CN100468935C - Power supply circuit - Google Patents
Power supply circuit Download PDFInfo
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- CN100468935C CN100468935C CNB2005101378403A CN200510137840A CN100468935C CN 100468935 C CN100468935 C CN 100468935C CN B2005101378403 A CNB2005101378403 A CN B2005101378403A CN 200510137840 A CN200510137840 A CN 200510137840A CN 100468935 C CN100468935 C CN 100468935C
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Abstract
A power-supply circuit used for various pieces of electronic equipment, communication equipment, etc., adapted to produce voltage pulses by the action of resonance of the primary side of a transformer, which voltage pulses are stepped up for outputting from the secondary side, the power-supply circuit suppressing a fluctuation in the current value to prevent noise from appearing on the screen. The power-supply circuit is arranged such that while a first switching element (24) is ON, a second switching element (32) is switched to OFF by a control circuit (27), and after a current has flowed through a first diode (26) with the first switching element (24) held OFF, the second switching element (32) is switched to ON when the voltage value of a primary coil (22) is greater than that of a driving power supply (23).
Description
The application be the applicant on February 2nd, 2000 submit to, application number for " 00800122.7 ", denomination of invention divides an application for the application for a patent for invention of " power circuit ".
Technical field
The present invention relates to the power circuit that various electronic installations, communicator etc. are used, this power circuit utilizes the resonance of primary to produce potential pulse, and this potential pulse is boosted, and is exported from secondary.
Background technology
Below, with reference to the existing power circuit of description of drawings.
Figure 16 represents the circuit diagram of existing power circuit, and Figure 17 is voltage, electric current, the time dependent oscillogram of switching pulse in this power circuit of expression.
Existing power circuit shown in Figure 16 is in order to make transformer add to the high pressure output voltage stabilization of display.Its structure comprises the driving power 403 that connects transformer 401 primary coils 402 1 ends, connects switch element 404 and the capacitor 405 and the diode 406 of these primary coil 402 other ends.
The secondary coil 408 of transformer 401 is connected to level and all high display 409 (CRT) of vertical frequency.
Figure 17 illustrates the waveform that voltage in this power circuit, electric current, switching pulse changed with respect to the time.
In Figure 17, (a) the time dependent oscillogram of responding in transformer 401 primary coils 402 in the O point of expression power circuit of magnitude of voltage, (b) the time dependent oscillogram of current value in the O point of expression power circuit, (c) the expression pwm control circuit is input to the time dependent oscillogram of output waveform of switch element 404.
During A-B for Figure 17, if the impulse wave of some cycles (output wave) is input to switch element 404 from pwm control circuit 407 and makes switch element 404 be conducting (ON) state in (c), then in (b) in the O point length of the ON state of current value and switch element 404 increase in time pro rata, thereby make primary coil 402 store electrical energy.
During B-C, if pwm control circuit 407 stops to switch element 404 input pulse ripples switch element 404 being by (OFF) state in (c), then the energy storage in the primary coil 402 begins to capacitor 405 chargings, in (b), current value reduces in time in the O point, in case charging finishes, the magnitude of voltage of primary coil 402 just reaches peak value in (c).
During C-D, in case finish to capacitor 405 chargings, the electric energy that then is stored in the capacitor 405 just charges to primary coil 402 once more, in (b), current value in the O point reduces in time, in case charging finishes, the magnitude of voltage in (a) in the primary coil 402 just is zero.
During D-E, if finish to primary coil 402 chargings, the electric energy that then is stored in the primary coil 402 begins once more to capacitor 405 chargings, at this moment, according to the both positive and negative polarity relation of primary coil 402 both end voltage, begin to capacitor 405 chargings from ground connection once more.But, the diode 406 that between the other end of primary coil 402 and ground, has plus earth, so can be to capacitor 405 chargings, electric current flows through through the low diode 406 of impedance, current value increases in time in the O point in (b), not to capacitor 405 chargings, thereby the magnitude of voltage of primary coil 402 still is zero in (a).
During E-F, this moment, the energy that is stored in the primary coil 402 discharged because of electric current flows through through diode 406, (b) in the O current value of ordering, in theory as long as switch element 404 is not the ON state, just still be zero in (c), but in fact, current value increase certain hour in the O point in (b).
Along with the increase of this O point electric current, primary coil 402 can store certain electric energy.
During F-G, same as described above like this, in case finish to primary coil 402 energy storage, the electric energy that is stored in primary coil 402 just begins charging to capacitor 405, (b) the O point current value in reduces in time, in case charging finishes, (a) magnitude of voltage of middle primary coil 402 just reaches peak value.
During G-H, finish as if charging to capacitor 405, the electric energy that is stored in the capacitor 405 just begins energy storage once more to primary coil 402, and (b) middle O point current value reduces in time, in case energy storage finishes, (a) voltage of middle primary coil 402 just is zero.
During H-J, if primary coil 402 energy storage finish, the electric energy that is stored in the primary coil 402 just begins charging once more to capacitor 405, and O point current value increases in time in (b), but not to capacitor 405 chargings, thereby the magnitude of voltage of primary coil 402 still is zero (a).
During I-J, same as described above, the current value that O is ordered in (b) increases certain hour once more, thereby to primary coil 402 energy storage.
During J-K (A), if finish to primary coil 402 energy storage, the electric energy that then is stored in primary coil 402 begins to capacitor 405 chargings, (b) current value that O is ordered in reduces in time, in case charging finishes, (a) magnitude of voltage of middle primary coil 402 just reaches peak value, in this process, (c) switch element 404 becomes the ON state in, thereby again with this as the starting point, repeats process same as described above once more.
In said structure, the output voltage of secondary coil 408 changes with the magnitude of voltage of primary coil 402, and the magnitude of voltage of primary coil 402 changes according to the time length of the ON state of switch element 404, and promptly the ON state is long, and magnitude of voltage is just big.
At this moment, pwm control circuit 407 is input to switch element 404 with the impulse wave of some cycles, and at the ON of this impulse wave constantly, magnitude of voltage moment of primary coil 402 is zero.Because this magnitude of voltage variation is fierce, so the current value that O is ordered during switch element 404 is the ON state, shown in Figure 17 (b), produces fluctuating (W) and increase.Especially when impulse wave at ON constantly the time, the magnitude of voltage of primary coil 402 is from the value vanishing bigger than driving power magnitude of voltage, this moment is should influence bigger.
Therefore, the influence that in said structure, rises and falls owing to this current value, thus the problem that picture produces noise appears.
Summary of the invention
The object of the present invention is to provide a kind of power circuit that current value rises and falls that suppresses, this power circuit can prevent that for example display being used as under the situation of load noise from appearring in picture.
