CN1976388B - Picture tube image scanning device - Google Patents

Abstract

An image scanning device of picture tube consists of deflecting coil. It is featured as setting electric deflecting plate at the same side of deflecting coil for obtaining larger scanning deflection angle on superthin CRT TV set or display of computer.

Description

The image-scanning device of picture tube

Technical field

The present invention relates to a kind of picture tube, especially a kind of image-scanning device of picture tube.

Background technology

General cathode-ray tube CRT display, as: CRT oscilloscope, CRT television set and CRT computer monitor all have a scanning circuit that is used for electron beam is carried out deflection.Electron beam is carried out deflection, two kinds of methods are arranged at present, a kind of is electric deflection, is called for short electric deflection, and another kind is a magnetic core logical circuit deflection, is called for short magnetic deflection.Before a kind of CRT oscilloscope that is mainly used in, the back a kind of CRT television set and CRT computer monitor of being mainly used in.

The principle of electric deflection is exactly that a pair of or two pairs of pole plates are installed among display; On two pole plates, add voltage then; Centre at pole plate will produce electric field, and when electron beam passed between electric field, electron beam will receive the repulsion and the attraction of electric field; Thereby make electron beam produce deflection, the principle of electric deflection is as shown in Figure 1.The advantage of electric deflection is that scanning linearity is good, and scanning frequency is high, and scanning frequency or deflection speed can change arbitrarily, and shortcoming is that deflection sensitivity is low, needs very high deflecting voltage.

The principle of magnetic deflection is exactly near the neck place a pair of or two pairs of coils to be installed in the outside of display; Generally all be referred to as deflecting coil, let coil flow through a sawtooth current then, between two coils, will produce magnetic field; When electron beam passes between magnetic field; Electron beam will receive the effect of magnetic field long-range navigation thatch power, and produces deflection, and the principle of magnetic deflection is as shown in Figure 2.The characteristics of the magnetic deflection just in time characteristics with electric deflection are opposite, and its advantage is that deflection sensitivity is high, and deflecting voltage is low, and shortcoming is that scanning linearity is poor, and scanning frequency is low, and scanning frequency or deflection speed can not change arbitrarily.

Because television set and computer monitor are much bigger compared with oscillographic volume, in order to reduce the thickness of volume, generally all select for use deflection sensitivity than higher magnetic scanning circuit.On principle, if the scanning circuit of CRT television set or CRT computer monitor selects for use electric deflection also to be fine, just under same deflection angle; Needing electric deflection voltage very high, for example, is the television set of 90 degree for deflection angle; Approximately needing deflecting voltage is more than 2000 volts; If adopt the horizontal sweep output circuit of ordinary oscilloscope, want to realize that so high voltage output is very difficult, and select magnetic deflection for use; Wherein the vertical deflection output voltage approximately only needs 24V, and the horizontal deflection output voltage approximately only needs 120V.It is thus clear that the magnetic deflection operating voltage is low, this is the advantage that CRT television set or CRT computer monitor all select to adopt magnetic scanning.Therefore; The CRT picture tube that CRT television set that occurs in the market and CRT computer monitor use generally all is magnetic deflection; One group of deflecting coil with vertical and horizontal scan function promptly is installed on the CRT picture tube; And let deflecting coil flow through a sawtooth current, in deflecting coil, will produce the magnetic field that is directly proportional with electric current of one group of vertical and horizontal direction, when the cathode emission electron beam of CRT picture tube passes the magnetic field of deflecting coil generation; Because receive the effect of long-range navigation thatch power, electron beam will produce yaw motion.Deflecting coil generally all is to make the horn mouth shape, and is close to the rear wall glass of picture tube, dark angle occurs to prevent that image from showing.Fig. 2 is the fundamental diagram of CRT picture tube magnetic scanning.

