JPS6334703B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides, for example, a magnetic recording and reproducing device.
The present invention relates to a motor having a braking mechanism that is effective for reproducing still images without noise on the screen during frame-by-frame reproduction.

In order to obtain a still image, a conventional magnetic recording/playback device simply drives a capstan shaft for a predetermined period of time with a motor to advance one image, or one frame, of a recorded magnetic tape frame by frame.
Since braking is performed, it is difficult to stop the tape at the ideal tape stop position, and noise is likely to appear on the screen. In particular, rather than the motor configuration that drives the capstan shaft using a belt drive system,
This tendency is particularly noticeable in a direct drive motor configuration with relatively low torque. The present invention has been made in view of the above points, and an object of the present invention is to obtain a direct drive type motor having a braking mechanism that allows noise-free still images to be obtained.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall configuration diagram of a still image reproducing device for a magnetic recording tape including a motor having a braking mechanism according to the present invention. In particular, when transmitting a still image one frame at a time, noise appears on the screen of the reproducing image device. The configuration of a still image playback device that attempts to advance frames without skipping is shown below. In the figure, 1 is a magnetic tape, 20 is a capstan shaft, the magnetic tape 1 is sandwiched between a pinch roller pressed against this shaft, and the magnetic tape 1 is sent in the direction of arrow 10 by rotation of the shaft. The capstan shaft 20 is directly driven by a motor 2, and 3 is a drive circuit.
A braking mechanism 4 is added to the motor 2, which is applied when performing frame-by-frame forwarding. Reference numeral 5 denotes a read head for reading control pulses C0, C1, C2, etc. recorded on the lower part of the magnetic tape 1. Reference numeral 7 designates a rotating drum for rotating two magnetic heads Aa and Bb, which are provided at symmetrical positions with respect to the rotation axis. Reference numeral 8 denotes a drive circuit for a drive motor built in the rotating drum 7. Also 9 is 2
This is a position detection circuit for detecting the positions of the magnetic heads Aa and Bb during rotation. Reference numeral 6 denotes a still image reproducing circuit to which a control pulse reading signal CN from the reading head 5 is input, and a head position detection signal PG from a position detecting circuit 9 as an input.
The still image reproducing circuit 6 operates when it receives the frame feed signal CS from the system control device 16, and also provides DR and BL signals, which are drive and braking signals, to the capstan motor drive circuit 3. An operation signal (BR) is given to the braking mechanism 4.

In the still image reproducing apparatus configured as described above, the magnetic tape 1 comes to a standstill just before the time to, and the magnetic heads Aa and Aa provided on the rotating drum 7
Assume that Bb traces 11 ranges on the magnetic tape 1. The already recorded recording tracks are A1, B1, A2, B2 on the magnetic tape 1.
It is formed like this. Tracks A1, B1, A2, and B2 recorded while the magnetic tape 1 was running are as follows:
This means that recording is performed with a greater slope in the horizontal direction of the magnetic tape 1 than in the trajectory traveled by the magnetic heads Aa and Bb while the magnetic tape 1 is stationary. It is assumed that the rotating drum 7 always rotates at a constant speed regardless of whether the magnetic tape 1 is running or stopping. It is also assumed that the widths of the magnetic heads Aa and Bb are approximately equal, and recording tracks A1, B1, A2, . . . are formed with widths slightly narrower than this width. During 7 and a half revolutions of the rotating drum, magnetic heads Aa and Bb run from the bottom to the top of the tape 1 in the direction of arrow B. Magnetic head Aa sends signals corresponding to tracks A1, A2, etc., and magnetic head Bb sends signals corresponding to tracks B1. , B2, etc., and it is assumed that the signals on the other track side cannot be reproduced. This is magnetic head Aa, Bb
According to a known technique, this can be easily achieved by making a difference in azimuth angle between the two to be larger than a predetermined value.

