JPH0127500B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetic tape running drive and braking mechanism of a magnetic recording and reproducing device, and in particular, when playing still images sequentially on the screen during image playback, the present invention does not cause noise to appear on the playback screen. This relates to the control of a capstan shaft or its drive motor for sequentially stopping and feeding a magnetic tape.

To advance the magnetic tape frame by frame by one image (called one frame) while playing a noise-free still image, the motor for driving the capstan shaft for running the magnetic tape is simply driven for a predetermined period of time. In this case, it is difficult to stop the magnetic tape at an ideal stopping position, and noise appears on the screen. This tendency is particularly noticeable when a direct drive type capstan shaft drive system is adopted, which has a relatively low torque including load, compared to a motor configuration in which the capstan shaft is driven by a belt drive system. The prior art in this case will be explained using figures.

In FIG. 1, 1 is a magnetic tape, 20 is a capstan shaft, the tape 1 is sandwiched between a pinch roller pressed against this shaft, and the magnetic tape 1 is moved in the direction of arrow 10 by rotation of the shaft 20. send to The capstan shaft 20 is directly driven by the motor 2, and this drive circuit is 3,
A braking mechanism 4, which is applied when performing frame-by-frame forwarding, is added to the motor 2. Reference numeral 5 denotes a fixed head for reading, which receives control pulses C0, C1, and C1 as reference signals recorded at the bottom of the magnetic tape 1.
This is for reading C2 etc. Reference numeral 7 denotes a rotating drum, which rotates two rotating magnetic heads Aa and Bb provided at symmetrical positions with respect to the rotation axis.
A drive motor is built in this drum 7, and its drive circuit is 8. Also two heads
A position detection circuit 9 for detecting the positions of Aa and Bb during rotation constitutes a position detection means. A control pulse read signal CN is inputted from the reading head 5, and a head position detection signal PG is also inputted from the position detection circuit 9. The still image sequential reproduction circuit 6 operates when a frame feed signal 16 is obtained by a system control device (not shown), and it supplies signals DR and BL, which are drive and braking signals, to the capstan motor drive circuit 3. Further, an operation signal BR is given to the braking mechanism 4.

Now, just before time _t0 , the tape 1 comes to a standstill, and the rotating magnetic head Aa, which is provided on the drum 7,
Suppose that Bb traces within range 11 on the tape. Already recorded recording tracks are formed on the tape 1 as A1, B1, A2, and B2. Tracks recorded while the tape is running are recorded with a greater gradient in the horizontal direction of the tape than in the trajectory of the magnetic head running while the tape is stationary. It is assumed that the drum 7 always rotates at a constant speed regardless of whether the tape is running or stopping. Also magnetic head
It is assumed that the widths of Aa and Bb are approximately equal, and recording tracks A1, B1, A2, . . . are formed with widths slightly narrower than this width. While the drum 7 rotates half a rotation, the magnetic tape runs from the bottom to the top of the heads in the direction of arrow B, head Aa sends signals corresponding to tracks A1 and A2, and head Bb sends signals corresponding to tracks B1 and B.
It is assumed that the signal corresponding to track number 2 is to be reproduced, and the signal on the other track side cannot be reproduced.
This is achieved by a known technique that can be easily achieved by using heads Aa and Bb with different azimuths. When heads Aa and Bb alternately run within 11 ranges on the tape, head Aa moves the shaded area a1 in track A1 to head Bb.
Accordingly, the shaded portion b1 in the track B1 is alternately reproduced. This state is a correct sequential still image reproduction state and no noise appears on the screen of the device. For example, when head Aa traces within range 11 on the tape in the direction of arrow 13, the reproduced signal first reproduces signal a2' on track A2, and the level of that signal drops, appearing as noise on the screen. After passing the position d2, the signal of the portion a1 is reproduced after passing the position d1 where noise also appears. Therefore, it is sufficient that the timing of passing through portions d2 and d1 is such that it does not appear as noise on the screen of the image reproducing device. For example, the second
Assuming that the range 18 in the figure corresponds to the entire area of the image reproduction signal driven by the electron beam, and the part 19 is the vertical synchronizing signal period, the retrace period of the vertical scanning of the electron beam corresponds to approximately the part 19, and the horizontal scanning There is no signal and no image appears on the screen. The area within the frame 17 outside the period T ₂ immediately before the vertical synchronization signal section 19 and the period T ₁ immediately after the vertical synchronization signal section 19 is the range that appears on the screen of the image reproducing device, and the portions d1 and d2 in FIG. 1 are the periods. If tape 1 is positioned so that it is within T ₁ and T ₂ , a still image without noise appearing on the screen can be reproduced. If the tape 1 is to the left of the state shown in FIG. 1, positions d1 and d2 will rise, and noise will appear at position 22 in FIG. On the other hand, if the tape moves to the right and the tape remains stationary, the points where the playback signal of head Bb falls, e1 and e2, fall and noise appears at position 21 in the drawing.
Therefore, in order to reproduce a noise-free still image, it is necessary to fit the portions d1 and d2 where the signal level drops and the portions e1 and e2 within the above-mentioned periods T ₁ and T ₂ .

