CN87214310U

CN87214310U - Retrace oscillating ott field scan amplifier

Info

Publication number: CN87214310U
Application number: CN 87214310
Authority: CN
Inventors: 陈江潮
Original assignee: CHONGQING RODIO FACTORY
Current assignee: CHONGQING RODIO FACTORY
Priority date: 1987-10-14
Filing date: 1987-10-14
Publication date: 1988-10-05

Abstract

The utility model relates to a retracing oscillating OTL field scan amplifier used for the field scanning portion of a magnetic field deflection display system. The utility model comprises an OTL amplifier, a deflecting coil, a diode, an electrical source and an oscillating capacitor. In the utility model, the energy stored in the deflecting coil is thoroughly utilized in retracing duration; at minute before the retracing is started, the electric current-Ip of the deflecting coil is reversed in phase to 0.928 Ip in 0.3 ms by the oscillating capacitor, and accordingly, the utilization rate and efficiency of the supply voltage are improved. The utility model has the advantages of simple circuit the electric current-Ip and low cost, and solves the contradiction between efficiency and cost existing in the prior art.

Description

Retrace oscillating OTT field scan amplifier

The utility model is used for the magnetic core logical circuit deflection display system, and for example the field scan of television receiver partly.

In existing field scan technology, often adopt basic model OTL field scan amplifier and modified model field scan amplifier.The voltage utilization of basic model OTL field scan amplifier is very low, have only below 40%, thereby efficient is very low, only more than 20%, the big corresponding caloric value of power consumption is also big, must adopt than the large-power semiconductor device, cost is difficult to further decline like this, and further miniaturization also is impossible.Modified model field amplifier, as pumping source field amplifier, supply voltage bootstrap type field amplifier etc., they all adopt and use during scan(ing) stroke than low supply voltage, supply voltage is raise with extension wire at retrace interval, need low-voltage high-power to satisfy frame-scan circuit in the trace phase, return period, need the low power requirement of high voltage, though such circuit can be brought up to efficient about 40%, but because extension wire is arranged, thereby cause the complex circuit of whole field scan amplifier, element is many, and cost is also high.

At the contradiction of efficient in the prior art and cost, the utility model provides a kind of efficient height, circuit is simple, cost is low flyback oscillatory type OTL field scan amplifier.

A kind of flyback oscillatory type OTL field scan amplifier that is used for the magnetic core logical circuit deflection display system, it comprises that an OTL amplifier (100), (25) one of deflecting coils are serially connected in the diode (15) of (40) end of the feeder ear (35) of OTL amplifier (100) and power supply (10) and one and carry out handing at retrace interval and deflecting coil (25) and change the oscillating capacitance (20) of And with the electric current paraphase of deflecting coil (25).(40) end of its oscillating capacitance (20) one end ground connection (45) or power supply (10), the output (50) of another termination OTL amplifier (100) or (55) end.When oscillating capacitance (20) was connected between the output (55) of ground (45) and OTL amplifier (100), oscillating capacitance (20) can be the electrolytic capacitor that has only polarity.

This flyback oscillatory type OTL field scan amplifier does not adopt the method that improves supply voltage at retrace interval, but is stored in the energy in deflecting coil (25) inductance in a flash before making full use of flyback and beginning, and makes it to convert to the desirable electric current of trace.That finishes this task is one and carries out handing at retrace interval and deflecting coil (25) and change And oscillating capacitance (20) and diode (15) that OTL amplifier power supply end is isolated from the outside at retrace interval with the yoke current paraphase.

Below in conjunction with description of drawings operation principle of the present utility model and its superior part.

Fig. 1 is the electrical schematic diagram of basic model OTL field scan amplifier in the prior art

Fig. 2 is the oscillogram of the current i V in the deflecting coil among Fig. 1 (25) and the oscillogram of the voltage Vo on the deflecting coil (25)

Fig. 3 is the isoboles of Fig. 1 circuit at retrace interval

Fig. 4 is the figure that realizes a kind of scheme of the present utility model

Fig. 5 is the oscillogram of the voltage V55 of (55) point in the oscillogram and Fig. 4 of current i V in the deflecting coil among Fig. 4 (25)

Fig. 6 is the isoboles of Fig. 4 at retrace interval

Fig. 7 is a kind of optimum implementation figure of the utility model in television set

Fig. 1 is the electrical schematic diagram of basic model OTL of the prior art field amplifier, and an OTL amplifier (100) is wherein arranged, and its inductance of deflection coil (25) is Lv, and its voltage of resistance R v and power supply (10) is Ec. It is Ec/2 that (55) point in Fig. 1 has the mid point DC potential. According to existing utility data, the time constant τ=Lv/Rv=2ms. Tr is retrace interval among Fig. 2, (ts-tr) is trace interval, according to standing order tr=1ms, (ts-tr)=19ms. Below in conjunction with Fig. 2, the course of work of Fig. 3 key diagram 1 described circuit.

