Output protection circuit and light source device using same

Abstract

The utility model discloses an output protection circuit and a light source device adopting the output protection circuit, the output protection circuit comprises sampling modules connected with each load branch of a load unit and a signal processing module connected with the sampling modules and a power supply unit, and at least one sampling module is connected with one load branch; wherein the signal processing module comprises a signal processing branch circuit corresponding to the sampling module and a signal integration circuit, the signal processing branch circuit at least comprises a comparison element and a switch element, the sampling end of the comparison element is connected with the sampling module, and the output end of the comparison element is connected to one end of the switch element; the other end of the switch element is connected with the input end of the signal integration circuit, and the output end of the signal integration circuit is connected with the power supply unit. The beneficial effects of the utility model are that adjusting signals are provided for the power supply unit to adjust the voltage in real time according to the voltage condition of the load branch, the structure is simple, and the accuracy is high.

Description

Technical Field

[0001] The present application relates to the field of voltage protection technology, and in particular to an output protection circuit and a light source device using the output protection circuit. Background Art

[0002] In related technologies, LED switching power supplies convert energy through a control transformer, and the secondary uses a diode or synchronous rectification circuit to output current, driving the LED light source, causing the LED to emit light. Constant current control relies on feedback from a secondary detection circuit to the primary side, which adjusts the output, or on a primary-side feedback circuit to adjust the output.

[0003] like Figure 1 The conventional switching power supply circuit shown above adjusts the position of the secondary-side voltage detection control circuit to adjust the output voltage of the constant-voltage circuit to follow the changes in the LED load, thereby improving the efficiency of the entire circuit. However, simply stabilizing the LED control device does not address the problem of excessive power consumption by the remaining light sources in actual applications when a series or parallel LED light source fails. In the event of a series or parallel LED light source failure, such as when one or more LEDs fail, the LED switching power supply lacks a light source-side feedback signal to detect whether the light sources are functioning properly and instead supplies power according to the original set current. After an LED fails, the current is shared by the remaining parallel LEDs. In this situation, the remaining LEDs are immediately overloaded and burn out within a short period of time, further increasing losses.

[0004] The Chinese patent "A Multi-branch Independent Current Sampling Closed-Loop Control Circuit for LED Light Sources," publication number CN204305416U, publication date April 29, 2015, specifically discloses an LED light source circuit, a current closed-loop control circuit for controlling voltage stability, and a current sampling circuit for collecting current signals. The LED light source circuit is provided with one or more LED light source branches, which are connected in parallel to a main power supply. The current sampling circuit is provided with one or more current sampling branches, which are connected between the main power supply and the LED light source circuit. The current sampling branches are electrically connected to the LED light source branches. The number of current sampling branches is the same as the number of LED light source branches. A filter capacitor C1 is provided on the main circuit of the LED light source circuit, and the other end of the filter capacitor C1 is grounded. The main power supply is an alternating current with a frequency of 50 Hz. In this solution, when an LED light-emitting tube fails, the remaining LED light-emitting tubes are still powered by a constant current by turning on and off the thyristor. However, the thyristor has high requirements for the trigger signal and has low stability and reliability. Direct control through the thyristor is not only prone to miscontrol but also difficult to achieve high-precision current control.

[0005] The Chinese patent "Dimming circuit for realizing multiple dimming modes", publication number CN109922567A, publication date April 29, 2019, specifically discloses a dimming circuit including a connection terminal CON1, a voltage dividing circuit, a first branch with a comparison device, and a second branch with an amplifier device and a microprocessor U1. The input end of the connection terminal CON1 receives a dimming signal from a controller, generating a voltage signal between two output pins. The voltage dividing circuit feeds back the voltage signal to the comparison device and the amplifier device after voltage division. The first branch uses the comparison device to compare the voltage division signal with a preset reference voltage to obtain a high-low level signal, so as to control the subsequent circuit to dim the light source to be dimmed according to the high-low level signal. The second branch uses the amplifier device to amplify the voltage division signal and output it to the microprocessor U1, which converts the amplified signal into a PWM signal to control the subsequent circuit to dim the light source to be dimmed using the PWM signal. In this scheme, the dimming purpose is achieved by controlling the external signal, which relies on the external signal and cannot be protected according to the failure of the device itself. Utility model content