To advance the next frame, move tape 1 to the arrow 10
The magnetic head Aa on the rotating drum 7 is sent in the direction of
The locus drawn by Bb can be relatively shifted to range 12. Range 11 and range 12 have the same relative relationship between the tape and the rotating drum, and the track for obtaining the reproduced image signal moves from A1, B1 to A2, B2. It has just moved; everything else remains the same.

FIG. 3 shows the movement of the magnetic head as it moves from position 11 to position 12 in FIG.
When considering the trajectory of the range 11, the lower ends of the heads Aa and Bb run on the line Q1, and the still image reproduction signals are obtained from a1 and b1 in FIG. Now, when the tape starts running, if the tape 1 starts to accelerate when the lower end of the head Aa reaches the point P1, then the locus of the lower end of the head Aa relatively draws a dotted line Q2.
Thus, during this period, the recorded signal in the shaded area a11 is reproduced. After passing point P2, the next step is a trajectory Q3 in which the lower end of head Bb is drawn from point P3 toward point P4.
draw During this time, track B shown in the range of points
The signal b11 above 1 is reproduced. Point P from point P3
If the speed of the tape matches the speed during normal playback on the way to 4, the tape is not accelerated and runs at a constant speed from that point on. Passing point P4,
The trajectory Q4 between point P5 and point P6 is the trajectory of the lower end of head Aa, and the shaded portion a12 on track A2 is reproduced. The tape 1 begins to be decelerated midway through this period. Head Bb between point P7 and point P8
While the locus Q5 of the lower end of the head is drawn, the range b12 of the point group on the track B2 is reproduced, and when it reaches point P8 and the tape 1 just stops, from then on the lower end of the head draws the locus of the solid line Q6, and within the range 12 Head Aa,
Bb alternates and ranges a2 and b2 in FIG. 1 are obtained as reproduced signals. At this time, as described above, a reproduced image without noise is obtained.

As is clear from the situation in Figure 3, when the tape is fed in this way, the playback signals from the two magnetic heads are not always lost while the tape is running, and noise is removed from the screen. It turns out that it does not appear in FIG. 4 shows how the trajectory moves from range 11 to range 12, with the time axis as the horizontal axis. Figure a shows how one of the two magnetic heads is selected, and figure b shows how the tape running speed changes. head
The period during which Aa and Bb operate once each is T ₁ , T ₁₁ , T ₁₂ ,
T ₂ corresponds to the reproduction period of one frame of an image during normal reproduction, and the values are the same in both cases. Therefore, it is clear from this figure that one still image frame can be advanced frame by frame in the time it takes two frames during normal playback.

The sequential playback circuit 6 that advances the still screen frame by frame,
This circuit is used to run the tape as described above, and it is a circuit that advances the tape one frame in a time period of about two frames and stops the tape at a position where no noise appears on the screen when it is stopped. It is. The braking mechanism 4 is a means necessary for stopping the tape, and is an indispensable means for stopping the tape with high accuracy. FIG. 5 shows the configuration of these devices, means, a capstan motor, and its drive circuit, and FIG. 6 shows a time chart for explaining the operation of this circuit. Further, a schematic configuration of the capstan motor and the braking mechanism 4 is shown in FIG.