When flyback began, the current i v in the deflection coil (25) changed to Ip from-Ip, and when reaching Ip, flyback finishes. Iv from-when Ip begins to change, the deflection coil (25) that is connected on the output (50) of OTL amplifier (100) makes (55) point induce a high voltage, thereby make transistor BG1 reverse-conducting make the voltage of (55) point be clamped at Ec, owing to the DC potential difference of Ec/2 is arranged, so V on the electric capacity (70)₀Also rise to Ec/2, current i v from-that Ip changed to for 0 time is shorter, puts aside that when iv changed to Ip from 0, transistor BG1 became forward conduction, its saturation voltage drop is Vces, this moment, the circuit equivalence of Fig. 1 was Fig. 3, voltage source among Fig. 3 (11) Voltage be Ec/2, and current i v changes by index law. That is:

iv＝ (Ec／2－Vces)/(Rv) （1－e ^－t／τ）…………（1）

When retrace interval t=1ms, require iv=Ip, substitution τ=2ms gets:

Ip＝ (Ec／2－Vces)/(Rv) （1－e ^－0.5）≈0.4 (Ec／2－Vces)/(Rv)

So the effective amplitude peak of sawtooth waveforms is:

Ip·Rv＝0.4（Ec／2－Vces）…………（2）

This shows the utilance of supply voltage is had only about 40%.

For sawtooth waveforms, the efficient of OTL amplifier is:

η＝ 2/3 × (Rv·Ip)/(Ec／2) …………（3）

Vces is 0 if make, and (2) formula substitution (3) is got:

η＝ 2/3 ×0.4≈26.7％

Changed to for 0 used time if consider iv from-Ip, the t of substitution (1) formula is also just lower less than 1ms voltage utilization and efficient.Can find out that from above analysis in order to satisfy retrace interval 1ms, basic model OTL field efficiency of amplitude is too low really.

If in return period the Ec in (2) formula is switched to the high voltage of 2.5Ec, then voltage utilization can arrive 100%, and it is the highest that efficient reaches, and theoretical value is 66.7%.Modified model field amplifier, as pumping source field amplifier, voltage bootstrap type field amplifier all is to have utilized voltage-switching method, improved voltage utilization and efficient, but the commutation circuit complexity, element is many, cost is high, be difficult to be accepted by cheap products such as black and white electric press.

Fig. 4 realizes a conceptual scheme of the present utility model, in Fig. 4, compare with circuit shown in Figure 1, it is an only many diode (15) that carries out handing over (40) of changing feeder ear (35) that And is serially connected in OTL amplifier (100) with oscillating capacitance (20) and of the current i v paraphase of deflecting coil (25) and power supply (10) to hold at retrace interval and deflecting coil (25), oscillating capacitance (20) be connected between (45) and the OTL amplifier out (50).Utilize the description of drawings course of work of the present utility model and its superior part below.

Begin t in flyback ₀Before in a flash, iv is-Ip, iV is by electric capacity (70), transistor BG2 and deflecting coil (25) constitute the loop, when reaching t ₀The time flyback begin, transistor BG2 and BG3 end, the current i v of deflecting coil (25) can not suddenly change, it has only the voltage on the oscillating capacitance (20) by low capacity to raise rapidly, and the voltage V of (55) point ₅₅Also increase, as the voltage V of (55) point with the voltage on the oscillating capacitance (20) ₅₅When being higher than Ec, diode (15) is partially anti-.At this moment, the oscillation circuit that is made of deflecting coil (25) and oscillating capacitance (20) is not subjected to ectocine, and its oscillating circuit equivalence is Fig. 6, can be got the differential equation in RLC loop by Fig. 6:

d ²iv／dt ²＋ (Rv)/(Lv) div／dt＋ 1/(LvC1) iv＝0…………（4）

Wherein iv is the electric current in the deflecting coil, and Rv is the resistance of deflecting coil, and Lv is the inductance of deflecting coil, and C1 is the capacity of oscillating capacitance (20).

