IGNITION DEVICE FOR INTERNAL COMBUSTION ENGINE

Abstract

Ignition device for an internal combustion engine, which ignites an internal combustion engine by supplying a control signal to a control switch (71) of an ignition circuit, the device comprising: a control circuit (61) which outputs the control signal to the control switch (71); a first differential circuit (51) for operating the control circuit (61) in a first operating mode by outputting a first differential signal to the control circuit (61); and a second differential circuit (52) for operating the control circuit (61) in a second operating mode by outputting a second differential signal to the control circuit (61), wherein the first differential circuit (51) and the second differential circuit (52) each contain a transistor (MP20, MP21) and are configured such that a control current for supplying the control signal flows through the transistor (MP20, MP21), which is common to the first operating mode and the second operating mode.

Description

Technical field

[0001] The present invention relates to a device for igniting an internal combustion engine. background

[0002] An ignition system for an internal combustion engine is equipped with a protective circuit that cuts off the current to prevent damage to the ignition coil and the switching element of the primary winding from overcurrent. The protective circuit generally has two operating modes: (a) a soft-off mode, in which the primary winding current is gradually reduced so that an abnormally high voltage is not generated on the secondary side of the ignition coil after the primary winding current has been conducted for a long time; and (b) a current-limiting mode, in which the switching element is controlled to reduce the current on the primary side of the winding.

[0003] The PTL 1 (Japanese Patent No. 5765689) described below discloses a technique relating to a soft-off operating mode. In the technique described in PTL 1 (Japanese Patent No. 5765689), when a long conduction detection circuit detects a long conduction duration exceeding a predetermined time while the switching element is in a conducting state, a discharge current is output from a soft-off capacitor, and the switching element is gradually switched from the conducting state to an off state, thus realizing the soft-off operating mode. Citation list - Patent literature

[0004] PTL 1: Japanese Patent No. 5765689 Overview of the invention Technical problem

[0005] When transitioning from normal ignition operation to a protective circuit operation, such as a soft-off mode or a current-limiting mode, it is desirable to implement a gradual transition of the conducting state of a switching element to prevent unintentional ignition. If the switching element is, for example, an IGBT, a gradual transition of the gate voltage is necessary.

[0006] The technique described in PTL 1 (Japanese patent no. 5765689) uses a capacitive element to generate a soft-off curve. It is assumed that the capacitive element absorbs switching noise during the transition from normal firing operation to soft-off operation and prevents a sharp change in the gate voltage of the switching element (IGBT). However, (a) the capacitive element is required exclusively for soft-off operation, which increases the cost, and (b) the soft-off curve is determined by the value of the capacitive element and the IGBT gate input resistance or capacitance, so problems such as a large load dependency and the need for adjustments are conceivable.

[0007] The invention was made with regard to the problems described above and is intended to provide an ignition device for an internal combustion engine which is able to prevent a significant change in the output signal level of a control circuit when transitioning from a normal ignition mode to a protection mode, while at the same time reducing the cost of special parts and the like. Solution to the problem

[0008] An ignition device according to the invention for an internal combustion engine comprises a first differential circuit for outputting a control signal in a first operating mode and a second differential circuit for outputting a control signal in a second operating mode, wherein the first differential circuit and the second differential circuit each contain a transistor and are designed such that a control current for supplying the control signal flows through the transistor, which is common to the first operating mode and the second operating mode. Advantageous effects of the invention

[0009] According to the ignition device for an internal combustion engine according to the invention, the output signal level of a control signal can be smoothly switched when switching from a normal operating mode to a protective operating mode. Problems, configurations, and effects other than those described above arise from the following description of embodiments. List of characters [ Fig. 1] Fig. Figure 1 is a configuration diagram of an ignition device for an internal combustion engine according to a first embodiment. [ Fig. 2] Fig. 2 is a timing diagram illustrating the operation of an ignition control device. 100 illustrated. [ Fig. 3A] Fig. 3A is a circuit diagram of a differential circuit 51 , a differential circuit 52 and a control circuit 61 . [ Fig. 3B] Fig. 3B is a diagram illustrating a smooth transition from a normal ignition mode to a soft-off mode. [ Fig. 4] Fig. Figure 4 is a configuration diagram of an ignition device for an internal combustion engine according to a second embodiment. [ Fig. 5] Fig. 5 is a timing diagram showing the operation of the ignition control unit 100illustrated according to the second embodiment. [ Fig. 6A] Fig. 6A is a circuit diagram of the differential circuit 51 , a differential circuit 53 and the control circuit 61 . [ Fig. 6B] Fig. Figure 6B is a diagram illustrating a smooth transition from the normal ignition mode to the current-limiting mode. [ Fig. 7] Fig. Figure 7 is a configuration diagram of an ignition device for an internal combustion engine according to a third embodiment. [ Fig. 8] Fig. 8 is a timing diagram showing the operation of the ignition control unit 100 illustrated according to the third embodiment. [ Fig. 9A] Fig. 9A is a circuit diagram of differential circuits 51 until 53 and the control circuit 61 . [ Fig. 9B] Fig. Figure 9B is a diagram illustrating the current flow when switching from the normal ignition mode to the current limiting mode and then to the soft-off mode. Description of the embodiments: First embodiment