The angular dimension of the electron beam deflecting is relevant with the size of magnetic field intensity, and obviously, the angle of the electron beam deflecting is big more; The thickness of picture tube just can be thin more, and the thickness of picture tube is thin more, requires the bell-mouthed tapering of deflecting coil just big more; And the electric current that requires to flow through deflecting coil is also big more, but the bell-mouthed tapering of deflecting coil is greatly after to a certain degree, and tapering is greatly in fact also too big meaning not again; Because the bell-mouthed tapering of deflecting coil is big more, its deflection sensitivity will significantly reduce, and the electric current that requires to flow through deflecting coil thus is just very big; Make scanning circuit, particularly the power output of line-scan circuit is difficult to realize the requirement of deflecting coil.

The length-width ratio of general CRT picture tube all is 4: 3 or 16: 9; Therefore the horizontal deflection angle is more a lot of greatly than vertical deflection angle; The magnetic field intensity of the horizontal deflection also magnetic field intensity than vertical deflection is a lot of greatly; In addition, because horizontal frequency is than vertical scanning frequency big very many (hundred times), therefore to flow through the current-rising-rate of horizontal sweep deflecting coil also a lot of greatly than the current-rising-rate that flows through the vertical scanning deflecting coil in requirement.In order to satisfy these requirements, the operating voltage of general line-scan circuit all obtains very high, and that the inductance value of deflecting coil is obtained is littler than the inductance value of field scan deflecting coil, therefore requires the power output of line-scan circuit very big.

Occurred a kind of new large screen flat plate display in the market,, made the thickness of CRT image display also constantly dress, constantly to ultra-thin, large-screen development to flat-panel monitor like PDP, LCD flat panel display; In addition, line by line scan, the appearance of high definition (16: 9) tv product, also require the CRT image display constantly to develop, the corresponding raising of technical performance that this two aspect all requires CRT picture tube and scanning circuit to the high definition direction.

In order to reduce the thickness of CRT image display, it is big to increase the bell-mouthed tapering of deflecting coil, also must improve the scan deflection power of CRT image display simultaneously; Because after the horn mouth tapering of deflecting coil increases to certain angle, the leakage inductance of deflecting coil will enlarge markedly, this is that some exposes outside the magnetic core because of line deflector coil; The bell-mouthed tapering of deflecting coil is big more; The coil exposed portions serve is just many more, and magnetic field is not concentrated, and promptly magnetic flux density descends; Leakage inductance increases, and bending also appears in the magnetic line of force that produces in two groups of coils.

The yaw motion that leakage inductance increases electron beam is very disadvantageous because the direction of the leakage inductance magnetic line of force just in time with deflecting coil in magnetic field in the opposite direction, it also can be to the electron production deflecting action, but direction is just in time opposite; In addition, magnetic flux density also will reduce in the leakage inductance increase deflecting coil, thereby reduces the operating efficiency of deflecting coil.Facts have proved that the every increase of the angle of CRT picture tube beam deflection 30 degree, its deflection power will approximately increase and be twice.For example: CRT picture tube beam deflection angle increases to 120 degree by 90 degree, and its deflection power will increase to 80 watts by 40 watts, increases to 150 degree like electron beam deflecting angle by 120 degree, and its deflection power will increase to 160 watts by 80 watts.

In order to realize high definition, the scan line of image must be increased, thereby the line-scanning frequency of CRT image display must be improved, equally also must improve the line scanning deflection power of CRT image display.But improve the deflection power of CRT image display line scanning; A kind of method is to improve the operating voltage of line-scan circuit; Promptly improve the voltage that is added to the scanning deflection coil two ends; Another kind method is to reduce the method for scanning deflection coil inductance value, to guarantee under situation about not improving, improving scan deflection power at output voltage.Before a kind of method require the withstand voltage parameter of scanning circuit, particularly line-scan circuit device and deflecting coil all to need corresponding raising, but be difficult to find the withstand voltage higher device of using always than common CRT monitor of high tension apparatus at present; The electric current output that a kind of method in back need increase the scan power amplifier equally also runs into the problem that big electric current, high power device difficulty are looked for, and the loss of scan power amplifier is increased, and operating efficiency reduces.

