CN85105245A - Magnetic recording system - Google Patents

Abstract

In having the magnetic recording circuit of bias current circuit, be suitable for the bias current that bias oscillator produces is superimposed upon on the tracer signal, and first composite signal of supply magnetic, magnetic recording circuit has a resistor that is used for detecting the bias current that flows through magnetic head, one is carried out rectification and level and smooth rectifier circuit to the signal that forms on the resistor, with one be used for a rectifier circuit output voltage relatively with reference voltage, and the control circuit of generation control bias oscillator oscillation level output signal, thereby the bias current that flows through magnetic head can be transferred to predetermined level automatically.Can save variohm and the variable-resistance regulating step of regulating bias current.

Description

Magnetic recording system

The present invention relates to the writing circuit of a kind of magnetic recording and reproducer, specifically, relate to a kind of video recorder (video tape recorder that is suitable for doing, VTR) writing circuit that vision signal is used in, for example, spiral scans type, also is suitable for use as the writing circuit of audio frequency FM record and reproducer, and perhaps control adds the bias current circuit that gives sound-track engraving apparatus record-header bias current.

Such as video recorder or more such magnetic recordings of sound-track engraving apparatus and reproducer, in their audio signal recording circuit, a bias current circuit is arranged, with recorde audio signal, this sound signal is superimposed upon on the bias current, so that suppress wave form distortion when reappearing sound signal.But the bias current that be added on the magnetic head this moment does not have a suitable value, and the frequency characteristic of the sound signal of reproduction will be degenerated, and its level descends, and is accompanied by wave form distortion and increases.In order to address this problem, way is to add a variohm of regulating bias current level in bias current circuit.In mass-produced magnetic recording and reproducer, for single product employing is that this method is very time-consuming, and pretty troublesome by variable resistor adjusting level.In addition, for the ease of regulating, must consider that variable-resistance wiring has damaged the degree of freedom of design.

The purpose of this invention is to provide a magnetic recording circuit, this circuit can automatically be transferred to the current signal that flows through magnetic head on the predetermined level value, and needn't rely on the variohm of regulating current signal level.

In order to achieve the above object, according to requirement of the present invention, a magnetic recording system is provided, recorded information on the recording medium that magnetic head passed through with booking situation characteristic, it comprises a recording signal processing apparatus, be recorded the input signal of information with the reception expression, and handle this received input signal, make it produce a tracer signal that is added to the preset level of magnetic head; It comprises that also a control signal that the tracer signal that detects is responded produces equipment, to produce a control signal that is suitable for the tracer signal level that passes through on the magnetic head is transferred to predetermined level; Also comprise a control device, be used for the controlling recording signal processing apparatus, just can be transferred to predetermined level to the tracer signal of passing through on the magnetic head the response of this control signal.

The simple declaration of accompanying drawing:

Fig. 1 represents the circuit diagram of common biasing circuit example.

Fig. 2 represents the curve map of magnetic head biasing characteristic.

Fig. 3 represents the block scheme of normal domestic use video recorder video signal recording circuit.

Fig. 4 represents the relation curve of video recorder record current and playback output characteristics, and it is a parameter with used frequency.

Fig. 5 is according to embodiments of the invention, the block scheme of the magnetic recording circuit of sound signal.

Fig. 6 is a circuit diagram of realizing Fig. 5 embodiment circuit arrangement.

Fig. 7 is a circuit diagram of realizing the circuit arrangement of bias oscillator shown in Figure 6.

Fig. 8 is the block scheme according to the magnetic recording system of embodiment of the invention sound signal.

Fig. 9 is the circuit diagram that expression realizes the part circuit arrangement of magnetic recording system shown in Figure 8.

Figure 10 is the circuit diagram that expression realizes the circuit arrangement of Fig. 9 used current-control type amplifier of embodiment (CCA).

Figure 11 is the block scheme of expression according to other embodiment of sound signal magnetic recording system of the present invention.

Figure 12 is the block scheme that expression the present invention is used for the frequency modulation modulation magnetic recording system embodiment of sound signal.

The explanation of preferential embodiment:

Before introducing the present invention with the method for giving an example referring to accompanying drawing, will be at first referring to figs. 1 to 4, introduce common magnetic recording system, with better understanding the present invention.

The common bias current circuit that sound-track engraving apparatus is used is shown in the example of Fig. 1, and it comprises a bias oscillator 1, capacitor 2 and 9, variohm 3, resistor 5, input end 7 and amplifier 8.And tape 6 closely-related magnetic heads 4 are connected between variohm 3 and the resistance 5.

In Fig. 1, the offset signal that bias oscillator 1 produces is passed through direct current block-condenser 2, and converts to by the determined bias current value i of the resistance of variohm 3 _BBias current i _BWinding and resistance 5 by magnetic head 4 are incorporated into earth terminal.

On the other hand, sound signal is added to input end 7 and is fed to amplifier 8, is amplified to predetermined level in amplifying product, and reaches desired frequency characteristic, to reach amplitude and phase equalization and high-frequency correction or the like purpose.The output audio signal that is come out by amplifier 8 blocks electric capacity 9 by direct current, so that be superimposed upon bias current i _BOn, and the device recording by magnetic head 4 is on tape 6.

Based on the bias current circuit of the said structure of AC bias recording, the wave form distortion that tracer signal is followed can be reduced to minimum, thereby all can use in many occasions.

Fig. 2 represents the biasing characteristic of head.

In Fig. 2, abscissa is represented bias current, and the ordinate on the left side is represented the output level that reappears, and the ordinate on the right is represented distortion factor.Tracer signal during to different preset frequency, draw and reappear output level, draw family curve a, simultaneously to the tracer signal of preset frequency to e with the situation that the variation of bias current changes, the distortion factor that draws changes the situation that the variation with bias current changes, and draws family curve g.

To see that to unsuitable bias current value, the output level variation range of reproduction is very big, and frequency characteristic and distortion factor performance degradation from Fig. 2.

Owing to rise and fall from the bias signal level of bias oscillator 1 output, and the impedance of a magnetic head is different from the impedance of another magnetic head slightly, makes bias current depart from optimum value.

Traditionally, because the pressure drop v on the resistor 5 shown in Figure 1 _BMeasured,, then, variable resistor 3 is transferred on certain value the pressure drop v that resistance 5 two ends are set up to detect the size of bias current by manual adjustment _BCorresponding with the optimum value of bias current.

Put photograph in the open country, Tianjin of publishing " Nikkan Kogyo Shimbun " in April, 1971 and show in " sound-track engraving apparatus " 71-72 page or leaf, disclosed the example of similar common bias current circuit shown in Figure 1.

To introduce video recorder vision signal magnetic recording circuit now.

