CN203135403U - Over-current protection circuit for loader - Google Patents
Over-current protection circuit for loader Download PDFInfo
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- CN203135403U CN203135403U CN201220705096.8U CN201220705096U CN203135403U CN 203135403 U CN203135403 U CN 203135403U CN 201220705096 U CN201220705096 U CN 201220705096U CN 203135403 U CN203135403 U CN 203135403U
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Abstract
The utility model discloses an over-current protection circuit for a loader. The over-current protection circuit comprises a sensing resistor, a difference amplifier, a comparator, a current control circuit, a constant voltage source, a decoding deck connection interface and an on-off switch, wherein the difference amplifier linearly converses the current flowing through the sensing resistor from the input end of a power supply into voltage value and amplifies the voltage value, the comparator outputs L or H level by comparing the detected voltage value output by the difference amplifier with threshold voltage value, the current control circuit is on upon reception of H level output by the comparator, and the on-off switch is on when the decoding deck is on. When the current control circuit and the on-off switch are on, the input end of the power supply inputs current to the header through the over-current protection circuit. The over-current protection circuit solves the problem of over-current protection of the input port of the header power supply and ESD static damage, thereby minimizing the possibility of damage of the header and lowering the maintenance cost.
Description
Technical Field
The utility model relates to an overcurrent protection technical field of circuit especially relates to a core optical head overcurrent protection circuit.
Background
As is known, when a disc reading capability test is performed on a decoding board, a LOADER (LOADER) is mounted in a fixture, and the decoding board and the LOADER are connected by a thimble to perform a disc reading test. After a certain number of tests are carried out in the production test process, the optical head (LD) of the movement on the movement can be degraded and damaged, and the phenomenon of disk reading is avoided, which is mainly caused by that a large impact current passes through the optical head of the movement when the movement is electrified or static electricity is abnormally discharged, and the damage of the optical head of the movement undoubtedly also causes the cost improvement of raw material replacement and manpower maintenance.
SUMMERY OF THE UTILITY MODEL
A primary object of the present invention is to provide a core optical head overcurrent protection circuit, which aims to solve the problem of deterioration damage caused by the passing of large impact current in the core optical head.
In order to achieve the above object, the present invention provides a differential amplifier including a sensing resistor, a differential amplifier for converting the current of the power input end passing through the sensing resistor into voltage and amplifying the voltage, a comparator for monitoring the voltage value output by the differential amplifier and outputting the L level and the H level, a current control circuit for realizing self circuit conduction after receiving the H level output by the comparator, a decoding board, and an on-off switch for realizing self circuit conduction after the decoding board is powered on;
the sensing resistor, the current control circuit and the on-off switch are sequentially connected to a circuit from the power input end to the power output end, a sensing voltage positive input end and a sensing voltage negative input end of the differential amplifier are respectively connected with the current input end and the current output end of the sensing resistor, and the output end of the differential amplifier is connected with the reverse input end of the comparator; the output end of the comparator is connected with the control end of the current control circuit; the decoding board is connected with the control end of the on-off switch.
Preferably, the movement optical head overcurrent protection circuit further includes an electrostatic resistor element (i.e., an ESD element) disposed between the on-off switch and the power supply output terminal.
Preferably, the core optical head overcurrent protection circuit further comprises a delay driving circuit for performing delay connection on the current output after the decoding board is electrified, wherein the delay driving circuit is arranged between the on-off switch and the decoding board.
Preferably, the movement optical head overcurrent protection circuit further comprises a constant voltage source used as a reference of a threshold reference voltage of the comparator, wherein the constant voltage source is connected with a positive input end of the comparator.
Preferably, the differential amplifier comprises a first resistor, a second resistor, a fourth resistor, a first capacitor and a current test chip; the first resistor is connected with one end of the current input end of the sensing resistor, and the other end of the first resistor is connected with the sensing voltage positive input end of the current testing chip; the second resistor is connected with one end of the current output end of the sensing resistor, and the other end of the second resistor is connected with the negative input end of the sensing voltage of the current testing chip; the output end of the current test chip is connected with the comparator; the fourth resistor is connected between the output end of the current test chip and the ground; the positive power supply end of the current test chip is connected with a first power supply, and the power supply end, the control end and the grounding end of the current test chip are connected with the ground after being connected in parallel, wherein the first capacitor is arranged on a circuit which is connected with the positive power supply end of the current test chip and the ground.