[0010] Fig. Figure 1 is a configuration diagram of an ignition device for an internal combustion engine according to a first embodiment of the present invention. The ignition device for an internal combustion engine includes an electronic control unit (ECU). 21 , an ignition control device 100 , a battery 11 , a switching element 71 , an ignition coil 74 (a primary-side winding) 72 , a secondary-side winding 73 ) and a spark plug 75 The ignition control unit 100 It also includes an input buffer circuit. 31 , a conductivity control circuit 41, a circuit 42 For the detection of abnormal conduction, a differential circuit is used. 51 , a differential circuit 52 and a control circuit 61 .

[0011] The switching element 71 ignites the combustion engine by sending a control signal to the ignition coil 74 outputs. The switching element 71 is achieved by feeding in a signal from the ignition control unit 100 The output control signal is controlled via a gate connection.

[0012] The ECU 21 The ignition control unit indicates 100 to ignite the combustion engine. The conductivity control circuit 41 is a circuit that, in normal ignition mode, sends a conductivity control signal to the switching element 71 outputs. The circuit 42 to detect abnormal conduction, it was detected that the switching element 71was in a conductive state for a longer period than normal (abnormal conduction). Upon detection of abnormal conduction, the circuit reports... 42 To detect abnormal conductivity, the detection is sent to the conductivity control circuit. 41 The conductivity control circuit 41 stops the conductivity control signal, and then the circuit outputs 42 To detect abnormal conduction, a conductivity control signal is sent to the switching element. 71 off, in order to execute a soft-off operating mode.

[0013] Differential circuits 51 and 52 These are circuits that amplify the difference between two input signals. Differential circuits 51 In normal ignition mode, it outputs a control signal and the differential circuit 52 In soft-off mode, it outputs a control signal. The differential circuit 51This amplifies the difference between the two values ​​from the conductivity control circuit. 41 received conductivity control signals. The differential circuit 52 This increases the difference between the circuit and the output of the circuit. 42 for the detection of abnormal conductivity, the received conductivity control signal and the signal from the output of the control circuit. 61 feedback signal. Specific examples of differential circuits. 51 and 52 and the control circuit 61 are described below.

[0014] Fig. 2 is a timing diagram showing the operation of the ignition control unit 100 This illustrates the signal curves on the main signal lines. The following describes operation in both normal ignition mode and soft-off mode, referring to the signal curves of... Fig. 2 described.

[0015] In normal ignition mode, the signal line is used. 1 a conductivity control signal from the ECU 21 The conductivity control signal is fed in. It is used as a control signal via the input buffer circuit. 31 , the conductivity control circuit 41 , the differential circuit 51 , the control circuit 61 and a signal line 9 to the switching element 71 output. The switching element 71 It operates according to the control signal.

[0016] In the differential circuit 51 is a signal line 4 connected to the (+) terminal and a signal line 5 is connected to the (-) terminal. If there is a change on the signal line 4 a high-level signal is located on the signal line 5 The control circuit is located at a low level signal. 61 outgoing signal line 9on the high level and the switching element 71 is switched on. If on the signal line 4 a low-level signal is located on the signal line 5 The signal line is located where the signal is high-level. 9 at a low level and the switching element 71 is switched off. When the switching element 71 When switched on, current flows through the primary winding. 72 the ignition coil 74 . At the same time, when the switching element 71 is switched off in the primary winding 72 a primary voltage and in the secondary winding 73 A secondary voltage corresponding to the turns ratio is generated through mutual induction. This secondary voltage is then supplied to the spark plug. 75 supplied, which ignites the combustion engine.

