Safety switch circuit

Abstract

The utility model discloses a safety switch circuit, which comprises a switch, a first port and a second port which are used for being connected with a positive electrode or a negative electrode of a power supply, a first driving circuit and a second driving circuit which are used for driving the switch, a first holding circuit and a second holding circuit which are used for enabling the switch to be in a self-holding state, and a time control adjusting circuit, the time control adjusting circuit controls the output of the safety switch circuit by limiting the time difference when the first port and the second port are sequentially connected to a power supply, and the first driving circuit, the second port, the time control adjusting circuit and the second holding circuit are connected with each other. The first driving circuit is connected with the time control adjusting circuit through the first port and the second driving circuit, and is also connected with the second driving circuit through the first holding circuit; the output of the circuit is safely set, the time difference of the first port and the second port connected to the power supply is limited, misoperation is avoided, and the safety is high.

Description

Technical Field

[0001] This utility model belongs to the technical field of industrial automation control, and specifically relates to a safety switch circuit. Background Technology

[0002] In industrial production, two-hand synchronized control devices are crucial for ensuring operational safety. While traditional two-hand button control devices improve safety to some extent, they also pose safety hazards. For example, if one button is held down for an extended period, pressing the other button can start the equipment, potentially causing injury to the operator. Furthermore, many companies, due to cost or technical reasons, do not use standard-compliant two-hand synchronized modules, instead simply connecting the two buttons in series, which significantly reduces the effectiveness of safety protection. Utility Model Content

[0003] To address the aforementioned problems in the prior art, this application proposes a safety switch circuit that links the control of both hands with the start and stop of the equipment. This forces the operator to use both hands simultaneously for the equipment to start normally, preventing the operator's hands from entering the danger zone and thus meeting safety requirements.

[0004] The present invention adopts the following technical solution:

[0005] A safety switch circuit includes: a switch, a first port and a second port for connecting to the positive or negative terminal of a power supply, a first driving circuit and a second driving circuit for driving the switch, a first holding circuit and a second holding circuit for holding the switch in a self-holding state, and a timing control circuit. The timing control circuit controls the output of the safety switch circuit by limiting the time difference between the first port and the second port being connected to the power supply sequentially. The first driving circuit, the second port, the timing control circuit, and the second holding circuit are interconnected. The first driving circuit is connected to the timing control circuit through the first port and the second driving circuit, and is also connected to the second driving circuit through the first holding circuit. This solution has a simple overall circuit structure, is easy to manufacture and maintain, and helps to reduce costs and improve reliability. By requiring simultaneous operation with both hands, i.e., the first port and the second port are connected to the corresponding power supply, and the operation time meets the conditions of the timing control circuit before the safety switch circuit outputs, dangerous situations caused by single-handed misoperation or accidental triggering can be avoided, effectively ensuring the safety of operators and equipment.

[0006] Preferably, the timing control circuit includes a delay capacitor, a MOS transistor, and a bipolar junction transistor (BJT). One end of the delay capacitor is connected to the second port, the gate of the MOS transistor, and the base of the BJT. The drain of the MOS transistor is connected to the second driving circuit, and the source of the MOS transistor is connected to the collector of the BJT. The other end of the delay capacitor is connected to the emitter of the BJT, the second holding circuit, and the first driving circuit. The use of MOS transistors and BJTs addresses the common-cause failure problem of the system and enhances system stability through heterogeneous configuration.

[0007] More preferably, the timing control circuit includes two transistors, one of which has its collector connected to the source of the MOS transistor, and its emitter connected to the collector of the other transistor. The emitter of the other transistor is grounded and connected to the second holding circuit and the first driving circuit. This redundant design of the two transistors ensures that even if one transistor fails and short-circuits, the other transistor can still function as a cutoff circuit, improving the stability of the safety switch circuit.

[0008] More preferably, the circuit further includes: a first diode, a normally closed switch, a second diode, and a first resistor. The first driving circuit, the timing adjustment circuit, and the second holding circuit are all connected to the second port through the first diode. The second port is connected to one end of the delay capacitor through a normally closed switch, the second diode, and the first resistor connected in series. The first diode prevents reverse current flow, protecting the components in the first driving circuit, the timing adjustment circuit, and the second holding circuit from damage by reverse voltage, thus improving the stability and reliability of the circuit. The second diode and the first resistor are connected in series in the circuit, serving as voltage dividers and current limiters. The second diode prevents reverse current and, in conjunction with the first resistor, limits and regulates the current flowing to the delay capacitor, ensuring that the delay capacitor operates under appropriate voltage and current conditions. This prevents damage to the delay capacitor due to excessive voltage or current, thereby ensuring the normal operation of the timing adjustment circuit and improving the stability and safety of the entire safety switch circuit.

[0009] More preferably, the switch includes a relay, and the normally closed switch includes a normally closed contact of the relay. Using a relay satisfies the complex logic of this application, which requires simultaneous two-handed operation with a specified time difference before conduction, thus improving both safety and reliability while achieving precise control.

[0010] More preferably, it further includes: a power supply circuit, a control switch, a third port connected to the positive terminal of the power supply circuit, and a fourth port connected to the negative terminal of the power supply circuit. The control switch includes a first control switch and a second control switch. In the initial state, the second port is connected to the third port, and the fourth port is connected to the first port. When the first control switch is pressed alone, the first port is connected to the third port, and the second port is disconnected from the third port. When the second control switch is pressed alone, the second port is connected to the fourth port, and the first port and the fourth port are disconnected. When both the first and second control switches are pressed, the second port is connected to the fourth port, and the first port is connected to the third port. By changing the connection of the four ports through the control switches, it is ensured that the module will only work normally when both hands are operated simultaneously, avoiding incorrect triggering of the module due to single-handed misoperation or accidental touch, thus improving the safety and reliability of operation. Only when the timing difference between the operation of the first and second control switches is less than the turn-off time of the MOS transistor and the triode, the first drive circuit and the second drive circuit drive the relay, triggering the safety switch circuit to output a start signal.