When the magnetic heads Aa and Ba alternately run within the 11 ranges on the magnetic tape 1, the diagonal line part G1 in track A1 is reproduced by the magnetic head Aa, and the point group part b1 in track B1 is reproduced by the magnetic head Bb alternately. be done. This state is a correct still image playback state, and no noise appears on the screen of the image playback device. For example, when the magnetic head Aa traces within the range 11 on the magnetic tape 1 in the direction of the arrow 13, the reproduction signal first reproduces the signal a2' on the track A2, and
The level of the signal drops and appears as noise on the screen when it passes through d2. After passing through the position d2 and passing through the position d1 where noise also appears, the signal of the a1 portion is reproduced. Therefore, it is only necessary that the timing at which the signal passes through portions d2 and d1 is at a time when the signal does not appear as noise on the screen of the image reproducing device. For example, in FIG. 2, which shows one frame of an image reproduction signal driven by an electron beam, it is assumed that the range 18 corresponds to the entire image reproduction signal, and the part 19 is the vertical synchronization signal period. The retrace period of the vertical scanning corresponds to approximately a portion 19, and there is no horizontal scanning signal, and no image appears on the screen in this portion 19. T1 immediately before and after the period T2 of the vertical synchronization signal section 19
The area within the 17 areas outside the period d is the range that appears on the screen of the image reproducing device, and is indicated by d in Figure 1 above.
If the magnetic tape 1 is positioned so that the portions 1 and d2 are within the periods T1 and T2, a still image without noise appearing on the screen can be reproduced. If the magnetic tape 1 is to the left of the state shown in FIG. 1, d1,
The position d2 rises and, for example, noise appears at position 22 in FIG. Conversely, if the tape moves to the right and the tape remains stationary, the points e1 and e2 where the playback signal of the magnetic head Bb falls will come down to 21 on the screen 17.
Noise appears at positions such as . Therefore, in order to reproduce a noise-free still image, the d1 and d2 portions and the e1 and e2 portions where the signal level falls are set to the above-mentioned period T.
1, it is necessary to keep it within T2.

To feed the next frame, feed the magnetic tape 1 in the direction of the arrow 10 until it reaches the magnetic head on the rotating drum 7.
The trajectories drawn by Aa and Bb can be relatively shifted to the 12 range.The 11 range and the 12 range have the same relative relationship between the magnetic tape 1 and the rotating drum 7, and the tracks for obtaining the reproduced image signal are the same. A1, B1 to A
2, the state is the same except for moving to B2.
FIG. 3 shows the process in which the traveling trajectories of the magnetic heads Aa and Bb on the magnetic tape 1 move from position 11 to position 12 in FIG. 1. When considering the trajectory of 11 ranges,
The lower ends of each of the magnetic heads Aa and Bb run on the Q1 line, and still image reproduction signals are obtained from a1 and b1 in FIG. Now, when the magnetic tape 1 starts running, if the magnetic tape 1 starts to accelerate when the lower end of the Aa head reaches point P1, then the magnetic tape 1 starts to run.
The locus of the lower end of Aa relatively draws the broken line Q2.
Thus, during this period, the recorded signal in the shaded area a11 is reproduced. After passing the P2 point, the magnetic head
Draw a trajectory where the lower end of Bb becomes Q3, which is drawn from point P3 to point P4. During this time, the signal b11 on the track B1 indicated by the range of points is reproduced. Magnetic tape 1 on the way from point P3 to point P4
If the speed matches the speed during normal reproduction, the magnetic tape 1 is not accelerated from that point on and runs at a constant speed. Trajectory Q after passing point P4 and between point P5
4 is the trajectory of the lower end of magnetic head Aa, track A2
The upper perspective part a12 is reproduced. The tape 1 begins to be decelerated midway through this period. P from P7 point
While the locus Q5 of the lower end of the magnetic head Bb between the 8 points is drawn, the range b12 of the point group on the track B2 is reproduced, and when the tape 1 stops exactly when it reaches point P8, from then on the lower end of the head is drawn at Q6. The magnetic heads Aa and Bb alternately run within the range 12, and the 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 there is no noise when feeding one still image frame. It turns out that it doesn't appear on the screen. Figure 4 shows that from the range of 11, 1
The state during which the locus moves to range 2 is shown with the time axis as the horizontal axis. Drawing a shows how one of two magnetic heads is selected, and drawing b shows how the tape running speed changes. Aa,
Time T1 for each magnetic head of Bb to operate once,
T11, T12, and T2 correspond to the playback time of one frame of an image during normal playback, and the time values are all equal. 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 still image playback circuit 6 that performs frame-by-frame advance shown in FIG.
This is a device for scanning the magnetic tape 1 as described above, and the magnetic tape 1 is advanced by one frame in a time period of about two frames, and when the magnetic tape 1 is stopped, the nozzle does not appear on the screen. This is a circuit that stops the magnetic tape 1.