[0006] The utility model provides an output protection circuit and a light source device using the same, which can accurately and simply control the power output according to the failure of a single load in the device with serial-parallel load in the prior art. Each sampling module is connected to one load branch in the load unit, acquires the voltage signal of each load branch, and transmits it to the corresponding signal processing branch. The comparison element compares and judges based on the reference voltage and the voltage signal of the sampling output, controls the level signal of the output end according to the comparison result, and further controls the conduction and cutoff of the switching element. When the switching element is turned on, the power end forms a loop through the signal integration circuit to the switching element. The signal integration circuit generates a corresponding current output to the power supply unit according to the formed loop superposition, thereby providing an adjustment signal to the power supply unit to adjust the voltage in real time according to the voltage condition of the load branch. The structure is simple and the control accuracy is improved.

[0007] To achieve the above technical purpose, the utility model provides a technical scheme, an output protection circuit connected to the power supply unit and the load unit of the device, comprising: a sampling module for collecting the electric parameter signal of each load branch of the load unit, a signal processing module connected to the sampling module and the power supply unit, and at least one sampling module connected to one load branch; the signal processing module includes a signal processing branch corresponding to the sampling module and a signal integration circuit, the signal processing branch at least includes a comparison element and a switching element, the sampling end of the comparison element is connected to the sampling module, the output end of the comparison element is connected to one end of the switching element, the other end of the switching element is connected to the input end of the signal integration circuit, and the output end of the signal integration circuit is connected to the power supply unit.

[0008] Further, the signal processing branch further comprises an amplification element, a sampling end of the amplification element is connected with the sampling module, and an output end of the amplification element is connected with an input end of the comparison element.

[0009] Further, the amplification element is an operational amplifier, the comparison element is a comparator, the switch element is a switch diode, and the signal integration circuit at least comprises an optoelectronic coupler.

[0010] For any one signal processing branch, there are:

[0011] The signal output end of the sampling module is connected with the non-inverting input end of the operational amplifier, the output end of the operational amplifier is connected with the inverting input end of the comparator, the non-inverting input end of the comparator is connected with a reference voltage, the output end of the comparator is connected with the negative electrode of the switch diode, and the positive electrode of the switch diode is connected with the negative electrode of the light-emitting diode of the optoelectronic coupler.

[0012] Further, the signal processing branch further comprises a first feedback resistor and a second feedback resistor, one end of the first feedback resistor is connected with the output end of the operational amplifier, the other end of the first feedback resistor is connected with the inverting input end of the operational amplifier, one end of the second feedback resistor is connected with the inverting input end of the operational amplifier, and the other end of the second feedback resistor is grounded.

[0013] Another technical scheme provided by the utility model is a light source device, which comprises a control unit, a power supply unit, a light source module and an output protection circuit as described above, wherein the light source module is connected to the power supply unit, the power supply unit is connected to the control unit, the sampling module of the output protection circuit collects electrical parameter signals of each load branch of the light source module, and the signal integration circuit of the output protection circuit outputs a control signal to the control unit.

[0014] Further, the light source module at least comprises a plurality of parallel load branches, and each load branch comprises a plurality of series-connected LED light source loads.

[0015] Further, the power supply unit is connected to an alternating current power supply and at least comprises a transformer, an auxiliary power supply circuit, a secondary rectification filter circuit and a reference source circuit, the transformer is connected to the alternating current power supply, the auxiliary power supply circuit is connected to the transformer, the reference source circuit and a signal processing module, the reference source circuit is connected to the signal processing module, and the secondary rectification filter circuit is connected to the transformer and the light source module.

[0016] Further, the secondary rectification filter circuit comprises a first rectification diode, a first resistor, a first capacitor, a load resistor, a second capacitor and a third capacitor, the positive pole of the first rectification diode is connected to the transformer, the negative pole of the first rectification diode is connected to the light source module, the first resistor and the first capacitor are connected in series and are connected in parallel to the first rectification diode, one end of the load resistor is connected to the negative pole of the first rectification diode, the other end of the load resistor is grounded, the second capacitor is connected in parallel to the load resistor, and the third capacitor is connected in parallel to the second capacitor.