[0017] The circuit 42 For the detection of abnormal conduction, a detection occurs when the conduction time of the switching element is exceeded.71 longer than a predetermined duration (abnormal conduction). If the circuit 42 To detect abnormal conduction, if abnormal conduction is detected, the ignition control unit switches. 100 from normal ignition mode to soft-off mode. In soft-off mode, the control signal for the gate connection of the switching element is 71 The signal gradually changes from a high level to a low level. This causes the switching element to... 71 gradually transitions from the conducting state to the switched-off state.

[0018] Since the switching element 71 In the conductive state, the signal line is located before the transition to soft-off operating mode. 4 at the high level, the signal line 5 at the low level, a signal line 6 at the low level, and the signal line 9It outputs a high-level signal. If it detects abnormal conduction, the circuit outputs... 42 for the detection of abnormal conduction in soft-off mode from the signal line 6 a signal curve. The signal curve in soft-off mode gradually changes from a high level to a low level.

[0019] The soft-off signal from the signal line 6 is connected to the (+) terminal of the differential circuit 52 fed in. The signal line 9 (the output of the control circuit 61 ) is connected to the (-) terminal of the differential circuit 52 negative feedback. That is, a curve shape that matches the curve shape of the signal line. 6 The following is transmitted via the signal line 9 to the differential circuit 52 returned.

[0020] The conductivity control circuit 41 receives the detection of abnormal conduction from the circuit42 for the detection of abnormal conduction via a signal line 3 Upon receiving the signal, the conductivity control circuit changes. 41 the signal line 4 from high level to low level and maintains the signal line 5 at the low level. By setting the time at which the signal line 4 from the high level to the low level after the signal line 6 Once the signal line has switched to the high level (that is, switched to soft-off mode), the signal line remains... 9 at the high level. This ensures that when switching from normal ignition mode to soft-off mode, the operating mode changes smoothly without a significant change in the control signal level.

[0021] Fig. 3A is a circuit diagram of the differential circuit 51 , the differential circuit 52 and the control circuit 61The following describes the configurations of these circuits with reference to Fig. 3A described.

[0022] The differential circuit 51 contains a constant current source 11 , NMOS ( MN1 , MN2 ) and PMOS ( MP20 , MP21 The differential circuit 52 contains the constant current source I1 , NMOS ( MN3 , MN4 ) and PMOS ( MP20 , MP21 The constant current source I1 and the PMOS ( MP20 , MP21 ) are from the differential circuits 51 and 52 shared.

[0023] The control circuit 61 contains MP23 and MN12 The output current of the MP23 is achieved by mirroring the output current on the (+) terminal side of the differential circuit based on the current mirror ratio of MP21 to MP23 received. The output current of MN12 is achieved by mirroring the output current on the (-) terminal side of the differential circuit based on the current mirror ratio of MP20 to MP22 and the current mirror ratio of MN10 to MN12 received. The output signal (signal line) 9 ) the control circuit 61 is applied to the (-) terminal of the differential circuit 52 negative feedback.

[0024] Fig. 3B is a diagram showing a smooth transition from normal ignition mode to soft-off mode. A thick dotted line in Fig. 3B indicates that the output signal of the control circuit 61 through the current mirror between MP21 and MP23 is formed. The dotted line in Fig. Figure 3B illustrates the current path in normal ignition mode. An alternating long and short dashed line in Fig. Figure 3B shows a current path in soft-off mode.

[0025] Before switching to soft-off mode, the input signal of the signal line is located 4 at the (+) terminal of the differential circuit 51 at the high level and the input signal of the signal line 6 at the (+) terminal of the differential circuit 52 is at a low level, so that MN1 is switched on MN3 is switched off. The one to MP21 flowing current flows through MN1 .

[0026] When the operating mode switches to soft-off mode, the signal line receives power first. 6 a high level, so that MN1 and MN3 be switched on, but the MP21 The current flow changes due to the operation of the constant current source. I1 no. The following will be MN1 switched off and MN3 is switched on. The one to MP21 flowing current flows through MN3 Even during this period, the value changes. MP21 current flowing due to the operation of the constant current source I1 No. Because the output signal of the control circuit 61 through a current mirror between MP21 and MP23 As it is formed, the changes to MP23 flowing current not, unless the one to MP21 The flowing current changes. Therefore, during the process of switching from normal ignition mode to soft-off mode, the operating mode can be switched smoothly without affecting the output current of the control circuit. 61 changes rapidly. First embodiment: Summary

[0027] When switching from normal ignition mode to soft-off mode, the ignition device for an internal combustion engine according to the first embodiment directs the current through the circuit common to both operating modes. MP21 Since the control current passes through the current mirror between MP21 and MP23 The control current generated does not change significantly at the time of the operating mode switch. This allows for a smooth switching of the operating mode.