The braking mechanism 4 is a means necessary for stopping the magnetic tape 1 during frame-by-frame reproducing operation, and for example, when the driving torque of the motor is about 800 grcm,
This is to generate a braking torque of about 20 grcm, and applying this small amount of braking torque is an essential means for accurately stopping the vehicle.
FIG. 5 shows the structure of the still image reproduction circuit 6, braking mechanism 4, capstan motor and its drive circuit 3, and FIG. 6 shows a time chart for explaining the operation of this circuit. Further, FIG. 7 shows a schematic configuration of the capstan motor and the braking mechanism 4 of the present invention.

The still image reproducing circuit 6 in Fig. 5 has a frame feed signal.
CS, head switching signal PG, and control pulse signal CN are input. 51 is a three-input AND gate circuit, 62 and 65 are flip-flop circuits, and 63, 64, 66, and 67 are one-shot circuits, and 62 to 67 are set or triggered when the input voltage changes from low to high voltage. shall be. When a set input S is input to the flip-flop circuit, the output Q() changes to a high (low) potential, and when a reset input (R) is input, the output Q() changes vice versa. In addition, the one-shot circuit operates when the trigger input (T) changes from low to high potential, and outputs Q() for a predetermined period of time.
Assume that a high (low) potential appears at 62-67
It is assumed that everything is in the reset state at the beginning.

Now, at the moment of time to, the playback head starts from Bb.
Assume that the voltage has been switched to Aa, and that the PG signal is obtained from the position detection circuit as a low-to-high potential signal. If the frame feed signal CS is obtained at a high potential just before the to time, the braking mechanism 4 starts operating via the amplifier 68. Further, since the output of the one-shot circuit 63 remained at a high potential, the output of the AND gate circuit 61 changes to a high potential immediately after time to, and the flip-flop circuit 62 is set. The one-shot circuit 64 triggered by this output Q provides a Q output for a predetermined period TD. This output provides a motor drive signal to the capstan motor drive circuit 3. The capstan motor continues to be accelerated until time t1 when the TD period ends, and after time t1, the motor stops accelerating and runs at a substantially constant speed. The one-shot circuit 63 is simultaneously driven by the setting of the flip-flop circuit 62, and operates for at least two frame periods during frame forwarding, and its output becomes a low potential, disabling the AND gate 61, and , the reset input R side of another flip-flop 65 is made free, allowing it to be set.

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 still image reproduction circuit 6 as CN. This control pulse is applied to the lower end of the magnetic tape 1 as shown in FIG.
This is written for each set of two tracks when the magnetic heads Aa and Bb play back, as shown in FIG. In reality, the control pulse is not generated in the form of a pulse; for example, it is magnetized over 50% of the length of the tape corresponding to one frame period, and the control pulse is generated by picking up the change in the location where the tape changes from a non-magnetized state to a magnetic state. used as. Such control signals correspond to C0, C1, etc. in FIG. Now, when the control signal CN is obtained at time t2, the flip-flop circuit 65 is set, and as a result, the one-shot circuit 66 is activated. The output of the one-shot circuit 66 is at a low potential during TC until time t3, and returns to a high potential again at time t3. At this time, the one-shot circuit 67 is triggered and a high potential appears at the Q terminal during the period TB.
Assuming that this output is lost at time t5, the Q output of the one shot circuit 67 during this period TB is used as a braking signal for the capstan motor. Assuming that the magnetic tape 1 just comes to a standstill at time t5, 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 Figure b. The position of the tape movement amount O is when the magnetic heads Aa and Bb travel in the range 11 in Fig. 1, and the position where the tape stops after moving 12 is 12
This corresponds to the case where two magnetic heads run in the range of .