[0017] Further, the auxiliary power supply circuit comprises a second rectification diode, a fourth capacitor and a fifth capacitor, the positive pole of the second rectification diode is connected to the transformer, the negative pole of the second rectification diode is connected to the reference source circuit and the signal processing module, the positive pole of the fourth capacitor is connected to the negative pole of the second rectification diode, the negative pole of the fourth capacitor is grounded, and the fifth capacitor is connected in parallel to the fourth capacitor.

[0018] Further, the reference source circuit comprises a voltage stabilizing regulator, the negative pole of the voltage stabilizing regulator is connected to the output end of the auxiliary power supply circuit, the positive pole of the voltage stabilizing regulator is grounded, and the regulating end of the voltage stabilizing regulator is connected to the non-inverting input end of the comparator.

[0019] The light source device has the advantages that: the current intensity output by the photoelectric coupler protects the LED light source, when the LED light source is in series and parallel failure, the power output current is adjusted in time, so that other normal LED particles will not be used excessively, the light source device only reduces the power and luminous flux, and can be normally used for a long time, and the user can repair or replace the light source module in time after finding, so that greater loss is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a circuit schematic diagram of a switching power supply circuit in the related art.

[0021] Figure 2 It is a circuit schematic diagram of a signal processing module in the output protection circuit.

[0022] Figure 3 It is a whole circuit schematic diagram of the light source device.

[0023] Figure 4 It is a circuit schematic diagram of a light source module in the light source device.

[0024] Figure 5 It is a circuit schematic diagram of a secondary rectification filter circuit in the light source device.

[0025] Figure 6 It is a circuit schematic diagram of an auxiliary power supply circuit in the light source device.

[0026] Figure 7A circuit schematic diagram of a reference source circuit in the light source device of the application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the utility model more clear and obvious, the utility model will be further described in detail below in combination with the drawings and examples. It should be understood that the specific embodiments described here are only one of the best embodiments of the utility model, which are used to explain the utility model and do not limit the protection scope of the utility model. All other embodiments obtained by the ordinary skilled in the art without creative labor belong to the protection scope of the utility model.

[0028] As shown in Figure 2 As an embodiment of the application, the output protection circuit is connected to the power supply unit and the load unit of the device, comprising: a sampling module for collecting the electrical parameter signals of each load branch of the load unit, a signal processing module connected to the sampling module and the power supply unit, and at least one sampling module is connected to one load branch.

[0029] The signal processing module comprises a signal processing branch corresponding to the sampling module and a signal integration circuit. The signal processing branch comprises at least a comparison element and a switching element. The sampling end of the comparison element is connected to the sampling module. The output end of the comparison element is connected to one end of the switching element. The other end of the switching element is connected to the input end of the signal integration circuit. The output end of the signal integration circuit is connected to the power supply unit.

[0030] In this embodiment, each sampling module is connected to one load branch in the load unit to obtain the voltage signal of each load branch, which is transmitted to the corresponding signal processing branch. The comparison element compares and judges based on the reference voltage and the voltage signal output by the sampling. According to the comparison result, the level signal of the output end is controlled to be high or low, thereby controlling the conduction and cutoff of the switching element. When the switching element is turned on, the loop formed by the signal integration circuit to the switching element at the power supply end is formed. The signal integration circuit generates corresponding current output to the power supply unit according to the superposition of the formed loop, thereby providing an adjustment signal to the power supply unit to adjust the voltage in real time according to the voltage condition of the load branch. The structure is simple and the control accuracy is improved.

[0031] When the power supply unit does not comprise the voltage regulation module, the output protection circuit further comprises the voltage regulation module, the voltage regulation module is connected to the power supply unit and the output end of the photoelectric coupler, the voltage regulation module adjusts the PWM signal according to the current intensity of the photoelectric coupler, thereby controlling the on-off time of the switch tube of the power supply unit, and realizing the voltage regulation of the load end. It can be understood that the output protection circuit without the voltage regulation module can be installed between the power supply unit with the regulation chip and the load unit, and the output protection circuit with the voltage regulation module can also be installed between the power supply unit without the regulation chip and the load unit, thereby being applicable to different device requirements and avoiding control redundancy.

[0032] In the embodiment, the signal processing branch further comprises an amplifying element, the sampling end of the amplifying element is connected to the sampling module, and the output end of the amplifying element is connected to the input end of the comparing element.

[0033] The sampling signal of the sampling module is amplified by the amplifying element first, and then compared by the comparing element, thereby improving the accuracy of comparison and further improving the precision of control.