In FIG. 5, a frame advance signal 16, a head switching signal PG, and a control pulse CN signal are input to the sequential reproduction circuit 6. 61 is a 3-input AND gate, 62 and 65 are flip-flops, 6
3, 64, 66, and 67 are one-shot circuits, and 62 to 67 are set or triggered when the input potential changes from a low potential to a high potential.
When the flip-flop receives a set input S, its output Q changes to a high (low) potential, and the reset input R changes to a high (low) potential.
enters and changes in the opposite direction. It is also assumed that the one shot operates when the trigger input T changes from a low potential to a high potential, and a high (low) potential appears at the output Q for a predetermined time. 62 to 67 are all initially in a reset state.

Now, at the moment of time t ₀ , the playback head moves from Bb.
Assume that the switch is switched to Aa, and the signal from the position detection circuit is
Assume that PG is obtained as a low to high potential signal. Assuming that the frame advance signal 16 was obtained at a high potential just before time t ₀ , the output of the one shot 63 was stationary at a high potential, so the output of the AND gate 61 would be at a high potential immediately after time t ₀ . The flip-flop 62 is set. This output Q
The one shot 64 triggered by
Gives output Q during TD. This output provides a motor drive signal to the capstan motor drive circuit. The capstan motor continues to be accelerated until time t ₁ when period TD ends, and after time t ₁ the motor stops accelerating and runs at a preset substantially constant speed.
Also, the one-shot circuit 63 is a flip-flop 6
They are driven simultaneously by the two sets of flip-flops 65 and 2, but they operate for at least two frame periods during frame advance, and their output becomes a low potential, disabling the AND gate 61 and driving another flip-flop 65. The reset input R side is made free and settable.

At time _t2 , which has passed time _t1 , the head 5 reads a control pulse from the control track of the running magnetic tape 1, detects it, and outputs an output pulse.
It is given to the sequential reproduction circuit 6 as CN. This control pulse is applied to the lower end of the magnetic tape 1 for one frame (A1, C2, etc.) as shown in FIG.
2 when heads Aa and Bb play like B1
This is written for each set of tracks at the time of recording. In reality, it is not recorded in a pulse-like manner, but is recorded in saturation so that the direction of magnetization demagnetizes at intervals of, for example, one frame period, and the change in the location where one magnetization state changes to the other is discarded. It is used as a control signal.
Such control signals are C0 and C in Figure 1.
This is equivalent to 1st prize. Now, when the control signal CN is obtained at time _t2 , the flip-flop 65 is set, and as a result, the one shot 66 is operated. The output of the one shot 66 is up to time _t3 .
The potential between TC is low and returns to high potential again at time _t3 .
At this time, one shot 67 is triggered and the period TB continues.
A high potential appears at terminal Q. Assuming that this output is lost at time _t5 , the output Q of the one shot 67 during this period TB is used as a braking signal for the capstan motor. At time t ₅ , exactly tape 1
Assuming that the tape is stationary, the tape movement amount 1 becomes like the curve shown by the solid line in FIG. 6a when time t is plotted on the horizontal axis. The tape speed VT changes as shown by the solid line shown in FIG. The position where the tape movement amount is 0 is when the heads Aa and Bb are traveling in the range 11 in FIG. 1, and the position where the tape has moved to _l2 and is stationary is when the two heads are traveling in the range 12.

The driving time of the one shot 64 indicates the time during which the motor accelerates, and the output time width of the one shot 66 indicates the delay time from when a control signal is received until a braking signal is applied to the motor. The control signal CO in Figure 1 is intended to cause heads Aa and Bb to correspond to tracks A1 and B1 as a reference position signal to be traced during normal playback, but the position on the tape is not correlated as shown. It doesn't have to be in a position where it has, it can be in any position. It is determined by the correlation between the position of the drum 7 and the position of the reading head 5, and there is no restriction such that it is always recorded at the bottom of the track traced by the head Aa. It's good if it's in position. Therefore, the time t ₂ when the control signal arrives
may occur before _t1 , and in this case, the time output width of the one shot 66 becomes long until time _t3 . However, time t ₂ must be earlier than time t ₃ . Otherwise, when the tape is held still,
It is not possible to stop the tape at a position that will play a still image without noise on the screen. The output time width of one shot 67 in FIG. 5 determines the braking time of the capstan motor.
It is necessary to adjust the output time width to be slightly shorter than the output time width of , so that the braking signal is released when the motor just stops. The output time width of the one shot 63 may be adjusted to be longer than the two frame period and a variable time width setting means may be added so that the output is continued only during a period in which no frame advance is performed.