The driving time of the one-shot circuit 64 indicates the time during which the motor accelerates, and the output time width of the one-shot circuit 66 indicates the delay time from when the control signal comes to when the braking signal is applied to the motor. . The control signal CO in Fig. 1 is intended to cause the magnetic heads Aa, Bb, and tracks A1 and B1 to correspond as reference position signals to be traced during normal playback, but the positions on the tape are not shown in the figure. It does not have to be located at a position that has a correlation such as , but may be located at an arbitrary position.
This is determined by the correlation between the position of the rotating drum 7 and the position of the reading head 5.
There is no restriction that Aa is always recorded at the bottom end of the track traced; in short, it is sufficient that it is recorded at a predetermined position for each frame. Therefore, the time t2 at which the control signal arrives may be before t1, and in this case, the one-shot circuit 6 continues until time t3.
6, the time output width becomes longer. But t2
The time must be earlier than the t3 time. Otherwise, when the magnetic tape 1 is stopped, it will not be possible to stop the magnetic tape 1 at a position where a noise-free still image will be reproduced on the screen. The output time width of the one-shot circuit 67 in FIG. 5 determines the braking time of the capstan motor, and is made slightly shorter than the output time width of the one-shot circuit 64 so that the braking signal is released when the motor has just stopped. It is necessary to adjust as much as possible. The output time width of the one-shot circuit 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 the period in which frame forwarding is not performed.

Reference numeral 2 in FIG. 5 assumes a brushless transistor motor as the capstan motor, and position sensors 27, 28, 29 for detecting the positions of its drive armature coils 24, 25, 26 and field rotor. It shows. FIG. 3 shows the main structure of the motor drive circuit, and 31 is a preamplifier section which receives signals from the position sensors 27 to 29 and selects and drives the transistors to be driven in the drive inverter section 32. At the same time, the DC side current of the inverter section 32 is detected, for example as a voltage drop across the resistor 33, and controlled so as to match the command input value. In this case, the outputs of the one-shot circuits 64 and 67 in the still image reproduction circuit 6 described above are received as a current command signal S, and the current is controlled to this value. Further, when a high potential signal is received at the forward/reverse switching signal terminal (F/R), the inverter section 32 functions to reverse the motor. Therefore, the reverse mode is set only while the one-shot circuit 67 is outputting, but since the motor was previously rotating in the forward direction, the reverse braking mode is set. In this way, the motor drive circuit 37 receives the drive signal DR and the braking signal BL, rapidly accelerates and decelerates the motor, and drives the capstan shaft by a predetermined angle. The operation of the drive section of a transistor motor is well known, so we have avoided a detailed explanation of it, but it is the same when using a DC motor such as a coreless motor as a capstan motor, and in order to rapidly accelerate and decelerate, it receives drive and braking signals. A circuit that operates 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 can be considered.

As an example of an element for operating the braking mechanism 4, a DC solenoid coil energized by the energization of the amplifier 68 in the still image reproducing circuit 6 is shown in FIG. This coil is always excited while receiving the signal CS when performing frame-by-frame forwarding.
FIG. 7 shows a schematic configuration of a transistor motor section, a braking mechanism, and a speed detection mechanism as the capstan motor 2. Figure a shows the capstan shaft 20.
A sectional view taken along a plane passing through 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 has a ring shape. An armature coil 24 and coils 25 and 26 (not shown) are mounted on the stator magnetic plate 203, facing the main magnet 23 in the axial direction, and a position sensor (for example, a Hall element) is mounted on the stator magnetic plate 203.
It is fixed together with 27 etc. A braking mechanism 4 is provided on the side surface of the rotating magnetic plate 200, and a support fitting 42 provided with a brake pad 43 is rotatably attached to a stationary shaft 46. When the solenoid 41 is de-energized, the support fitting 42 is pulled to the position indicated by the broken line by the spring 44, and the brake pad 43 is pulled by the rotating magnetic plate 20.
It doesn't hit 0. 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 weak braking torque that is always substantially constant in the direction of rotation is applied to the motor.

Next, the effect of the weak braking torque by the braking mechanism 4 will be described. In FIG. 6, when the tape 1 just stops at time t5, the correct stopping position can be secured. However, if the starting and braking times of the motor 2 are controlled almost constant as in the circuit shown in Figure 5, the load torque of the capstan shaft, motor shaft, tape take-up reel shaft, and running resistance of the tape running path will be reduced. Since it takes a different value each time and it is practically impossible to make this value a constant value, the speed at which the motor rotates at a constant speed differs each time frame feeding is performed. Therefore, if the speed of the capstan motor when rotating at a constant speed is higher than the ideal speed, braking will stop and the motor will still be in the normal rotation state, and if the speed is low, the braking mode will be canceled and the motor will be in the reverse rotation state. However, it has not stopped.