For achieving the above object, power circuit of the present invention, comprise transformer with primary coil and secondary coil, the driving power of an end that connects the described primary coil of described transformer, the 1st switch element that connects the other end of described primary coil, capacitor and the 1st diode, with produce impulse wave and control the control circuit of described the 1st switch element, described the 1st switch element is a 1MOS type field-effect transistor, the drain electrode of described 1MOS type field-effect transistor connects the other end of described primary coil, its source ground, its grid connects control circuit, one end of described capacitor connects the other end of described primary coil, the other end ground connection of described capacitor, the negative electrode of described the 1st diode connects the other end of described primary coil, its plus earth, between described transformer and described control circuit, be provided with the noise suppressed means that suppress noise, wherein, the 1st switch element is the MOS type field-effect transistor with internal body diodes, between the drain electrode of the negative electrode of the 1st diode and described MOS type field-effect transistor, be provided with the 3rd diode, the negative electrode of described the 3rd diode connects the drain electrode of described MOS type field-effect transistor, anode connects the negative electrode of described the 1st diode, and an end of capacitor is connected between the negative electrode and primary coil of the 1st diode, or be connected between the anode of the negative electrode of the 1st diode and the 3rd diode, reverse current recovery time of described the 1st diode and described the 3rd diode is than the weak point of internal body diodes in the described MOS type field-effect transistor.
Can suppress to produce noise according to said structure.
Description of drawings
Fig. 1 is the circuit diagram of expression the present invention the 1st embodiment power circuit, and Fig. 2 is voltage, electric current and the time dependent oscillogram of switching pulse in this power circuit of expression.
Fig. 3 is voltage, electric current and the time dependent oscillogram of switching pulse in expression the present invention the 2nd embodiment power circuit.
Fig. 4 is the circuit diagram of expression the present invention the 3rd embodiment power circuit, and Fig. 5 is voltage, electric current and the time dependent oscillogram of switching pulse in this power circuit of expression.
Fig. 6 is the circuit diagram of expression the present invention the 4th embodiment power circuit, and Fig. 7 is voltage, electric current and the time dependent oscillogram of switching pulse in this power circuit of expression.
Fig. 8 is the circuit diagram of expression the present invention the 5th embodiment power circuit, and Fig. 9 is voltage, electric current and the time dependent oscillogram of switching pulse in this power circuit of expression.
Figure 10 is the circuit diagram of expression the present invention the 6th embodiment power circuit, Figure 11 is the high-tension oscillogram of transformer output in this power circuit of expression, Figure 12 is the high-tension oscillogram of the dynamic characteristic difference of indication transformer output, and Figure 13 is the high-tension oscillogram of the rising edge difference of indication transformer output.
Figure 14 is the circuit diagram of expression the present invention the 7th embodiment power circuit, and Figure 15 is voltage, electric current and the time dependent oscillogram of switching pulse in this power circuit of expression.
Figure 16 is the circuit diagram of the power circuit of expression prior art, and Figure 17 is voltage, electric current and the time dependent oscillogram of switching pulse in this power circuit of expression.
Embodiment
(embodiment 1)
Below, with reference to the power circuit of description of drawings the present invention the 1st embodiment.
The power circuit of the present invention the 1st embodiment comprises among Fig. 1: the driving power 23 that connects transformer 21 primary coils 22 1 ends; The 1st switch element 24, capacitor 25 and the 1st diode 26 that connect these primary coil 22 other ends.
The 1st switch element 24 is got the 1MOS type field-effect transistor (MOS FET) with internal body diodes, the drain electrode of this 1MOS type field-effect transistor connects the other end of primary coil 22, source ground, grid connects the control circuit 27 of PWM mode, this control circuit 27 produces pulse to control the 1st switch element 24, and internal body diodes keeps its plus earth to be connected the state of primary coil 22 other ends with negative electrode.One end of capacitor 25 connects the other end of primary coil 22, the other end ground connection of capacitor 25.The negative electrode of the 1st diode 26 connects the other end of primary coil 22, plus earth.One end of the negative electrode of the 1st diode 26 and capacitor 25 is connected in the drain electrode of 1MOS type field-effect transistor and the tie point of primary coil 22.
Also be provided with this primary coil 22 and produce the ancillary coil 30 of mutual inductance and one end ground connection, be provided with the 2nd diode 31 and the 2nd switch element 32 that connect these ancillary coil 30 other ends simultaneously.The 2nd switch element 32 is got 2MOS type field-effect transistor, the drain electrode of 2MOS type field-effect transistor connects the other end of ancillary coil 30 through the 2nd diode 31, source ground, grid connects the control circuit 27 of PWM mode, the anode of the 2nd diode 31 connects the other end of ancillary coil 30, and negative electrode connects the drain electrode of 2MOS type field-effect transistor.When control circuit 27 is conducting (ON) state at the 1st switch element 24, the 2nd switch element 32 is switched to by (OFF) state, when the 1st switch element 24 is the OFF state, electric current flows into the 1st diode 26, when the magnitude of voltage of elementary coil 22 during greater than the driving power magnitude of voltage, the 2nd switch element 32 just switches to the ON state afterwards.
The output of secondary coil 28 connects horizontal frequency or the high display 29 (CRT) of vertical frequency.
At this moment, Fig. 2 illustrates voltage in this power circuit, electric current, the time dependent oscillogram of switching pulse.
Among Fig. 2, (a) be magnitude of voltage time of transformer 21 primary coils 22 inductions that power circuit is ordered at O among Fig. 1 to change oscillogram, (b) be that power circuit changes oscillogram in the current value time that O is ordered, (c) be the output waveform time variation oscillogram that control circuit 27 is defeated by the 1st switch element 24, (d) the output waveform time of being defeated by the 2nd switch element 32 for control circuit 27 changes oscillogram, (e) be the time variation oscillogram of the current value that power circuit is ordered at P among Fig. 1.
During A-B of Fig. 2, if control circuit is to the impulse wave (output wave) of the 1st switch element 24 output some cycles in (c), make the 1st switch element 24 be the ON state, then the length of current value that the O of Fig. 1 is ordered in (b) and the 1st switch element 24 conducting states increases pro rata in time, makes primary coil 22 energy storage.
During B-C, if control circuit 27 stops to the 1st switch element 24 output impulse waves in (c), make the 1st switch element 24 become the OFF state, the electric energy that then has been stored in the primary coil 22 begins to capacitor 25 chargings, in (b), in case the current value that O is ordered reduces to make charging to finish in time, then in (a), the magnitude of voltage of primary coil 22 reaches peak value.
During C-D, in case finish to capacitor 25 chargings, the electric energy that is stored in the capacitor 25 just begins to primary coil 22 energy storage once more, in (b), the current value that O is ordered reduces in time, in case energy storage finishes, then the magnitude of voltage of primary coil 22 is zero in (a).
During D-E, if finish to the energy storage of primary coil 22, the electric energy that then is stored in the primary coil 22 just begins charging to capacitor 25 once more, and at this moment, the both positive and negative polarity relation according to primary coil 22 both end voltage begins charging from the ground end once more to capacitor 25.But the 1st diode 26 that between primary coil 22 other ends and ground, has plus earth, so can be to capacitor 25 chargings, electric current flows through the low diode 26 of impedance, in (b), the current value that O is ordered increases in time, but not to capacitor 25 chargings, therefore, in (a), the magnitude of voltage of primary coil 22 keeps zero.
During E-F, be stored in electric energy in the primary coil 22 this moment and flow through the 1st diode 26 through electric current and obtain discharging, in theory, as long as switch element 24 is not a conducting state in (c), (b) O point current value just still should be zero in, but in fact, O point current value can increase certain certain hour.