Preferably, the comparator comprises an operational amplifier, a second capacitor, a third resistor and a fifth resistor; the constant voltage source comprises a twelfth resistor, a reference source and a fourth capacitor; the inverting input end of the operational amplifier is connected with the differential amplifier, and the third resistor is connected to a connecting circuit between the differential amplifier and the inverting input end of the operational amplifier; the second capacitor and the fifth resistor are connected in series between the inverting input end and the output end of the operational amplifier; the negative power supply end of the operational amplifier is connected with the ground; the positive power supply end of the operational amplifier is connected with the second power supply and the ground, and the third capacitor is connected on a circuit between the positive power supply end of the operational amplifier and the ground;
in addition to this, the present invention is,
the twelfth resistor is arranged on a connecting circuit of the third power supply and the equidirectional input end of the operational amplifier; a first connecting point, a second connecting point and a third connecting point are arranged on a connecting circuit between the twelfth resistor and the equidirectional input end of the operational amplifier, wherein the current input end of the fourth capacitor is connected with the third connecting point, and the current output end of the fourth capacitor is connected with the ground; the anode of the reference source is connected with the first connection point, the reference electrode is connected with the second connection point, and the cathode is connected with the ground.
Preferably, the current control circuit includes a sixth resistor, a seventh resistor, an eighth resistor, a first triode and a second triode, the first triode is in a PNP structure, and the second triode is in an NPN structure; the emitter of the first triode is connected with the sensing resistor, and the collector of the first triode is connected with the on-off switch; a sixth resistor is arranged on a connecting circuit of one end of the emitting electrode of the first triode and the base electrode of the first triode; the seventh resistor is arranged on a connecting circuit of the base electrode of the first triode and the collector electrode of the second triode; the eighth resistor is arranged on a connecting circuit of the comparator and the base electrode of the second triode; and the emitter of the second triode is connected with the ground.
Preferably, the on-off switch comprises a ninth resistor, a switching element, a reverse pulse absorption diode and a relay composed of a tenth resistor, an eleventh resistor and a third triode, and the third triode is of an NPN structure; the normally open contact of the switch element is connected with the current control circuit; the ninth resistance current input end is arranged on a connecting circuit of the normally closed contact of the switching element and the ground; an electromagnetic coil is arranged in the switch element, a metal elastic sheet controlled by the electromagnetic coil is arranged between a normally closed contact and a normally open contact in the switch element, and one end of the metal elastic sheet is connected with the output end of the switch element; the output end of the switch element is connected with the ESD element; the electromagnetic coil and the reverse pulse absorption diode form a parallel circuit, and two ends of the parallel circuit are respectively connected with a collector of the third triode and a fourth power supply; the current input end of the tenth resistor is connected with the decoding board, and the current output end of the tenth resistor is connected with the base electrode of the third triode; and the current input end of the eleventh resistor is arranged on a circuit connecting the current output end and the base of the third triode, and the eleventh resistor is connected with the emitting electrode of the third triode in parallel and then connected with the ground.
Preferably, the delay driving circuit comprises a delay chip and a fifth capacitor; the input end of the delay chip is connected with the decoding board, one end of the fifth capacitor is connected to the circuit for connecting the input end of the delay chip with the decoding board, and the other end of the fifth capacitor is connected with the ground; the ground terminal of the delay chip is connected with the ground, and the output end of the delay chip is connected with the on-off switch.
Preferably, the ESD element includes a thirteenth resistor, a sixth capacitor, a filter inductor, and an electrostatic ESD protection diode; the filter inductor is arranged on a connecting circuit of the on-off switch and the power output end, a first connecting point, a second connecting point and a third connecting point are arranged on the connecting circuit of the filter inductor and the power output end, current input ends of a thirteenth resistor, an electrostatic ESD protection diode and a sixth capacitor are respectively connected with the first connecting point, the second connecting point and the third connecting point, and current output ends of the thirteenth resistor, the electrostatic ESD protection diode and the sixth capacitor are connected with the ground after being connected in parallel.
The utility model provides a core optical head overcurrent protection circuit, including sensing resistor, differential amplifier, a comparator, the current control circuit, decoding board and on-off switch, wherein, differential amplifier is used for passing through the linear conversion of the current on the sensing resistor of power input end and enlargies to the magnitude of voltage, the comparator is used for monitoring the magnitude of voltage of differential amplifier output and decides output L level and H level according to the setting value of internal settlement, current control circuit is used for switching on the circuit after receiving comparator output H level, on-off switch sets up between current control circuit and power output end, and on-off switch and decoding board are connected, on-off switch switches on and realizes switching on of circuit control circuit and power output end after decoding board power-on, after power input end and decoding board all power-on, when the electric current that power input end input was greater than the setting value, the overcurrent protection circuit works, and when the overcurrent protection circuit is smaller than a set value, the overcurrent protection circuit fails, so that the overcurrent protection circuit of the machine core optical head limits the maximum current input by the circuit of the machine core, and overcurrent is prevented.