Because deflecting coil has internal resistance, for the electric current that flows through in the scanning deflection coil that gives way is a linear sawtooth waveforms that rises, desirable situation should be the trapezoidal sawtooth waveforms of scan power amplifier output that gives way; With the voltage drop of internal resistance generation in the counteracting deflecting coil, but because the operating voltage of line scanning power amplifier is very high, and operating current is very big; Requiring to produce a trapezoidal sawtooth waveforms is not a nothing the matter; So, generally all be that the saturation inductors of series connection of being expert in the scan power output circuit is carried out linear compensation, and the parameter of saturation inductors generally is nonadjustable; Therefore, carry out fine compensation and be not easy scanning linearity.

Only adopt this method of magnetic deflection; Want to make present CRT television set and CRT computer monitor further to dwindle thickness, such as making the CRT monitor deflection angle surpass 150 degree, this is impossible; For 16: 9 high-definition large-screen television set, require to realize ultra-thin just difficult especially.Because, along with television set or computer monitor to the increase of deflection angle, require the also corresponding raising of magnetic scanning output power of circuit, make the magnetic scanning output power of circuit be difficult to reach the requirement of deflection angle at last.

Summary of the invention

The image-scanning device that the purpose of this invention is to provide a kind of picture tube, the technical problem that solve are the deflection angles that increases the display of television set or computer, improve sweep speed.

The present invention adopts following technical scheme: a kind of image-scanning device of picture tube, comprise deflecting coil, and the homonymy of said deflecting coil also is equipped with the electric deflection plate.

Deflecting coil of the present invention is a pair of, and the electric deflection plate is a pair of.

Electric deflection plate of the present invention is installed in the centre of deflecting coil.

Electric deflection plate of the present invention is installed in the place ahead of deflecting coil.

Electric deflection plate of the present invention is the electric conducting material that directly is coated in the picture tube internal glass surface.

The deflecting voltage of electric deflection plate of the present invention is secondary through step-up transformer by the line scanning output voltage, integrating resistor, integrating capacitor output sawtooth voltage.

Electric deflection scanning of the present invention is boosted and is scanned the shared transformer of flyback.

The present invention compared with prior art; Adopt electromagnetism mixing deflection scanning, on common CRT monitor, increased electric deflection, therefore; Its scan deflection angle is more a lot of greatly than the scan deflection angle of common CRT monitor, is particularly useful for ultra-thin CRT television set or computer monitor.

Description of drawings

Fig. 1 is the fundamental diagram of prior art electric deflection.

Fig. 2 is the fundamental diagram of prior art magnetic deflection.

Fig. 3 is the structural representation of the embodiment of the invention.

Fig. 4 is the fundamental diagram of the embodiment of the invention.

Fig. 5 is the electron gun fundamental diagram of the embodiment of the invention.

Fig. 6 is the embodiment of the invention line scanning output voltage integrating circuit schematic diagram that boosts.

Fig. 7-a is the function curve diagram () of embodiment of the invention capacitor charging/discharging process.

Fig. 7-b is the function curve diagram (two) of embodiment of the invention capacitor charging/discharging process.

Fig. 8 is the fundamental diagram () that the shared transformer of flyback was boosted and scanned in the scanning of embodiment of the invention electric deflection.

Fig. 9 is the fundamental diagram (two) that the shared transformer of flyback was boosted and scanned in the scanning of embodiment of the invention electric deflection.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is described in further detail.As shown in Figure 3, the image-scanning device of picture tube of the present invention, deflecting coil 3,4 is arranged on the neck place of picture tube, and its effect is that electron beam is carried out magnetic deflection; Electric deflection plate 5,6 is arranged on the horn mouth place of picture tube glass bulb, and its effect is that electron beam is carried out electric deflection.The present invention adopts electromagnetism mixed sweep CRT monitor, has Duoed the one-level electric deflection than common CRT monitor, and therefore, its scan deflection angle is more a lot of greatly than the scan deflection angle of common CRT monitor.