The speed states of dashed dotted lines 610 and 630 in FIG. 6b are faster and slower than ideal, and after time t5, the braking torque of the braking mechanism 4 causes the vehicle to stop around time t6. do. During this time,
The magnetic tape movement keys 1 correspond to 650 and 660 in FIG. 6a, respectively. If there is no braking torque, the speed (VT) will be the 6th after time t5.
The movement distance 1 of the tape changes as indicated by dotted lines 620 and 640 in figure b, and the distance 1 of the tape moves is indicated by dotted lines 670 and 680 in figure a.
It will look like this. Noise permissible periods T1 and T2 to prevent noise from appearing on the screen of the image reproduction device
is shown in Fig. 2, and the permissible width of the tape moving distance 1 corresponding to this permissible range is shown in Fig. 6 a.
When shown as lT1, lT2, 650,660
No noise appears in the case of the dashed line, but 67
Noise appears in the state of the dotted line of 0,680. In other words, due to the presence of braking torque, the load torque on the capstan shaft increases, and after the braking force to the motor is lost, the motor stops rapidly even if it is rotating in the forward or reverse direction, and the tape becomes ideal. It can be stopped at a nearby location. When this braking torque is not present, the tape stop position varies and it is difficult to reproduce frame-by-frame still images without noise.

Since the braking mechanism 4 increases the load torque of the capstan shaft, when the resistance component of the shaft is r,
This value increases. Therefore, when the inertial component is τ, the mechanical time constant τ/r has a small value. Therefore, if this condition continues during normal driving, rotational unevenness will increase and there is a possibility that the quality of reproduced images will deteriorate. Furthermore, since an increase in the resistance component r increases the driving torque of the capstan shaft and thus the driving current, it is desirable to suppress this increase in order to achieve power saving during normal operation. Therefore, the braking mechanism 4
is configured to operate only when playing still images. In the above explanation, we have explained the operation when moving still images frame by frame. However, if you want to stop and view any image while obtaining an image from the tape under normal running conditions, you can perform the operations after time t1 in FIG. 6. In other words, it goes without saying that the presence of this braking mechanism 4 is effective even in a still mode in which still images are obtained from normal driving, rather than frame-by-frame forwarding.

Another embodiment of the braking mechanism is shown in FIG. The plate spring material 44 supported by the fixed part 46 supports the brake yoke 42 made of a magnetic material, but the main yoke 42
A coil 41 is wound around the coil 41 to serve as an excitation coil.
Further, a thin brake pad 43 is provided on the side of the brake yoke 42 facing the rotating magnetic plate 200 of the capstan motor, and there is a slight gap on this opposing surface when the coil 41 is not excited. When a current is passed through the coil 41, a magnetic flux is closed in the path shown by the broken line in FIG. 8a. This is York 42
An attractive force is generated between the brake pad 43 and the rotating magnetic plate 200, and the brake pad 43 comes into contact with the rotating magnetic plate 200. As a result, a predetermined load torque can be applied to the rotational direction of the rotating magnetic plate 200. The braking mechanism 4 functions regardless of whether direct current or alternating current is passed through the coil 41. Instead of the rotating magnetic plate 200, the braking mechanism will function wherever it is placed on the rotating body of the motor and made of a magnetic material. It goes without saying that the surface on the rotating body that the brake pad 43 comes into contact with does not have to be a flat surface like the example shown in FIG. 8, but may be any curved surface. Like this,
Since the braking mechanism can be provided as a part of the motor structure, there is no need for a separate solenoid or spring as in the example shown in Figure 7, and the system can be miniaturized so that it can be included in a part of the motor structure. Another advantage is that it can be made into any shape.

Still another embodiment of the braking mechanism is shown in FIG.
41 excitation coil, 42 brake yoke, 43
The eighth point is that the brake pads are always fixed stationary.
This is different from the embodiment shown in the figure. 44 Magnetic leaf spring material is
Here, it is fixed to the rotating magnetic plate 200 and rotates in a ring shape, but if the coil 41 is in a non-excited state, it is at the position indicated by the broken line in FIG. 9a, and no braking torque is generated. When the coil 41 is energized, the leaf spring material 44 is attracted to the position indicated by the solid line, and comes into contact with the brake pad 43 to obtain control torque. Leaf spring material 4
44' in Fig. 9b to facilitate the deformation of 4.
In this case, it is practical to provide holes such as the following, and the plate spring material 44 used is sufficiently thin.

