JPS5920175B2 - magnetic playback device - Google Patents

Description

[Detailed description of the invention]

In a helical scan type VTR (magnetic recording/playback device), by using a time axis correction device, you can adjust the tape speed by changing the tape running speed while keeping the rotating magnetic head rotating at the frame frequency. You can perform still or slow motion playback, or fast motion playback at the selected playback speed. Therefore, VTRs have been developed that allow so-called joystick control, in which the tape runs at a speed that corresponds to the angle of the lever or knob, and can therefore be played back at a speed that corresponds to the angle of the knob. . In other words, this VTR has a joystick control knob in addition to the playback button, and when you operate the playback button, it enters the normal playback mode, and when you switch to joystick control and turn the control knob, you can change the direction and angle of rotation. The tape runs in the corresponding direction and speed and can be played back in any direction and speed. According to such a VTR, therefore, any field can be easily searched for, so that videotape editing can be performed effectively. However, in the past, tape running was controlled by linking a variable resistor or a multi-contact switch to the joystick control knob, which resulted in many failures due to poor contact, and problems with longevity and reliability. There is a drawback that the price is low. Furthermore, when approaching the edit point,
The tape speed is gradually slowed down to achieve a stale state at the editing point, but conventionally it has been difficult to find out which rotational angle position of the knob is the stale state. Therefore, the operation is complicated and there are also disadvantages of poor operability. In view of these points, the present invention aims to improve reliability and operability. Therefore, in the present invention, a joystick control knob is rotatably provided, and the running direction and running speed of the tape are controlled in accordance with the rotation direction and rotation angle of the knob, and when switching from the playback button to joystick control, Regardless of the rotation angle position of the control knob, the tape will run at the speed at which it is being played.
When the control knob is turned, the playback speed is accelerated or decelerated. An example of this will be explained below. In Figure 1, 1
, 2 designate rotating magnetic heads, which have an angular spacing of 180 times from each other and are rotated at a frame frequency by a servo circuit 3 in synchronization with vertical synchronization pulses from an external synchronization disk. Further, 4 indicates a magnetic tape, on which the video signal is
One field is recorded as one diagonal magnetic track, and a control pulse is recorded at the frame frequency at the edge of the track. The tape 4 is then taken out from the supply reel 5, wound obliquely over an angle range of approximately 1800 degrees with respect to the rotating circumferential surfaces of the heads 1 and 2, and then wound onto the take-up reel 6. Note that 7 is a capstan, 8 is a pinch roller, 15 and 16 are reel motors, and 17 is a capstan motor. The reproduced signals from the heads 1 and 2 are outputted to an output terminal 10 through a reproduction circuit 9. Further, 20 indicates a control circuit, which controls the motors 15 to 17 and the pinch roller 8.
is controlled to control the running of the tape 4. That is, when the speed of the tape 4 is faster than 0 and lower than the recording speed, an alternating voltage with a frequency corresponding to the tape speed is applied from the control circuit 20 to the motor 1 through the amplifier 27.
At the same time, voltage is supplied from the control circuit 20 to the plunger 18 through the amplifier 28, and the pinch roller 8 is brought into contact with the capstan 7. Therefore, the tape 20 is run at a predetermined speed by the capstan drive.
At this time, voltage is supplied from the control circuit 20 to the motors 15 and 16 through the amplifiers 25 and 26, and tension is applied to the tape 4. Further, in this case, the polarity of the alternating voltage supplied to the motor 17 is switched, and the running direction of the tape 4 is switched. Furthermore, if the speed of tape 4 is faster than that during recording,
Voltage is no longer supplied to the motor 17 and plunger 18, voltage is supplied only to the motors 15 and 16, and the tape 4 is run by the reel drive. Note that the running speed and direction of the tape 4 in this case are determined by the voltages supplied to the motors 15 and 16. Note that 21 is a play button, 22 is a stop button, and 23 is a mode switch for switching between normal operation and joystick control. 30 indicates a mechanical section for joystick control. That is, the rotating shafts 31 and 41 are rotatably supported on the same axis, and an electromagnetic clutch 33 is provided between the rotating shafts 31 and 41. 41 are connected. Further, a knob 34 is provided at the free end of the rotating shaft 31, and a photo disk 35 is further provided on the rotating shaft 31. The photo disk 35 has a disk shape and has, for example, 120 light shielding portions 35A radially around the photo disk. and,
Two photocouplers 36, 37 are provided such that their light emitting element and light receiving element sandwich the light shielding part 35A of the photo disk 35. Therefore, when the disc 35 rotates, the couplers 36, 37 are connected by the light shielding part 35A. The light is intermittent, and an alternating signal having a number of cycles (number of pulses) proportional to the rotation angle of the disk 35 is taken out from the couplers 36 and 37. In this case, the angular spacing of the couplers 36, 37 is selected such that the alternating signals from the couplers 36, 37 have a phase difference of 900 degrees with respect to each other. Further, an arm 4 is attached to the rotating shaft 41.
2 is provided, and a spring 43 is provided between this arm 42 and the chassis, and the arm 42 is defined at a neutral rotation angle position. Further, a photocoupler 44 is provided so as to sandwich the arm 42 when the arm 42 is in this neutral position. Further, a stopper 45 is provided to limit the rotation angle range of the arm 42. The alternating signals obtained from the couplers 36 and 37 by turning the knob 34 are supplied to the Schmitt circuits 56 and 57 and shaped into rectangular wave signals, and the rectangular wave signals from the Schmitt circuit 56 are sent to the switch circuit 53. The signal is supplied to, for example, a 5-bit 25-base presettable reversible counter 51 as its counting input. Also, at this time, the rectangular wave signals from the Schmitt circuits 56 and 57 are supplied to the D flip-flop circuit 52,
When the knob 34 is turned clockwise and counterclockwise, a signal of ``0'' or 111, that is, a signal indicating the rotation direction of the knob 34, is formed, and this direction signal is , is supplied to the reversible counter 51 as a control signal for addition counting or subtraction counting. In this example, it is assumed that when the knob 34 is turned clockwise, the counter 51 performs addition counting. When the power is turned on,