Fig. 3 represents the ordinary video signal magnetic recording circuit that adopts in the family expenses video recorder, and for example spiral scans type.In Fig. 3, vision signal h is low pass filtering and abbreviates LPF as below the device 10() and bandpass filter 11(below abbreviate BPF as) be divided into luminance signal j and carrier chrominance signal k.Luminance signal j is fed to mixer 14 by level regulator 13 thereafter by frequency modulator circuit 12 frequency modulation.Carrier chrominance signal k is changed by the low strap of low strap change-over circuit 15, then be fed to mixer 14 by level regulator 16, these signals at mixer 14 by mixing, then by recording amplifier circuit 17, pass to stake resistance 19, via magnetic head 18 synthetic mixed frequency signal is recorded on the tape 20, the signal monitoring level regulator 13 and 16 that utilizes output terminal 21 to draw is to carry out level adjustment.

The special case of Fig. 4 diagramming record current characteristic, it is that solar corona society is introduced in rugged strong one " video recorder " the 49th page of Figure 41 2 in pool in October, 1971.In Fig. 4, abscissa is represented the record current by magnetic head 18, and ordinate is represented the output level that reappears.To see output signal level and frequency characteristic that the record current variable effect reappears from Fig. 4.Therefore, the deviation of record current and optimum value causes the visual signal to noise ratio (S/N ratio) decline that video recorder reappears.

In order to solve this problem of family expenses video recorder,, use level regulator 13 and 16 to regulate the record current of magnetic heads 18, so that slow down the fluctuation of record current because magnetic head 18 impedances and circuit gain change.

So, for luminance signal j, manual adjustment level regulator 13, make the voltage drop at resistance 19 two ends that output terminal 21 is set up corresponding to the optimum value of used magnetic head, simultaneously for carrier chrominance signal k, manual adjustment level regulator 16, so that the record current that does not comprise luminance signal is usually than low about 10 decibels of the record current level that comprises luminance signal, the record current that does not comprise luminance signal will cause that carrier chrominance signal enters magnetic head, disturb thereby avoid occurring cross beat between carrier chrominance signal and luminance signal.

In video recorder, record current must be done manual adjustment to luminance signal and carrier chrominance signal after this manner, and as long as adopt expensive variable resistor just can finish the adjusting of trouble.

Japan broadcasting association of publishing house in March, 1972 former positive one and high bridge three youths' " small and exquisite video recorder " the 93rd page disclose an example of similar above record current adjusting current circuit structure.

Introduce the present invention now with reference to accompanying drawing by example.In following introduction, with Fig. 1 to 3 components identical with identical reference numerals, be not described in detail.

Fig. 5 represents an embodiment, and the present invention is used for the sound signal magnetic recording system of some devices as video recorder or sound-track engraving apparatus in this embodiment.Among Fig. 5, the controlled bias oscillator 22 of amplitude of oscillation blocks electric capacity 2 by direct current and receives magnetic head 4.Magnetic head 4 is by resistance 5 ground connection.Sound signal is recorded, and on the other hand, is added on the input end 7 again and is fed to amplifier 8, is amplified to the frequency characteristic of predetermined level and given necessity at amplifier 8.The sound signal that is exaggerated that amplifier 8 is drawn is blocked electric capacity 9 by direct current, and is superimposed upon bias current v _BOn, by magnetic head 4 composite signal is recorded on the tape 6.Capacitor 4 and an end of 9 are connected on the magnetic head jointly, and play mixing sound signal and bias current.Amplifier 8, capacitor 2 and 9 and bias oscillator 22 form audio signal processing circuits, the sound signal that is added on the input end 7 is converted to the tracer signal that is fit to magnetic head 4 application.

Amplifier 23 has an input end to receive contact between resistance 5 and the magnetic head, and output terminal is received the input end of rectifier circuit 24.Rectifier circuit 24 output terminals are received an input end of control signal generation circuit 25, and voltage level is that the reference voltage source 26 of V reference is connected between another input end and ground of control signal generation circuit 25.25 1 output terminals of control signal generation circuit are received on the control input end of bias oscillator 22.

In the work, resistance and two ends set up with bias current i _BProportional voltage v _B, be exaggerated device 23 and be amplified to suitable level, and,, be added in an input end of control signal generation circuit 25 again so that convert d. c. voltage signal to by rectifier circuit 24 rectifications and level and smooth.

Control signal generator 25 detect the predetermined voltage level V of d. c. voltage signals and reference voltage source 26 with reference between difference, and add a control signal that is suitable for offsetting this voltage level difference in the control input end of bias oscillator 22.

So the output signal level controlled signal control of bias oscillator 22 is so that bias current i _BBe transferred to the predetermined optimum value of reference voltage source 26 appointments.

Because predetermined just bias current i _BAutomatically set up after this manner, on the generation line of magnetic recording and reproducer, can save, and be enough to remove the general layout that to consider in the tunable component design, thereby improve design freedom the common desired regulating step of bias current.

Fig. 5 magnetic recording circuit can be realized by example shown in Figure 6.

With reference to figure 6, comprise capacitor 27 and 33, amplifier 28, resistance 30,31 and 32 and voltage source 29 corresponding to the circuit of amplifier circuit 23 shown in Figure 5.

Circuit corresponding to rectifier circuit 24 shown in Figure 5 comprises NPN transistor 34, resistance 36 and electric capacity 37.

The circuit of corresponding diagram 5 control signal generator circuit 25 comprises amplifier 38, resistance 39,40 and 42 and transistor 41.

The circuit of corresponding diagram 5 bias oscillators 22 comprises resistance 44 and 45, NPN transistor 43, voltage source 46 and oscillator 100.

Contact between resistance and the magnetic head 4 blocks the not inverting terminal that electric capacity 27 is received amplifier 28 by direct current.By bias current i _BThe voltage v that causes _BWith sound signal stack, the voltage v that resistance 5 two ends are set up _BBlock the not inverting terminal that electric capacity 27 is added in amplifier 28 by direct current.Inverting terminal is not received voltage source 29 by resistance 30 yet.The DC voltage of voltage source 29 causes voltage v _BCentered level be displaced on certain level in the input voltage range that amplifier 28 can work.Amplifier 28 has one by resistance 31 and 32 and the gain determined of unity feedback electric capacity 33.Electric capacity 33 can prevent that also the DC voltage of voltage source 29 can not be exaggerated device 28 and amplify.

The output terminal of amplifier 28 is received the base stage of transistor 34 and is exaggerated the voltage v that device 28 is amplified to predetermined level now _BBe added on the transistor 34.

The collector of transistor 34 is connected with power supply 35, and emitter is connected with electric capacity 37 with resistance 36, thereby forms an emitter follower detector circuit.The signal that is fed out by amplifier 28 is by this circuit rectification and deliver to the not inverting terminal of amplifier 38.By the time constant of resistance 36 and electric capacity 37 being transferred to the oscillation period that is sufficiently more than oscillator 100, can accessing the voltage v that has corresponding to being exaggerated _BThe smooth dc voltage of peak level.