Along with the increase of this O point current value, the energy storage of primary coil 22 just will finish.
During F-G, same as described above, if finish to the energy storage of primary coil 22, the electric energy that then is stored in the primary coil 22 just begins to capacitor 25 chargings, the current value that O is ordered in (b) reduces in time, in case charging finishes, the magnitude of voltage of primary coil 22 just reaches peak value in (a).
During G-H, if finish to the charging of capacitor 25, the electric energy that is stored in the capacitor 25 just begins energy storage once more to primary coil 22, in (b), O point current value reduces in time, if energy storage finishes, then the magnitude of voltage of primary coil 22 just is zero in (a).
During H-I, if the energy storage to primary coil 22 finishes, the electric energy that then is stored in the primary coil 22 just begins charging to capacitor 25 once more, in (b), the current value that O is ordered increases in time, no longer charge simultaneously, thereby the magnitude of voltage of primary coil 22 is still zero in (a) to capacitor 25.
During I-J, same as described above, in (b), the current value that O is ordered increases certain time, thereby to primary coil 22 energy storage.
During J-K (A), if the energy storage to primary coil 22 finishes, the electric energy that then is stored in the primary coil 22 just begins to capacitor 25 chargings, the current value that O is ordered in (b) reduces in time, in case charging finishes, then the magnitude of voltage of primary coil 22 reaches peak value in (a), but in this charging way, because the 1st switch element 24 becomes the ON state in (c), thus with this as new starting point.
Flow into the 1st diode 26 at the 1st switch element 24 for electric current under the OFF state, after this when the magnitude of voltage of elementary coil 22 is bigger than driving power magnitude of voltage (X and (X)), the 2nd switch element 32 is switched to the ON state, when the 1st switch element 24 is ON state (Y and (Y)), the 2nd switch element 32 is switched to the OFF state.
At this moment, if the 2nd switch element 32 is the ON state, then conform to therewith in (e) in (d), electric current flows into the P point.
In (A)-(D), repeat process same as described above.
Wave period according to (a) preestablishes the waveform time relationship of (c), (d).
Utilize said structure, at the 1st switch element 24 is under the OFF state, electric current flows into the 1st diode 26, when the magnitude of voltage of elementary coil 22 is bigger than driving power magnitude of voltage (X and (X)) afterwards, the 2nd switch element 32 is switched to the ON state, thereby, when the magnitude of voltage of primary coil 22 is bigger than driving power magnitude of voltage, reach the moment of ON at the 2nd switch element 32, the magnitude of voltage of primary coil 22 is reduced to the driving power magnitude of voltage, reach moment of ON state at the 1st switch element 24, the magnitude of voltage of primary coil 22 is zero.
During this, the magnitude of voltage of primary coil 22 is reduced to the driving power magnitude of voltage gradually, and this is because the electric energy that is stored in transformer 21 inside discharges the cause with ancillary coil 30 short circuits gradually.
Also promptly, the moment of the 1st switch element 24 conductings, always change to zero from the value below the driving power magnitude of voltage, hurried change in voltage can not take place therefore, can suppress current waveform and rise and fall.
According to the invention described above the 1st embodiment, the 1st switch element 24 always changes to zero from the value below the driving power magnitude of voltage in the moment of conducting, therefore hurried change in voltage can not take place, and can suppress current waveform and rise and fall.
(embodiment 2)
Below, the power circuit of the present invention the 2nd embodiment is described with reference to Fig. 1, Fig. 3.
The 2nd embodiment power circuit of the present invention has changed the control action of the control circuit 27 control power circuits of the 1st embodiment among Fig. 1.
The control circuit 27 of the present invention's the 2nd embodiment power circuit produces the impulse wave of control the 1st switch element 24 and the 2nd switch element 32, and when the 1st switch element 24 is the ON state, the 2nd switch element 32 is switched to the OFF state, during electric current flows into the 1st diode 26, the 2nd switch element 32 is switched to the ON state.
At this moment, Fig. 3 represents voltage in this power circuit, electric current, the switching pulse variation oscillogram to the time.
In Fig. 3, (a) time of the O point voltage value of transformer 21 primary coils 22 inductions changes oscillogram in the expression power circuit, (b) time of O point current value changes oscillogram in the expression power circuit, (c) expression control circuit 27 is defeated by the time variation oscillogram of the output waveform of the 1st switch element 24, (d) expression control circuit 27 is defeated by the time variation oscillogram of the output waveform of the 2nd switch element 32, and (e) time of the P point current value of presentation graphs 1 power circuit changes oscillogram.
During A-C of Fig. 3, in (c), control circuit 27 is to the impulse wave (output wave) of the 1st switch element 24 input some cycles, when the 1st switch element 24 becomes the ON state, the length of the ON state of current value that O is ordered in (b) and the 1st switch element 24 increases pro rata in time, makes primary coil 22 energy storage.During electric current flowed into the O point, (e) the P point in did not have electric current, thereby the current value that P is ordered is zero.
At this moment, the B of any time during A-C point, (d) impulse wave (output wave) of the some cycles of middle control circuit 27 inputs the 2nd switch element 32 interrupts, and the 2nd switch element 32 changes the OFF state over to.
During C-D, if control circuit 27 stops to the 1st switch element 24 input pulse ripples in (c), make the 1st switch element 24 become the OFF state, the electric energy that then is stored in the primary coil 22 begins to capacitor 25 chargings, the current value that O is ordered in (b) reduces in time, in case charging finishes, (a) magnitude of voltage of middle primary coil 22 just reaches peak value.
During D-E, if the charging of capacitor 25 finishes, be stored in electric energy in the capacitor 25 just once more to primary coil 22 beginning energy storage, (b) in the O current value of order reduce in time, in case energy storage finishes (a) the magnitude of voltage vanishing of middle primary coil 22.
During E-G, if the energy storage of primary coil 22 finishes, the electric energy that then is stored in the primary coil 22 begins charging to capacitor 25 once more.At this moment, the both positive and negative polarity relation according to primary coil 22 both end voltage begins charging from earth terminal to capacitor 25 once more.But the 1st diode 26 that between the other end of primary coil 22 and ground, has plus earth, thereby, can be to capacitor 25 chargings, electric current the 1st low diode 26 of impedance of flowing through, (b) current value that O is ordered in increases in time, and not to capacitor 25 chargings, thereby the voltage of primary coil 22 still is zero (a).
At this moment, the F of any time during E-G point, (d) the 2nd switch element 32 is defeated by in the some cycles pulse (output wave) of middle control circuit 27, makes the 2nd switch element 32 become the ON state.
During G-H, at this moment, be stored in electric energy in the primary coil 22 and flow through the 1st diode 26 through electric current and obtain discharging, as long as the 1st switch element is not the ON state, (c) O point current value still is zero in theory in, but in fact (b) middle O point current value can increase certain hour.
So, along with the increase of current value in this O point, primary coil 22 can be stored certain electric energy, this moment any time F point during E-G, the 2nd switch element 32 is in the ON state, thereby ancillary coil 30 is short-circuit condition, does not have power storage in primary coil 22.
Here it is in constituting 2 coils of mutual inductance, if a coil is short-circuit condition, though another coil have electric current flow through also not can energy storage phenomenon.