The t when if flyback begins ₀Be 0 moment, then initial condition is:

iv（0＋）＝－Ip iv′（0＋）＝0

With one group of parameter: Lv=20mH Rv=10 Ω C1=0.47 μ F substitution (4) just can solve:

iv＝－Ipe ^－250t〔Cos1.0314×10 ⁴t－2.418×10 ^－2Sin1.0314×10 ⁴t〕

≈－Ipe ^－250tCos1.0314×10 ⁴t…………（5）

By the visible iv of (5) formula is that a damped expoential is e ^-250tWaveform.V from Fig. 5 ₅₅Waveform is iv=0 when t1 as can be known, and V ₅₅Reach the highlyest, this shows that energy storage in the deflecting coil (25) all transferred to oscillating capacitance (20) and gone up.From t1 to t2 the time, energy is transferred to deflecting coil (25) by oscillating capacitance (20) again, forms iv, and this moment, iv was for just, arrived t ₂The time, V ₅₅Be lower than Ec, diode (15), triode BG1 conducting, then V ₅₅By clamper in Ec.So this oscillating current only lasts till that t2 constantly.Because of Ec with respect to t ₁The time V ₅₅Peak value much smaller, we are similar to and think t ₀To t ₂Be the half period of (5) formula oscillating current during this period of time, current i v is at t ₂The time with respect to t ₀The time by paraphase.That is:

Cos1.0314×10 ⁴t＝Cosπ＝－1 …………（6）

Can get thus: t=(π)/1.0314 * 10 ^-4=0.3 * 10 ^-3(S)

＝0.3ms …………（7）

With (6), (7) formula substitution (5) formula, can get:

iv＝－Ipe ^{－250×0.0003}Cosπ

＝Ipe ^－0.075＝0.928Ip …………（8）

That is: at t ₂During=0.3ms, iv=0.928Ip, and this moment 1ms retrace interval just pass by 0.3ms, also remain 0.7mS, be t during this period of time ₂-t ₃At t ₂-t ₃During this time, the BG1 saturation conduction in Fig. 4 circuit, its initial condition is:

iv（0＋）＝0.928Ip

And during this, the equivalent electric circuit of Fig. 4 such as Fig. 3 can be got by Fig. 3 so:

iv＝ (E′c／2－Vces－0.928IpRv)/(Rv) （1－e ^－t／t）＋0.928Ip …………（9）

(9) E ' c is the forward voltage drop that Ec deducts diode (15) in the formula

Make t ₃-t ₂During=0.7ms, iv=Ip

Substitution τ=2ms is by (9) Shi Kede:

Ip＝0.87 (Ec／2－Vces)/(Rv)

Then the effective amplitude peak of sawtooth waveforms is:

Ip·Rv＝0.87（Ec／2－Vces）…………（10）

This shows, power utilization rate of the present utility model is about 87%, compare with the power utilization rate 40% of basic model OTL field amplifier, power utilization rate of the present utility model improves a lot, if Vces is 0, (10) formula substitution (2) formula is got: as seen η=0.87 * 2/3=58% the utlity model has efficient height, simple, the low cost and other advantages of circuit.

Fig. 7 is the most preferred embodiment of the utility model in television receiver.Its adopts and to look the base stage power supply of the resistance (60) of discharge source voltage (100V) by big resistance to triode BG1, BG2 in television set, this base current several mA that only have an appointment, so 100V supply voltage burden is little.Because of the resistance of resistance (60) is big, the gain that triode BG3 produces is also just very high, and Ji makes the base stage of triode BG1, BG2 not have bias voltage, and intermodulation distortion also can be overcome in insignificant degree.

Claims

1, a kind of flyback oscillatory type 0TL field scan amplifier that is used for the magnetic core logical circuit deflection display system, comprise a 0TL amplifier (100), deflecting coil (25), the diode (15) of (40) end of feeder ear (35) that is serially connected in 0TL amplifier (100) and power supply (10), it is characterized in that also comprising that one is carried out handing at retrace interval and deflecting coil (25) and changes the oscillating capacitance (20) of And with the electric current paraphase of deflecting coil (25), one end ground connection (45) of oscillating capacitance (20) or (40) of power supply (10) end, the output (50) of another termination 0TL amplifier (100) or (55) end.

2, flyback oscillatory type OTL according to claim 1 raises sweep amplifier, when it is characterized in that oscillating capacitance (20) is connected between the output (55) of ground (45) and OTL amplifier (100), oscillating capacitance (20) is the electrolytic capacitor that has only polarity.