[0034] The sampling module comprises a sampling resistor, and one sampling resistor is connected to each load branch. The sampling resistor collects the voltage on each load branch and transmits the voltage signal to the corresponding signal processing branch for signal processing. By acquiring the voltage information on each load branch, when any load branch is damaged, the voltage signal output by the corresponding sampling resistor changes, the judgment result of the corresponding comparator in the signal processing branch changes, the conduction state of the corresponding switching diode changes, and the current signal generated by the photoelectric coupler changes, thereby controlling the output voltage of the device power supply unit to change. When any load changes, the output voltage of the power supply unit can be adaptively changed to ensure that even when a certain load is abnormal, the remaining loads can still operate at normal power, reduce the operation risk of the remaining loads, and improve the overall safety of the device. It can be understood that in other embodiments, the sampling module can also be any combination of a voltmeter, ammeter or multimeter with a detection signal output function, for example, a small resistance is connected in series to the corresponding load branch, and a voltmeter is connected in parallel to the small resistance. The voltage on the corresponding load branch is collected, and the corresponding digital signal is output to the operational amplifier through the AD differential circuit quantization conversion, so that the electrical parameters of the load branch can be collected to the corresponding signal processing branch.

[0035] In the embodiment, the amplifying element is an operational amplifier, the comparing element is a comparator, the switching element is a switching diode, and the signal integration circuit at least comprises a photoelectric coupler. For any signal processing branch, there is:

[0036] The signal output end of the sampling resistor is connected to the non-inverting input end of the operational amplifier, the output end of the operational amplifier is connected to the inverting input end of the comparator, the non-inverting input end of the comparator is connected to the reference voltage, the output end of the comparator is connected to the cathode of the switching diode, and the anode of the switching diode is connected to the cathode of the light-emitting diode of the photocoupler.

[0037] The non-inverting input of the operational amplifier is the sampling terminal of the operational amplifier. When the sampling resistor collects the voltage signal of the load branch and transmits it to the non-inverting output of the operational amplifier, after a first stage of non-inverting proportional operational amplification, the comparator compares the amplified voltage signal with the reference voltage. If the amplified voltage is greater than the reference voltage, that is, the voltage at the inverting terminal of the comparator is greater than the voltage at the non-inverting terminal, the output of the comparator is low. With respect to ground, the positive electrode voltage of the switching diode is higher than the negative electrode voltage of the switching diode, and the switching diode is turned on. If the amplified voltage is less than the reference voltage, that is, the voltage at the inverting terminal of the comparator is greater than the voltage at the non-inverting terminal, the output of the comparator is high. The negative electrode voltage of the switching diode is higher than the positive electrode voltage of the switching diode, and the switching diode is turned off.

[0038] The positive electrode of the switching diode in any signal processing branch is connected to the negative electrode of the light-emitting diode of the optocoupler, and the positive electrode of the light-emitting diode of the optocoupler is connected to the power supply terminal. When the switching diode is turned on, a current loop is formed from the power supply terminal through the light-emitting diode of the optocoupler to the switching diode. Current flows through the light-emitting diode of the optocoupler, and the photodetector side of the optocoupler generates current proportionally. When the switching diode is turned off, the current loop cannot be formed, no current flows through the light-emitting diode of the optocoupler, and no current is generated on the photodetector side of the optocoupler. Then, the current of the light-emitting diode of the optocoupler is controlled according to the voltage signal of each load branch, and the amount of current generated proportionally on the photodetector side of the optocoupler is controlled. The control chip or voltage control module of the power supply unit adjusts the PWM signal according to the current amount to control the current and voltage output of the power supply unit. For example, when a load in a load branch fails, the load branch is disconnected, no voltage signal is output, the switching diode in the signal processing branch corresponding to the load branch is cut off, and the current output by the optocoupler is reduced. At this time, the control chip or the voltage control module of the control unit receives the current reduction signal and controls the output energy of the power supply unit to reduce, thereby preventing the remaining load branches from bearing a higher voltage and ensuring the safe operation of the remaining load branches. For example, the output end of the optocoupler in this embodiment is connected to the NH series adjustable voltage-regulated constant-current switching power supply. Since the NH series adjustable voltage-regulated constant-current switching power supply itself has an analog signal external control, it can directly adjust its own output energy according to the current signal output by the output end of the optocoupler to stably provide reliable voltage and current to the load end.