During H-I, because of not having store electrical energy in the coil 22, capacitor 25 is storage of electrical energy not also, (b) in O point current value reduce in time, the current value vanishing, (a) in the magnitude of voltage of magnitude of voltage maintenance driving power 23 of primary coil 22.
During I-J (A), in case current value is zero (b), then electric current begins to flow into the P point in (e), and the magnitude of voltage of primary coil 22 constitutes the magnitude of voltage that remains driving power, and this situation continues up to and is the ON state in (c).
In (A)-(G), repeat above-mentioned same process.
According to said structure, the pulse that utilizes control circuit 27 to produce makes the 1st switch element 24 become the OFF state from the ON state, the 1st primary current flows into the 1st diode 26, at magnitude of voltage is after zero, electric current to primary coil 22 energy storage flows into primary coil 22, even if this electric current flows into primary coil 22, also can prevent primary coil 22 energy storage.
Thereby after the 1st primary current flowed into the 1st diode 26, voltage waveform was that benchmark carries out LC resonance with the magnitude of voltage of driving power 23 usually, and in this process, the magnitude of voltage of driving power 23 remains unchanged, and makes magnitude of voltage than 0 big suitable value.
But, the 2nd time later electric current does not flow into the 1st diode 26, when impulse wave is the ON state, can prevent that electric current from not flowing into the phenomenon of the 1st switch element 24, even if thereby the primary coil 22 of transformer 21 also can produce voltage reliably for the display 29 of level, high definition that vertical frequency is high.
Especially during electric current flows into the 1st diode 26, control circuit 27 switches to the ON state with the 2nd switch element 32, thereby the 1st primary current flow into the 1st diode 26, the magnitude of voltage vanishing, afterwards, even the electric current supposition to primary coil 22 energy storage flows into primary coil 22, in fact also can be to primary coil 22 energy storage.
Consequently, be that the electric energy of the LC resonance of benchmark can not be stored in primary coil 22 owing to constitute with driving power 23 magnitudes of voltage, so can prevent resonance, after the 1st primary current flows into the 1st diode 26, voltage waveform can be remained on the magnitude of voltage of driving power 23.
According to above-mentioned the 2nd embodiment, during electric current flows into the 1st diode 26, control circuit 27 switches to the ON state with the 2nd switch element 32, thereby the 1st primary current flow into the 1st diode 26, after the magnitude of voltage vanishing, even if formation flows into primary coil 22 to the electric current supposition of primary coil 22 energy storage, in fact can be to primary coil 22 energy storage yet, the result constitute with driving power 23 magnitudes of voltage be benchmark carry out the electric energy of LC resonance can be to primary coil 22 energy storage, so can prevent resonance, after the 1st primary current flows into the 1st diode 26, voltage waveform can be remained on the magnitude of voltage of driving power 23
Thereby, when the 1st switch element 24 is the ON state, can prevent that electric current from not flowing into the phenomenon of the 1st switch element 24, even if to level, high-resolution display 29 that vertical frequency is high, the primary coil 22 of transformer also can reliably produce voltage.
(embodiment 3)
Below, with reference to the power circuit of description of drawings the present invention the 3rd embodiment.
In Fig. 4, Fig. 5, the transformer frequency response circuit of the present invention the 3rd embodiment is the improvement to the transformer frequency response circuit of the present invention the 1st embodiment, and identical component part is composed with same label.
The structure of the power circuit of the present invention the 3rd embodiment is, between the negative electrode of the drain electrode of the MOS type field-effect transistor that constitutes the 1st switch element 24 and the 1st diode 26, be provided with the 3rd diode 33, the negative electrode of the 3rd diode 33 connects the drain electrode of the MOS type field-effect transistor of the 1st switch element 24, and the anode of the 3rd diode 33 connects the negative electrode of the 1st diode 26.
At this moment, Fig. 5 illustrates the waveform that voltage in this power circuit, electric current and switching pulse relative time change.
Among Fig. 5, (a) the time dependent oscillogram of magnitude of voltage of induction in transformer 21 primary coils 22 that O is ordered in the expression power circuit, (b) the time dependent oscillogram of current value that O is ordered in the expression power circuit, (c) expression control circuit 27 is defeated by the time dependent oscillogram of output waveform of the 1st switch element 24, (d) expression control circuit 27 is defeated by the time dependent oscillogram of output waveform of the 2nd switch element 32, (e) the time dependent oscillogram of current value that P is ordered in presentation graphs 4 power circuits, the oscillogram of the 3rd embodiment is except (a), (b) outside during middle E-K (A), identical with the oscillogram of the 1st embodiment.
Owing to be provided with the 3rd diode 33, thus during E-K (A), though the electric current that produces (b) diminishes and (a) in the magnitude of voltage that produces be that LC resonance is made at the center with driving power voltage, magnitude of voltage can be not littler than zero.
Therefore, in (c), after the 1st primary current flows into the 1st diode 26, the 2nd time later electric current no longer flows through, the 1st switch element 24 can prevent that electric current from not flowing into the phenomenon of the 1st switch element 24 when being the ON state, thereby, even if also can produce voltage reliably at the primary coil 22 of transformer for level, vertical frequency height, high-resolution display 29.
The same with the power circuit of the 1st embodiment, be under the OFF state at the 1st switch element 24, electric current flows into the 1st diode 26, when the magnitude of voltage of elementary coil 22 is bigger than driving power magnitude of voltage (X and (X)) afterwards, the 2nd switch element 32 is switched to the ON state, when the 1st switch element 24 is the ON state (Y and (Y)), switch to the OFF state, thereby, when the magnitude of voltage of elementary coil 22 is bigger than driving power magnitude of voltage, the moment that the magnitude of voltage of primary coil 22 is connected at the 2nd switch element 32 is reduced to the driving power magnitude of voltage, in the moment vanishing of the 1st switch element 24 connections.
Also promptly, the moment that the 1st switch element 24 is connected always changes to zero from the value below the driving power magnitude of voltage, thereby does not have fierce change in voltage, can suppress to produce in the current waveform to rise and fall.
According to above-mentioned the 3rd embodiment, can prevent that electric current from not flowing into the phenomenon of the 1st switch element 24, even also can in the primary coil 22 of transformer, produce voltage reliably for level, vertical frequency height, high-resolution display 29 etc., always change to zero in the moment that the 1st switch element 24 is connected simultaneously from the value lower than driving power magnitude of voltage, thereby voltage can fierce not change, and can suppress to produce in the current waveform to rise and fall.
(embodiment 4)
Below, with reference to the power circuit of description of drawings the present invention the 4th embodiment.
Among Fig. 6, the power circuit of the present invention the 4th embodiment is the improvement to power of transformer circuit among the present invention the 1st embodiment.
The power of transformer circuit comprises the driving power 123 that connects transformer 121 primary coils 122 1 ends among the present invention the 4th embodiment, connects the 1st switch element 124, capacitor 125 and the 1st diode 126 of these primary coil 122 other ends.