Amplifier 38 is received resistance 39 and 40 and is made gain-adjusted, receives reference voltage source 26 in its inverting terminal by resistance 40.The output terminal of differential amplifier 38 is received the base stage of transistor 41.Detected the voltage v that adds the signal level of giving inverting terminal not and reference voltage source 26 with reference between poor, and this voltage difference is amplified to predetermined level, be added to then on the transistor 41.

Transistor 41 emitters are by resistance 42 ground connection, and collector is received the base stage of transistor 43.

The base stage of transistor 43 is passed through resistance 44 ground connection, and receives the collector of transistor 43 and receive voltage source 46 by resistance 45.

The voltage signal level response that 38 feedbacks of transistor 41 pair amplifiers come is with the base voltage of oxide-semiconductor control transistors 43.

Suppose that transistorized collector current is I ₁, the voltage of voltage source 46 is vcc, the emitter voltage of transistor 43 is v ' _Cc, the resistance of resistor 45 is that R and forward base-emitter voltage are v _F, the result

v′ _cc＝vcc-（I ₁·R+v _F） ……（1）

Emitter voltage v ' _CcAs the supply voltage of feedback, so the output signal level of bias oscillator 100 can emitter voltage v ' toward bias oscillator 100 _CcChange pro rata.

When the impedance of used magnetic head 4 surpassed setting, bias current descended the voltage v that the resistance two ends are set up according to surpassing amount _BDrop to and be lower than predetermined value.As a result, the voltage v reference that the signal level that is added in differential amplifier 38 becomes and is lower than reference voltage source 26, thereby the collector current of reduction transistor 41.Thereby according to equation (1), the pressure drop at resistance 45 two ends reduces, and makes emitter pole tension v ' _CcRaise, natural raising the output signal level of bias oscillator 100.Therefore, bias current i _BCan remain on the optimum value of reference voltage source 26 regulations.

On the contrary, when used magnetic head 4 has a little impedance, bias current i _BIncrease, thus the voltage v that resistance 5 two ends are set up _BIncrease, the result is added in the voltage v reference that voltage on the differential amplifier 38 is higher than reference voltage source 26.Finally, the stack of the output signal level of differential amplifier 38, the collector current I of transistor 41 superposes thereupon.Thereby according to equation (1), supply voltage or emitter voltage v ' _CcDescend, with the output signal level of minimizing biased amplifier 100, thereby bias current maintains predetermined value.

Fig. 7 is the circuit diagram of presentation graphs 6 oscillators 100 examples.Emitter voltage v ' _CcReceive the center tap of 47 grades of windings of biasing transformer.One stature of biasing transformer 47 elementary windings is received the collector of transistor 48.The grounded emitter of transistor 48, base stage are received on the termination of electric capacity 49,50 and resistance 51.The other end ground connection of capacitor 50.The other end of capacitor 49 and resistance 51 is connected with another termination of biasing transformer 47 elementary windings.

One end ground connection of biasing transformer 47 secondary winding, the other end is connected with output terminal 53 with capacitor 52.The other end ground connection of capacitor 52.Vibration output is drawn at output terminal 53.Resistance 51 plays transistor 48 base biasing resistors, and electric capacity 49 and 50 decisions feed back to the size of transistor 48 base stage AC signal, and electric capacity 52 cooperates the decision oscillation frequency with the inductance of biasing transformer 52 secondary winding.The oscillator 100 that constitutes according to above narration produces a vibration output, and its output level is by emitter voltage v ' _CcControl.

Oscillator 100 will never be limited to and can only adopt oscillator shown in Figure 7, and it obviously may be the controlled oscillator of output of any kind.

As above chat, because according to present embodiment, FEEDBACK CONTROL is effective, so that keep bias current in optimum value, can save the manual shift bias current fully, and be enough to need not to consider that the layout of bias current regulating device designs magnetic recording and reproducer, thereby improve design freedom.In view of these reasons, adopt the sound signal magnetic recording circuit of bias current circuit can eliminate the shortcoming of general technology and functional.

Fig. 8 represents that the present invention is used for the embodiment of sound signal magnetic recording system.

In Fig. 8, with Fig. 3 components identical with identical reference numerals, here do not introduce in detail.

With reference to figure 8, input end 54 is used for receiving video signals h, and LPF10, BPF11 FM circuit 12, low-frequency band change-over circuit 15, mixer 14 and record amplifier circuit 17 constitute a tracer signal to be handled partly.Current Control formula amplifier circuit (abbreviating the CCA circuit later on as) 55 is inserted between the frequency interleaved modulation modulator circuit of using for luminance signal J frequency modulation 12 and mixer 14.Similarly, CCA circuit 56 is inserted in for carrier chrominance signal K low-frequency band and changes between the low-frequency band change-over circuit 15 and mixer 14 of usefulness.CCA circuit controlling recording signal Processing part is so that regulate the level of luminance signal and carrier chrominance signal.By situation about will introduce in detail later on, these CCA circuit workings are to the variation response of control signal I control, so that according to control signal I _ControlRelevant (the I of I/O gain G with the CCA circuit _ControlOCG) the fact, the level of change luminance signal and carrier chrominance signal.On the other hand, represent the voltage signal of the record current that resistance 19 two ends set up to be input to the tracer signal control of dashdotted box indicating partly 57, the output signal of this part 57 is as control signal I _ControlAdd to CCA circuit 55 and 56.In tracer signal control part 57, the voltage signal that detects from resistance 19 at first adds to Hi-pass filter (being designated hereinafter simply as HPF) 58, the signal that the luminance signal component that HPF58 only comprises by the record current that flows through magnetic head 18 characterizes, and luminance component signal is fed to gating circuit 84, and this circuit 84 extracts synchronization signal components from luminance component signal.For this reason, the output control that gating circuit 84 is received by sync separator circuit 83, this circuit 83 detects the synchronizing signal of vision signal h.The output voltage of gating circuit 84 is exaggerated device circuit 59 and amplifies, and rectifier circuit 60 rectifications then are input to comparer 61.Comparer 61 also has a reference voltage input from reference voltage source 62, is used for determining the record current of hope, and in comparer 61, voltage after the rectification and reference voltage are relatively.The difference voltage of gained is compared device 61 amplifies, and is added on the voltage-current converter (or abbreviating the V/I circuit as) 63.Like this, control is 57 output current (being converted to electric current corresponding to output voltage values by converter 63 from the output voltage of comparer 61) partly, as control signal I _ControlBe added on CCA circuit 55 and 56,, make the tracer signal that flows through magnetic head 18 be controlled in the value of hope consistently with the level of control luminance signal and carrier chrominance signal.

The circuit diagram of Fig. 9 is a partly example of 57 of explanation control, and other elements among the figure beyond the control partly are with the block scheme formal specification.The record current that flows through magnetic head 18 causes the voltage drop at resistance 19 two ends, represents the voltage of record current to be added in an end of electric capacity 64.