Drawings
Fig. 1 is a schematic block diagram of a core optical head overcurrent protection circuit according to an embodiment of the present invention.
Fig. 2 is a schematic circuit diagram of an embodiment of the core optical head overcurrent protection circuit of the present invention.
The objects, features and advantages of the present invention will be further described with reference to the accompanying drawings.
Detailed Description
The technical solution of the present invention is further explained below with reference to the drawings and the specific embodiments of the specification. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the utility model provides a solution is mainly: the over-current protection circuit comprises a sensing resistor, a differential amplifier, a comparator, a current control circuit, a decoding board and an on-off switch, wherein the differential amplifier is used for converting a current on a power supply input end into a voltage value linearly through the sensing resistor and amplifying the voltage value, the comparator is used for monitoring the voltage value output by the differential amplifier and determining to output an L level and an H level according to an internally set value, the current control circuit is used for conducting the circuit after receiving the H level output by the comparator, the on-off switch is arranged between the current control circuit and the power supply output end and is connected with the decoding board, and the on-off switch is conducted after the decoding board is electrified and realizes the conduction of the circuit control circuit and the power supply output end. After the power input end and the decoding board are powered on, when the current input by the power input end is greater than a set value, the overcurrent protection circuit works, and when the current input by the power input end is less than the set value, the overcurrent protection circuit fails, so that the overcurrent protection circuit of the optical head of the movement limits the maximum current input by the circuit of the movement, and the overcurrent is prevented.
Referring to fig. 1, fig. 1 is a schematic circuit block diagram of a core optical head overcurrent protection circuit according to the present invention. The utility model discloses in, including power input end 1, sensing resistor 3, differential amplifier 2, comparator 9, current control circuit 5, constant voltage source 4, decoding board connection interface 11, on-off switch 6, ESD component 7, time delay drive circuit 10, power output end 8. The sensing resistor 3, the current control circuit 5, the on-off switch 6 and the ESD element 7 are sequentially connected to a circuit from the power input end 1 to the power output end 8, in addition, a sensing voltage positive input end and a sensing voltage negative input end of the differential amplifier 2 are respectively connected with a current input end and a current output end of the sensing resistor 3, and a current output end of the differential amplifier 2 is connected with a reverse input end of the comparator 9; the output end of the constant voltage source 4 is connected with the positive input end of the comparator 9; the output end of the comparator 9 is connected with the control end of the current control circuit 5; the delay drive circuit 10 is connected between the on-off switch 6 and the decoder board 11.
In the present invention, the differential amplifier 2 is used to convert the current at the power input terminal 1 through the sensing resistor 3 into a voltage value and amplify the voltage value. The comparator 9 is configured to monitor a voltage value output by the differential amplifier 2, a comparison voltage value is set in the comparator 9, the comparison voltage value can be adjusted according to actual needs, and when the voltage value output by the differential amplifier 2 received by the comparator 9 is higher than the comparison voltage value, the comparator outputs an L level, otherwise, the comparator outputs an H level. The current control circuit 5 is used for forming a conducting circuit in the internal circuit after receiving the H level output by the comparator 9, and on the contrary, forming a breaking circuit in the internal circuit if the L level is received. The on-off switch 6 is turned on after the decoding board 11 is powered on. During the period, the comparator 9 outputs high level, the current control circuit 5 is turned on, at this time, the decoding board 11 is turned on, and after the on-off switch 6 is turned on, the current path formed between the power input terminal 1 and the power output terminal 8 is finally enabled, and the power output terminal 8 outputs current to the movement (not shown in the figure).
In further implementation, because can not normally work at once after the electricity is gone up to the decoding board 11, the level of each control port is uncertain, there is the height to have low, the bright head LD circuit drive third triode Q3 of core OPU appears the saturation conduction phenomenon, lead to surge current on the bright head LD of core OPU, make bright head LD degradation damage, only wait to all chips reset, software normal operating back, just can obtain the control right of various circuits, in order to solve this problem, the utility model discloses set up a delay drive circuit 10 between decoding board 11 and on-off switch 6, will decode and switch on by on-off switch 6 again after 11 end electric current delays of decoding board 240 ms.
