded; The first end of the second capacitor is connected to the positive electrode of the laser and the negative electrode of the diode respectively, and the second end of the second capacitor is connected to the negative electrode of the laser, the positive electrode of the diode and the drain of the first MOS tube respectively; The source of the first MOS transistor is connected to one end of the feedback network and the first end of the first resistor, and the gate of the first MOS transistor is connected to the second end of the target circuit; A second end of the first resistor is grounded.

4. The laser safety protection circuit according to claim 2, characterized in that: The feedback network includes: a first operational amplifier, a second resistor, a third resistor, a fourth resistor and a third capacitor; The first end of the second resistor is connected to the second end of the constant current circuit, and the second end of the second resistor is connected to the positive input end of the first operational amplifier; The first end of the third resistor is respectively connected to the negative input end of the first operational amplifier and the first end of the fourth resistor, and the second end of the third resistor is grounded; The output end of the first operational amplifier is respectively connected to the first end of the target circuit and the second end of the fourth resistor; The fourth resistor is connected in parallel with the third capacitor.

5. The laser safety protection circuit according to claim 2, characterized in that: The target circuit includes: a fifth resistor, a sixth resistor, a seventh resistor, a second operational amplifier and a fourth capacitor; The first end of the fourth capacitor is connected to the negative input end of the second operational amplifier, and the second end of the fourth capacitor is connected to the output end of the second operational amplifier respectively; A first end of the fifth resistor is connected to the negative input end of the second operational amplifier, and a second end of the fifth resistor is connected to the second end of the feedback network; A first end of the sixth resistor is connected to the positive input end of the second operational amplifier, and a second end of the sixth resistor is connected to a voltage input port or a voltage follower circuit; A first end of the seventh resistor is connected to the output end of the second operational amplifier, and a second end of the seventh resistor is connected to the second end of the constant current circuit.

6. The laser safety protection circuit according to claim 5, characterized in that: The voltage follower circuit comprises: a fifth operational amplifier, a sixth capacitor, a seventh capacitor and an eighteenth resistor; The positive input terminal of the fifth operational amplifier is respectively connected to the first terminal of the sixth capacitor and the voltage input port, the negative input terminal of the fifth operational amplifier is connected to the first terminal of the eighteenth resistor, and the output terminal of the fifth operational amplifier is respectively connected to the second terminal of the eighteenth resistor and the second terminal of the sixth resistor in the target circuit; The second end of the sixth capacitor is grounded; The seventh capacitor is connected in parallel with the eighteenth resistor.

7. The laser safety protection circuit according to claim 1, characterized in that: The sampling circuit comprises: a fifth capacitor, an eighth resistor, a ninth resistor and a third operational amplifier; The positive input terminal of the third operational amplifier is connected to the first end of the ninth resistor and the photoelectric sensor respectively, the negative input terminal of the third operational amplifier is connected to the first end of the eighth resistor, and the output terminal of the third operational amplifier is connected to one end of the threshold detection circuit; The fifth capacitor is connected in parallel with the eighth resistor, and a second end of the ninth resistor is grounded.

8. The laser safety protection circuit according to claim 1, characterized in that: The threshold detection circuit comprises: a threshold comparator, a third MOS tube and a twelfth resistor; The gate of the third MOS tube is respectively connected to the threshold comparator and the first end of the twelfth resistor, the drain of the third MOS tube is connected to the gate of the first MOS tube in the laser driving circuit, and the source of the third MOS tube is grounded.

9. The laser safety protection circuit according to claim 8, characterized in that: The threshold detection circuit further includes: a second MOS tube, a tenth resistor, an eleventh resistor and a thirteenth resistor; The drain of the second MOS tube is connected to the gate of the first MOS tube in the laser driving circuit, and the source of the second MOS tube is grounded; the gate of the second MOS tube is respectively connected to the first end of the tenth resistor, the first end of the eleventh resistor, and the first end of the thirteenth resistor; the first end of the eleventh resistor is also connected to the gate of the third MOS tube; The second end of the tenth resistor is connected to the power supply voltage and the second end of the eleventh resistor respectively.

10. The laser safety protection circuit according to claim 9, characterized in that: The threshold comparator comprises: a target diode, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor and a fourth operational amplifier; The cathode of the target diode is connected to the first end of the fourteenth resistor and the output end of the third operational amplifier in the sampling circuit respectively, and the anode of the target diode is grounded; The positive input terminal of the fourth operational amplifier is respectively connected to the second end of the fourteenth resistor and the first end of the seventeenth resistor, the negative input terminal of the fourth operational amplifier is connected to the first end of the fifteenth resistor, and the output terminal of the fourth operational amplifier is respectively connected to the first end of the sixteenth resistor and the second end of the seventeenth resistor; The first end of the sixteenth resistor is connected to the second end of the seventeenth resistor, and the second end of the sixteenth resistor is connected to the gate of the third MOS tube; The second end of the fifteenth resistor is connected to the threshold voltage setting port.

Images