The 1st switch element 124 is got the 1MOS type field-effect transistor (MOS FET) with internal body diodes, the drain electrode of this 1MOS type field-effect transistor connects the other end of primary coil 122, source ground, grid connects the control circuit 127 of PWM mode, this control circuit 127 produces impulse wave and controls the 1st switch element 124, the plus earth of internal body diodes, negative electrode connects the other end of primary coil 122.One end of capacitor 125 connects the other end of primary coil 122, the other end ground connection of capacitor 125.The negative electrode of the 1st diode 126 connects the other end of primary coil 122, plus earth.One end of the negative electrode of the 1st diode 126 and capacitor 125 is connected between the drain electrode and primary coil 122 of 1MOS type field-effect transistor.
Also further be provided with the LC resonant circuit 135 that connects primary coil 122, connect the 2nd diode 131 of this LC resonant circuit 135, with the 2nd switch element 132 that is connected the 2nd diode 131.
The 2nd switch element 132 is got 2MOS type field-effect transistor, and the drain electrode of 2MOS type field-effect transistor connects the negative electrode of the 2nd diode 131, source ground, and grid connects control circuit 127.The anode of the 2nd diode 131 connects LC resonant circuit 135.One end of LC resonant circuit 135 connects the other end of primary coil 122, and the other end of LC resonant circuit 135 connects the anode of the 2nd diode 131.
At this moment, Fig. 7 illustrates the time dependent oscillogram of voltage, electric current and switching pulse in this power circuit.
Among Fig. 7, the time dependent oscillogram of magnitude of voltage of transformer 121 primary coils 122 inductions that (a) power circuit O is ordered in the presentation graphs 6, (b) represent the time dependent oscillogram of current value that power circuit O is ordered, (c) the expression control circuit is defeated by the time dependent oscillogram of output waveform of the 1st switch element 124, (d) the expression control circuit is defeated by the time dependent oscillogram of output waveform of the 2nd switch element 132, (e) the time dependent oscillogram of current value that power circuit P is ordered in the presentation graphs 6.
During A-B, if control circuit 127 is the ON state to the impulse wave (output wave) of the 1st switch element 124 input some cycles (c), then the length of the ON state of current value that O is ordered in (b) and the 1st switch element 124 increases pro rata in time, to primary coil 122 energy storage.
During B-C, if control circuit 127 stops to provide impulse wave to make it become the OFF state to the 1st switch element 124 in (c), the electric energy that then is stored in the primary coil 122 begins to capacitor 125 chargings, (b) current value that O is ordered in reduces in time, in case charging finishes, (a) magnitude of voltage of middle primary coil 122 just reaches peak value.
During C-D, if finish to the charging of capacitor 125, the electric energy that is stored in capacitor 125 is just once more to primary coil 122 beginning energy storage, (b) in the O current value of ordering reduce in time, in case energy storage finishes, (a) magnitude of voltage of middle primary coil 122 is with regard to vanishing.
During D-E, if finish to primary coil 122 energy storage, the electric energy that is stored in the primary coil 122 just begins charging to capacitor 125 once more, and at this moment, capacitor 125 begins charging according to the voltage both positive and negative polarity relation at primary coil 122 two ends once more from earth terminal.But, the 1st diode 126 that between the other end of primary coil 122 and ground, has plus earth, thereby can be to capacitor 125 chargings, electric current flows through the 1st low diode 126 of impedance, (b) current value that O is ordered in increases in time, and can be to capacitor 125 chargings, so the magnitude of voltage of primary coil 122 still is zero (a).
During E-F, here the electric energy that is stored in primary coil 122 flows through the 1st diode 126 by electric current and obtains discharging, as long as switch element 124 is not the ON state (c), then the current value that O is ordered in (b) still should be zero in theory, but the electric current that O is ordered in fact, (b) is planted the increase certain hour.
Then, along with the increase of this O point current value, primary coil 122 just stores certain electric energy.
During F-G, with above-mentioned the same, if primary coil 122 energy storage finish, the electric energy that then is stored in the primary coil 122 begins to capacitor 125 chargings, (b) current value that O is ordered in reduces in time, in case charging finishes, (a) magnitude of voltage of middle primary coil 122 just reaches peak value.
During G-H, if finish, be stored in electric energy in the capacitor 125 just once more to primary coil 122 energy storage to capacitor 125 charging, (b) in the O current value of order reduce in time, in case energy storage finish, (a) in the magnitude of voltage of primary coil 122 just be zero.
During H-I, if finish to primary coil 122 energy storage, the electric energy that then is stored in the primary coil 122 begins charging to capacitor 125 once more, (b) current value that O is ordered in increases in time, and not to capacitor 125 chargings, thereby in (a), the magnitude of voltage of primary coil still is zero.
During I-J, with above-mentioned the same, the current value that O is ordered in (b) increases certain certain hour, thereby to primary coil 122 energy storage.
During J-K, if finish to primary coil 122 energy storage, the electric energy that then is stored in the primary coil 122 begins charging to capacitor 125, (b) current value that O is ordered in reduces in time, in case charging finishes, (a) magnitude of voltage of middle primary coil 122 just reaches peak value, in this process, (c) the 1st switch element 124 becomes the ON state in, thereby, again with this as the starting point.
At the 1st switch element 124 is under the OFF state, electric current flows into the 1st diode 126, when the magnitude of voltage of elementary coil 122 is bigger than the magnitude of voltage of driving power 123 (X and (X)) afterwards, the 2nd switch element 132 is switched to the ON state, (Y reaches (Y)) switches to the OFF state when the 1st switch element 124 is the ON state.
At this moment, then corresponding therewith if the 2nd switch element 132 becomes the ON state (d), (e) in electric current flow into the P point, through LC resonant circuit 135, thereby the output voltage values of primary coil 122 is lower than the magnitude of voltage of driving power 123 (a).
Here, LC resonant circuit 135 is as waveform shaping circuit, make the output voltage values of primary coil 122 be lower than the magnitude of voltage of driving power 123, the shaping ripple that the fluctuating of the current waveform that produces in output and the primary coil 122 is cancelled out each other makes the fluctuating of the current waveform that produces in resonance time constant and the primary coil 122 synchronous simultaneously.
This resonance time constant can be set inductance value used in the LC resonant circuit 135 (L) and capacitance (C) according to the condition that satisfies (cycle of the fundamental frequency of fluctuating)=1/ (resonance frequency of LC resonant circuit 135).
In (A)-(D), repeat process same as described above.
According to said structure, at the 1st switch element 124 is under the OFF state, electric current flows into the 1st diode 126, afterwards as the magnitude of voltage of elementary coil 122 during (X and (X)) greater than the driving power magnitude of voltage, the 2nd switch element 132 is switched to the ON state, when the magnitude of voltage of elementary coil 122 is bigger than driving power magnitude of voltage, in the moment that the 2nd switch element 132 is connected, the magnitude of voltage of primary coil 122 is reduced to near-zero, in the moment that the 1st switch element 124 is connected, the magnitude of voltage vanishing of primary coil 122.
Also promptly, the moment of the 1st switch element 124 conductings, always change to zero from the value below the driving power magnitude of voltage, hurried change in voltage can not take place therefore, can suppress current waveform and rise and fall.
But the magnitude of voltage of primary coil 122 has been zero, so the 1st switch element 124 can not be the ON state, thereby follows this voltage difference how much to have fluctuating.