In a further embodiment, in order to prevent the influence of transient variation, surge current and static electricity occurring in the current output from the on-off switch 6 on the movement head, the ESD element 7 is provided on the circuit between the on-off switch 6 and the power output terminal 8.
Referring to fig. 2, fig. 2 is a schematic circuit structure diagram of a preferred embodiment of the over-current protection circuit for a core optical head of the present invention. The utility model discloses in, including power input end (not reference numeral in the figure), sensing resistor 3, differential amplifier 2, comparator 9, current control circuit 5, constant voltage source 4, decoding board 11, break-make switch 6, power output end (not reference numeral in the figure). The differential amplifier 2 comprises a first resistor R1, a second resistor R2, a fourth resistor R4, a first capacitor C1 and a current test chip U2; the constant voltage source 4 comprises a twelfth resistor R12, a reference source D4 capable of adjusting precision voltage and a fourth capacitor C4; the current control circuit 5 comprises a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first triode Q1 and a second triode Q2, wherein the first triode Q1 is of a PNP structure, and the second triode Q2 is of an NPN structure; the on-off switch 6 comprises a ninth resistor R9, a switching element K, a reverse pulse absorption diode D6 and a relay consisting of a tenth resistor R10, an eleventh resistor R11 and a third triode Q3, wherein the third triode Q3 is of an NPN structure; the comparator 9 includes an operational amplifier U9, a second capacitor C2, a third capacitor C3, a third resistor R3, and a fifth resistor R5.
One end of a first resistor R1 in the differential amplifier 2 is connected with the current input end of the sensing resistor 3, and the other end of the first resistor R1 is connected with a sensing voltage positive input end j23 of a current test chip U2; one end of the second resistor R2 is connected with the current output end of the sensing resistor 3, and the other end is connected with the sensing voltage negative input end j26 of the current test chip U2; the output terminal j28 of the current test chip U2 is connected with R3 of the comparator 9; the fourth resistor R4 is connected between the output terminal j28 of the current test chip U2 and the ground; the chip power supply terminal j27 of the current test chip U2 is connected to the first 5V power source VCC, and the power supply terminal j27, the control terminal j21 and the chip ground terminal j24 of the current test chip U2 form a parallel circuit and are connected to the ground, wherein the first capacitor C1 is disposed on a circuit where the positive power supply terminal j27 of the current test chip U2 is connected to the ground. The sensing resistor 3 is a precision resistor, the resistance value and the power are selected according to the current value range of actual use, when the current of the power input end 1 passes through the sensing resistor 3, a voltage difference is generated at two ends of the sensing resistor 3, and the current testing chip U2 obtains the current difference value at two ends of the sensing resistor 3 through the sensing voltage positive input end j23 and the sensing voltage negative input end j26, and linearly converts the current difference value into a voltage difference value to be output from the output end j 28. In practical operation, different ranges can be obtained by adjusting the values of the sensing resistor 3, the first resistor R1 and the second resistor R2, wherein the relationship between the output voltage and the current is: the output voltage (the actual current sensed by the precision sensing resistor x output voltage-regulating resistor x)/the gain resistor.
A twelfth resistor R12 in the constant voltage source 4 is arranged on a connection circuit of the third 5V power supply VCC and the equidirectional input terminal J93 of the operational amplifier U9; a first connection point, a second connection point and a third connection point are arranged on a connection circuit between the twelfth resistor R12 and the equidirectional input end J93 of the operational amplifier U9, wherein the current input end of the fourth capacitor C4 is connected with the third connection point, and the current output end is connected with the ground; the anode J42 of the reference source D4 is connected to the first connection point, the reference pole J41 is connected to the second connection point, and the cathode J43 is connected to ground.
The inverting input terminal J92 of the operational amplifier U9 in the comparator 9 is connected to the third resistor R3; the second capacitor C2 and the fifth resistor R5 in the comparator 9 are connected in series between the inverting input terminal J92 and the output terminal J91 of the operational amplifier U9, the negative power supply terminal J94 of the operational amplifier U9 is connected to ground, the positive power supply terminal J98 is connected to the second 5V power supply VCC and to ground, and the third capacitor C3 is connected to a circuit between the positive power supply terminal J98 of the operational amplifier U9 and ground. The operational amplifier U9 receives the voltage difference value output from the positive power supply terminal J28 of the current test chip U2 through the third resistor R3, and performs voltage value constancy through the constant voltage source 4 connected to the equidirectional input terminal J93, and finally the operational amplifier U9 determines the voltage value and converts the voltage value into an L level and an H level to output from the output terminal J91 of the operational amplifier U9.