[0039] In some embodiments, the signal processing branch further comprises a first feedback resistor and a second feedback resistor, one end of the first feedback resistor is connected to the output terminal of the operational amplifier, the other end of the first feedback resistor is connected to the inverting input terminal of the operational amplifier, one end of the second feedback resistor is connected to the inverting input terminal of the operational amplifier, and the other end of the second feedback resistor is grounded.

[0040] The amplification ratio of the operational amplifier is controlled by the first feedback resistor and the second feedback resistor, so that the signal amplification ratio can be adjusted according to actual needs.

[0041] In the present embodiment, the signal integration circuit further comprises a protection resistor and a compensation resistor, the protection resistor is connected between the anode of the light-emitting diode of the optocoupler and the power supply terminal, and the compensation resistor is connected in parallel to the light-emitting diode of the optocoupler.

[0042] Since the operating voltage of the light-emitting diode is relatively low, and the power supply voltage in the circuit is often relatively high, direct connection can cause unstable voltage and current of the light-emitting diode, and a protection resistor in series can share part of the voltage, prevent damage to the light-emitting diode or affect the normal operation of the optocoupler due to excessive current, and ensure stable voltage across the light-emitting diode. The compensation resistor is used for dead zone compensation to offset the influence of dead zone time on output voltage or current, thereby improving the performance and efficiency of the output protection circuit.

[0043] In other embodiments, the output protection circuit comprises a sampling module connected to each load branch of the load unit, a signal processing module connected to the sampling module and the power supply unit, and at least two or more sampling modules are connected to one load branch, and the signal processing module corresponds to the sampling module one by one.

[0044] In this case, multiple sampling modules are set on the load branch according to actual needs, thereby improving the accuracy of sampling.

[0045] As shown in Figure 3 As shown in FIG. 2, as an embodiment of the present application, a light source device comprises a power supply unit, a control unit, a light source module, and an output protection circuit, the output protection circuit is connected to the power supply unit, the control unit, and the light source module, the power supply unit is connected to the control unit and the power supply unit, and the power supply unit is connected to the light source module.

[0046] As shown in Figure 4 As shown in FIG. 2, the light source module comprises at least a plurality of parallel load branches, and each load branch comprises a plurality of series-connected LED light source loads. A sampling resistor is connected to the load branch to obtain a voltage signal on the load branch. The connection position of the sampling resistor can be set according to actual needs, such as being set near the ground terminal of the load branch or being set near the power terminal of the load branch.

[0047] The power supply unit is connected to an AC power supply and comprises at least a transformer T1, an auxiliary power supply circuit, a secondary rectification filter circuit and a reference source circuit. The transformer T1 is connected to the AC power supply. The auxiliary power supply circuit is connected to the transformer T1, the reference source circuit and a signal processing module. The reference source circuit is connected to the signal processing module. The secondary rectification filter circuit is connected to the transformer T1 and a light source module.

[0048] The auxiliary power supply circuit is connected to a signal processing branch and a signal integration circuit. The reference source circuit is connected to the signal processing branch. The auxiliary power supply circuit processes the AC power supply to provide power supply for the signal processing branch, the signal integration circuit and the reference source circuit. The reference source circuit provides a reference voltage for an operational amplifier. The secondary rectification filter circuit filters the AC power supply to provide power supply for the light source module.

[0049] As shown in Figure 5 , the secondary rectification filter circuit comprises a first rectification diode D1, a first resistor R1, a first capacitor C1, a load resistor RL1, a second capacitor C2 and a third capacitor C3. The positive electrode of the first rectification diode D1 is connected to the transformer T1. The negative electrode of the first rectification diode D1 is connected to the light source module. The first resistor R1 and the first capacitor C1 are connected in series and in parallel to the first rectification diode D1. One end of the load resistor RL1 is connected to the negative electrode of the first rectification diode D1. The other end of the load resistor RL1 is grounded. The second capacitor C2 is connected in parallel to the load resistor RL1. The third capacitor C3 is connected in parallel to the second capacitor C2.

[0050] The secondary rectification filter circuit converts the AC power output by the transformer T1 into DC power to provide a stable voltage for the light source module.