[0011] More preferably, it further includes: an output circuit for outputting signals, the output circuit including the contacts of the relay; the power supply circuit including a rectifier diode, a thermistor, a fuse, and a filter capacitor, the positive terminal of the power supply being connected to the third port through the rectifier diode, the thermistor, and the fuse connected in series, and the third port being connected to the fourth port through the filter capacitor. The rectifier diode is used for input reverse protection and half-wave rectification, making the input AC / DC voltage universal; the thermistor is used for short-circuit protection between channels; the fuse is used for power supply short-circuit protection; and the filter capacitor is used for power supply filtering. The design of the above power supply circuit reduces the risk of equipment damage due to operational errors, is compatible with the safety switch circuit of this application, extends the service life of the safety switch circuit, and the safety switch circuit can flexibly adapt to diverse power supply environments without the need for additional complex circuit designs for different power supply types, improving the versatility and application range of the product, and reducing research and development and production costs.

[0012] More preferably, the first driving circuit includes: a normally closed contact of a first relay, a first Zener diode, a third diode, and a fourth diode connected in series, as well as a charging circuit diode and a second relay coil. The second relay coil is connected in parallel with the fourth diode. The anode of the charging circuit diode is connected to the anode of the fourth diode, and the cathode of the charging circuit diode is connected to the cathode of the first Zener diode. The anode of the first Zener diode is connected to the anode of the third diode, and the cathode of the third diode is connected to the cathode of the fourth diode. The first driving circuit drives the relay to enable the safety switch circuit to output safely. When no switch is pressed, it acts as a charging circuit for the delay capacitor, simplifying the circuit structure, improving the stability and reliability of the system, and enhancing the overall performance of the safety switch circuit.

[0013] More preferably, the first holding circuit includes: a second Zener diode, a fifth diode, and a normally open contact of a second relay connected in series. The cathode of the second Zener diode is connected to the first port and the normally closed contact of the first relay, the anode of the second Zener diode is connected to the anode of the fifth diode, and the normally open contact of the second relay is connected to the cathode of the fourth diode and the coil of the second relay. It possesses a stable and reliable self-holding function, achieving strong overvoltage protection through the second Zener diode and reverse current isolation through the fifth diode. The structure is simple and efficient, offering not only fast response and low power consumption but also good compatibility and expandability.

[0014] More preferably, the second driving circuit includes: a first transistor, a second transistor, a sixth diode, and a first relay coil connected in parallel with the sixth diode. The emitter of the first transistor is connected to the first port, the first driving circuit, and the first holding circuit. The base of the first transistor is connected to the first holding circuit. The collector of the first transistor is connected to the emitter of the second transistor and the cathode of the sixth diode. The emitter and base of the second transistor are connected through a resistor. The collector of the second transistor is connected to the gate of the MOS transistor. The drain of the MOS transistor is connected to the sixth diode, the second holding circuit, and the base of the second transistor connected through a resistor. The second driving circuit safely drives the relay. The sixth diode, connected in parallel with the first relay coil, provides a discharge path for the reverse electromotive force generated by the coil when the relay is de-energized, protecting other components in the circuit from reverse voltage surges and enhancing the reliability and stability of the circuit.

[0015] More preferably, the second holding circuit includes: a normally open contact of a first relay, a third Zener diode, and a seventh diode connected in series, with the anode of the third Zener diode connected to the anode of the seventh diode. The closing of the normally open contact of the first relay achieves self-holding of the circuit, ensuring that the state of the safety switch circuit remains stable after triggering. This simple structure effectively avoids changes in circuit state caused by external trigger signal interruptions, resulting in high reliability. The third Zener diode stabilizes the voltage, limiting it within a safe range and preventing damage to sensitive components in the circuit from excessive voltage, effectively improving circuit stability and component lifespan, and enhancing the overall circuit system's anti-interference capability. The seventh diode, utilizing its unidirectional conductivity, prevents reverse current flow, avoiding adverse effects of reverse current on the preceding circuit, ensuring the correct current flow direction in the circuit, and providing necessary protection for the normal operation of the circuit.

[0016] More preferably, the base of the first transistor is connected to the first holding circuit via a current-limiting resistor, a pull-up resistor is provided between the emitter of the first transistor and the current-limiting resistor, the gate of the MOS transistor and the base of the transistor are both connected to one end of the delay capacitor via a diode and a resistor, a bypass capacitor is provided between the gate and source of the MOS transistor, a pull-down resistor is provided between the gate and ground, a bypass capacitor and a pull-down resistor are connected in parallel between the base of the transistor and ground, and the collector of the second transistor is connected to the gate of the MOS transistor via a resistor. The current-limiting resistor and pull-up resistor of the first transistor can accurately limit the current flowing into the base and effectively stabilize the static operating point of the transistor; the bypass capacitor and pull-down resistor provided for the MOS transistor and the transistor can efficiently filter out high-frequency noise and interference signals, prevent false turn-on phenomena caused by external interference, stabilize the potential, reduce signal fluctuations, ensure accurate signal transmission, and ensure the stable operation of the safety switching circuit of this application.