Note that from time t1 to time _t3 , the capstan motor is decelerated by the braking torque of the braking mechanism, but rotates at a substantially constant speed within this short period _of time. Keeping the capstan motor rotation speed constant from time t ₂ when the control pulse is detected to time t ₃ when braking starts is because the integral value of the speed corresponds to the running distance of the tape. This will keep the amount of travel constant. Since the deceleration rate is approximately constant during deceleration, the amount of tape travel during this period, for example, up to time _t5 , is also approximately constant. However, if the above-mentioned drive stops and the trailing speed of the motor changes high or low, the amount of tape travel from time t ₂ to time t ₅ will differ, and the tape stop position will be accurately kept within a predetermined range. Therefore, the motor speed during slow travel must be kept within a certain range of accuracy. Therefore, by controlling the tape speed after inputting the control pulse so that it always remains at a substantially constant value, it is possible to keep the amount of tape running from inputting the control pulse to stopping the tape approximately constant.

FIG. 5 assumes that the motor 2 is a transistor motor, which is a plasticless machine, and shows its drive armature coils 24, 25, 26 and position sensors 27, 28, 29 for detecting the position of the field rotor.
The figure shows the main configuration of 1 motor drive circuit 3.
Reference numeral 1 denotes a preamplifier section, which connects the position sensors 27 to
In response to the signal 29, the transistors to be driven in the drive inverter 32 are selectively driven. At the same time, detect the DC side current of the inverter 32,
For example, it is detected as a voltage drop across the resistor 33 and controlled to match the command input value. In this case, one shot 6 in the above-mentioned sequential re-output circuit 6
The outputs of 4 and 67 are received as a current command signal S, and the current is controlled to this value. When a high potential signal is received at the forward/reverse switching signal terminal (F/R), the inverter 32 functions to reverse the motor. Therefore, the reverse mode is set only while the one shot 67 outputs, but since the motor was previously rotating in the forward direction, the reverse braking mode is set. In this way, in the motor drive circuit 3, the drive signal
In response to the DR and braking signal BL, the motor is rapidly accelerated or decelerated to drive the capstan shaft in predetermined angle increments. The operation of the drive section of a transistor motor is well known, so a detailed explanation will be omitted, but the same is true when using a DC motor such as a coreless motor as a capstan motor. The operating circuit can be easily created. As is clear from the above description, the motor 2 and the drive circuit 3 are not limited to the example shown in FIG. 5, but various other types are possible.

As an element for operating the braking mechanism 4, a DC solenoid coil, which is excited by the excitation of the amplifier 68 in the sequential image reproduction circuit 6, is shown in FIG. 5 as an example. This coil is excited in response to the signal 16 when frame feeding is performed. FIG. 7 shows a schematic configuration of a motor section, a braking mechanism, and a speed detection mechanism when a transistor motor is used as the capstan motor 2. Figure a
2 is a sectional view taken along a plane passing through the capstan shaft 20, FIG. 1B is an example of the braking mechanism 4, and FIG. In the figure, 200 is a rotating magnetic plate located on a plane perpendicular to the capstan shaft 20, and 23 is a permanent magnet forming a rotating field, which is ring-shaped. An armature coil 24 and coils 25 and 26 (not shown) are fixed on the stator magnetic plate 203 axially facing the magnet 23 along with a position sensor (for example, a Hall element) 27 and the like. A braking mechanism 4 is provided on the side surface of the rotating magnetic plate 200, and a stationary shaft 4
6, a support fitting 42 equipped with a brake pad 43;
is rotatably mounted. When the solenoid 41 is de-energized, the support fitting 42 is pulled to the position indicated by the dotted line by the spring 44, and the brake pad 43 does not touch the rotating magnetic plate 200. When the solenoid 41 is energized, the support fitting 42 is pulled by the spring 45 and moves to the position indicated by the solid line, so that the brake pad 43 constantly hits the rotating magnetic plate 200 with a predetermined force. At this time, a substantially constant braking force can be applied to the motor at all times in the direction of rotation. Further, a multi-pole magnetized magnet plate 201 is provided on the upper surface of the rotating magnetic plate 200, and a printed board 202 having a copper foil pattern that matches the magnetized pitch of this plate is placed oppositely to constitute a speed detection mechanism. be done.