[0028] The ignition device for an internal combustion engine according to the first embodiment carries the output signal of the control circuit. 61 as an input signal for the negative terminal of the differential circuit 52 back. Thus, the output signal of the control circuit can be returned. 61 in soft-off mode, the input signal of the differential circuit 52 The following can be generated. That is, a control signal that corresponds to an input signal of the differential circuit. 52 The following can be output without being affected by the load of the control circuit. 61 depends.

[0029] Since in the first embodiment the input connection states of the switching element 71Since they differ, it is necessary to determine the load control capability of the control circuit. 61 to optimize. Since in the first embodiment the control signal is generated by mirroring the signal produced by the differential circuit 51 or 52 The flowing current is generated, the control circuit can 61 optimized according to the current-mirror ratio. Second embodiment

[0030] In the first embodiment, a configuration example was described in which the normal ignition mode and the soft-off mode are switched smoothly. In a second embodiment of the invention, a configuration example is described in which the normal ignition mode and a current-limiting mode are switched smoothly. The current-limiting mode is an operation in which the gate voltage of the switching element is 71is lowered to make an adjustment so that the current through the primary winding is correct. 72 The flowing current does not exceed a set current limit.

[0031] Fig. Figure 4 is a configuration diagram of the ignition device for an internal combustion engine according to the second embodiment. Fig. 4 is instead of the circuit described in the first embodiment 42 A circuit is used to detect abnormal conductivity. 43 designed to generate a threshold voltage and instead of the differential circuit 52 is a differential circuit 53 planned. The circuit 43 To generate a threshold voltage, a threshold voltage is applied to the (+) terminal of the differential circuit. 53 off, without being affected by the ECU 21 to be dependent on the conductivity control signal output. The result of the measurement by the primary-side winding. 72current flowing through a detection resistor 76 is inserted into the (-) terminal of the differential circuit 53 fed in.

[0032] Fig. 5 is a timing diagram illustrating the operation of the ignition control device. 100 as illustrated in the second embodiment. The operation in current-limiting mode is described below using the signal curves of Fig. 5 described. Operation in normal ignition mode is the same as in the first embodiment.

[0033] Because the current limiting operating mode is active while the primary winding is 72 If the line is conductive, the normal ignition signal is at the high level. That means the signal line... 4 is at the high level, the signal line 5 is at a low level and the signal line 9 is at the high level. If the primary winding is... 72As the current increases, so does the voltage of a signal line. 10 .

[0034] The differential circuit 53 The output current gradually increases as the voltage of the signal line changes. 10 the voltage of a signal line 7 , which is a threshold voltage. This lowers the output signal of the control circuit. 61 gradually decreases from the high level. This is because the gate voltage of the switching element... 71 decreases when the output signal of the control circuit changes 61 The amount of wind on the primary side decreases. 72 Current flowing. This feedback loop balances every signal and limits the current through the primary winding. 72 flowing current in such a way that it does not exceed the threshold voltage.

[0035] Fig. 6A is a circuit diagram of the differential circuit 51 , the differential circuit 53and the control circuit 61 The differential circuit 53 contains a constant current source 12 , NMOS ( MN5 , MN6 ) and PMOS ( MP20 ). The PMOS ( MP20 ) is from the differential circuits 51 and 53 shared. One (+) terminal of the differential circuit 53 is a gate connector of the MN5 , and a threshold voltage is applied via the signal line 7 fed in. The side of the (-) terminal of the differential circuit 53 is a gate connector of the MN6 , and a detection result of the primary-side winding 72 The flowing current is transmitted via the signal line. 10 fed in.

[0036] Fig. Figure 6B is a diagram illustrating a smooth transition from normal ignition mode to current-limiting mode. A thick dotted line in Fig. 6B indicates that the output signal of the control circuit 61 through the current mirror between MP21 and MP23 is formed. A dotted line in Fig. 6B shows the current path in normal ignition mode. A two-dotted chain line in Fig. 6B indicates a current path in current limiting mode.