[0051] As shown in Figure 6 , the auxiliary power supply circuit comprises a second rectification diode D2, a fourth capacitor C4 and a fifth capacitor C5. The positive electrode of the second rectification diode D2 is connected to the transformer T1. The negative electrode of the second rectification diode D2 is connected to the reference source circuit and the signal processing module. The positive electrode of the fourth capacitor C4 is connected to the negative electrode of the second rectification diode D2. The negative electrode of the fourth capacitor C4 is grounded. The fifth capacitor C5 is connected in parallel to the fourth capacitor C4.

[0052] The auxiliary power supply circuit rectifies the AC power output by the transformer T1 to provide power supply for the reference source circuit and the signal processing module. In the signal processing module, the power supply end connected to the positive input end of the operational amplifier and the power supply end connected to the negative electrode of the light emitting diode of the optocoupler are both output ends of the auxiliary power supply circuit, i.e. the negative electrode of the second rectification diode D2.

[0053] As shown in Figure 7As shown, the reference source circuit includes a voltage regulator U4, the negative electrode of the voltage regulator U4 is connected to the negative electrode of the second rectifier diode D2, the positive electrode of the voltage regulator U4 is grounded, and the regulating end of the voltage regulator U4 is connected to the non-inverting input end of the comparator.

[0054] Further improve the stability of the reference source circuit, the reference source circuit further includes a protection resistor R11, the protection resistor R11 is connected between the voltage regulator U4 and the negative electrode of the second rectifier diode D2, and the voltage regulator U4 is TL431.

[0055] In a specific embodiment, taking the light source module containing n load branches as an example, n LED power supplies are connected in series on each load branch, and there are n sampling resistors and n signal processing branches. Taking L1, L2, and Ln three load branches, corresponding sampling resistors R4, R5, and R6, and obtaining LED light source sampling signals VL1, VL2, and VLn. There are protection resistors R9, R10, R14, R15, R18, and R19, wherein:

[0056] In the signal processing branch corresponding to the L1 load branch, there are:

[0057] One end of the resistor R10 is connected to the output end of the sampling resistor R4, the other end of the resistor R10 is connected to the non-inverting input end 3 pin of the operational amplifier U1A, one end of the second feedback resistor R8 is connected to the inverting input end 2 pin of the operational amplifier U1A, the other end of the second feedback resistor R8 is grounded, one end of the first feedback resistor R3 is connected to the output end 1 pin of the operational amplifier U1A, the other end of the first feedback resistor R3 is connected to the inverting input end 2 pin of the operational amplifier U1A, the power supply positive input end 8 pin of the operational amplifier U1A is connected to the output end VCC2 of the auxiliary power supply circuit, the power supply negative input end 4 pin of the operational amplifier U1A is grounded, the output end 1 pin of the operational amplifier U1A is connected to the inverting input end 6 pin of the comparator U1B, the non-inverting input end 5 pin of the comparator U1B is connected to the output end of the reference source circuit, the output end 7 pin of the comparator U1B is connected to the negative electrode of the switching diode D3, one end of the resistor R9 is connected to the positive electrode of the switching diode D3, and the other end of the resistor R9 is connected to the negative electrode of the light-emitting diode of the photoelectric coupler U2.

[0058] In the signal processing branch corresponding to the L2 load branch, there are:

[0059] One end of the resistance R15 is connected to the output end of the sampling resistance R5, the other end of the resistance R15 is connected to the non-inverting input end 3 pin of the operational amplifier U3A, one end of the second feedback resistance R13 is connected to the inverting input end 2 pin of the operational amplifier U3A, the other end of the second feedback resistance R13 is grounded, one end of the first feedback resistance R12 is connected to the output end 1 pin of the operational amplifier U3A, the other end of the first feedback resistance R12 is connected to the inverting input end 2 pin of the operational amplifier U3A, the power supply positive input end 8 pin of the operational amplifier U3A is connected to the output end VCC2 of the auxiliary power supply circuit, the power supply negative input end 4 pin of the operational amplifier U3A is grounded, the output end 1 pin of the operational amplifier U3A is connected to the inverting input end 6 pin of the comparator U3B, the non-inverting input end 5 pin of the comparator U3B is connected to the output end of the reference source circuit, the output end 7 pin of the comparator U3B is connected to the negative pole of the switching diode D4, one end of the resistance R14 is connected to the positive pole of the switching diode D4, the other end of the resistance R14 is connected to the light emitting diode negative pole end of the photoelectric coupler U2.