[0017] Compared with the prior art, the beneficial results of this utility model are as follows:

[0018] This invention provides a safety switch circuit that links the control of both hands with the start and stop of the equipment, forcing the operator to use both hands simultaneously for the equipment to start normally, thus meeting the operator's safety requirements. It also incorporates a redundant timing control circuit, ensuring safe operation even if any component is damaged or short-circuited, achieving highly reliable synchronous safety control for both hands. Furthermore, it utilizes a simple circuit to achieve dual-channel synchronous detection consisting of a first channel entering from the first port and a second channel entering from the second port, reducing material costs. Attached Figure Description

[0019] The accompanying drawings provide further illustration of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the present invention. Other embodiments and many anticipated advantages of the embodiments will be readily recognized as they become better understood through reference to the following detailed description. Other features, objects, and advantages of this application will become more apparent from reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0020] Figure 1 This is a block diagram of the safety switch circuit structure of Embodiment 1 of this application;

[0021] Figure 2 This is a block diagram of the safety switch circuit structure of Embodiment 2 of this application;

[0022] Figure 3 This is a block diagram of the safety switch circuit structure of Embodiment 3 of this application;

[0023] Figure 4 This is a block diagram of the safety switch circuit structure of Embodiment 4 of this application;

[0024] Figure 5 This is a circuit diagram of a control switch according to a specific embodiment of this application;

[0025] Figure 6 This is a schematic diagram of the output circuit of a specific embodiment of this application;

[0026] Figure 7 This is a circuit diagram of a power supply circuit according to a specific embodiment of this application;

[0027] Figure 8 This is a circuit diagram of the safety switch circuit of Embodiment 5 of this application;

[0028] Figure 9 This is a circuit diagram of the safety switch circuit of Embodiment 6 of this application;

[0029] Figure 10 This is a circuit diagram of the safety switch circuit of Embodiment 7 of this application.

[0030] The numbers in the diagram represent the following: 1-Power supply circuit, 2-First drive circuit, 3-First holding circuit, 4-Second drive circuit, 5-Second holding circuit, 6-Time control adjustment circuit, 7-Output circuit, S22-First port, S12-Second port, S11-Third port, S21-Fourth port, VD0-Rectifier diode, VD1-First diode, VD2-Second diode, VD3-Third diode, VD4-Fourth diode, VD5-Fifth diode, VD6-Sixth diode, VD7-Seventh diode, VD8-Eighth diode, VD9-Ninth diode, VD10-Tenth diode, VD11-Charging circuit diode, DZ1-First Zener diode, DZ2-Second Zener diode, DZ3-Third Zener diode, PTC1-Thermistor, F1-Fuse, C0-Time delay circuit. Capacitors: C1 - First capacitor, C2 - Second capacitor, C3 - Third capacitor, C4 - Filter capacitor, R1 - First resistor, R2 - Second resistor, R3 - Third resistor, R4 - Fourth resistor, R5 - Fifth resistor, R6 - Sixth resistor, R7 - Seventh resistor, R8 - Eighth resistor, R9 - Ninth resistor, R10 - Tenth resistor, R11 - Eleventh resistor, R12 - Twelfth resistor, M1 - MOS transistor, Q1 - First transistor, Q2 - Second transistor, Q3 - Third transistor, Q4 - Fourth transistor, JK1B - Normally closed contact of first relay, JK1F - Normally open contact of first relay, JK1A - First relay coil, JK2A - Second relay coil, JK2C - Normally closed contact of second relay, JK2G - Normally open contact of second relay, S1 - First control switch, S2 - Second control switch. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] In the description of this utility model, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Directional terms such as "top," "bottom," "left," "right," "upper," and "lower" are used with reference to the orientation of the described figures. Because components of the embodiments can be positioned in several different orientations, directional terms are used for illustrative purposes and are not intended to be limiting. Terms such as "installed," "equipped," "sleeved / connected," and "connected" should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0033] In this embodiment, a relay is used as an example of a switch. In other embodiments, other devices with switching functions may be used.

[0034] Example 1:

[0035] Figure 1 The safety switch circuit structure block diagram of Embodiment 1 is shown, as follows: Figure 1As shown, a safety switch circuit includes: a relay, a first port S22 and a second port S12 for connecting to the positive or negative terminal of a power supply, a first driving circuit 2 and a second driving circuit 4 for driving the relay, a first holding circuit 3 and a second holding circuit 5 for keeping the contacts of the relay in a self-holding state, and a timing control circuit 6. The timing control circuit 6 controls the output of the safety switch circuit by limiting the time difference between the first port S22 and the second port S12 being connected to the power supply. The first port S22 is connected to the second driving circuit 4 and the first driving circuit 2. The first holding circuit 3 is connected to the first driving circuit 2 and the second driving circuit 4. The second driving circuit 4 is connected to the timing control circuit 6. The timing control circuit 6 is connected to the second port S12, the second holding circuit 5, and the first driving circuit 2. The second port S12 is connected to the first driving circuit 2 and the second holding circuit 5. The first driving circuit 2 is connected to the second holding circuit 5. When the time difference between the first port S22 being connected to the positive terminal of the power supply and the second port S12 being connected to the negative terminal of the power supply meets the conduction time limit of the time control adjustment circuit 6, the first drive circuit 2 and the second drive circuit 4 drive the relay, the first holding circuit 3 and the second holding circuit 5 enter the self-holding state, and the safety switch circuit outputs a start signal; if the time difference does not meet the limit, the time control adjustment circuit 6 does not conduct, and the safety switch circuit does not output a start signal; if the first port S22 is connected to the negative terminal of the power supply and the second port S12 is connected to the positive terminal of the power supply, the time control adjustment circuit 6 charges and stores energy, and the safety switch circuit does not output.