In the above specific application of the circuit of the present invention, when the current passing through the sensing resistor 3 is smaller than the set value, the output voltage of the output terminal J28 of the current test chip U2 is smaller than 2.5V, and the output of the operational amplifier U9 is H level; when the current passing through the sensing resistor 3 is larger than the set value, the output voltage of the output terminal j28 of the current test chip U2 is larger than 2.5V, and the output of the operational amplifier U9 is at L level.
In addition, the emitter of the first triode Q1 in the current control circuit 5 is connected with the sensing resistor 3, and the collector thereof is connected with the normally open contact J65 of the switching element of the on-off switch 6; a sixth resistor R6 is arranged on a connecting circuit of one end of an emitting electrode of the first triode Q1 and a base electrode thereof; the seventh resistor R7 is arranged on the connection circuit of the base of the first triode Q1 and the collector of the second triode Q2; the eighth resistor R8 is arranged in the comparator 9 at the connection circuit of the output terminal J91 of the operational amplifier U9 and the base of the second triode Q2; the emitter of the second transistor Q2 is connected to ground. The base electrode of the second triode Q2 is responsible for receiving the output level of the operational amplifier U9, when the base electrode of the second triode Q2 receives the H level, the base electrode is conducted, the level of the collector electrode is changed from H to L, Vb of the first triode Q1 is smaller than Ve, at the moment, the first triode Q1 is conducted, and the current of the input end of the power supply outputs current to the direction of the on-off switch 6 after passing through the sensing resistor 3 and the current control circuit 5; when the base of the second triode Q2 receives the L level, the base is cut off, the collector level is changed from L to H, and Vb = Ve of the first triode Q1 is enabled, at this time, the first triode Q1 is cut off, and the current cannot be output.
Meanwhile, on the basis of the current control circuit 5, another on-off switch 6 which determines the circuit connection from the power input end 1 to the power output end 8 is also arranged. The current input end of a ninth resistor R9 in the on-off switch 6 is arranged on a connecting circuit of a normally closed contact J63 of the switch element K and the ground; an electromagnetic coil (not numbered in the figure) is arranged inside the switch element K, and a metal elastic sheet (not numbered in the figure) controlled by the electromagnetic coil is arranged between the normally closed contact J63 and the normally open contact J65 inside the switch element K, and the metal elastic sheet is fixedly connected with an output end J64 of the switch element; the electromagnetic coil and the reverse pulse absorption diode D6 form a parallel circuit, and two ends of the parallel circuit are respectively connected with a collector of a third triode Q3 and a fourth 5V power supply VCC; the current input end of the tenth resistor R10 is connected with the decoding board 11, and the current output end is connected with the base electrode of the third triode Q3; the current input end of the eleventh resistor R11 is arranged on a circuit which is connected with the current output end and the base electrode of the third triode Q3, and the eleventh resistor R11 is connected with the emitting electrode of the third triode Q3 in parallel and then is connected with the ground. When the decoding board is not electrified, the end of the decoding board inputs L level, the third triode Q3 is not conducted, at the moment, the electromagnetic coil does not generate magnetic force, the metal elastic sheet is connected with the normally closed contact J63, the circuit path of the on-off switch 6 is disconnected, the circuit between the power input end 1 and the power output end 8 is disconnected, and the voltage or the generated static current on the power output end 8 is grounded and discharged after passing through a ninth resistor R9 with 100 ohm resistance; when the decoding board is electrified, the end of the decoding board inputs H level, the third triode Q3 is conducted, the electromagnetic coil generates magnetic force, the metal elastic sheet moves downwards and is connected with the normally open contact J65, current is output by the output end J64 of the on-off switch 6, and finally normal circuit connection between the power input end 1 and the power output end 8 is achieved.
After the decoding board 11 is powered on, meanwhile, the current value output by the power input end 1 does not exceed the set maximum current value, the current control circuit 5 and the on-off switch 6 can both realize the passage, so that the circuit between the power input end 1 and the power output end 8 is conducted, and the normal output of the current is realized.