The other end of electric capacity 64 is by resistance 65 ground connection.Electric capacity 64 and resistance 65 constitute HPF58.Voltage blocks electric capacity 66 by direct current and is added on the transistor 87.

The base stage of transistor 87 is presented a direct bias voltage by resistance 69 from bias voltage source.Transistor 87 collectors are received power supply 74, and emitter is received the negative electrode of transistor 88 collectors and diode 89.The anode of diode 89 is received a not end of inverting terminal of resistance 90 and amplifier 69.The other end of resistance 90 is received power supply 74.Transistor 88 and emitter resistance 91 constitute the back together with the constant current circuit of introducing.The base stage of transistor 88 is controlled by the output of sync separator circuit 83.When the output ground connection of sync separator circuit, the output of sync separator circuit 83 produces but when unearthed, the back one-level of amplifier circuit 59 delivered to the output of HPF58 by gating circuit 84.When sync separator circuit 83 has output, just the output of HPF58 is not delivered to the back one-level of amplifier circuit 59.The output of sync separator circuit 83 is synchronizing signals of extracting from vision signal h, and gating circuit 84 is controlled by this synchronizing signal, so the synchronizing signal that can only comprise from the record current luminance signal component that flows through magnetic head 18 obtains.

The synchronizing signal of separating from vision signal with sync separator circuit 83 is a constant voltage signal.Therefore, the emitter voltage of transistor 88 is a constant voltage, and is lower than the constant voltage of synchronizing signal, differs the base-emitter voltage VBE of a transistor 88.Then the resistance with resistor 91 removes the emitter current that emitter voltage obtains transistor 88, if collector current is constant, it just becomes constant current value.Therefore, transistor 88 and resistance 91 constitute the constant current circuit of mentioning in the past.In order to be described in further detail the work of gating circuit 84, when transistor is connected by synchronizing signal, diode also is switched on, its anode potential becomes in essence and equates with the base potential of transistor 87, the sync signal level that the result is detected by resistance 19 is transferred to the not inverting terminal of amplifier 67 backs one utmost point, and amplifier 67 joins with the anode of diode 89.

In amplifier circuit 59, the output terminal of amplifier 67 is received inverting terminal by resistance 70, and resistance 71 and direct current unity feedback electric capacity 72 are connected between inverting terminal and the ground.Under this structure situation, the gain of the closed-circuit of amplifier 67, that is the gain of amplifier circuit 59 is by resistance 70 and 71 decisions.

The output terminal of amplifier 67 is received the base stage of transistor 73.Transistor 73 collectors connect power supply 74, emitter connecting resistance 75,77 and electric capacity 76.Transistor 73, resistance 75 and electric capacity 76 constitute the emitter follower detector circuit, and the output voltage of this circuit rectification and level and smooth amplifier 67 provides a DC voltage.

The inverting terminal of another termination amplifier 78 of resistance 77 and an end of resistance 79.The output terminal of another termination amplifier 78 of resistance 79.The not inverting terminal of amplifier 78 adds reference voltage by reference voltage source 22, and it is equivalent to the desirable value that flows through the record current of magnetic head 18.Difference voltage between transistor 73 emitter voltages and the reference voltage is exaggerated according to resistance 77 and 79 gains that determine, as the output voltage of amplifier 78.When the emitter voltage of transistor 73 surpassed reference voltage, the output voltage of amplifier 78 descended, and when emitter voltage was lower than reference voltage, the output voltage of amplifier 78 increased.

The base stage of the output termination transistor 80 of amplifier 78.The emitter of transistor 80 is by resistance 81 ground connection, and collector connects CCA circuit 55 and 56.The output voltage of amplifier 78 converts Control current I to according to the emitter voltage of transistor 80 and the resistance of resistor 81 _ControlControl signal I _ControlChange the gain of CCA circuit 55 and 56, thereby change the level of luminance signal and carrier chrominance signal.

Amplifier circuit 59, rectifier circuit 60, comparer 61 and V/I circuit (converter) 63 have the structure identical with the amplifier circuit 23 of above introduction, rectifier circuit 24 and control circuit 25 basically.

Referring now to the example of CCA circuit shown in Figure 10,, how will specifically narrate the CCA circuit gain with control signal I _ControlChange.

In Figure 10, the output signal of FM circuit 12 and/or low-frequency band change-over circuit 15 shown in signal source 92 representative graphs 8 or 9.The output terminal 124 of CCA circuit is suitable for receiving the input end of mixting circuit 14.

The input signal V of signal source 92 _iBlock the base stage that electric capacity 93 is added to transistor 94 by direct current.The base stage of transistor 94 adds a direct current biasing that comes from bias voltage source (identical with Fig. 9, but easy to understand is described) here by biasing resistor 95.

Direct current biasing also is added on the base stage of transistor 96 by biasing resistor 97, and transistor 96 and 94 constitutes the first order of differential amplifier together, and transistor 94 and 96 emitter are R by resistance value _ETwo resistance 98 and 99 be connected together.The steady current I that causes by constant current source 110.Resistance 98 and 99 and ground between contact flow.

Transistor 94 and 96 collector are received the negative electrode of diode 111 and 112 respectively, so just can make the load of the operating resistance of these two diodes as transistor 94 and 96.Diode 111 and 112 negative electrode are connected to the negative electrode of diode 113 jointly, to adapt to the DC voltage drift.The anode of diode 113 is received on the power lead 74.

Transistor 94 and 96 collector are connected respectively to the base stage of transistor 114 and 115, constitute the second level of differential amplifier.Transistor 114 and 115 emitter are received on the variable constant current source 116 jointly.Steady current I to constant current source 116 _ConstantControl, just can change the gain of CCA circuit.

The collector of transistor 114 is received the collector and the base stage of transistor 117, and the base stage of transistor 117 is received the base stage of transistor 118, constitutes a current mirror circuit.

The collector of transistor 115 is received the collector and the base stage of transistor 119.The base stage of transistor 119 is received the base stage of transistor 120, constitutes a current mirror circuit.When the collector current of transistor 118 and 120 changes, can obtain signal V from transistor 118 and 120 _i

The base stage of transistor 121 and 122 is connected together mutually, forms current mirror circuit, the collector of transistor 121 is received the collector of transistor 118, and the collector of transistor 122 is received the collector of transistor 120.

Transistor 120 is received the resistance R that is connected with bias supply 68 jointly with 122 collector _LPull-up resistor 123 on.The output signal current i.On pull-up resistor 123, flow, and be converted into output signal voltage V _O

When work, for example, can suppose, at input signal V _iMoment of occurring of positive half period, be added with positive voltage on the base stage of transistor 94.Be added with under the negative voltage situation work similarly, will not introduce in this manual.Therefore, under the situation of positive voltage, the base current of transistor 94 increases, transistor 94 become than before the state of conducting more.Consequently, the collector current of transistor 94 increases, and the voltage drop that the operating resistance rel of diode 111 causes is also risen thereupon.So the collector voltage of transistor 94 descends, be constant electric current because constant current source 110 sends, so the increase of the collector current of transistor 94 will cause the collector current of transistor 96 to descend.Therefore, when the collector potential of the base potential of transistor 114 and transistor 94 is identical, the collector current of transistor 114 just descends, and when the current potential of the base potential of transistor 115 and the collector of transistor 96 was identical, the collector current of transistor 115 is increase just.In this case, obtain the application of nonadjustable steady current from constant current source 116, the collector current of transistor 114 suitably reduces, and will cause that the collector current of transistor 115 suitably increases, thus the increase of transistor 115 collector current will rise.