[0060] In the signal processing branch corresponding to the Ln load branch, there are:

[0061] One end of the resistance R19 is connected to the output end of the sampling resistance R6, the other end of the resistance R19 is connected to the non-inverting input end 3 pin of the operational amplifier U5A, one end of the second feedback resistance R17 is connected to the inverting input end 2 pin of the operational amplifier U5A, the other end of the second feedback resistance R17 is grounded, one end of the first feedback resistance R16 is connected to the output end 1 pin of the operational amplifier U5A, the other end of the first feedback resistance R16 is connected to the inverting input end 2 pin of the operational amplifier U5A, the power supply positive input end 8 pin of the operational amplifier U5A is connected to the output end VCC2 of the auxiliary power supply circuit, the power supply negative input end 4 pin of the operational amplifier U5A is grounded, the output end 1 pin of the operational amplifier U5A is connected to the inverting input end 6 pin of the comparator U5B, the non-inverting input end 5 pin of the comparator U5B is connected to the output end of the reference source circuit, the output end 7 pin of the comparator U5B is connected to the negative pole of the switching diode D5, one end of the resistance R18 is connected to the positive pole of the switching diode D5, the other end of the resistance R18 is connected to the light emitting diode negative pole end of the photoelectric coupler U2.

[0062] In this embodiment, the operational amplifier of model LM358 is selected. Taking the signal processing branch corresponding to the L1 load branch as an example, the signal VL1 is introduced into the 3-pin same-phase input end of the LM358 operational amplifier, and is amplified by one same-phase proportional operational amplifier. R3 and R8 are feedback networks, VL1 is amplified, and the output of 1-pin is (1+R3 / R8)*VL1. This signal is introduced into the 6-pin opposite-phase input end of another level of the operational amplifier, and the 5-pin is introduced into a reference voltage. This operational amplifier is used as a comparator. When the VL1 path is connected, there is a voltage signal, which is compared with the reference voltage after same-phase amplification. The voltage of the opposite-phase end is greater than that of the same-phase end, and the output of 7-pin is low relative to the ground. At this time, D3 is turned on. VCC2 passes through R2, the photoelectric coupler 1, 2-pin, R9, D3, and the ground to form a loop. There is a current flowing through the photoelectric coupler 1, 2-pin, and a current is generated in the photoelectric coupler 3, 4-pin in proportion. The control unit adjusts the PWM signal according to the current intensity of the photoelectric coupler, so as to control the on-off time of the primary side switch tube. At this time, in the multi-path operation, the photoelectric coupler 1, 2-pin is the main loop; R9, D3 is a branch; R14, D4 is a branch; and R18, D5 is a branch. Under the one-way conduction of the diode, the branches do not interfere with each other, and the signals of the branches are superimposed into the main loop.

[0063] Conversely, when the VL1 path is disconnected, there is no voltage of VL1. After one same-phase proportional operational amplification, the voltage is compared with the reference voltage. The voltage of the same-phase end is greater than that of the opposite-phase end, and the output of 7-pin is high relative to VCC2. At this time, D3 is cut off, and the loop cannot be formed. There is no current flowing through the D3 branch of the photoelectric coupler 1, 2-pin. The current generated in the photoelectric coupler 3, 4-pin in proportion is small. The control unit adjusts the PWM signal according to the current intensity of the photoelectric coupler, so as to control the on-off time of the primary side switch tube, reduce the output energy, and reduce the secondary current, thereby protecting other paths of the LED light source from overuse.

[0064] The output protection circuit of the present application protects the LED light source through the current intensity of the photoelectric coupler output. When the LED light source is in series and parallel failure, the output current of the power supply is adjusted in time, so that the other normal LED particles will not be overused. The light source device only reduces the power and luminous flux, and can still be used normally for a long time. The user can find it in time and repair or replace the light source module, so as to avoid greater loss.

[0065] The above-described specific embodiments are the preferred embodiments of the output protection circuit and the light source device adopting the output protection circuit of the present application, and are not intended to limit the specific implementation range of the present application. The scope of the present application includes but is not limited to the specific embodiments. Any equivalent changes made according to the shape and structure of the present application are within the protection scope of the present application.