[0036] Example 2:

[0037] Figure 2 A block diagram of the safety switch circuit structure of Embodiment 2 of this application is shown; as follows: Figure 2As shown, based on Embodiment 1, the timing control circuit 6 includes: a delay capacitor C0, a MOS transistor M1, and a third transistor Q3. The second port S12 is connected to one end of the delay capacitor C0, the gate of the MOS transistor M1, and the base of the third transistor Q3. The drain of the MOS transistor M1 is connected to the second driving circuit 4 and the second holding circuit 5. The source of the MOS transistor M1 is connected to the collector of the third transistor Q3. The emitter of the third transistor Q3 is connected to the other end of the delay capacitor, the second port S12, the second holding circuit 5, and the first driving circuit 2, and is grounded. When the first port S22 is connected to the negative terminal of the power supply and the second port S12 is connected to the positive terminal, the delay capacitor C0 is charged through the second port S12. The current then returns to the negative terminal of the first port S22 through the first drive circuit 2, forming a charging loop. When the first port S22 is connected to the positive terminal of the power supply and the second port S12 is connected to the negative terminal, taking the first port S22 being connected to the positive terminal as an example, the first drive circuit 2 drives the relay, and the second drive circuit 4 drives the relay, but the current cannot return to the negative terminal of the power supply through the timing adjustment circuit 6. At this time, the delay capacitor C0 discharges, and the discharge path is through the MOS transistor M1 and the third transistor Q3. If the second port S12 is connected to the negative terminal of the power supply before the MOS transistor M1 and the third transistor Q3 are turned off, the drive current returns to the negative terminal of the power supply, and the safety switch circuit outputs normally; otherwise, the safety switch circuit does not output. High-reliability dual-hand synchronous safety control is achieved through simple electronic components, and dual-channel synchronous monitoring is achieved through a simple circuit. Compared with single-chip microcomputer program monitoring, this reduces material costs and enhances system reliability.

[0038] Example 3:

[0039] Figure 3 A block diagram of the safety switch circuit structure of Embodiment 3 of this application is shown, as follows: Figure 3 As shown, based on Embodiment 2, Embodiment 3 employs a redundant combination of a MOS transistor M1 and two transistors, namely a third transistor Q3 and a fourth transistor Q4, in the timing control circuit 6. The second port S12 is connected to one end of the delay capacitor C0, the gate of the MOS transistor M1, the base of the third transistor Q3, and the base of the fourth transistor Q4. The drain of the MOS transistor M1 is connected to the second driving circuit 4 and the second holding circuit 5. The source of the MOS transistor M1 is connected to the collector of the third transistor Q3, and the emitter of the third transistor Q3 is connected to the collector of the fourth transistor Q4. The collector of the fourth transistor Q4 is connected to the second holding circuit 5, the other end of the delay capacitor C0, the second port S12, and the first driving circuit 2, and is grounded. On the one hand, considering the common-cause failure of the system, a heterogeneous design of the MOS transistor and transistors is adopted; on the other hand, the redundant design of the two transistors ensures that when a single transistor fails and short-circuits, the other transistor can still function as a cutoff.

[0040] Example 4:

[0041] Figure 4 This shows a block diagram of the safety switch circuit structure of Embodiment 4 of this application, as follows: Figure 4 As shown, based on embodiment 3, the timing control circuit 6 further includes: a first diode VD1, a second relay normally closed contact JK2C, a second diode VD2, and a first resistor R1. The second port S12 is connected in series with the second relay normally closed contact JK2C, the second diode VD2, and the first resistor R1 to one end of the delay capacitor C0, the gate of the MOS transistor M1, the base of the third transistor Q3, and the base of the fourth transistor Q4. The positive terminal of the second diode VD2 is connected to the second relay normally closed contact JK2C, and the negative terminal of the second diode VD2 is connected to the first resistor R1. The negative terminal of the first diode VD1 is connected to the second port S12 and the second relay normally closed contact JK2C. The positive terminal of the first diode VD1 is connected to the first driving circuit 2, the other end C0 of the delay capacitor, the emitter of the fourth transistor Q4, and the second holding circuit 5 and grounded. By adding the first diode VD1, the second diode VD2, and the first resistor R1, the components in the first drive circuit 2, the timing control circuit 6, and the second holding circuit 5 are protected, ensuring the normal operation of the timing control circuit 6 and enhancing the overall stability and safety of the safety switch circuit.

[0042] In a specific embodiment, Figure 5 The diagram illustrates a circuit diagram of a control switch according to a specific embodiment of this application. The control switch includes a first control switch S1 and a second control switch S2. In the initial state, as shown in the figure, the second port S12 is connected to the third port S11, and the fourth port S21 is connected to the first port S22. When the first control switch S1 is pressed alone, the first port S22 is connected to the third port S11, and the second port S12 is disconnected from the third port S11, i.e., the first port S22 is connected to the positive terminal of the power supply while the second port S12 is floating. When the second control switch S2 is pressed alone, the second port S12 is connected to the fourth port S21, and the first port S22 is disconnected from the fourth port S21, i.e., the second port S12 is connected to the negative terminal of the power supply while the first port S22 is floating. When both the first control switch S1 and the second control switch S2 are pressed, the second port S12 is connected to the fourth port S21, and the first port S22 is connected to the third port S11, i.e., the first port S22 is connected to the positive terminal of the power supply, and the second port S12 is connected to the negative terminal of the power supply. This design ensures that the module will only work properly when both hands are used simultaneously, avoiding incorrect triggering of the module due to misoperation or accidental touch with one hand, thus improving the safety and reliability of operation.

[0043] In a specific embodiment, Figure 6 This is a schematic diagram of an output circuit 7 according to a specific embodiment of this application. The output circuit 7 includes a normally open contact of a first relay and a normally open contact of a second relay. The contact JK1G of the first relay and the contact JK2F of the second relay are connected in series and output safely through output port OUTA or OUTB. Redundant output is achieved by using one normally open contact from each of the two relays to form the output circuit.