For this fluctuating, take to allow the fluctuating of the current waveform that produces in the resonance time constant of LC resonant circuit 135 and the primary coil 122 synchronous, and output and this fluctuating shaping ripple of cancelling out each other, thereby can greatly suppress fluctuating.
According to above-mentioned the 4th embodiment, the moment of connecting at the 1st switch element 124 always changes to zero from the magnitude of voltage that is lower than driving power 123, therefore hurried change in voltage can not take place, and can suppress current waveform and rise and fall.
In the moment that the 1st switch element 124 is connected, though the magnitude of voltage of primary coil 122 is lower than the voltage of driving power 123, but it is because non-vanishing, therefore in the current waveform that primary coil 122 produces, how many fluctuatings is arranged, fluctuating in the current waveform of the resonance time constant that make LC resonant circuit 135 this moment and primary coil 122 generations is synchronous, and the output shaping ripple of cancelling out each other with this fluctuating, therefore can suppress fluctuating.
(embodiment 5)
Below, with reference to the power circuit of description of drawings the present invention the 5th embodiment.
The transformer frequency response circuit of the 5th embodiment is the improvement to the transformer frequency response circuit of the 4th embodiment among Fig. 8, Fig. 9, and same section is composed with same label.
The structure of the transformer frequency response circuit of the 5th embodiment is, on the basis of the power circuit of the 4th embodiment, between the negative electrode of the drain electrode of the MOS type field-effect transistor of the 1st switch element 124 and the 1st diode 126, be provided with the 3rd diode 133, the negative electrode of the 3rd diode 133 connects the drain electrode of the MOS type field-effect transistor of the 1st switch element 124, and the anode of the 3rd diode 133 connects the negative electrode of the 1st diode 126.
At this moment, Fig. 9 illustrates the time dependent oscillogram of voltage, electric current and switching pulse in this power circuit
Among Fig. 9, (a) the time dependent oscillogram of magnitude of voltage of induction in transformer 121 primary coils 122 that O is ordered in presentation graphs 8 power circuits, (b) the time dependent oscillogram of current value that O is ordered in the expression power circuit, (c) expression control circuit 127 is defeated by the time dependent oscillogram of output waveform of the 1st switch element 124, (d) expression control circuit 127 is defeated by the time dependent oscillogram of output waveform of the 2nd switch element 132, (e) the time dependent oscillogram of current value that P is ordered in presentation graphs 8 power circuits, the oscillogram of the 5th embodiment is except (a), (b) outside during middle E-K (A), identical with the oscillogram of the 3rd embodiment.
Owing to be provided with the 3rd diode 133, thus during E-K (A), though the current value that produces (b) diminishes and (a) in the magnitude of voltage that produces be that LC resonance is made at the center with driving power voltage, magnitude of voltage can be not littler than zero.
Therefore, in (c), after the 1st primary current flows into the 1st diode 126, the 2nd time later electric current no longer flows through, the 1st switch element 124 can prevent that electric current from not flowing into the phenomenon of the 1st switch element 124 when being the ON state, thereby, even if also can produce voltage reliably at the primary coil 122 of transformer 121 for level, vertical frequency height, high-resolution display 129.
The same with the power circuit of the 3rd embodiment, be under the OFF state at the 1st switch element 124, electric current flows into the 1st diode 126, when the magnitude of voltage of elementary coil 122 is bigger than driving power magnitude of voltage (X of Fig. 9 and (X)) afterwards, the 2nd switch element 132 is switched to the ON state, when the 1st switch element 124 is the ON state (Y of Fig. 9 and (Y)), switch to the OFF state, thereby, when the magnitude of voltage of elementary coil 122 is bigger than the magnitude of voltage of driving power 123, the moment that the magnitude of voltage of primary coil 122 is connected at the 2nd switch element 132 is reduced to driving power 123 magnitudes of voltage, in the moment vanishing of the 1st switch element 124 connections.
Also promptly, the moment that the 1st switch element 124 is connected always changes to zero from the value below the magnitude of voltage of driving power 123, thereby does not have fierce change in voltage, can suppress to produce in the current waveform to rise and fall.
According to above-mentioned the 5th embodiment, except effect with the 4th embodiment, can also prevent that electric current from not flowing into the phenomenon of the 1st switch element 124, even also can in the primary coil 122 of transformer 121, produce voltage reliably for level, vertical frequency height, high-resolution display 129 etc., always change to zero in the moment that the 1st switch element 124 is connected simultaneously from the value lower than the magnitude of voltage of driving power 123, thereby voltage can fierce not change, and can suppress to produce in the current waveform to rise and fall.
According to embodiments of the invention, adopt LC resonant circuit 135 as waveform shaping circuit, but, also can produce identical effect as the resistance circuit of exporting the shaping ripple that can absorb the current waveform fluctuating that produces in the primary coil 122.
(embodiment 6)
Below, with reference to the power circuit of description of drawings the present invention the 6th embodiment.
The power circuit of the present invention the 6th embodiment is the improvement to the power circuit of the 1st embodiment shown in Figure 1 among Figure 10.
The power circuit of the present invention the 6th embodiment comprises: by the kickback transformer that transformer 234 constitutes, have primary coil 231 and secondary coil 232, be used for providing anode voltage to displays such as display unit 233; The control circuit 235 of the PWM working method that the low output voltage of this primary coil 231 outputs is controlled; With with the high output voltage of secondary coil 232 output as detecting the high-voltage detecting circuit 236 that voltage is detected.
At this moment, the capacitance of the 1st detection container 238 (C1), the 2nd detection container 239 capacitances (C2), the relation of the resistance value (R2) of resistance value of the 1st resistance 241 (R1) and the 2nd resistance 242 is set at: (C1) * (R1)=(C2) * (R2), the scope of the capacitance of such the 3rd detection container 251 (C3) can be wide, thereby, the increase and decrease of the capacitance of the 2nd detection container 239 (C2) relation of (C1) * (R1)=(C2) * (R2) that can make becomes (C1) * (R1)〉(C2) * (R2), or (C1) * (R1)＜(C2) * (R2).
Figure 11 shows the oscillogram of the high output voltage of transformer 234.In this oscillogram, the rising edge characteristic when regional A represents the power circuit energising, area B is represented dynamic characteristic.
According to said structure, owing between the 1st mid point 244 of the 1st detection container 238 and the 2nd detection container 239 and the 1st resistance 241 and the 2nd resistance 242 and the 2nd mid point 245, be connected the 3rd detection container 251, thereby during the initial energized of power circuit, the electric capacity of the 1st detection container 238 (C1), the electric capacity of the 2nd detection container 239 (C2), the electric capacity of the 3rd detection container 251 (C3) does not accumulate electric charge, each capacitance just is zero, in the moment of energized, the capacitance of the 2nd detection container 239 (C2) becomes the capacitance of the capacitance (C3) that adds the 3rd detection container 251, and the resistance of the 1st resistance 241 (R1) with the pass of the resistance (R2) of the 2nd resistance 242 is: (C1) * (R1)＜(C2) * (R2).
The common moment behind the power connection, the electric capacity (C2) of the electric capacity of the 1st detection container 238 (C1), the 2nd detection container 239, the electric capacity (C3) of the 3rd detection container 251 all accumulates that electric charge is arranged, thereby the capacitance of the 2nd detection container 239 (C2) becomes: (C1) * (R1)〉(C2) * (R2).