On the other hand, because the collector current of transistor 114 is identical with the emitter current of transistor 117, and transistor 117 and 118 formation current mirror circuits, so the collector current of transistor 114 and 118 is equal to each other.Because the collector current of transistor 115 is identical with the emitter current of transistor 119, and transistor 119 and 120 formation current mirror circuits, so the collector current of transistor 115 and 120 is equal to each other.In addition, the transistor 121 and 122 that forms current mirror circuit also has same collector current, and the collector current of transistor 121 is identical with the collector current of transistor 118.Owing to this reason, it is equal with the collector current of transistor 114 that the collector current of transistor 122 also will become at last.

According to the method described above with transistor 114,115 when 117 to 122 are connected, when the collector current of transistor 114 reduces and the collector current of transistor 115 when increasing, then the collector current of transistor 120 collector current that increases transistor 122 then reduces.Difference between transistor 120 and 122 collector current is then as output current i _OProvide, it flows through pull-up resistor 123, produces output voltage V _OFrom above-mentioned introduction as can be seen, the effect of transistor 120 is to provide output current i to pull-up resistor 123 _O, the effect of transistor 122 is projected current i _O

The I/O gain calculating of the CCA circuit of said structure is as follows.The operating resistance of supposing the emitter of transistor 94 and 96 is r _Eo, diode 111 and 112 operating resistance are r _EL, transistor 114 and 115 emitter operating resistance are r _Ez

So, flow through the transistor 94 of first order differential amplifier and 96 current i ₁Be expressed from the next:

$i_1=\frac{\mathrm{V\; i}}{{\mathrm{2\; \times (\; r}}_{\mathrm{e\; o}}{\mathrm{+\; R}}_E)}=\frac{\mathrm{V\; i}}{\mathrm{2\; \times \; (}\frac{\mathrm{2\; A}}{I_O}{\mathrm{+\; R}}_e)}\mathrm{(\; 2\; )}$

In the formula, A=(KT)/(q)=26mV, K: Boltzmann constant (8.6 * 10 ^-5Ev/K), T: absolute temperature, q: the quantity of electric charge.

Can get the output voltage V of first order differential amplifier thus ₁Be

${\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="85105245\_DRIMG2.png,85105245\_DRIMG8.png"\; state="\{\{state\}\}">V</figure-callout>}}_1=\frac{\mathrm{V\; i}}{\mathrm{2\; \times (}\frac{\mathrm{2\; A}}{I_O}{\mathrm{+\; R}}_E)}=\frac{\mathrm{2\; A}}{I_O}=\frac{\frac{\mathrm{2\; A}}{I_O}}{\frac{\mathrm{2\; A}}{I_O}{\mathrm{+\; R}}_E}{\mathrm{\times \; V}}_i\mathrm{(\; 3\; )}$

Flow through the transistor 114 of second level differential amplifier and 115 current i ₂Be expressed from the next:

$i_2=\frac{V_i}{{\mathrm{2\; \times \; r}}_{\mathrm{e\; l}}}=\frac{\frac{\mathrm{2\; A}}{I_O}}{\frac{\mathrm{2\; A}}{I_O}{\mathrm{+\; R}}_E}\times \frac{1}{\mathrm{2\; \times }\frac{\mathrm{2\; A}}{I_{}}}{\mathrm{\times \; V}}_i\mathrm{(\; 4\; )}$

So output current i _OFor

$i_o\mathrm{=\; 2\; <figure-callout\; id="2"\; label="i"\; filenames="85105245\_DRIMG3.png"\; state="\{\{state\}\}">i</figure-callout>}{}_2=\frac{1}{\frac{\mathrm{2\; A}}{I_O}\mathrm{+\; R\; \prime E}}\times \frac{I_{}}{I_O}{\mathrm{\times \; V}}_i\mathrm{(\; 5\; )}$

And output voltage V _OFor

$V_o\mathrm{=\; i}{}_{O}R{}_l\mathrm{=\; (}\frac{1}{\frac{\mathrm{2\; A}}{I_O}\mathrm{+\; R\; E}}\times \frac{I_{}}{I_O}{\mathrm{)\; \times \; V}}_i\mathrm{(\; 6\; )}$

Therefore, the circuit of CCA circuit (I/O) gain G is provided by following formula

$\mathrm{G\; =}\frac{V_O}{V_i}=\frac{1}{\frac{\mathrm{2\; A}}{I_O}\mathrm{+\; R\; E}}\times \frac{I_{}}{I_O}{\mathrm{\times \; R}}_1\mathrm{(\; 7\; )}$

In equation (6), (2A)/(I _O), R _E, I _OAnd R _LBe fixed value, so have

G=K * I _Control

In the formula,

This just represents variation and the control signal I of the output gain G of CCA circuit _ControlBe directly proportional.

Under above-mentioned vision signal, if in the example of the magnetic recording system that comprises control system and CCA circuit, along with the minimizing of record current, the impedance of magnetic head 18 becomes greatly gradually, and resulting detection voltage also will reduce on the resistance 19 so.This output of rectifier circuit 60 will compare in comparator circuit 61, promptly compare with reference voltage with predetermined recording electric current corresponding reference voltage source 62.When the output voltage of rectifier circuit 60 was lower than reference voltage, the output voltage of comparator circuit 61 raise, and the Control current of CCA circuit 55 and 56 is increased.Consequently, CCA circuit 55 and the gain of 56 circuit (I/O) are risen, and the output signal level of CCA circuit 55 and 56 is increased, thereby make record current be increased to predetermined steady state value.

In contrast, if the impedance of magnetic head 18 diminishes gradually with the increase of record current, the detection voltage that obtains from resistance 19 will increase so, and the output of rectifier circuit 60 simultaneously will increase.This output of rectifier circuit 60 surpasses the reference voltage of reference voltage source 62, so the output voltage of comparator circuit 61 reduces, so make the Control current decline of CCA circuit 55 and 56.Consequently, CCA circuit 55 and 56 circuit gain will reduce, and the output signal level of CCA circuit 55 and 56 be descended, thereby make record current drop to predetermined steady state value.

By the agency of utilize the above-mentioned Control work of the scrambling of magnetic head impedance, with it is example and not obvious, a kind of similar work may be more effective, and in this work, record current changes with the unevenness of record amplifier 17 gains and the unevenness of other network constants.