[0044] In a specific embodiment, Figure 7 This is a circuit diagram of a power supply circuit 1 according to a specific embodiment of this application, as follows: Figure 7 As shown, the third port S11 is connected to the positive terminal V+ of the power supply circuit 1, and the fourth port S21 is connected to the negative terminal V- of the power supply circuit 1. The power supply circuit 1 includes a rectifier diode VD0, a thermistor PTC1, a fuse F1, and a filter capacitor C4. The positive terminal V+ of the power supply is connected to the positive terminal of the rectifier diode VD0. The negative terminal of the rectifier diode VD0 is connected to one end of the thermistor PTC1. The other end of the thermistor PTC1 is connected to one end of the fuse F1. The other end of the fuse F1 is connected to the third port S11 and the positive terminal of the filter capacitor C4. The negative terminal of the filter capacitor C4 is connected to the fourth port S21 and the negative terminal V- of the power supply. The rectifier diode VD0 is used for input reverse protection and half-wave rectification, making the input AC and DC voltages universal. The thermistor PTC1 is used for short-circuit protection between channels. The fuse F1 is used for power supply short-circuit protection. The filter capacitor C4 is used for power supply filtering. The design of the above power supply circuit 1 reduces the risk of equipment damage due to operational errors. It is compatible with the safety switch circuit of this application, extends the service life of the safety switch circuit, and the safety switch circuit can flexibly adapt to diverse power supply environments without the need for additional complex circuit designs for different power supply types. This improves the versatility and application range of the product and reduces R&D and production costs.

[0045] Example 5:

[0046] Figure 8 This is a circuit diagram of the safety switch circuit of Embodiment 5 of this application, as follows: Figure 8As shown, the first port S22 is connected in series with the first normally closed contact JK1B of the first relay, the first Zener diode DZ1, the third diode VD3, and the fourth diode VD4. One end of the normally closed contact JK1B of the first relay is connected to the first port S22, and the other end is connected to the negative terminal of the first Zener diode DZ1 and the negative terminal of the second Zener diode DZ2. The positive terminal of the first Zener diode DZ1 is connected to the positive terminal of the third diode VD3, the negative terminal of the third diode VD3 is connected to the negative terminal of the fourth diode VD4, and one end of the second relay coil JK2A is connected. The positive terminal of the charging circuit diode VD11 is connected to the positive terminal of the fourth diode VD4 and the other end of the second relay coil JK2A. The anode of the first diode VD1, the other end of the delay capacitor C0, the emitter of the third transistor Q3, and the cathode of the seventh diode VD7 are connected and grounded (GNDA). The first port S22 is also connected in series with the second Zener diode DZ2, the fifth diode VD5, and the normally open contact of the second relay JK2G. The cathode of the second Zener diode DZ2 is connected to the first port S22, the normally closed contact of the first relay JK1B, and the emitter of the first transistor Q1. The anode of the second Zener diode DZ2 is connected to the anode of the fifth diode VD5. The cathode of the fifth diode VD5 is connected to the base of the first transistor Q1 and one end of the normally open contact of the second relay JK2G. The other end is connected to the negative terminal of the fourth diode VD4 and one end of the second relay coil JK2A. The collector of the first transistor Q1 is connected to the emitter of the second transistor VD2, one end of the second resistor R2, the negative terminal of the sixth diode VD6, and one end of the first relay coil JK1A. The base of the second transistor Q2 is connected to the other end of the second resistor R2 and one end of the third resistor R3. The collector of the second transistor Q2 is connected to the gate of the MOS transistor M1, one end of the first resistor R1, one end of the delay capacitor C0, and the base of the third transistor Q3. The other end of the third resistor R3 is connected to the positive terminal of the sixth diode VD6, the other end of the first relay coil JK1A, the drain of the MOS transistor, and... One end of the normally open contact JK1F of the first relay is connected to the negative terminal of the third Zener diode DZ3. The positive terminal of the third Zener diode DZ3 is connected to the positive terminal of the seventh diode VD7. The second port is connected to one end of the normally closed contact JK2C of the second relay and the negative terminal of the first diode VD1. The other end of the normally closed contact JK2C of the second relay is connected to the positive terminal of the second diode VD2. The negative terminal of the second diode VD2 is connected to one end of the first resistor R1. The other end of the first resistor R1 is connected to the gate of the MOS transistor M1, the base of the third transistor Q3, and one end of the delay capacitor C2. The source of the MOS transistor M1 is connected to the collector of the third transistor Q3.In this embodiment, a MOS transistor and a triode are used to avoid common-cause failures in the system. Compared with ordinary control devices, it has higher reliability and safety. Through the cooperation of the first driving circuit 2, the second driving circuit 4, the first holding circuit 3 and the second holding circuit 5, a highly efficient and safe safety switching circuit is realized.

[0047] Example 6:

[0048] Figure 9 This is a circuit diagram of the safety switch circuit of Embodiment 6 of this application, as follows: Figure 9 As shown, based on Embodiment 5, the timing control circuit 6 employs a redundant combination of a MOS transistor M1 and two transistors, namely the third transistor Q3 and the fourth transistor Q4. The other end of the first resistor R1 is connected to one end of the delay capacitor C0, the gate of the MOS transistor M1, the base of the third transistor Q3, and the base of the fourth transistor Q4. The emitter of the third transistor Q3 is connected to the collector of the fourth transistor Q4. The collector of the fourth transistor Q4 is connected to the negative terminal of the seventh diode VD7, the other end of the delay capacitor C0, the positive terminal of the first diode VD1, the other end of the second relay coil JK2A, the positive terminal of the fourth diode VD4, and the positive terminal of the charging circuit diode VD11, and grounded to GNDA. This redundant design of two transistors ensures that if one transistor fails and short-circuits, the other transistor can still function as a cutoff, improving the stability of the safety switch circuit.