As shown in Figure 4; The operation principle of electromagnetism mixed sweep CRT monitor of the present invention, our hypothesis, the electron beam trace of l0 when not receiving any deflection; L1 is the track that deflecting coil is made the time spent electron beam deflecting separately, and l2 is the track that the electric deflection plate is made the time spent electron beam deflecting separately; Deflecting coil is

1 to the angle of the electron beam deflecting; The electric deflection plate is 2 to the angle of the electron beam deflecting, total so deflecting coil and electric deflection plate to the electron beam deflecting angle is exactly 1 with

2 sums.We can also see; If there is not the effect of electric deflection plate; Even deflecting coil can make that the scan deflection angle reaches 1 with

2 sums; Electron beam also can't scan the edge of crt screen; Because; Electron beam can be got on the picture tube neck when maximum deflection angle; Only if make the very big horn shape of opening angle to deflecting coil, but that kind can reduce the magnetic scanning deflection sensitivity again, and be easy to generate scanning linearity aberration.Hence one can see that, and the electric deflection plate just in time can remedy the shortcoming of CRT monitor deflecting coil scanning, and can increase the scan deflection angle of display, and the thickness of CRT monitor is dwindled.The mechanism of magnetic deflection and electric deflection can be regarded as a kind of relay race, and in fact their effect can overlap, and is as shown in Figure 3, and the electric deflection plate can be installed in the centre of deflecting coil.

General picture tube all has an emitting electrons device that is electron gun, and its effect is emitting electrons, electron beam is focused on.Electron gun generally all is made up of the negative electrode of the special emitting electrons cylinder electrode different with a plurality of current potentials, and an end of cylinder electrode has aperture, pass with the electronics that limits different directions, and the other end is unlimited fully.Electron gun mechanical structure and Electric Field Distribution are very complicated comparatively speaking; Because before and after between the different potentials cylinder electrode is not a plane; So electric-field intensity distribution is very complicated, this special electric-field intensity distribution people are referred to as electron lens, can produce focussing force to electron beam.

The picture tube of different model; The structure of its electron gun focusing utmost point also has very big difference; The at present nearly BPF of structure, UPF, HI-BPF, HI-UPF, B-UPF, U-BPF, U-UPF, the TPF of picture tube electron gun focusing electrode, and kinds more than ten such as B-U, EA-UB, EA-DF, wanting the movement velocity of electron beam in every kind of electron gun is carried out accurate Calculation is difficulty very; Therefore, we analyze some limiting cases in the electron gun earlier.In order to simplify, we simplify the electron gun of various different structures.As shown in Figure 5, the negative electrode K7 of electron gun is arranged in order thereafter to control grid G1 8 at front end, also is Wehnelt electrode, and screen grid G2 9 is intensifying ring, focusing electrode G3 10, high-voltage anode G4 11.Generally, negative electrode K is added with the positive voltage relevant with picture material, and electron beam current is played modulating action; Control grid G1 ground connection, its current potential is zero; Screen grid G2 is added with 500～600 volts positive voltage, and electron motion is played acceleration; Focusing electrode G3 also is added with 5000～10000 volts positive voltage, and it also plays acceleration to electron motion; High-voltage anode G4 is added with 25000～30000 volts positive voltage, and it mainly plays acceleration to electron motion.Because each electrode K, G2, G3, G4 are not planes, therefore, neither straight line by negative electrode K to the electroline direction of other electrode G2, G3, G4 generation; But form by a lot of arc curves; Because the electroline direction always will with the Surface Vertical of charged object, so electronics is through these electrodes G2, G3, G4 the time, just just as pellet shot from a slingshot is beated; Be to beat by curve on one side; Travelling forward on one side, and much electronics also can run foul of each other in motion, makes the movement velocity of electron beam always be lower than single electronic motion speed.Some electronics also will be captured by electrode in motion process, forms I _G2, I _G3, I _G4Electric current, only some speed can become the ray electric current than higher electronics, gets on the phosphor screen.Several kinds of simple scenarios that the just electronics of in Fig. 5, describing roughly moves, the in fact track of electron motion much complicated than described in Fig. 5.

Since electron beam deflecting angle be added to the electric deflection plate on the numerical value of voltage U relevant, also to pass through the speed of electric deflection plate relevant with electron beam, therefore, below our analytical electron bundle speed of in CRT monitor, moving first.