Next, the necessity of a brake mechanism will be discussed below. If it is assumed that the tape stops exactly at time _t5 in FIG. 6, an ideal stop can be achieved. However, it is difficult to stop the motor drive and reverse braking when the motor is reliably stopped, and the drive circuit is actually cut off when the motor is slightly rotating in the forward or reverse direction. In the circuit example shown in FIG. 5, even if the driving time is constant, there will be a difference in the drifting speed at which the motor rotates at a constant speed thereafter. This is because the resistance value of the running path of the magnetic tape 1 differs each time the frame is advanced, and this is also due to the difference in the resistance value of the reel such as a cassette that stores the tape. Furthermore, it changes depending on the difference in the power supply voltage of the motor drive circuit, and is never constant. Naturally, therefore, when the braking time is constant, it is almost impossible to stop reverse braking when the capstan motor has just stopped. If the reverse braking stops at time t ₄ before time t ₅ in Figure 6, that is, if the speed of the motor during constant running is high, the motor will continue to rotate in the forward direction, and eventually the shaft, etc. It comes to a natural stop due to static force. When the braking mechanism 4 is not present, the tape speed V _T changes as indicated by a two-dot chain line 610 in FIG. 6b, and finally stops at time _t9 . During this time, the movement of the tape is indicated by the two-dot chain line 6 in Figure 6a.
It will look like 20. If the braking mechanism 4 is working, the speed
V _T changes as indicated by the dotted line 630, and the motor stops at time _t7 . This is due to the braking torque due to the action of the braking mechanism 4 in addition to the static torque of the shaft, and the movement of the tape is as shown by the dotted line 640 in FIG. 6a. Conversely, even at time _t5 , the motor continues to be in the reverse braking state, and when the brake is released at time _t6 , the motor begins to reverse between times _t5 and _t6 . After time t ₆ , the tape speed (that is, corresponding to the rotational speed of the capstan motor) changes as indicated by a two-dot chain line 650 in FIG. 6b, and finally stops at time t ₁₀ . During this time, the amount of tape movement l changes as indicated by a dotted line 660 in the middle of FIG. Braking mechanism 4
If there is, the speed V _T changes as 670 and the tape movement amount l changes as shown by the dotted line 680. In the above explanation, the period TB for performing reverse braking of the motor was explained in different forms, but on the other hand, when the motor rotates at a constant speed, the speed changes large and small, and one shot Reverse braking period TB due to the output of
If is constant, it is relatively equivalent to the case according to the above explanation, that is, the case where TB is changed.

In order to prevent noise from appearing on the screen, the tape stopping position is limited so that the period in which the noise occurs falls within the period T ₁ or T ₂ in FIG. 2. If the tape positions corresponding to this period are lT ₁ and lT ₂ in Fig. 6, the position where the tape stops must be within the ranges 21' and 22' of the dashed-dotted lines corresponding to this position. Good. In the state shown in Figure 6, dotted lines 640, 680
is allowed, while cases of two-dot chain lines 620 and 660 are not allowed and noise will appear on the screen. In this way, if the braking mechanism 4 is provided, it is possible to prevent noise from appearing on the screen. If the braking mechanism 4 is operated only during frame-by-frame advance and released during other normal running modes, the load on the motor shaft will be reduced and power savings will be achieved, as well as the mechanical time constant will increase. is reduced and performance is improved.

Now, in principle, noiseless throw is possible using the conventional technology described above. However, in reality, there is also torque unevenness in the braking mechanism 4, so noise may appear on the screen during reverse braking for a certain period of time T _B. Furthermore, skill is required to adjust T _B to the optimum value.