In further implementation, because the decoding board 11 can not normally work immediately after being electrified, the level of each control port is uncertain, and the level has a high level and a low level, the optical pickup LD control circuit of the movement OPU has a saturation conduction phenomenon, so that surge current passes through the optical pickup LD of the movement OPU, the optical pickup LD is deteriorated and damaged, and the LD control circuit can be recovered to a normal working state only when all chips are reset and software normally runs, in order to solve the problem, the utility model discloses set up a delay drive circuit 10 between the decoding board 11 and the on-off switch 6, including delay chip U10 and fifth capacitor C5; the input end J103 of the delay chip U10 is connected with the decoding board 11, one end of a fifth capacitor C5 is connected with the connection circuit of the input end J103 of the delay chip U10 and the decoding board 11, and the other end of the fifth capacitor C5 is connected with the ground; the grounding end J101 of the delay chip U10 is connected with the ground, and the delay output end J102 is connected with the tenth resistor R10 in the on-off switch. In the practical application process, after the decoding board 11 is powered on, the delay chip U10 delays the current at the end of the decoding board 11 for 240ms and outputs the H level, and finally the third triode Q3 is turned on.
In a further implementation process, in order to prevent the influence of transient variation, surge current and static electricity on the movement head of the current output by the on-off switch 6, the ESD element 7 is arranged on the circuit between the on-off switch 6 and the power output end 8, and comprises a thirteenth resistor R13, a sixth capacitor C6, a filter inductor L1 and an electrostatic ESD protection diode D7; the L1 is connected to the power output terminal 8, a first connection point, a second connection point and a third connection point are provided on a connection circuit of the L1 and the power output terminal 8, wherein current input terminals of a thirteenth resistor R13, an ESD protection diode D7 and a sixth capacitor C6 are respectively connected to the first connection point, the second connection point and the third connection point, and current output terminals of the thirteenth resistor R13, the ESD protection diode D7 and the sixth capacitor C6 are connected in parallel and then connected to ground. The filter inductor L1 prevents transient large current from passing through the inductor, and the ESD protection diode D7 can discharge electrostatic pulse voltage up to 10 KV.
In the above embodiments, the core optical head overcurrent protection circuit is mainly applied to an overcurrent protection circuit for current of a relatively precise electronic device, such as an optical head LD, a laser diode, a constant current source, and various power supplies of a CD, a DVD, and a BD video disk player, to provide overcurrent protection, short circuit protection, and ESD electrostatic protection.
In current core test process, owing to not set up corresponding overcurrent protection circuit, this makes the core lead to the core optical head to damage easily because the passing through of too big electric current when using, compares in the not enough of prior art, the utility model discloses a set up an overcurrent protection circuit before the input power of core, this makes the utility model has the advantages of it is following:
(1) the utility model discloses a core optical head overcurrent protection circuit carries out overcurrent protection to the electric current through the core, fine protection the core optical head, makes core optical head life more of a specified duration, reduces former and other materials use cost, also reduces the production line simultaneously and changes the cost that damages anchor clamps change and manpower maintenance.
(2) The utility model discloses a core optical head overcurrent protection circuit all normal back reconnection core circuit at peripheral circuit, avoid on the decoding board behind the electricity can not normal work at once, each control port's level uncertain and the surge current that leads to producing problem that the damage appears in the optical head behind the core optical head.
(3) The utility model discloses a core optical head overcurrent protection circuit application current range is wide, including CD, DVD and BD video disc player's optical head LD, laser diode, constant current source, various mains operated's overcurrent protection, short-circuit protection and ESD electrostatic protection.
(4) The utility model discloses a core optical head overcurrent protection circuit can adjust the maximum current overcurrent protection scope according to the setting of sensing resistance and differential amplifier circuit element parameter, and the overcurrent protection threshold value sets up the method simply.
(5) The utility model discloses an operation scheme of core optical head overcurrent protection circuit is with low costs, no environmental noise pollution.
The above only is the preferred embodiment of the present invention, not limiting the scope of the present invention, all the equivalent structures or equivalent flow changes made by the contents of the specification and the drawings, or directly or indirectly applied to other related technical fields, are included in the same way in the protection scope of the present invention.