If we have known the speed of electron beam through high-voltage anode G4, just be easy to obtain the electric deflection sensitivity of CRT picture tube, we can analyze the computational methods of single electronic movement velocity first for this reason.

We know that electronics will be done uniformly accelerated motion in uniform electric field, acceleration can by

$a=\frac{F}{m}$ With $F=\mathrm{EE}=e\frac{U}{d}$ Obtain:

$a=\frac{\mathrm{eU}}{\mathrm{md}}---\left(1\right)$

M is the quality of electronics in the formula, m=0.91 * 10 ^-30Kilogram, e is the quantity of electric charge of electronics, e=1.60 * 10 ^-19Coulomb, d is the distance between two electrified bodies that produce electric field strength, U is the potential difference between two electrified bodies.

We can suppose earlier that be uniform electric field from negative electrode K to the Electric Field Distribution the intensifying ring G4, that is: negative electrode K and intensifying ring G4 are two planes parallel to each other,

The instantaneous velocity from negative electrode K to intensifying ring G4 is calculated as example with electronics for we, establishes electronics and leaves negative electrode to arrive that speed constantly of G4 be v _G4, v so _G24With time t, and electron motion apart from the relation of S is:

v _G4＝at

$S=\frac{{\mathrm{at}}^2}{2}---\left(2\right)$

Or $t=\sqrt{\frac{2S}{a}}$

Try to achieve thus:

${\mathrm{<figure-callout\; id="4"\; label="v\; G"\; filenames="H061F7638120061229E000012.png"\; state="\{\{state\}\}">v</figure-callout>}}_G=\mathrm{at}=\sqrt{2\mathrm{aS}}$

$=\sqrt{\frac{2\mathrm{eUS}}{\mathrm{md}}}---\left(4\right)$

Because electronics is the direction moving linearly against electric field, therefore, the distance of electron motion is exactly the distance between the two charged pole plates, i.e. S=d, and (4) formula can be rewritten as again thus:

$v_{\mathrm{<figure-callout\; id="4"\; label="G"\; filenames="H061F7638120061229E000012.png"\; state="\{\{state\}\}">G</figure-callout>}4}=\mathrm{at}=\sqrt{\frac{2\mathrm{eU}}{m}}---(4*)$

Can know that by (4*) formula the end speed of electron motion is only relevant with the voltage (potential difference) of this point, and and range-independence, this be because, acceleration is directly proportional with electric field strength, and electric field strength with apart from the cause that is inversely proportional to.

The anode voltage of general CRT picture tube is up to 30000 volts,

Known e=1.60 * 10 ^-19Coulomb, m=0.91 * 10 ^-30Kilogram, U=30000 volt, by (4*) formula can in the hope of:

${\mathrm{<figure-callout\; id="4"\; label="v\; G"\; filenames="H061F7638120061229E000012.png"\; state="\{\{state\}\}">v</figure-callout>}}_G=\sqrt{\frac{2\mathrm{eU}}{m}}=\sqrt{\frac{2\&times;1.6\&times;{10}^{-19}\&times;30000}{0.91\&times;{10}^{-30}}}$

$=\sqrt{105.4945055\&times;{10}^{14}}$

(5) formula is the maximum speed that the CRT picture tube beam possibly reach, and in fact will to reach this speed be impossible to electron beam.On the one hand this speed has surpassed 1/3rd of the light velocity, according to Einsteinian the theory of relativity:

$m_v=\frac{{\mathrm{<figure-callout\; id="0"\; label="m"\; filenames="H061F7638120061229E000031.png"\; state="\{\{state\}\}">m</figure-callout>}}_0}{\sqrt{1-{\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="H061F7638120061229E000042.png"\; state="\{\{state\}\}">v</figure-callout>}}^2/c^2}}---\left(6\right)$

M in the formula _vBe electronic motion quality, m ₀Be the rest mass of electronics, light velocity c=30 * 10 ⁷(meter per second).