[0049] Example 7:

[0050] Figure 10This is a circuit diagram of the safety switch circuit of Embodiment 7 of this application. Based on Embodiment 6, it further includes: a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a first capacitor C1, a second capacitor C2, a third capacitor C3, an eighth diode VD8, a ninth diode VD9, and a tenth diode VD10. One end of the fifth resistor R5 is connected to the emitter of the first transistor Q1, and the other end is connected to the cathode of the fifth diode VD5 and one end of the sixth resistor R6. The other end of the sixth resistor R6 is connected to the base of the first transistor Q1. One end of the fourth resistor R4 is connected to the collector of the second transistor Q2, and the other end is connected to the gate of the MOS transistor M1. One end of the delay capacitor C0 is connected to the positive terminal of the eighth diode VD8 through the tenth resistor R10. The cathode of the eighth diode VD8 is connected to the gate of the MOS transistor M1. One end of the seventh resistor R7 is connected to the gate of the MOS transistor M1, and the other end is grounded. The gate and source of the MOS transistor M1 are connected through the first capacitor C1. One end of the delay capacitor C0 is connected to the anode of the ninth diode VD9 through the eleventh resistor R11. The cathode of the ninth diode VD9 is connected to the base of the third transistor Q3 and one end of the eighth resistor R8. The other end of the eighth resistor R8 is grounded. The second capacitor C2 is connected in parallel with the eighth resistor R8. One end of the delay capacitor C0 is also connected to the anode of the tenth diode VD10 through the twelfth resistor R12. The cathode of the tenth diode VD10 is connected to the base of the fourth transistor Q4 and one end of the ninth resistor R9. The other end of the ninth resistor R9 is connected to the other end of the delay capacitor C0 and grounded. The third capacitor C3 is connected in parallel with the ninth resistor R9.

[0051] The following is combined Figure 10 The working principle of a safety switch circuit described in this application is as follows:

[0052] In a specific embodiment, when the safety switch circuit of this application is in the initial state, that is, when neither of the two control switches is pressed, the third port S11 is connected to the second port S12, and the first port S22 is connected to the fourth port S21. That is, the first port S22 is connected to the negative terminal of the power supply, and the second port S12 is connected to the positive terminal of the power supply. Then, the delay capacitor C0 is charged through the normally closed contact JK2C of the second relay, the second diode VD2, and the first resistor R1. The charge returns to the negative terminal of the power supply at the first port S22 through the charging circuit diode VD11 and the normally closed contact JK1B of the first relay. This is the charging circuit.

[0053] In a specific embodiment, when one of the control switch buttons is pressed (taking pressing only the first control switch S1 as an example), the third port S11 is connected to the first port S22, and the third port S11 is disconnected from the second port S12. That is, the first port S22 is connected to the positive terminal of the power supply, and the second port S12 is floating. At this time, the first port S22 receives the positive power supply from the third port S11. The driving circuit of the second relay is formed by the first normally closed contact JK1B of the first relay, the first Zener diode DZ1, the third diode VD3, the second relay coil JK2A of the second relay, and the first diode VD1. Since the second port S12 is floating at this time, the driving current of the second relay cannot return to the negative terminal of the power supply, so the second relay is not driven. At the same time, the delay capacitor C0 discharges through three paths. The first path is through the tenth resistor R10, the eighth diode VD8, the seventh resistor R7 as a pull-down resistor, and the first capacitor. C1 is the bypass capacitor and MOS transistor M1; the second path uses the eleventh resistor R11, the ninth diode VD9, the eighth resistor R8 as pull-down resistors, the second capacitor C2 as the bypass capacitor, and the third transistor Q3; the third path uses the twelfth resistor R12, the tenth diode VD10, the ninth resistor R9 as pull-down resistors, the third capacitor C3 as the bypass capacitor, and the fourth transistor Q4; the MOS transistors M1, Q3, and Q4 are briefly turned on by the discharge of the delay capacitor C20 and the capacitors. As the capacitor charge is released, the MOS transistors M1, Q3, and Q4 are turned off. That is, the second control switch S2 must be pressed during the time when the MOS transistors M1, Q3, and Q4 are turned on to drive the second relay for the safety switch circuit to output normally; otherwise, the safety switch circuit will not work. The normally closed contact JK1B of the first relay is connected in series in the drive circuit of the second relay. In order to diagnose the first relay, due to the characteristics of the forced-guided relay, the normally closed contact can reflect the state of the normally open contact. Once the normally open contact of the first relay fails dangerously, i.e. sticking, the normally closed contact JK1B of the first relay will open, and at the same time, the drive circuit of the second relay will be disconnected.

[0054] In a specific embodiment, when one button of the control switch is pressed and then the other button is pressed (taking pressing the first control switch S1 first and then the second control switch S2 as an example), the second port S12 is connected to the fourth port S21, and the first port S22 is connected to the third port S11. That is, the first port S22 is connected to the positive terminal of the power supply, and the second port S12 is connected to the negative terminal of the power supply. Based on the time difference between the two control switch buttons being pressed, there are two cases: The first case is that when the time limit is exceeded, MOS transistors M1, Q3, and Q4 have been turned off, and the positive power supply of the first port S22 drives the second... The relay coil JK2A returns to the second negative terminal S12 of the power supply through the first diode VD1; the normally open contact JK2G of the second relay closes and enters self-holding through the second Zener diode DZ2 and the fifth diode VD5; at this time, current flows through the base circuit of the first transistor Q1, and the first transistor Q1 is turned on. The fifth resistor R5 acts as a pull-up resistor, and the sixth resistor R6 acts as a base current limiting resistor; since the first transistor Q1 is turned on, but the MOS transistor M1, the third transistor Q3, and the fourth transistor Q4 are turned off, the first relay cannot be driven, that is, the safety switch circuit does not work, and enters and remains in a safe state, indicating that the hands are out of sync. In the second scenario, when the time difference between pressing the two control switches is within the limit, similarly, after the first transistor Q1 is turned on, it passes through the base resistor of the second transistor Q2 (i.e., the third resistor R3), through the MOS transistor M1, the third transistor Q3, the fourth transistor Q4, and the first diode VD1, returning to the second negative terminal S12 of the power supply. The second transistor Q2 is turned on and accelerates the drive of the MOS transistor M1, which drives the first relay. Through the normally open contact JK1F of the first relay, the third Zener diode DZ3 and the seventh diode VD7 enter self-holding mode. At this time, the safety switch circuits all normally enter the action holding mode, and the output circuit 7 outputs safely.