Claims (10)
1. The utility model provides a core optical head overcurrent protection circuit which characterized in that: the circuit comprises a sensing resistor, a differential amplifier, a comparator, a current control circuit, a decoding board and an on-off switch, wherein the differential amplifier is used for converting the current of a power supply input end through the sensing resistor into voltage and amplifying the voltage, the comparator is used for monitoring the voltage value output by the differential amplifier and outputting an L level and an H level, the current control circuit is switched on after the H level output by the comparator is received, the decoding board is switched on, and the on-off switch is switched on after the decoding board is powered on;
the sensing resistor, the current control circuit and the on-off switch are sequentially connected to a circuit from the power input end to the power output end, a sensing voltage positive input end and a sensing voltage negative input end of the differential amplifier are respectively connected with the current input end and the current output end of the sensing resistor, and the output end of the differential amplifier is connected with the reverse input end of the comparator; the output end of the comparator is connected with the control end of the current control circuit; the decoding board is connected with the control end of the on-off switch.
2. The optical head overcurrent protection circuit of the movement according to claim 1, characterized in that: the electrostatic impeder element is arranged between the on-off switch and the power supply output end.
3. The optical head overcurrent protection circuit of the movement according to claim 2, characterized in that: the decoding circuit comprises a decoding board and a delay driving circuit, wherein the decoding board is used for outputting current to the decoding board, the current is output after the decoding board is electrified, and the delay driving circuit is arranged between the on-off switch and the decoding board.
4. The optical head overcurrent protection circuit of the movement according to claim 1, characterized in that: the constant voltage source is used as a reference of the threshold reference voltage of the comparator, wherein the constant voltage source is connected with the positive input end of the comparator.
5. The optical head overcurrent protection circuit of the movement according to any one of claims 1 to 4, characterized in that: the differential amplifier comprises a first resistor, a second resistor, a fourth resistor, a first capacitor and a current test chip;
the first resistor is connected with one end of the current input end of the sensing resistor, and the other end of the first resistor is connected with the sensing voltage positive input end of the current testing chip; the second resistor is connected with one end of the current output end of the sensing resistor, and the other end of the second resistor is connected with the negative input end of the sensing voltage of the current testing chip; the output end of the current test chip is connected with the comparator; the fourth resistor is connected between the output end of the current test chip and the ground;
the positive power supply end of the current test chip is connected with a first power supply, and the power supply end, the control end and the grounding end of the current test chip are connected with the ground after being connected in parallel, wherein the first capacitor is arranged on a circuit which is connected with the positive power supply end of the current test chip and the ground.
6. The optical head overcurrent protection circuit of the movement according to any one of claims 1 to 4, characterized in that: the comparator comprises an operational amplifier, a second capacitor, a third resistor and a fifth resistor; the constant voltage source comprises a twelfth resistor, a reference source and a fourth capacitor; wherein,
the inverting input end of the operational amplifier is connected with the differential amplifier, and the third resistor is connected to a connecting circuit between the differential amplifier and the inverting input end of the operational amplifier;
the second capacitor and the fifth resistor are connected in series between the inverting input end and the output end of the operational amplifier;
the negative power supply end of the operational amplifier is connected with the ground;
the positive power supply end of the operational amplifier is connected with the second power supply and the ground, and the third capacitor is connected on a circuit between the positive power supply end of the operational amplifier and the ground;
the twelfth resistor is arranged on a connecting circuit of the third power supply and the equidirectional input end of the operational amplifier;
a first connecting point, a second connecting point and a third connecting point are arranged on a connecting circuit between the twelfth resistor and the equidirectional input end of the operational amplifier, wherein the current input end of the fourth capacitor is connected with the third connecting point, and the current output end of the fourth capacitor is connected with the ground; the anode of the reference source is connected with the first connection point, the reference electrode is connected with the second connection point, and the cathode is connected with the ground.
7. The optical head overcurrent protection circuit of the movement according to any one of claims 1 to 4, characterized in that: the current control circuit comprises a sixth resistor, a seventh resistor, an eighth resistor, a first triode and a second triode, wherein the first triode is of a PNP structure, and the second triode is of an NPN structure; wherein,
the emitter of the first triode is connected with the sensing resistor, and the collector of the first triode is connected with the on-off switch; a sixth resistor is arranged on a connecting circuit of one end of the emitting electrode of the first triode and the base electrode of the first triode;
the seventh resistor is arranged on a connecting circuit of the base electrode of the first triode and the collector electrode of the second triode;
the eighth resistor is arranged on a connecting circuit of the comparator and the base electrode of the second triode;
and the emitter of the second triode is connected with the ground.