V _G4=10.27 * 10 ⁷(meter per second) substitution (6) formula can in the hope of:

m _v＝1.064m ₀ (6*)

On the other hand; Electron beam and single electronic motion speed are inequality, and electron beam can produce space charge effect, and promptly the electronics in the electron beam can produce mutually and repel; Also can produce collision mutually between the electronics of friction speed during motion; And this collision is not that electronics directly contacts, but has an effect the electron production acceleration that the electronics that movement velocity is high can be low to movement velocity each other through the electric field that electronics produces around it; Energy is shifted each other, and last result is that the speed of most of electronics reaches unanimity basically.

As shown in Figure 5, when particularly electron beam was through focusing electrode, because the electric-field intensity distribution of focusing electrode is uneven, in the time of electron beam process non-uniform electric field intensity distributions, its direction of motion and speed all can be changed.When electronics from negative electrode, when getting into focusing electrode by different directions, the electronics of different directions can be changed its direction of motion by the power line of varying strength and different directions, and electronics is concentrated on impact point of arrival at last.

Hence one can see that, and the track of electron motion not exclusively is a straight line also, but a curve that is constantly reflected; Electronics is every by refraction once; Its radial velocity will be multiplied by a direction coefficient COS θ, and θ is an incidence angle, so the movement velocity of electron beam always is slower than the speed of single electron motion.

Want the speed of accurate Calculation electron beam; The accurate distribution of electric field strength to be known on the one hand, also the probability that electronics runs foul of each other will be known simultaneously, and the incident direction of electronics; Could calculate according to (4) formula and (6) formula pointwise then, promptly the variable in (4) formula will change differential variable analysis into.However, also some discrepancy always of theory analysis and practical application, but preceding surface analysis we also will verify through testing at last as a result.

We can be used for the oscilloscope picture tube with same computational methods, relatively know through result of calculation and actual test result then, and the actual motion speed of electron beam in picture tube is much smaller than the speed that calculates with (4) formula.Approximately has only about 1/3rd of result of calculation.

If we are v _G4Speed choose (5) formula result's 1/3rd, be approximately 3.4 * 10 ⁷(meter per second), that is: the speed of electron beam horizontal movement is:

v ₀=3.4 * 10 ⁷(meter per second) (7)

Known the speed v of electron beam horizontal movement ₀, and then that is engraved in the component velocity v of vertical direction for the moment leaving electric field to obtain electronics _⊥, just can obtain the electric deflection plate to electron beam deflecting angle

2.v _⊥With

2 can try to achieve by following method:

v _⊥Computational methods and v ₀Computational methods basic identical, when electronics between the electric deflection plate through out-of-date because electronics moves with uniform velocity in the horizontal direction, thus the time t that needs through pole plate, can be by the length l of pole plate speed v during with electronics entering pole plate ₀Obtain:

$t=\frac{l}{v_0}---\left(8\right)$

When electronics between the electric deflection plate through out-of-date, it is zero uniformly accelerated motion that electronics is done initial velocity in vertical direction.Acceleration can by

$a=\frac{F}{m}$ With $F=\mathrm{EE}=e\frac{U}{d}$ Obtain:

$a=\frac{\mathrm{eU}}{\mathrm{md}}---\left(9\right)$

(9) just the same with (1) formula form, just d representes the distance between the electric deflection plate, and U representes the voltage between the electric deflection plate.

Electronics leaves electric field, and that is engraved in the component velocity v of vertical direction for the moment _⊥=at, can be tried to achieve by (8) and (9) formula:

$v_{\&perp;}=\frac{\mathrm{eUl}}{\mathrm{md}{v}_0}---\left(10\right)$

Known v _⊥And v ₀, just can by

Here particularly point out, because the structure of the structure of CRT picture tube electron gun and electric deflection plate is very complicated, (4) formula of can not applying mechanically is simply calculated v with (10) formula ₀And v _⊥As shown in Figure 3, the electric deflection plate is not a constant apart from d in actual (10) formula, but therefore the function of horizontal range, preferably adopts the method for differential statistics to calculate when comparing accurate Calculation if desired.In the practical application, the electric deflection plate of CRT picture tube can directly be coated electric conducting material at the inner glass surface of picture tube and generate, and therefore, the structure of electric deflection CRT picture tube is different with the structure of common electrical deflection oscilloscope tube.