This invention was made in view of the above points, and detects the timing to end reverse braking after confirming that the motor is sufficiently stopped from the output signal of the speed generator of the capstan motor. The object of the present invention is to provide a magnetic recording/reproducing apparatus which can perform stable noiseless throw by minimizing the amount of tape movement after stopping braking.

An embodiment of the present invention will be described below based on the drawings. FIG. 8 shows an embodiment of the present invention, which is a circuit that improves accuracy in order to stop reverse braking when the capstan motor stops. This shows a circuit section that replaces the one shot 67 in FIG. This is an example of a circuit that uses a motor speed detection mechanism to stop reverse braking when the motor speed reaches approximately zero, instead of driving for a fixed period of time by one shot. As shown in FIG. 9a, the output from the motor speed detection mechanism, FG, obtains an approximately constant amplitude alternating current before time _t3 during constant speed rotation. Amplifier 672 amplifies its output and connects it to buffer 673 via a capacitor.
At C _X1 , the diode rectified (half-wave) DC voltage appears as shown in Figure 9b. In the comparator 674, the low reference voltage Vy created by resistors ₆₇₅ and ₆₇₆ is input to the positive phase side, and the voltages of C It's getting old. flipflop 67
When the output of the one shot 66 changes from a low potential to a high potential and is applied to the set input S of 1, a high potential appears at the output Q, and a reverse braking signal BL is output.
Since the speed of the motor decreases during braking, the capacitor
The potential across C _X1 also decreases, and at time t ₄ when the potential becomes lower than the potential Vy, the output of the comparator 674 changes from negative to positive. At this point, the flip-flop 671 is reset and the braking signal BL disappears.
The way the motor stops after this is shown at time t ₄ in Figure 6.
This is similar to the dotted line shown below. Stopping accuracy increases as the potential Vy is lowered, but since the discharge time constant of the capacitor C _X1 is determined by the relationship with the resistor _R Then, the motor may start to rotate in reverse, and the potential across capacitor C _X1 will start to rise again. Then, stop detection is no longer possible and the motor begins to reverse rotation and does not stop. A separate one-shot circuit 677 is provided assuming this case. This output time span is the 6th
By making the rotation correspond to the time period t ₃ to _{t 6} in the figure, the capstan motor can be appropriately stopped without continuing to be reversed more than necessary. In this way, the output time width of the one shot 677 is set to the maximum value within the allowable range, and at the same time the time constant for stop detection is set.
The comparator 674 compares the values of R _X1 and _C
If it is set so that it works, a highly accurate stop detection device can be realized. from the speed detection mechanism
The handling of FG signals is not limited to the example shown in Figure 8. If half-wave rectification of diodes is performed using a double-wave rectifier circuit, the time constants of Rx and CX can be lowered, and the accuracy of stop detection can be increased. Note that the resistor _R . As a braking mechanism, there is a method of short-circuiting the armature coil of the motor to perform electrical braking, but this effect cannot be expected at low speeds. This tendency is particularly noticeable when the capstan motor uses a direct drive.

When starting the capstan motor, the circuit configuration shown in FIG. 10 can be considered as a method of accurately setting the speed of the capstan motor to a constant value when the capstan motor runs at a constant speed thereafter. This shows a circuit section replacing the one shot 64 in FIG. This is an example of a circuit that uses a motor speed detection mechanism to stop acceleration of the motor when the motor speed reaches a predetermined speed, instead of driving for a fixed period of time by one shot. The output from the motor speed detection mechanism, FG, is after time t ₀ as shown in Figure 11a.
As the motor accelerates and speed increases, the AC amplitude gradually increases. The amplifier 642 amplifies its output, and the diode-rectified DC voltage appears in the capacitor C _X2 provided between the amplifier 642 and the buffer 643, as shown in FIG. 11b. Comparator 6
In 44, the reference voltage Vz of a predetermined magnitude created by resistors 645 and 646 is inputted to the negative phase side, and the voltage of C _X2 is inputted to the positive phase side. , its output is in the negative state. The set input S of the flip-flop 641 is given the result that the output Q of the flip-flop 62 changes from low to high potential, and a high potential appears at the output Q.
The motor drive signal DR was being output. When the motor accelerates and the output of the comparator 644 changes from negative to positive, at time _t1 , the flip-flop 641 is reset and the motor stops driving, and thereafter the motor runs at a constant speed. The time constant of capacitor C _X2 and resistor R _XT2 determines the potential of half _- wave rectified capacitor C
The operation of the comparator 644, which makes a comparison with the current speed, is delayed and the speed of the motor varies. Accordingly
The time constants of R _X2 and C _X2 must be adjusted to appropriate values. In addition, resistor R _Z2 in Figure 10
is provided to provide a positive feedback effect in order to quickly switch when the output of the comparator 644 changes, and does not affect the basic operation of the circuit.