8. The optical head overcurrent protection circuit of the movement according to any one of claims 2 to 4, characterized in that: the on-off switch comprises a ninth resistor, a switch element, a reverse pulse absorption diode and a relay consisting of a tenth resistor, an eleventh resistor and a third triode, and the third triode is of an NPN structure; wherein,
the normally open contact of the switch element is connected with the current control circuit; the ninth resistance current input end is arranged on a connecting circuit of the normally closed contact of the switching element and the ground; an electromagnetic coil is arranged in the switch element, a metal elastic sheet controlled by the electromagnetic coil is arranged between a normally closed contact and a normally open contact in the switch element, and one end of the metal elastic sheet is connected with the output end of the switch element;
the output end of the switching element is connected with the electrostatic impeder element;
the electromagnetic coil and the reverse pulse absorption diode form a parallel circuit, and two ends of the parallel circuit are respectively connected with a collector of the third triode and a fourth power supply;
the current input end of the tenth resistor is connected with the decoding board, and the current output end of the tenth resistor is connected with the base electrode of the third triode;
and the current input end of the eleventh resistor is arranged on a circuit connecting the current output end and the base of the third triode, and the eleventh resistor is connected with the emitting electrode of the third triode in parallel and then connected with the ground.
9. The optical head overcurrent protection circuit of the movement according to any one of claims 2 to 4, characterized in that: the delay driving circuit comprises a delay chip and a fifth capacitor; wherein,
the input end of the delay chip is connected with the decoding board, one end of the fifth capacitor is connected to the circuit for connecting the input end of the delay chip with the decoding board, and the other end of the fifth capacitor is connected with the ground;
the ground terminal of the delay chip is connected with the ground, and the output end of the delay chip is connected with the on-off switch.
10. The optical head overcurrent protection circuit of the movement according to any one of claims 2 to 4, characterized in that: the electrostatic impeder element comprises a thirteenth resistor, a sixth capacitor, a filter inductor and an electrostatic ESD protection diode; wherein,
the filter inductor is arranged on a connecting circuit of the on-off switch and the power output end, a first connecting point, a second connecting point and a third connecting point are arranged on the connecting circuit of the filter inductor and the power output end, current input ends of the thirteenth resistor, the electrostatic ESD protection diode and the sixth capacitor are respectively connected with the first connecting point, the second connecting point and the third connecting point, and current output ends of the thirteenth resistor, the electrostatic ESD protection diode and the sixth capacitor are connected with the ground after being connected in parallel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201220705096.8U CN203135403U (en) | 2012-12-18 | 2012-12-18 | Over-current protection circuit for loader |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201220705096.8U CN203135403U (en) | 2012-12-18 | 2012-12-18 | Over-current protection circuit for loader |
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| Publication Number | Publication Date |
|---|---|
| CN203135403U true CN203135403U (en) | 2013-08-14 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201220705096.8U Expired - Fee Related CN203135403U (en) | 2012-12-18 | 2012-12-18 | Over-current protection circuit for loader |
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| CN (1) | CN203135403U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108375935A (en) * | 2018-03-23 | 2018-08-07 | 海华电子企业(中国)有限公司 | A kind of navigation radar transceiver servo-control system with overcurrent delay protection |
| WO2020140656A1 (en) * | 2018-12-30 | 2020-07-09 | 惠州三华工业有限公司 | Overcurrent protection circuit, and overcurrent protection system |
| CN112769093A (en) * | 2019-11-05 | 2021-05-07 | 杭州海康威视数字技术股份有限公司 | Current-limiting control circuit, chip and power supply |
| CN116068244A (en) * | 2023-03-07 | 2023-05-05 | 常州同惠电子股份有限公司 | Wide-range overcurrent detection protection circuit, protection method and device for power meter |
-
2012
- 2012-12-18 CN CN201220705096.8U patent/CN203135403U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108375935A (en) * | 2018-03-23 | 2018-08-07 | 海华电子企业(中国)有限公司 | A kind of navigation radar transceiver servo-control system with overcurrent delay protection |
| WO2020140656A1 (en) * | 2018-12-30 | 2020-07-09 | 惠州三华工业有限公司 | Overcurrent protection circuit, and overcurrent protection system |
| CN112769093A (en) * | 2019-11-05 | 2021-05-07 | 杭州海康威视数字技术股份有限公司 | Current-limiting control circuit, chip and power supply |
| CN112769093B (en) * | 2019-11-05 | 2023-12-29 | 杭州海康威视数字技术股份有限公司 | Current-limiting control circuit, chip and power supply |
| CN116068244A (en) * | 2023-03-07 | 2023-05-05 | 常州同惠电子股份有限公司 | Wide-range overcurrent detection protection circuit, protection method and device for power meter |
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