[0055] Similarly, when only the second control switch S2 is pressed, the second port S12 is connected to the fourth port S21, and the first port S22 is disconnected from the fourth port S21, i.e., the first port S22 is floating. The second port S12 is connected to the negative terminal of the power supply. Since a circuit cannot be formed, the first port S22 cannot be driven by the first drive circuit 2 and the second drive circuit 4. When the first control switch S1 is pressed within the time limit, the first port S22 receives positive power and begins to drive the first drive circuit 2, then the second drive circuit 4 and the time control adjustment circuit 6, and then the safety switch circuit outputs. When the first control switch S1 is pressed after the time limit, the first port S22 receives positive power, but can only drive the first drive circuit 2 and the second drive circuit 4, while the time control adjustment circuit 6 cannot be driven. Therefore, the safety switch circuit does not work and enters and remains in a safe state. The driving sequence in this application is to drive the second relay first and then the first relay, thereby achieving orderly operation and reducing the risk of random failure. Whether the first switch S1 or S2 is disconnected first, the second relay cannot be driven. If the first switch S1 is disconnected first, the positive power supply of the charging circuit of the delay capacitor C0 is disconnected, charging stops, and discharge begins. The second relay can only be driven after another switch is pressed, and then the first relay is driven. If the second switch S2 is disconnected first, the negative power supply of the charging circuit of the delay capacitor C0 is disconnected, charging stops, and discharge begins. The second relay can only be driven after another switch is pressed, and then the first relay is driven.

[0056] In a specific embodiment, the selection of the delay capacitor C0 meets the synchronization time requirements of the ISO 13851 mechanical safety standard for two-handed operating devices.

[0057] Optionally, the time limit is 500ms, meaning the conduction time of the MOS transistor M1 and the transistor is 500ms. When the time difference between pressing the first control switch and the second control switch does not exceed 500ms, the time control adjustment circuit 6 remains in the conducting state. Then, the first drive circuit 2 and the second drive circuit 4 drive the relay, causing the output circuit 7 to output normally. This effectively avoids accidental triggering due to single-handed misoperation or improper sequence. When the time interval between pressing the two control switches is too long, it is also considered as non-two-handed operation, improving the accuracy and safety of operation and preventing accidental equipment startup that could lead to safety accidents.

[0058] Optionally, the first transistor Q1 is a PNP transistor, the second transistor Q2 is a PNP transistor, the third transistor Q3 is an NPN transistor, and the fourth transistor Q4 is an NPN transistor.

[0059] Optionally, the MOS (Metal Oxide Semiconductor) transistor M1 is an NMOS (N-type Metal Oxide Semiconductor) transistor.

[0060] Optionally, the relay includes a first relay and a second relay, the first relay including a normally closed contact and a normally open contact, and the second relay including a normally closed contact and a normally open contact.

[0061] It should be noted that this embodiment only uses a design with one MOS transistor and two bipolar transistors as a reference, and this design concept is not limited to the number of bipolar transistors and MOS transistors. The redundancy design of this application ensures that safe operation is not affected even if other components are damaged or short-circuited, thus filling the gaps in the safety switching circuits of the prior art.

[0062] Optionally, the relay in this application is a Class A forced-direction relay, conforming to the IEC61810-3 standard, with a single device diagnostic coverage of 99%. When the normally open safety contact of the output relay is stuck, the module will enter a safe state in the next operating cycle, thereby achieving fault diagnosis and reducing the risk of safety failure. Cross-short circuits between the first drive circuit and the first holding circuit and the second drive circuit and the second holding circuit can be detected and the module will enter a safe state without damaging the internal electronic components. Furthermore, the system can return to normal operation after the channel short-circuit fault is cleared. Specifically, the relay model can be one of HFA2, HFA4, HFA6A, HFA4A, and HFA6.

[0063] In a specific embodiment, the normally closed contact JK1B of the first relay and the normally closed contact JK2C of the second relay can be used to diagnose the adhesion of the safety output contacts. When adhesion occurs, due to the characteristics of the forced-guided relay, its normally closed contact remains non-conductive, that is, the charging circuit of the delay capacitor C0 cannot be conducted and the driving circuit of the first driving circuit 2 cannot be conducted. The entire circuit is in an inaccessible state, the safety switch circuit does not operate, and it enters and maintains a safe state, thereby realizing the diagnosis of the safety output.

[0064] This application proposes a safety switch circuit that ensures the device can only be started when both hands press the buttons simultaneously with a time difference within a preset range. This effectively prevents accidents caused by misoperation. It is applicable to dual-hand synchronous control safety switch circuits for dangerous equipment such as punch presses and cutting machines, aiming to improve the safety of equipment operation and prevent personal injury accidents caused by misoperation. The control safety switch circuit, as a logic control component of the dual-hand operating device, implements dual-hand synchronous logic control through electronic hardware, meeting relevant standards and achieving functional safety. Regarding component redundancy design, this application achieves the highest PLe level in terms of performance level according to the ISO 13849 mechanical safety standard, ensuring that the system does not lose its safety function even if any component fails. This application employs multiple redundancies, resulting in a lower failure rate and higher reliability compared to ordinary control devices.