Therefore, can not occur as shown in figure 12, dynamic characteristic degenerates, or as shown in figure 13, the situation that the rising edge characteristic degenerates can be improved rising edge characteristic and dynamic characteristic, as shown in figure 11 simultaneously.
According to above-mentioned the 6th embodiment, owing between the 1st mid point 244 of the 1st detection container 238 and the 2nd detection container 239 and the 1st resistance 241 and the 2nd resistance 242 and the 2nd mid point 245, be connected the 3rd detection container 251, can improve rising edge characteristic and dynamic characteristic simultaneously.
(embodiment 7)
Below, with reference to description of drawings the present invention the 7th embodiment.
The power circuit of the 7th embodiment is the improvement to the transformer frequency response circuit of the 1st embodiment shown in Figure 1 among Figure 14.
The power circuit of the present invention the 7th embodiment comprises the driving power 323 that connects transformer 321 primary coils 322 1 ends, connects the 1st switch element 324, capacitor 325 and the 1st diode 326 of these primary coil 322 other ends.
The 1st switch element 324 is got the MOS type field-effect transistor (MOS FET) with internal body diodes, this transistor drain connects the other end of primary coil 322, source ground, grid connects control circuit 327, this control circuit 327 produces pulse to control the 1st switch element 324, and internal body diodes keeps its plus earth to be connected the state of primary coil 322 other ends with negative electrode.One end of capacitor 325 connects the other end of primary coil 322, the other end ground connection of capacitor 325.The negative electrode of the 1st diode 326 connects the other end of primary coil 322, plus earth.One end of the negative electrode of the 1st diode 326 and capacitor 325 is connected between transistor drain and the primary coil 322.
The negative electrode that is provided with the 3rd diode 330, the 3 diodes 330 between the negative electrode of the 1st diode 326 and transistor drain connects transistor drain, and anode connects the negative electrode of the 1st diode 326.
An end that is connected capacitor 325 between the negative electrode of the 1st diode 326 and the primary coil 322.
The 1st diode 326 and the 3rd diode 330 with transistorized internal body diodes reduced in comparison the reverse recovery time of electric current, and secondary coil 328 connects the high display 329 (CRT) of horizontal frequencies or vertical frequency etc.
At this moment, Figure 15 illustrates voltage in this power circuit, electric current, the time dependent oscillogram of switching pulse.
Among Figure 15, (a) be magnitude of voltage time of transformer 321 primary coils 322 inductions that power circuit is ordered at O among Figure 14 to change oscillogram, (b) be that power circuit changes oscillogram in the current value time that O is ordered, (c) be the output waveform time variation oscillogram that control circuit 327 is defeated by the 1st switch element 324, during A-B, if control circuit 327 is to the impulse wave (output wave) of the 1st switch element 324 output some cycles in (c), make the 1st switch element 324 be the ON state, then the length of current value that O is ordered in (b) and the 1st switch element 324 conducting states increases pro rata in time, makes primary coil 322 energy storage.
During B-C, if control circuit 327 stops to the 1st switch element 324 output impulse waves in (c), make the 1st switch element 324 become the OFF state, the electric energy that then has been stored in the primary coil 322 begins to capacitor 325 chargings, in (b), in case the current value that O is ordered reduces to make charging to finish in time, then in (a), the magnitude of voltage of primary coil 322 reaches peak value.
During C-D, in case finish to capacitor 325 chargings, the electric energy that is stored in the capacitor 325 just begins to primary coil 322 energy storage once more, in (b), the current value that O is ordered reduces in time, in case energy storage finishes, then the magnitude of voltage of primary coil 322 is zero in (a).
During D-E, if the energy storage to primary coil 322 finishes, the electric energy that then is stored in the primary coil 322 just begins charging to capacitor 325 once more, at this moment, both positive and negative polarity relation according to primary coil 322 both end voltage begins charging from the ground end once more to capacitor 325.But the 1st diode 326 that between primary coil 322 other ends and ground, has plus earth, so can be to capacitor 325 chargings, electric current flows through the 1st low diode 326 of impedance, in (b), the current value that O is ordered increases in time, but not to capacitor 325 chargings, therefore, in (a), the magnitude of voltage of primary coil 322 keeps zero.
During E-F, being stored in electric energy in the primary coil 322 this moment flows through the 1st diode 326 through electric current and obtains discharging, in theory, as long as the 1st switch element 324 is not a conducting state in (c), (b) O point current value just still should be zero in, but in fact, O point current value can increase certain certain hour.
Along with the increase of this O point current value, primary coil 322 is just stored certain electric energy.
During F-G, same as described above, so if finish to the energy storage of primary coil 322, the electric energy that then is stored in the primary coil 322 just begins to capacitor 325 chargings, the current value that O is ordered in (b) reduces in time, in case charging finishes, the magnitude of voltage of primary coil 322 just reaches peak value in (a).
During G-H, if the charging to capacitor 325 finishes, the electric energy that is stored in the capacitor 325 just begins energy storage once more to primary coil 322, in (b), O point current value reduces in time, if energy storage finishes, then the voltage of primary coil 322 just equals the magnitude of voltage of driving power 323 in (a).
During H-I, if the energy storage to primary coil 322 finishes, the electric energy that then is stored in the primary coil 322 just begins charging to capacitor 325 once more, in (b), the current value that O is ordered increases in time, in case charging finishes, then the magnitude of voltage of primary coil 322 is littler than the value of driving power 323 in (a), but greater than zero.
During I-J, if finish, then once more to primary coil 322 energy storage to the charging of capacitor 325, in (b), the current value that O is ordered increases in time, in case energy storage finishes, then the magnitude of voltage of primary coil 322 equals the magnitude of voltage of driving power 323 in (a).
During J-K, if the energy storage to primary coil 322 finishes, the electric energy that then is stored in the primary coil 322 just begins to capacitor 325 chargings, and the current value that O is ordered in (b) reduces in time, in case charging finishes, then the magnitude of voltage of primary coil 322 reaches peak value in (a).
During K-L, if finish to capacitor 325 chargings, the electric energy that then is stored in the capacitor 325 begins energy storage to primary coil 322 once more, and the current value that O is ordered in (b) reduces in time, energy storage one finishes, and then the voltage of (a) middle primary coil 322 equals the magnitude of voltage of driving power 323.
During L-K (A), if finish to primary coil 322 energy storage, the electric energy that then is stored in the primary coil 322 begins charging to capacitor 325 once more, and the current value that O is ordered in (b) increases in time, in case charging finishes, then the magnitude of voltage of primary coil 322 is littler than the magnitude of voltage of driving power 323 in (a), but bigger than zero, in this process, because the 1st switch element 324 becomes the ON state in (c), so this as new starting point, is repeated process same as described above once more.