[0037] In normal ignition mode, the (+) terminal of the differential circuit is located 51 at the high level, and the current flows to the MP21 side. In the differential circuit 53 is the value of the signal line 10 as detection voltage smaller than the value of the signal line 7 as a threshold voltage. Therefore, a current flows to the MN5 side and in a current path of MN6 to MP20 No current flows in the control circuit. 61 Current flows only on the MP23 side and no current flows on the MN12 side.

[0038] When the current in the primary winding 72 As the detection voltage increases, the voltage of the signal line also increases. 10 on. If the voltage of the signal line changes 10 the threshold voltage (signal line) 7 As the value approaches, the value decreases. MN5 The flowing current and the current path of MN6 to MP20 The flowing current increases. Then the current flows according to the current mirror ratio of the MP20 to MP22 and the current-mirrore ratio of the MN10 to MN12 certain current to the side of MN12 This lowers the output level (signal line). 9 ) off. If the output signal (signal line) 9 ) decreases, the gate voltage of the switching element decreases. 71 , so that the current in the primary winding 72 reduced and the detection voltage (signal line) 10) lowers the current. This feedback loop compensates for any signal and limits the current in the primary winding. 72 .

[0039] The current of MN6 It increases with increasing detection voltage. However, due to gradual changes in the MN6 current, the value also changes. MN12 The current flows smoothly, so that the output signal (signal line) 9 ) also changes smoothly. Therefore, it is possible to switch smoothly from the normal ignition mode to the current limiting mode. Second embodiment: Summary

[0040] The ignition device for an internal combustion engine according to the second embodiment increases the MN6 The current flowing during the switch from normal ignition mode to current-limiting mode is gradual. This is due to the current mirror between MP20 and MP22 and the current mirror between MN10 and MN12 increases through MN12 The flowing current gradually increases. When the MN12 As the current gradually increases, the output signal of the control circuit decreases. 61 gradually. Therefore, since the control current does not change significantly at the time of switching operating modes, the operating mode can be switched smoothly.

[0041] The ignition device for an internal combustion engine according to the second embodiment carries the output signal (specifically the result of the current detection through the detection resistor). 76 ) of the switching element 71 to a negative input terminal of the differential circuit 53 back. Accordingly, it increases when the current through the primary-side winding is reached. 72 the flowing current increases beyond the threshold voltage, which is caused by MN12 The flowing current increases gradually, and the drive current is adjusted so that it is in equilibrium with the threshold voltage. Therefore, the current-limiting operating mode can be executed smoothly. Third embodiment

[0042] Fig. Figure 7 is a configuration diagram of an ignition device for an internal combustion engine according to a third embodiment of the invention. In the third embodiment, a configuration example combining the first and second embodiments is described. Descriptions of the same configuration as those of the first and second embodiments are omitted accordingly. Control signals from the differential circuit 51 , the differential circuit 52 and the differential circuit 53 are connected in parallel to the control circuit 61 fed in.

[0043] Fig. 8 is a timing diagram showing the operation of the ignition control device 100as illustrated by the third embodiment. In the third embodiment, after the transition from the normal ignition mode to the current-limiting mode, if the abnormal conduction continues, the transition is further completed into the soft-off mode. The operating procedure in each mode is the same as in the first and second embodiments. When switching to the soft-off mode during the current-limiting mode, the output signal (signal line) changes. 9 ) gradually from a high level to a low level. As a result, the gate voltage of the switching element decreases. 71 gradually, so that the current in the primary winding 72 It gradually decreases. Accordingly, the voltage of the detection voltage (signal line) decreases. 10 ) gradually, and thus the current limiting operating mode ends. Then the soft-off operating mode ends.

[0044] Fig. 9A is a circuit diagram of differential circuits 51 until 53 and the control circuit 61 The configuration of each circuit is the same as described in the first and second embodiments.