From the equation (7) of expression CCA circuit gain, can be clear that, can obtain the luminance signal of record current and the desired level difference between the carrier chrominance signal easily, promptly, rely on differential amplifier steady current I to initial level at the initial period of line design _OSelection, also can rely on CCA circuit load resistance R _LSelection, so just can obtain desired gain inequality.

Figure 11 represents another one embodiment with the form of block scheme, in this embodiment, the present invention is applied in the vision signal magnetic recording system.Embodiment contrast with Fig. 8, in the embodiment of Fig. 8, tracer signal comprises only uses synchronizing signal to control luminance and chrominance information as luminance signal, in the embodiment of Figure 11, then plan to utilize the colour burst signal in the carrier chrominance signal is detected, come the carrier chrominance signal in the controlling recording electric current.

Be added on HPF58 and the BPF125 at the voltage of setting up on the resistance 19, to detect carrier chrominance signal.The output signal of BPF125 is delivered to second gating circuit 86.Gating circuit 86 can be controlled by the output of strobe pulse generator 85, and strobe pulse generator 85 provides vision signal h.Strobe pulse generator 85 is made up of an one shot multivibrator, and one shot multivibrator is triggered by the colour burst signal that is comprised in the vision signal.When adjusting one shot multivibrator, should make its with vision signal in the colour burst signal that comprised during in the corresponding time interval, produce the output signal of high level, in this time interval, gating circuit 86 can make the signal that is input in it pass through in the middle of it simultaneously.

Therefore, gating circuit 86 is suitable for taking out colour burst signal from the carrier chrominance signal of passing the tracer signal that magnetic head 18 flows.The output signal of gating circuit 86 is after amplifier circuit 126 amplifies, by rectifier circuit 127 rectifications and level and smooth, deliver to comparer 128 then, comparer 128 also can obtain reference voltage from reference voltage source, and resulting reference voltage is corresponding with carrier chrominance signal predetermined value in the record current.In comparer 128, with rectification and level and smooth after DC voltage and reference voltage compare, then, with the difference voltage amplification of gained.Utilize V/I circuit (converter) 130 to convert this difference voltage to an electric current, as control signal, be added on the CCA circuit 56, to mate, like this with regard to the carrier chrominance signal in the energy controlling recording electric current with the variation of carrier chrominance signal with this electric current.Obviously, adopt and luminance signal control part 57 more similar circuit, can finish carrier chrominance signal control function partly.

Therefore, according to the foregoing description, and referring to Fig. 8 to 11, in magnetic recording and reproducer, unnecessary employing variable resistor is regulated the luminance and chrominance information in the record current, therefore, has just cancelled some step of regulating record current.

Figure 12 represents another one embodiment with block scheme, and in this embodiment, the present invention is used for the writing circuit of the device of the sound signal that a kind of record and recurrent frequency modulate.In Figure 12, can suppose that input end 131 is that the amplitude modulation by tone signal of right-side channels (being called RCH later on) is used, and being amplitude modulation by tone signals of left side passage (being referred to as LcH later on), input end 132 uses.Receive row frequency modulation by the input signal that input end 131 is received through frequency modulator 133, after CCA circuit 134, the level that its output that is amplified to converter 145 is indicated is delivered to mixer 135 then.On the other hand, the input signal of being received by input end 132 carries out frequency modulation through frequency modulator 136, after CCA circuit 137 makes its level that output indicated that is amplified to converter 145, also delivers to mixer 135 then.The output signal of mixer 135 is delivered on the magnetic head 139 by a tracer signal amplifier circuit 138, with recorde audio signal, records simultaneously on tape 20.

Detect the record current that flows through magnetic head 139 with resistance 19, detection signal can replace HPF with LPF by HPF140(), this depends on that the carrier frequency of audio frequency is to take out from RcH or from LcH), so can in detection signal, take out predetermined channel signal.Channel signal after the taking-up amplifies through amplifier circuit 141, through rectifier circuit 142 rectifications and level and smooth after, be converted into DC voltage, then in comparer 143, the reference voltage of this DC voltage and reference voltage source 144 is compared.This reference voltage is then corresponding with desired record current.The difference voltage of gained process in comparer is amplified, and is converted into the electric current that can be used to control CCA circuit 134 and 137 by converter 145.Therefore, the level of this FM signal is also the same with vision signal in the record current, can control, and makes it can keep the record current of magnetic head 139 constant.

Revisal 85105245

After the preceding revisal of the capable revisal of file name page or leaf

Instructions 36 amplifies the product amplifier

66 produce the line production line

73 connections are connected in parallel

8 13 47 grades of winding 47 elementary windings

9 17 I control OCG) I controls OCG)

12 18 electric current I _OElectric current I,

13 11 electric current I _OElectric current I,

18 22 frequency modulators 133 are received frequency modulator 133 and are advanced

Claims (24)

1, a kind of magnetic recording system, its effect are the magnetic heads (4 that has predetermined recording characteristic by; 18; 139) at recording medium (6; 20) go up recorded information, the principal character of this device comprises:

Recording signal processing apparatus (2,7-9,22,10-12,14,15,17; 131-133,135,136,138), this device is suitable for being connected with said head and can receiving with electric means the input signal of the above-mentioned information of representative, so that the input signal that is received is handled, is sent to this magnetic head and the certain tracer signal of level thereby produce one;

Be suitable for being connected to the pick-up unit (5 of said head; 19),, thereby produce the detection signal of representing above-mentioned tracer signal with the above-mentioned tracer signal of detection by this magnetic head;

The control signal generator means (23～26 that is connected to above-mentioned detection device and above-mentioned detection signal is responded; 58～63,83,84; 85,125～130; 140～145) be suitable for the level of the above-mentioned tracer signal by said head is transferred to control signal on the predetermined optimum value to produce one;

The control device (22 that is connected to above-mentioned recording signal processing apparatus and above-mentioned control signal is responded; 55,56; 134,137), so that above-mentioned recording signal processing apparatus is controlled, the level of above-mentioned tracer signal that will be by said head is transferred to above-mentioned predetermined optimum value.

2, according to claim 1, the feature of magnetic recording system is that above-mentioned control signal generator means comprises: detection signal conversion equipment (23,24; 58～60,83,84,85,86,125～127; 140～142), it is converted into level and smooth direct current signal with above-mentioned detection signal; And comparison means (38,39,40; 61; 77～79; 128; 143), it is with above-mentioned level and smooth direct current signal and predetermined reference signal (26; 62; 129; 144) compare, and produce above-mentioned control signal according to the difference after the comparison.

3, according to claim 2, the feature of magnetic recording system is that above-mentioned detection signal conversion equipment comprises: the device (23 that amplifies above-mentioned detection signal; 59; 126; 141) and to the output signal of above-mentioned multiplying arrangement carry out rectification and level and smooth rectification and smoothing apparatus (24; 60; 127; 142).