While adopting the configuration shown in FIG. 9, a hysteresis magnetic material with a large coercive force is used in the leaf spring material 44 in order to generate braking torque while maintaining the leaf spring material 44 at the position indicated by the broken line in FIG. May be used. By excitation of the coil 41, a hysteresis brake acts between the coil 41 and the leaf spring material 44, and a sufficiently practical braking torque can be obtained. The gap between the brake yoke 42 and the leaf spring material 44 may be made sufficiently short, but in order to obtain a large braking force, a plurality of components centered around the brake yoke 42 may be arranged in the rotational circumferential direction of the rotating magnetic plate 200. Just set it up. Since a hysteresis brake is applied instead of using an eddy current brake, braking force can be obtained until the motor almost stops, so a braking torque close to that of mechanical contact can be obtained. There are no problems such as mechanical deformation or warping, resulting in long life and high reliability.

When using the hysteresis torque as the braking torque of the braking mechanism, the method shown in FIG. 10 can also be considered. In the embodiments described so far, the armature coil 24 of the motor is placed on the stator magnetic plate 203'',
An alternating magnetic flux due to rotation from the field magnet 23 was passing through this plate. Therefore, losses due to eddy current and hysteresis occur in this plate, reducing efficiency.
In order to avoid this, the configuration of the motor is shown in Fig. 10, in which a 203'' magnetic plate 203', which functions as a stator magnetic plate, is rotated.The 203'' stator plate, which supports the coils, etc., is made of non-magnetic material. Consists of. A hysteresis plate 200' is fixed in a ring shape to the back surface of a second rotating magnetic plate 203', and the braking mechanism 4, which is opposed to the brake yoke 42 with a slight gap in between, performs the hysteresis braking shown in Fig. 9. It has the same functions as the embodiment. braking mechanism,
This example shows that the field magnet 23 can be placed not only on the side of the plate 200 that supports it but also on the opposite side, and shows that the present braking mechanism has a high degree of freedom in its placement location.

In addition to this, it has a hysteresis material as a rotor,
A rubber ring or the like may be fitted onto the rotating shaft of the hysteresis brake, which is composed of a stator having an excitation coil consisting of a plurality of poles, and this may be pressed against the rotating portion of the capstan motor at all times. Hysteresis torque works only when the excitation coil works, but this is equivalent to the function of the braking mechanism described above.

As is clear from the above explanation, the braking mechanism of the present invention can accurately stop the magnetic tape at a predetermined position when stopping the magnetic tape during frame-by-frame playback, and its structure drives the capstan shaft. Since the device is configured to apply a braking force to the magnetic material in the motor, it is possible to set the device at any desired position in the motor, resulting in a structure with a high degree of freedom.

Also, since it only works during frame-by-frame playback and does not work normally, it does not increase loss during normal tape running.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a still image reproducing device for magnetic recording tape that includes the braking mechanism of the present invention, and FIGS. 2, 3, and 4 illustrate the operation of the still image reproducing device during frame advance. Figure 5 is a configuration diagram of the still image playback circuit and drive circuit during frame-by-frame forwarding, and Figure 6 is a diagram for
This figure is a diagram for explaining the operation of the circuit of FIG. 5. Figures 7a and b are sectional views and plan views showing one embodiment of the braking mechanism of the present invention, Figures 8a and b, Figures 9a and b, and Figure 10 are views of other embodiments of the invention. FIG. 2 is a cross-sectional view and a plan view. In the figure, 4 is a braking mechanism, 20 is a rotor, 42
43 is an electromagnet, 43 is a brake pad, 44 is a leaf spring, and 200 is a rotating magnetic plate. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A disc-shaped magnetic plate integrally fixed to the rotor, and a brake pad applied to the rotating magnetic plate by the magnetic force acting on the rotating magnetic plate to apply braking torque to the rotor. A motor comprising an electromagnet and a control means for applying current to the electromagnet to always apply a constant braking torque during a frame-by-frame driving operation. 2. A patent claim in which the disk-shaped magnetic plate is a rotating magnetic plate constituting the yoke of the rotor, and the electromagnet is suspended by a spring material and is configured so as not to generate frictional force when not energized. range 1
The motor described in section. 3 A disc-shaped magnetic plate is made of spring material,
Claim 1, wherein the electromagnet is configured so that no frictional force is generated when the electromagnet is not energized.
The motor described in section.