According to above-mentioned formation, between the transistor drain of the 1st diode 326 negative electrodes and the 1st switch element 324, be provided with the 3rd diode 330, the negative electrode of the 3rd diode 330 connects transistor drain, anode connects the negative electrode of the 1st diode 326, and an end of capacitor 325 is connected between the negative electrode and primary coil 322 of the 1st diode 326, the 1st diode 326 and the 3rd diode 330 with transistor internal body diodes reduced in comparison the reverse recovery time of electric current, thereby the impulse wave that produces by control circuit 327 makes switch element 324 become the OFF state from the ON state, the 1st primary current flows into the 1st diode 326, the magnitude of voltage vanishing, afterwards, electric current to primary coil 322 energy storage flows into primary coil 322, but can make this current value very low, reduce the energy storage in the primary coil 322.
Thus, after the 1st primary current flowed into the 1st diode 326, though voltage waveform is that benchmark is made LC resonance with the magnitude of voltage of driving power 323, its amplitude was little, and magnitude of voltage is bigger than zero.
Thereby, the 2nd time later electric current can not flow into the 1st diode 326, when impulse wave is the ON state, can prevent that electric current from not flowing into the phenomenon of the 1st switch element 324, even also can produce voltage reliably at the primary coil 322 of transformer 321 to level, vertical frequency height, high-resolution display 329 etc.
Particularly for the internal body diodes that certainly exists in the MOS type field-effect transistor, the 1st diode 326 and the 3rd diode 330 and the 1st switch element 324 be transistorized internal body diodes reduced in comparison the reverse recovery time of electric current, thereby, be under the situation of open circuit at the voltage that is added on the 1st diode 326 and the 3rd diode 330 two ends, the inhibition time (up to the immobilising time of electric current) (current reversal recovery time) of flowing through electric current is that the electric current inhibition time of transistorized internal body diodes is short than the 1st switch element 324.
Thus, the 1st diode 326, the electric current that lags that the 3rd diode 330 causes (the time till electric current inhibition means run to actual no current flows flow electric current) is suppressed to such an extent that time of the electric current that lags that causes than transistor internal body diodes in time is shorter, when electric current flows into negative electrode from the anode of the 1st diode 326, the electric current that lags that the transistor internal body diodes causes utilizes the 3rd diode 330 to suppress, because the 1st diode 326, the electric current that lags that the 3rd diode 330 causes is suppressed to such an extent that time of the electric current that lags that causes than transistor internal body diodes in time is shorter, therefore can prevent that unnecessary electrical power storage is in transformer or capacitor.
According to above-mentioned the 7th embodiment, at the negative electrode of the 1st diode 326 and switch element 324 is to be connected to the 3rd diode 330 between the transistor drain, the negative electrode of the 3rd diode 330 connects transistor drain, anode connects the negative electrode of the 1st diode 326, one end of capacitor 325 is connected between the negative electrode and primary coil 322 of the 1st diode 326, the 1st diode 326 and the 3rd diode 330 and the 1st switch element 324 be transistorized internal body diodes reduced in comparison the reverse recovery time of electric current, even thereby for level, the vertical frequency height, high-resolution display 329 grades also can produce voltage reliably at the primary coil 322 of transformer 321.
In the 7th embodiment,, also can obtain same effect but be connected between the anode of the negative electrode of the 1st diode 326 and the 3rd diode 330 though an end of capacitor 325 is connected between the negative electrode and primary coil 322 of the 1st diode 326.
Industrial applicability
According to above-described the present invention, between transformer and control circuit, be provided with the noise suppressed means, because of And a kind of power circuit can be provided, this power circuit can suppress to produce in the current waveform fluctuating, prevents in the picture Produce noise.
Attached number in the figure list
21 transformers
22 primary coils
23 driving powers
24 the 1st switch elements
25 capacitors
26 the 1st diodes
27 control circuits
28 secondary coils
29 displays
30 ancillary coils
31 the 2nd diodes
32 the 2nd switch elements
33 the 3rd diodes
121 transformers
122 primary coils
123 driving powers
124 the 1st switch elements
125 capacitors
126 the 1st diodes
127 control circuits
128 secondary coils
129 displays
130 ancillary coils
131 the 2nd diodes
132 the 2nd switch elements
133 the 3rd diodes
135 LC resonant circuits
231 primary coils
232 secondary coils
233 displays
234 transformers
235 control circuits
236 high-voltage test circuits
237 intermediate points
238 the 1st detection containers
239 the 2nd detection containers
240 capacitor groups
241 the 1st resistance
242 the 2nd resistance
243 resistor group
244 the 1st mid points
245 the 2nd mid points
246 the 1st switch elements
247 damping diodes
248 resonance capacitors
249 diodes
250 driving powers
251 the 3rd detection containers
321 transformers
322 primary coils
323 driving powers
324 the 1st switch elements
325 capacitors
326 the 1st diodes
327 control circuits
328 secondary coils
329 displays
330 the 3rd diodes
Claims (1)
1. power circuit, comprise transformer with primary coil and secondary coil, the driving power of an end that connects the described primary coil of described transformer, the 1st switch element that connects the other end of described primary coil, capacitor and the 1st diode, with produce impulse wave and control the control circuit of described the 1st switch element, described the 1st switch element is a 1MOS type field-effect transistor, the drain electrode of described 1MOS type field-effect transistor connects the other end of described primary coil, its source ground, its grid connects control circuit, one end of described capacitor connects the other end of described primary coil, the other end ground connection of described capacitor, the negative electrode of described the 1st diode connects the other end of described primary coil, its plus earth, between described transformer and described control circuit, be provided with the noise suppressed means that suppress noise, it is characterized in that
The 1st switch element is the MOS type field-effect transistor with internal body diodes, between the drain electrode of the negative electrode of the 1st diode and described MOS type field-effect transistor, be provided with the 3rd diode, the negative electrode of described the 3rd diode connects the drain electrode of described MOS type field-effect transistor, anode connects the negative electrode of described the 1st diode, and an end of capacitor is connected between the negative electrode and primary coil of the 1st diode, or be connected between the anode of the negative electrode of the 1st diode and the 3rd diode, reverse current recovery time of described the 1st diode and described the 3rd diode is than the weak point of internal body diodes in the described MOS type field-effect transistor.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27568/99 | 1999-02-04 | ||
| JP02757099A JP3283843B2 (en) | 1999-02-04 | 1999-02-04 | Power supply circuit for flyback transformer |
| JP27570/99 | 1999-02-04 | ||
| JP27567/99 | 1999-02-04 |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN00800122.7A Division CN1293864A (en) | 1999-02-04 | 2000-02-02 | Power-supply circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1855681A CN1855681A (en) | 2006-11-01 |
| CN100468935C true CN100468935C (en) | 2009-03-11 |
Family
ID=12224684
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005101378403A Expired - Fee Related CN100468935C (en) | 1999-02-04 | 2000-02-02 | Power supply circuit |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP3283843B2 (en) |
| CN (1) | CN100468935C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8817497B2 (en) * | 2008-12-03 | 2014-08-26 | Dialog Semiconductor Inc. | Switching power converter for reducing EMI from ring oscillation and its control method |
-
1999
- 1999-02-04 JP JP02757099A patent/JP3283843B2/en not_active Expired - Fee Related
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2000
- 2000-02-02 CN CNB2005101378403A patent/CN100468935C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP3283843B2 (en) | 2002-05-20 |
| CN1855681A (en) | 2006-11-01 |
| JP2000228877A (en) | 2000-08-15 |
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