Through calculating and comparative test, the CRT picture tube for 29 cun is added on the voltage on the electric deflection plate; The about deflection angle of every 1000V is 15 °～30 °; Deflection sensitivity is except with deflecting voltage is relevant, and is also relevant with the structure of electric deflection plate, and relevant with anode high voltage.

Wanting output amplitude for general electronic amplification circuit is that sawtooth waveforms deflecting voltage more than the 1000V is a difficulty very.The image-scanning device of picture tube of the present invention, the sawtooth waveforms deflecting voltage that electric deflection uses, integration produces through the line scanning output voltage is boosted.As shown in Figure 6, Vi is the line scanning output voltage, and τ 1, τ 2 are respectively trace sweep time and retrace scanning time and corresponding voltage waveform thereof; T1 is a step-up transformer, and secondary output voltage is divided into two-way, routing transformer secondary coil N21 output, another routing transformer secondary coil N22 output; Resistance R 1, R2 are respectively two-way sawtooth waveforms integrating resistor, and capacitor C 1, C2 are respectively two-way sawtooth waveforms integrating capacitor; Diode D1, D2 are the scan retrace discharge diodes, and its purposes is to make C1, C2 in scan retrace τ 2 repid discharge therebetween, shorten the discharge time of C1, C2, V _OX1, V _OX2Be respectively the output of two-way electric scanning sawtooth voltage.

In 1 trace sweep time of τ, step-up transformer T1 secondary output voltage charges to capacitor C 1, C2 respectively through R1, R2, and its charging process is as shown in the formula expression:

$u_c=U_{\mathrm{\&tau;}1}(1-{\mathrm{\&lambda;}}^{\frac{t}{\mathrm{\&tau;}}})---\left(12\right)$

(12) u in the formula _cBe the voltage at charging capacitor C1 or C2 two ends, U _{τ 1}During trace τ sweep time 1, T1 level of step-up transformer be one group of output voltage wherein, and τ is that (τ=RC), t is a capacitor charging time to the capacitor charging time constant.

In the 2 retrace scanning times of τ, capacitor C 1, C2 will pass through D1, D2 discharge and reverse charge, and its discharge and charging process are as shown in the formula expression:

$u_c=U_c{\mathrm{\&lambda;}}^{\frac{t}{\mathrm{\&tau;}}}+U_{\mathrm{\&tau;}2}(1-{\mathrm{\&lambda;}}^{\frac{t}{\mathrm{\&tau;}}})---\left(13\right)$

(12) U in the formula _cVoltage when beginning to discharge for capacitor C 1 or C2; U _{τ 2}During retrace scanning time τ 2, T1 level of step-up transformer be one group of output voltage wherein, U _{τ 2}Polarity of voltage and U _{τ 1}Polarity of voltage just in time opposite.It can also be seen that from (12) formula one of front is the capacitance discharges process, one of back is the reverse charge process of electric capacity.

Shown in Fig. 7-a, in the charging process of capacitor, when capacitor charging time was τ, the voltage at electric capacity two ends approximated peaked 0.63 times of charging voltage; When capacitor charging time was 2.3 τ, the voltage at electric capacity two ends approximated peaked 0.9 times of charging voltage; When capacitor charging time was infinity, the voltage at electric capacity two ends approximated the maximum of charging voltage.Shown in Fig. 7-b, in the charge and discharge process of capacitor, the charging process of capacitor and the time constant of discharge process are different, and the time constant of charging process is long, and the time constant of discharge process is short.