[0065] It is obvious that those skilled in the art can make various modifications and alterations to the embodiments of this application without departing from the spirit and scope of this application. In this way, this application also aims to cover such modifications and alterations if they fall within the scope of the claims and their equivalents. The word "comprising" does not exclude the presence of other elements or steps not listed in the claims. The simple fact that certain measures are described in mutually different dependent claims does not indicate that a combination of these measures cannot be used for profit. Any reference numerals in the claims should not be considered limiting in scope.

Claims

1. A safety switch circuit, characterized in that, include: The system includes a switch, a first port and a second port for connecting to the positive or negative terminal of a power supply, a first driving circuit and a second driving circuit for driving the switch, a first holding circuit and a second holding circuit for putting the switch in a self-holding state, and a time control adjustment circuit. The time control adjustment circuit controls the output of the safety switch circuit by limiting the time difference between the first port and the second port being connected to the power supply. The first driving circuit, the second port, the time control adjustment circuit, and the second holding circuit are interconnected. The first driving circuit is connected to the time control adjustment circuit through the first port and the second driving circuit, and is also connected to the second driving circuit through the first holding circuit.

2. The safety switch circuit according to claim 1, characterized in that, The timing control circuit includes a delay capacitor, a MOS transistor, and a transistor. One end of the delay capacitor is connected to the second port, the gate of the MOS transistor, and the base of the transistor. The drain of the MOS transistor is connected to the second driving circuit, and the source of the MOS transistor is connected to the collector of the transistor. The other end of the delay capacitor is connected to the emitter of the transistor, the second holding circuit, and the first driving circuit.

3. The safety switch circuit according to claim 2, characterized in that, The timing control circuit includes two transistors, one of which has its collector connected to the source of the MOS transistor and its emitter connected to the collector of the other transistor. The emitter of the other transistor is grounded and connected to the second holding circuit and the first driving circuit.

4. The safety switch circuit according to claim 2 or 3, characterized in that, Also includes: The first diode, normally closed switch, second diode, and first resistor are connected to the second port via the first diode. The second port is connected to one end of the delay capacitor via the normally closed switch, second diode, and first resistor connected in series.

5. The safety switch circuit according to claim 4, characterized in that, The switch includes a relay, and the normally closed switch includes a normally closed contact of the relay.

6. The safety switch circuit according to claim 5, characterized in that, Also includes: The system includes a power supply circuit, a control switch, a third port connected to the positive terminal of the power supply circuit, and a fourth port connected to the negative terminal of the power supply circuit. The control switch includes a first control switch and a second control switch. In the initial state, the second port is connected to the third port, and the fourth port is connected to the first port. When the first control switch is pressed alone, the first port is connected to the third port, and the second port is disconnected from the third port. When the second control switch is pressed alone, the second port is connected to the fourth port, and the first port is disconnected from the fourth port. When both the first and second control switches are pressed, the second port is connected to the fourth port, and the first port is connected to the third port.

7. The safety switch circuit according to claim 6, characterized in that, Also includes: The output circuit for outputting signals includes the contacts of the relay; the power supply circuit includes a rectifier diode, a thermistor, a fuse, and a filter capacitor. The positive terminal of the power supply is connected to the third port through the rectifier diode, the thermistor, and the fuse connected in series. The third port is connected to the fourth port through the filter capacitor.

8. The safety switch circuit according to claim 5, characterized in that, The first driving circuit includes: a normally closed contact of a first relay, a first Zener diode, a third diode, and a fourth diode connected in series, as well as a charging circuit diode and a second relay coil. The second relay coil is connected in parallel with the fourth diode. The anode of the charging circuit diode is connected to the anode of the fourth diode, and the cathode of the charging circuit diode is connected to the cathode of the first Zener diode. The anode of the first Zener diode is connected to the anode of the third diode, and the cathode of the third diode is connected to the cathode of the fourth diode.

9. The safety switch circuit according to claim 8, characterized in that, The first holding circuit includes: a second Zener diode, a fifth diode, and a normally open contact of a second relay connected in series. The cathode of the second Zener diode is connected to the first port and the normally closed contact of the first relay. The anode of the second Zener diode is connected to the anode of the fifth diode. The normally open contact of the second relay is connected to the cathode of the fourth diode and the coil of the second relay.

10. The safety switch circuit according to claim 5, characterized in that, The second driving circuit includes: a first transistor, a second transistor, a sixth diode, and a first relay coil connected in parallel with the sixth diode. The emitter of the first transistor is connected to the first port, the first driving circuit, and the first holding circuit. The base of the first transistor is connected to the first holding circuit. The collector of the first transistor is connected to the emitter of the second transistor and the cathode of the sixth diode. The emitter and base of the second transistor are connected through a resistor. The collector of the second transistor is connected to the gate of the MOS transistor. The drain of the MOS transistor is connected to the sixth diode, the second holding circuit, and the base of the second transistor connected through a resistor.

11. The safety switch circuit according to claim 5, characterized in that, The second holding circuit includes: a first normally open contact of a relay, a third Zener diode, and a seventh diode connected in series, wherein the anode of the third Zener diode is connected to the anode of the seventh diode.

12. The safety switch circuit according to claim 10, characterized in that, The base of the first transistor is connected to the first holding circuit through a current-limiting resistor. A pull-up resistor is provided between the emitter of the first transistor and the current-limiting resistor. The gate of the MOS transistor and the base of the transistor are both connected to one end of the delay capacitor through a diode and a resistor. A bypass capacitor is provided between the gate and the source of the MOS transistor, and a pull-down resistor is provided between the gate and ground. A bypass capacitor and a pull-down resistor are connected in parallel between the base of the transistor and ground. The collector of the second transistor is connected to the gate of the MOS transistor through a resistor.

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