As described above, according to the present invention, in a magnetic recording and reproducing apparatus, the motor that drives the capstan shaft for running the magnetic tape is driven to a predetermined set speed after detecting a predetermined position on the recording track, and the reference signal from the fixed head is driven. After detection,
It is equipped with a sequential regeneration circuit that performs reverse braking until the speed of the magnetic tape almost stops by referring to the output signal of the speed generator of the motor, and the capstan shaft or the rotary shaft of the motor is magnetized only when the motor is reverse braking. Equipped with a braking mechanism that brakes mechanically or mechanically, it can stop braking when the capstan motor is sufficiently close to a stop, minimizing the amount of tape movement after stopping the braking, and making it possible to play the magnetic tape sequentially. The stop position of the magnetic tape with respect to the rotating magnetic head can be made accurate, noise in the reproduced signal can be removed, and a high quality reproduced signal can be obtained.

In addition, since the braking mechanism continuously applies a braking force to the extent that the coasting speed of the magnetic tape is kept almost constant during the period of sequential reproduction of the magnetic tape,
It is possible to prevent the stop position of the magnetic tape from shifting with respect to the rotating magnetic head due to the intermittent operation of the braking mechanism, and it is possible to provide a magnetic recording and reproducing apparatus in which noise does not occur during still images.

[Brief explanation of drawings]

Figure 1 is an overall configuration diagram of the magnetic recording and reproducing device, Figure 2
3 and 4 are diagrams illustrating the correlation between the magnetic tape and the magnetic head during frame-by-frame feeding as a sequential reproduction operation. Figure 5 is a diagram showing the circuit configuration of the main parts related to this invention, Figure 6 is a time chart during operation of the circuit in Figure 5, and Figure 7 is a diagram showing the capstan shaft drive motor, braking mechanism, and speed detection. The structure of the mechanism, FIGS. 8 and 9 are illustrations of an embodiment of the motor stop detection circuit which is a component of the present invention, and its operation. FIGS. It is a circuit for accelerating and an explanatory diagram of its operation. In the figure, 1 is a magnetic tape, 2 is a motor, and 4 is a magnetic tape.
5 is a braking mechanism, 5 is a fixed magnetic head, 6 is a sequential reproducing circuit, 9 is a position detecting means, and 20 is a capstan shaft. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A rotating magnetic head that reads information signals sequentially recorded on recording tracks of a magnetic tape, a fixed magnetic head that reads reference signals recorded on the magnetic tape corresponding to the recording tracks, and a position detector that detects a predetermined position of the rotating magnetic head;
In a magnetic recording and reproducing device that sequentially reproduces still images, the device includes a motor that rotates the capstan shaft for running the magnetic tape, and a speed detector that generates a voltage proportional to the rotational speed of the motor, A circuit that starts driving the motor after detecting a predetermined position, a circuit that stops driving the motor when the output voltage of the test detector reaches a predetermined value, and a circuit that causes the motor to coast at a substantially constant speed after the drive ends. a circuit that starts braking after a predetermined time from this point when receiving a reference signal reproduced by the fixed magnetic head; and a circuit that ends braking of the motor when the output voltage of the speed detector approaches approximately 0V. a sequential reproducing means, which continuously magnetically or mechanically applies the tape running speed during the coasting to the capstan shaft or the rotary shaft of the motor during the control period of driving, coasting, and braking of the motor by the sequential reproducing means; 1. A magnetic recording and reproducing device comprising a braking mechanism that applies a braking force to a level that maintains substantially constant.