Claims

1. An output protection circuit connected to the power supply unit and the load unit of the device, characterized in that: include: A sampling module for collecting electrical parameter signals of each load branch of the load unit, and a signal processing module connected to the sampling module and the power supply unit, wherein at least one sampling module is connected to one load branch; Among them, the signal processing module includes a signal processing branch and a signal integration circuit corresponding to the sampling module. The signal processing branch includes at least a comparison element and a switching element. The sampling end of the comparison element is connected to the sampling module, the output end of the comparison element is connected to one end of the switching element, and the other end of the switching element is connected to the input end of the signal integration circuit. The output end of the signal integration circuit is connected to the power supply unit.

2. The output protection circuit according to claim 1, wherein: The signal processing branch further includes an amplifying element, a sampling end of the amplifying element is connected to the sampling module, and an output end of the amplifying element is connected to an input end of the comparing element.

3. The output protection circuit according to claim 2, wherein: The amplifying element is an operational amplifier, the comparing element is a comparator, the switching element is a switching diode, and the signal integration circuit includes at least a photocoupler; For any signal processing branch, there exists: The signal output end of the sampling module is connected to the non-inverting input end of the operational amplifier, the output end of the operational amplifier is connected to the inverting input end of the comparator, the non-inverting input end of the comparator is connected to the reference voltage, the output end of the comparator is connected to the cathode of the switching diode, and the anode of the switching diode is connected to the cathode of the light-emitting diode of the photoelectric coupler.

4. The output protection circuit according to claim 3, wherein: The signal processing branch also includes a first feedback resistor and a second feedback resistor, one end of the first feedback resistor is connected to the output end of the operational amplifier, the other end of the first feedback resistor is connected to the inverting input end of the operational amplifier, one end of the second feedback resistor is connected to the inverting input end of the operational amplifier, and the other end of the second feedback resistor is grounded.

5. A light source device, including a control unit, characterized in that: Also includes: A power supply unit, a light source module, and an output protection circuit according to any one of claims 1 to 4; Among them, the light source module is connected to the power supply unit, the power supply unit is connected to the control unit, the sampling module of the output protection circuit collects the electrical parameter signals of each load branch of the light source module, and the signal integration circuit of the output protection circuit outputs the control signal to the control unit.

6. The light source device according to claim 5, wherein: The light source module comprises at least a plurality of parallel load branches, and the load branches comprise a plurality of LED light source loads connected in series.

7. The light source device according to claim 5, wherein: The power supply unit is connected to an AC power supply and includes at least a transformer, an auxiliary power supply circuit, a secondary rectifier and filter circuit, and a reference source circuit. The transformer is connected to the AC power supply, the auxiliary power supply circuit is connected to the transformer, the reference source circuit, and the signal processing module, the reference source circuit is connected to the signal processing module, and the secondary rectifier and filter circuit is connected to the transformer and the light source module.

8. The light source device according to claim 7, wherein: The secondary rectifier and filter circuit includes a first rectifier diode, a first resistor, a first capacitor, a load resistor, a second capacitor and a third capacitor. The positive pole of the first rectifier diode is connected to the transformer, the negative pole of the first rectifier diode is connected to the light source module, the first resistor and the first capacitor are connected in series and in parallel with the first rectifier diode, one end of the load resistor is connected to the negative pole of the first rectifier diode, the other end of the load resistor is grounded, the second capacitor is connected in parallel with the load resistor, and the third capacitor is connected in parallel with the second capacitor.

9. The light source device according to claim 7, wherein: The auxiliary power supply circuit includes a second rectifier diode, a fourth capacitor and a fifth capacitor. The positive electrode of the second rectifier diode is connected to the transformer, the negative electrode of the second rectifier diode is connected to the reference source circuit and the signal processing module, the positive electrode of the fourth capacitor is connected to the negative electrode of the second rectifier diode, the negative electrode of the fourth capacitor is grounded, and the fifth capacitor is connected in parallel with the fourth capacitor.

10. The light source device according to claim 7, wherein: The reference source circuit includes a voltage regulator, the negative electrode of the voltage regulator is connected to the output end of the auxiliary power supply circuit, the positive electrode of the voltage regulator is grounded, and the regulating end of the voltage regulator is connected to the non-inverting input end of the comparator.

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