Can find out that from Fig. 7-a and Fig. 7-b when charging interval of capacitor during less than τ, the change in voltage curve at capacitor two ends is very near straight line, that is: the voltage at capacitor two ends is very near sawtooth waveforms; When charging interval of capacitor greater than τ, and during less than 2.3 τ, the change in voltage curved at capacitor two ends changes greatly; And when charging interval of capacitor during greater than 2.3 τ, it is very little that the change in voltage curved at capacitor two ends changes, and the voltage at illustrated capacitor two ends is tending towards saturated.If capacitor charge time greater than τ and less than 2.3 τ, like the τ among Fig. 7-b 1, during the voltage at capacitor two ends, being used for the CRT picture tube is very favorable as the scanning voltage of electric deflection.Though voltage on capacitor is a linear change, it is inconsistent because of scanning angle rate of change and screen distance rate of change just in time can to compensate the CRT picture tube, and the S type distortion that produces.

Therefore, when needs were adjusted the scanning S type distortion of CRT picture tube, the timeconstant that need only change the capacitor charging got final product, and changed the parameter of resistance R 1, R2 or capacitor C 1, C2 that is:.In fact, also be equivalent to a capacitor between the electric deflection plate of CRT picture tube, its capacity also can be calculated among capacitor C 1, the C2.

As shown in Figure 6, the elementary output that can directly be parallel to line-scan circuit of step-up transformer T1, perhaps direct and line scanning kickback transformer (high voltage package) parallel connection of primary windings through a dc-isolation electric capacity; Can also as another secondary coil of line scanning kickback transformer, be equivalent to save a high-tension transformer like this secondary coil of T1 directly around to the iron core of line scanning kickback transformer.

As shown in Figure 8, electric deflection scanning is boosted and is scanned the shared transformer of flyback, and wherein T1 is the line scanning driving transformer, and T2 has the line flyback high-tension transformer that electric deflection scanning is boosted and exported.Here polarity that it should be noted that the coil windings that polarity and the CRT tube anode high pressure of coil windings of output export of boosting T2 electric deflection scanning is just in time opposite.V1 is a line scanning drive signal amplifier, and T1 is the row driving transformer, and R1, C1 are the RC antihunt circuits, and+B2 is the operating voltage of line scanning drive signal amplifier; V2 is the line scanning power amplifier, and LD is the line scanning deflecting coil, and LX corrects inductance for the line linearity distortion; C2 is the line retrace resonant capacitance, and C3 is that line linearity S corrects electric capacity, and D1 is a damper diode; Also can be called the line scanning fly-wheel diode; T2 has the line flyback high-tension transformer that electric deflection scanning is boosted and exported, and also can be described as high voltage package, and D2 is kenotron (general more than one); R2, R3 are respectively two-way sawtooth waveforms integrating resistor, and C4, C5 are respectively two-way sawtooth waveforms integrating capacitor; D3, D4 are the scan retrace discharge diodes, V _OX1, V _OX2Be respectively the output of two-way electric scanning sawtooth voltage.

As shown in Figure 9, adjustable arbitrarily in order to make scanning starting position, increased a scan line displacements potentiometer R4, through the current potential of adjustment R4 tap position between over the ground, just can regulate the position of the move left and right of horizontal scanning line.

The angle of the general field scan of CRT picture tube is little more a lot of than the angle of line scanning, and therefore, for general CRT picture tube television set or computer monitor, field scan does not need to power up in addition the deflection scanning circuit again.

Claims (1)

1. the image-scanning device of a picture tube comprises deflecting coil, it is characterized in that: the homonymy of said deflecting coil also is equipped with the electric deflection plate;

Said deflecting coil is a pair of, and the electric deflection plate is a pair of;

Said electric deflection plate is installed in the centre of deflecting coil;

Said electric deflection plate is the electric conducting material that directly is coated in the picture tube internal glass surface;

The deflecting voltage of said electric deflection plate is secondary through step-up transformer by the line scanning output voltage, integrating resistor, integrating capacitor output sawtooth voltage;

Electric deflection scanning is boosted and is scanned the shared transformer of flyback;

The elementary output that directly is parallel to line-scan circuit through a dc-isolation electric capacity of said step-up transformer T1;

Perhaps the primary coil of step-up transformer T1 directly and line scanning kickback transformer parallel connection of primary windings;

Perhaps the secondary coil of step-up transformer T1 directly around to the iron core of line scanning kickback transformer, as another secondary coil of line scanning kickback transformer.

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