[0045] Fig. Figure 9B is a diagram illustrating the current flow when switching from normal ignition mode to current-limiting mode and then to soft-off mode. In normal ignition mode, the (+) terminal (signal line) is located 4 ) the differential circuit 51 on the high level and the control circuit 61 gives a current of MP23 off. When the operating mode switches to current limiting mode, current flows to MN12 a current that is one of MN6 to MP20 corresponds to the flowing current value, and the output level (signal line) 9) is lowered. If the system switches to soft-off mode in this state, the current paths of the differential circuits are 51 and 52 switched from the MN1 page to the MN3 page. Since the MP23 If the flowing current does not change, the output signal (signal line) changes. 9 ) no. If the signal level of the signal line 9 As the signal curve gradually decreases following the soft-off phase, the detection voltage also decreases, so that the MN6 to MP20 The flowing current decreases and becomes too MN12 The current flow is also reduced. Finally, the phase enters a state where the current limiting mode is not executed, and then the soft-off mode ends. Modification example of the present invention

[0046] The invention is not limited to the embodiments described above and includes various modification examples. For instance, the embodiments described above have been described in detail for ease of understanding of the invention and are not necessarily limited to those that have all the configurations described above. Part of the configuration of one embodiment can be replaced by the configuration of another embodiment, and the configuration of one embodiment can be added to the configuration of another embodiment. For any part of the configuration of each embodiment, it is possible to add, delete, or replace another configuration. Reference symbol list 1 to 10: Signal line 11: Battery 21: ECU 31: Input buffer circuit 41: Conductivity control circuit 42: Circuit for detecting abnormal conductivity 43: Circuit for generating a threshold voltage 51 to 53: Differential circuit 61: Control circuit 71: Switching element 72: Primary winding 73: Secondary winding 74: Ignition coil 75: Spark plug 76: Detection resistor I1 to 12: Constant current source MN1 to MN6, MN10, MN12: NMOS transistor MP20 to MP23: PMOS transistor 100: Ignition control unit QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 5765689 [0003, 0004, 0006]