4, according to claim 3, the feature of magnetic recording system is that above-mentioned rectification and smoothing apparatus comprise the peak-detector circuit (34,36,37 of an emitter follower; 73,75,76).

5, according to the magnetic recording system of claim 2, above-mentioned information within it is audio-frequency information, and the feature of said apparatus is that the treating apparatus of this tracer signal comprises:

Represent the sound signal of above-mentioned audio-frequency information to receive and amplify the multiplying arrangement (7,8) of usefulness;

Produce the bias current generation device (100) of the bias current of desirable value;

The output signal of above-mentioned multiplying arrangement is superimposed upon mixer arrangement (2,9) on the above-mentioned bias current,, and this tracer signal is delivered on the said head so that produce above-mentioned tracer signal.

Above-mentioned bias current generation device is controlled via above-mentioned control signal, is transferred on the predetermined optimum value with this bias current that will flow through said head.

6, according to claim 5, the feature of magnetic recording system is that above-mentioned bias current generation device comprises: one produces the oscillator (100) that size depends on the output signal of its current/voltage; The generation device variable (43,44,45,46) with some supply voltage, above-mentioned control signal is depended in the generation of this supply voltage, the variable generation device of above-mentioned supply voltage is controlled by above-mentioned control signal.

7, according to claim 6, the feature of magnetic recording system is that above-mentioned control signal generator means comprises detection signal conversion equipment (23,24) and comparison means (38,39,40).

Conversion equipment converts the above-mentioned detection signal of the above-mentioned bias current representative that above-mentioned detection device detected to a level and smooth direct current signal; Comparison means will this level and smooth direct current signal and predetermined reference voltage (26) compare, and produce above-mentioned control signal according to difference voltage relatively.

8, according to claim 7, the feature of magnetic recording system is, above-mentioned control signal generator means also comprises converter device (41,42), the poor threshold voltage that it draws according to above-mentioned comparison means, produce a Control current and a variable generation device of using as above-mentioned control signal of above-mentioned supply voltage, it is a kind of current-control type of being controlled by above-mentioned Control current.

9, according to claim 7, the feature of magnetic recording system is, above-mentioned detection signal conversion equipment comprises the device (23) that amplifies above-mentioned detection signal and the output signal of above-mentioned multiplying arrangement is carried out rectification and level and smooth device (24).

10, according to claim 2, a kind of magnetic recording system, the above-mentioned information in it is video information, the feature of this device is that above-mentioned recording signal processing apparatus comprises:

Receive the terminal (54) of the incoming video signal of the above-mentioned video information of representative;

Be connected to the luminance signal withdrawing device (10) of above-mentioned terminal, it takes out luminance signal in above-mentioned incoming video signal;

Be connected to the device of the output terminal of above-mentioned luminance signal pick-up unit, in order to this luminance signal is carried out the frequency modulation modulation;

Be connected to the carrier chrominance signal withdrawing device (11) of above-mentioned terminal, in order to from above-mentioned incoming video signal, to take out carrier chrominance signal;

Above-mentioned carrier chrominance signal is carried out the low-frequency band conversion equipment (15) of low-frequency band conversion usefulness;

Be connected to the mixer arrangement (14) on above-mentioned frequency modulation modulating device output terminal and the low-frequency band conversion equipment, will carry out mixing through the carrier chrominance signal after luminance signal after the frequency modulation modulation and the low-frequency band conversion.

Above-mentioned the sort of control device comprises:

First variable gain amplifying apparatus (55), it is connected between above-mentioned frequency modulation modulating device and the above-mentioned mixer device, and the luminance signal of above-mentioned frequency modulation modulation is carried out the amplification of variable gain.

Second variable gain amplifying apparatus (56), it is connected between above-mentioned low-frequency band conversion equipment and the above-mentioned mixer device, and the carrier chrominance signal after the above-mentioned low-frequency band conversion is carried out the amplification of variable gain.

Above-mentioned control signal generator means also comprises:

Synchronizing signal withdrawing device (58,83,84), it is connected between the input end of above-mentioned detection device output terminal and above-mentioned detection signal conversion equipment, so that take out synchronizing signal from the luminance signal component that above-mentioned detection signal comprised; Above-mentioned first and second variable gain amplifying apparatus are controlled in its gain, are promptly controlled by above-mentioned control signal according to above-mentioned synchronizing signal.

11, according to claim 10, the feature of magnetic recording system is that above-mentioned synchronizing signal withdrawing device comprises:

Be connected on the filter apparatus (58) of above-mentioned detection device output terminal, the above-mentioned luminance signal component that is comprised in the above-mentioned detection signal is passed through;

Be connected to the device (83) of above-mentioned terminal, it separates the synchronizing signal that comprises in the above-mentioned incoming video signal.

By the gating circuit device (84) of the output signal of above-mentioned tripping device control, can allow the above-mentioned synchronizing signal that comprises in the above-mentioned luminance signal component pass through, this luminance signal component then passes through from above-mentioned tripping device.

12, according to claim 10, the feature of magnetic recording system is, above-mentioned control signal generator means also comprises voltage/current conversion equipment (63), this device is received the output terminal of above-mentioned comparison means, to produce the Control current as above-mentioned control signal, size of current depends on the output voltage signal of above-mentioned comparison means output terminal.In addition, above-mentioned first and second variable gain amplifying apparatus comprise the current-control type variable gain amplifier by above-mentioned Control current control.

13, according to claim 1, above-mentioned information within it is the magnetic recording system of video information, and the feature of this device is that above-mentioned recording signal processing apparatus comprises:

Receive the terminal of the incoming video signal of the above-mentioned video information of representative;

Be connected the luminance signal withdrawing device (10) on the above-mentioned terminal, from above-mentioned incoming video signal, to take out luminance signal;

Be connected to the device (12) of above-mentioned luminance signal withdrawing device output terminal, above-mentioned luminance signal carried out the frequency modulation modulation by it;

Be connected to the carrier chrominance signal withdrawing device (11) of above-mentioned terminal, from above-mentioned incoming video signal, to take out carrier chrominance signal;

Above-mentioned carrier chrominance signal is carried out the low-frequency band conversion equipment (15) of low-frequency band conversion;

Be connected to the mixer arrangement (14) of above-mentioned frequency modulation modulating device and low-frequency band conversion equipment output terminal, luminance signal after it modulates frequency modulation and the carrier chrominance signal after the low-frequency band conversion are carried out mixing.

Above-mentioned control device comprises:

Be connected first variable gain amplifying apparatus (55) between above-mentioned frequency modulation modulating device and the above-mentioned mixer arrangement, the luminance signal after by it frequency modulation being modulated is carried out variable gain and is amplified;

Be connected second variable gain amplifying apparatus (56) between above-mentioned low-frequency band conversion equipment and the above-mentioned mixer arrangement, the carrier chrominance signal after by it above-mentioned low-frequency band being changed is carried out variable gain and is amplified.