Claims

[1] Ignition device for an internal combustion engine, which ignites an internal combustion engine by supplying a control signal to a control switch of an ignition circuit, the device comprising: a control circuit that outputs the control signal to the control switch; a first differential circuit for operating the control circuit in a first operating mode by outputting a first differential signal to the control circuit; and a second differential circuit for operating the control circuit in a second operating mode by outputting a second differential signal to the control circuit, wherein The first differential circuit and the second differential circuit each contain a transistor and are designed such that a control current flows through the transistor to supply the control signal, which is common to the first operating mode and the second operating mode. [2] Ignition device for an internal combustion engine according to claim 1, wherein the first differential circuit is formed using a first transistor, a second transistor and a first constant current source, the second differential circuit is formed using the first transistor, a third transistor connected in parallel to the first transistor and the second transistor, and the first constant current source, The first differential circuit outputs the first differential signal by means of a current flowing through the first transistor, the second transistor, and the first constant current source when the drive circuit is operated in the first operating mode, and The second differential circuit outputs the second differential signal by means of a current flowing through the first transistor, the third transistor and the first constant current source when the control circuit is operated in the second operating mode. [3] Ignition device for an internal combustion engine according to claim 1, wherein The first differential circuit, when the control circuit is operated in the first operating mode, switches off the first differential signal for a predetermined time after the first differential signal has been output to the control circuit, and The second differential circuit, when the control circuit is operated in the second operating mode, forms a signal curve of the second differential signal, so that the control switch transitions more slowly from a conducting state to an off state than in the first operating mode. [4] Ignition device for an internal combustion engine according to claim 2, wherein the ignition device for an internal combustion engine causes the control circuit to switch from the first operating mode to the second operating mode by bringing the third transistor into a state in which the first transistor and the second transistor are conducting, and then switching off the second transistor. [5] Ignition device for an internal combustion engine according to claim 1, wherein the ignition device for an internal combustion engine also includes a first feedback loop for feeding back the output signal of the control circuit, and The second differential circuit outputs the second differential signal by using an input signal of the second differential circuit and an output signal of the control circuit, which is fed back via the first feedback loop, as input signals. [6] Ignition device for an internal combustion engine according to claim 1, wherein the ignition device for an internal combustion engine further comprises, a conductivity control circuit for controlling the first differential circuit, and a control circuit for abnormal conduction to control the second differential circuit, and Upon detecting that the control switch has continued conducting for a predetermined time or longer, the abnormal conduction control circuit activates the second differential circuit, causing it to output the second differential signal, and then outputs a signal that instructs the conductivity control circuit to switch off the first differential signal. [7] Ignition device for an internal combustion engine according to claim 1, wherein the control circuit contains a first output transistor, which forms a first current mirror circuit to mirror a current flowing through the first differential circuit, and the first output transistor outputs a current with a current level that corresponds to a mirror ratio of the first current mirror circuit. [8] Ignition device for an internal combustion engine according to claim 1, wherein the ignition device for an internal combustion engine further includes a third differential circuit which operates the control circuit in a third operating mode by outputting a third differential signal to the control circuit, the third differential circuit is formed using a fourth transistor, a fifth transistor and a second constant current source, The third differential circuit, when the control circuit is operated in the first operating mode, allows a first current to flow through the fourth transistor and the second constant current source, and The third differential circuit, when the control circuit is operated in the third operating mode, allows the first current to flow through the fourth transistor and the second constant current source, and allows a second current to flow through the fifth transistor and the second constant current source. [9] Ignition device for an internal combustion engine according to claim 8, wherein the third differential circuit, when the control circuit is operated in the third operating mode, maintains an output current of the control switch at a predetermined current value or less by gradually increasing the ratio of the second current to the first current. [10] Ignition device for an internal combustion engine according to claim 8, wherein the ignition device for an internal combustion engine also includes a second feedback loop for feedback of the output current of the control switch, and The third differential circuit outputs the third differential signal by using an input signal of the third differential circuit and an output signal of the control circuit, which is fed back via the second feedback loop, as input signals. [11] Ignition device for an internal combustion engine according to claim 10, wherein the ignition device for an internal combustion engine continues to contain a conductivity control circuit for controlling the first differential circuit, and a circuit for generating a threshold voltage that outputs a threshold voltage to the third differential circuit, the fourth transistor is designed to induce conductivity by receiving the threshold voltage, the fifth transistor is configured to induce conductivity by receiving a voltage obtained by converting an output current of the drive switch fed back via the second feedback loop, and The second constant current source keeps the sum of the first current and the second current constant. [12] Ignition device for an internal combustion engine according to claim 8, wherein which contains the control circuit a first output transistor, which forms a first current mirror circuit to mirror a current flowing through the first differential circuit, and a second output transistor, which forms a second current mirror circuit to mirror a current flowing through the fifth transistor, the first output transistor outputs a current with a current level corresponding to a mirror ratio of the first current mirror circuit, and The second output transistor outputs a current with a current level that corresponds to a mirror ratio of the second current mirror circuit. [13] Ignition device for an internal combustion engine according to claim 1, wherein the first differential circuit is formed using a first transistor, a second transistor and a first constant current source, the second differential circuit is formed using the first transistor, a third transistor connected in parallel to the second transistor and the first constant current source, The first differential circuit, when the control circuit is operated in the first operating mode, outputs the first differential signal by means of a current flowing through the first transistor, the second transistor and the first constant current source. The second differential circuit, when the control circuit is operated in the second operating mode, outputs the second differential signal by means of a current flowing through the first transistor, the third transistor and the first constant current source. the ignition device for an internal combustion engine also contains a first feedback loop for feeding back an output signal of the control circuit, The second differential circuit outputs the second differential signal by using an input signal of the second differential circuit and an output signal of the control circuit, which is fed back via the first feedback loop, as input signals. the ignition device for an internal combustion engine continues to contain a conductivity control circuit for controlling the first differential circuit, and a control circuit for abnormal conduction to control the second differential circuit, Upon detecting that the control switch has continued conducting for a predetermined time or longer, the abnormal conduction control circuit activates the second differential circuit to output the second differential signal, and then outputs a signal that instructs the conductivity control circuit to switch off the first differential signal. The ignition device for an internal combustion engine further includes a third differential circuit that operates the control circuit in a third operating mode by outputting a third differential signal to the control circuit. the third differential circuit is formed using a fourth transistor, a fifth transistor and a second constant current source, The third differential circuit, when the control circuit is operated in the first operating mode, allows a first current to flow through the fourth transistor and the second constant current source, The third differential circuit, when the control circuit is operated in the third operating mode, allows the first current to flow through the fourth transistor and the second constant current source, and allows a second current to flow through the fifth transistor and the second constant current source. the ignition device for an internal combustion engine also contains a second feedback loop for feeding back an output current of the control switch, The third differential circuit outputs the third differential signal by using an input signal of the third differential circuit and an output signal of the control circuit, which is fed back via the second feedback loop, as input signals. the ignition device for an internal combustion engine further contains a circuit for generating a threshold voltage for outputting a threshold voltage to the third differential circuit, the fourth transistor is designed to induce conductivity by receiving the threshold voltage, the fifth transistor is designed to induce conductivity by receiving an output signal from the control switch, which is fed back via the second feedback loop, and The second constant current source keeps the sum of the first current and the second current constant.