Above-mentioned control signal generator means comprises:

First control signal generator means (58～63,83,84), it produces first control signal according to the synchronizing signal that comprises in the above-mentioned detection signal.Control the gain of above-mentioned first variable gain amplifying apparatus with first control signal;

Second control signal generator means (125～130,85,86), it produces second control signal according to the colour burst signal that comprises in the above-mentioned detection signal, controls the gain of above-mentioned second variable gain amplifying apparatus with second control signal.

14, according to claim 13, the feature of magnetic recorder is that above-mentioned first control signal generator means comprises:

Be connected the synchronizing signal withdrawing device (58,83,84) of above-mentioned detection device output terminal, to take out above-mentioned synchronizing signal the luminance signal component that in above-mentioned detection signal, is comprised;

The first detection signal converter apparatus (59,60) of first DC voltage after being converted into above-mentioned synchronizing signal smoothly;

First comparator device (61,62) that above-mentioned first DC voltage and first reference voltage (62) are compared, as above-mentioned first detection signal, it can produce first output signal according to difference relatively.

Above-mentioned second control signal generator means comprises:

Be connected to the colour burst signal withdrawing device (85,86,125) of above-mentioned detection device, to take out above-mentioned colour burst signal the chroma signal component contained in above-mentioned detection signal;

Above-mentioned colour burst signal is converted to the second detection signal converter apparatus (126,127) of the second level and smooth DC voltage;

Second comparison means (128,129) that above-mentioned second DC voltage and second reference voltage (129) are compared as second control signal, and produces second output signal according to difference relatively.

15, according to claim 14, the feature of magnetic recording system is that above-mentioned synchronizing signal withdrawing device comprises:

Be connected first filter apparatus (58) of above-mentioned detection device output terminal, it allows, and contained above-mentioned luminance signal component passes through in the above-mentioned detection signal;

Connect the device (83) of above-mentioned terminal, above-mentioned synchronizing signal contained in the above-mentioned incoming video signal is separated with it;

Gating circuit device (84) by the output signal of above-mentioned tripping device is controlled can make above-mentioned synchronizing signal contained in the above-mentioned luminance signal component pass through.

16, according to claim 14, the feature of magnetic recording system is that above-mentioned colour burst signal withdrawing device comprises:

Be connected second filter apparatus (125) on the above-mentioned detection device, it allows in the above-mentioned detection signal contained above-mentioned carrier chrominance signal pass through;

Be connected the pulse generator device (85) on the above-mentioned terminal, colour burst signal contained in pulse that it produces and the above-mentioned incoming video signal is synchronous, and pulse width equates with the width of above-mentioned colour burst signal basically;

Be connected the second gating circuit device (86) between above-mentioned second filter apparatus output terminal and the above-mentioned second detection signal conversion equipment, gate means is controlled by above-mentioned pulse, by it the above-mentioned colour burst signal that is comprised in the above-mentioned chroma signal component is sent in the above-mentioned second detection signal converter apparatus.

17, according to claim 16, the feature of magnetic recording system is that above-mentioned pulse generator device comprises an one shot multivibrator.

18, according to claim 14, the feature of magnetic recording system is, the above-mentioned first detection signal generation device also comprises the first converter device (63), it is connected the output terminal of above-mentioned first comparator device, above-mentioned first output signal is converted into first electric current, its value depends on the magnitude of voltage of above-mentioned first output signal, and the same with above-mentioned first control signal, obtains above-mentioned first electric current; Above-mentioned second control signal generator means also comprises the second converter device (130) that is connected on the above-mentioned second comparator device output terminal, it is converted into second electric current with above-mentioned second output signal, its value depends on the magnitude of voltage of above-mentioned second output signal, and the same with above-mentioned second control signal, obtain above-mentioned second electric current; And the multiplying arrangement of above-mentioned first and second gain-variables all is current-control types, and their gain is controlled by above-mentioned first and second electric currents respectively.

19, according to claim 15, the feature of magnetic recording system is that above-mentioned first filter apparatus comprises a Hi-pass filter (58).

20, according to claim 16, the feature of magnetic recording system is that above-mentioned second filter apparatus comprises a bandpass filter (125).

21, according to claim 2, above-mentioned information comprises independently first audio-frequency information and second audio-frequency information in the magnetic recording system, and the feature of this device is that above-mentioned recording signal processing apparatus comprises:

Receive first terminal (131) of first input audio signal of above-mentioned first sound signal of representative;

Receive second terminal (132) of above-mentioned second input audio signal of above-mentioned second audio-frequency information of representative;

Be connected to the first frequency modulation modulating device (133) of above-mentioned first terminal, above-mentioned first input audio signal is carried out the frequency modulation modulation;

Be connected to the second frequency modulation modulating device (136) of above-mentioned second terminal, above-mentioned second input audio signal is carried out the frequency modulation modulation;

To the device (135) that the first and second frequency modulation audio signal modulations carry out mixing, as above-mentioned tracer signal, it provides a signal after the mixing to said head.

Above-mentioned control device comprises:

Be connected first variable gain amplifying apparatus (134) between above-mentioned first frequency modulation modulating device and the above-mentioned mixer arrangement, first sound signal of above-mentioned frequency modulation modulation is carried out the amplification of variable gain;

Be connected second variable gain amplifying apparatus (137) between above-mentioned second frequency modulation modulating device and the above-mentioned mixer arrangement, second sound signal of above-mentioned frequency modulation modulation is carried out the amplification of variable gain.

Above-mentioned control signal generator means comprises:

Be connected the filter apparatus (140) on the above-mentioned detection device, the carrier signal of the selection above-mentioned first or second sound signal from above-mentioned detection signal, obtain above-mentioned control signal according to selected above-mentioned carrier signal again, control above-mentioned first or the gain of second variable gain amplifying apparatus with this control signal.

22, according to claim 21, the feature of magnetic recording system is, above-mentioned control signal generator means comprises the detection signal conversion equipment (141 that above-mentioned selected carrier signal is converted into level and smooth DC voltage, 142), and with above-mentioned after level and smooth DC voltage and predetermined reference voltage (144) compares and produce the comparison means (143,144) of above-mentioned control signal according to the difference that relatively obtains.

23, according to claim 22, the feature of magnetic recording system is that above-mentioned detection signal conversion equipment comprises amplifier installation (141) that amplifies above-mentioned detection signal and the device (142) that the output of this amplifier installation is carried out level and smooth and rectification.

24, according to claim 22, the feature of magnetic recording system is, above-mentioned control signal generator means also comprises voltage/current conversion equipment (145), it is received the output terminal of above-mentioned comparator device, as above-mentioned control signal, it produces a current value relevant with the magnitude of voltage of the output signal of above-mentioned comparator device; Above-mentioned first and second variable gain amplifying apparatus comprise the current-control type variable gain amplifier by above-mentioned control signal control.

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