[00000] is reset. Therefore, if the knob 34 is turned clockwise from the state in which the counter 51 is set, the position shown in FIG.
As shown in , the count value of the counter 51 is

[00000]
It increases by [1] from. Further, as the knob 34 is turned counterclockwise, the count value of the counter 51 untablos to [11111], and thereafter decreases by [1]. The count value of this counter 51 is then supplied to a decoder 61. In the decoder 61, as shown in FIG. 2B, the content of the most significant digit of the count value of the counter 51 is

In the case of [0], that is, when the counter 51 is not untablowing,
The last four digits of the calculated value of the counter 51 are sent directly to the decoder 61.
When the contents of the most significant digit of the count value of the counter 51 is [1], that is, when the counter 51 untablows, the contents of the lower four digits of the count value of the counter 51 are inverted and output from the decoder 61. be done. Therefore, even if the count value in the output of the decoder 61 after an untable blow occurs, the most significant digit is [1] and the lower four digits are equal to the output state of the addition count even if the counter 51 is in the subtraction count mode. becomes. The output of this decoder 61 is then sent to the control circuit 20.
The running direction of the tape 4 is controlled by the most significant digit, and the speed of the tape 4 is controlled by the lower four digits.
In this case, for example, the most significant digit is

At [0], the tape 4 is run in the forward direction (same direction as during recording), and at [1]
When , the vehicle is driven in the opposite direction. Also, the larger the value of the last four digits is, the faster the speed of the tape 4 is. For example, the last 4 digits are

At [0000], the tape 4 stops, and at [0110], the tape 4 is at the same speed as when recording, and at [1
111], the maximum speed is reached. In addition, line 2
4 is a line 70 for presetting the counter 51;
is a display device for displaying the playback speed (tape speed). During normal playback, the mode switch 23 is switched to the normal playback side, and the playback button 21 is operated. Then, based on the reproduction operation, voltage is supplied from the control circuit 20 to the motors 15 to 17 and the plunger 18, and the tape 4 is caused to run in the forward direction by the capstan drive at the same speed as during recording. Accordingly, the magnetic tracks of the tape 4 are scanned by the heads 1 and 2 to reproduce a video signal, and this signal is taken out to a terminal 10 through a reproduction circuit 9. In other words, normal playback is performed. In order to carry out joystick control, the switch 23 is switched to the joystick control side. Then, a preset signal is supplied from the control circuit 20 to the counter 51 through the line 24, and the counter 51 becomes [0011].
0]. Since this value is a value that causes the tape 4 to run in the forward direction at the same speed as during recording, normal reproduction is performed. Therefore, even if the switch 23 is switched from the state where the TR is in the playback mode by operating the playback button 21 to the joystick control, the same playback mode will continue. When the knob 34 is turned clockwise in this state, the count value of the counter 51 increases from the preset value [00110] in accordance with the rotation angle of the knob 34. The tape 4 travels in the forward direction at this speed. Furthermore, when turned counterclockwise, the count value of the counter 51 decreases from the preset value [00110] in accordance with the rotation angle of the knob 34, so as the rotation angle of the knob 34 increases, the speed of the tape 4 decreases. → Stop → Low speed in the opposite direction → Constant speed in the opposite direction → High speed in the opposite direction. Therefore, when the switch 23 is set to joystick control and the knob 34 is turned clockwise, first motion playback is performed in the forward direction at a speed corresponding to the rotation angle, and when the knob 34 is turned counterclockwise. When the rotation angle changes, forward slow motion playback → stay playback → reverse slow motion playback →
Reverse constant speed playback → reverse first motion playback is performed. That is, when switching from the playback mode using the playback button 21 to joystick control, the playback mode continues regardless of the rotational position of the knob 34 at that time, and when the knob 34 is turned, the rotational position of the knob 34 at the time of switching is used as a reference. At a speed (and direction) corresponding to the rotation angle, the tape 4 changes to the speed (and direction) during normal playback. When the count value of the counter 51 reaches [01111] by turning the knob 34 clockwise, and when the count value of the counter 51 reaches [01111] by turning the knob 34 counterclockwise, the count value of the counter 51 becomes [01111].
When the count value of 1 reaches [10000], that is, when the last four digits in the decoder 61 become [1111], this is detected by the detection circuit 62, and the detection output is sent through the OR circuit 66 and further through the amplifier 67. is supplied to the clutch 33, and the clutch 33 operates to rotate the rotating shaft 31.
A rotating shaft 41 is connected to the rotating shaft 41 . Therefore, by turning the knob 34, the arm 42 also rotates, and the arm 42 separates from the coupler 44, so that an output is provided to the coupler 44. The output of the coupler 44 is supplied to the AND circuit 68 through the shaping amplifier 54, and the detection output of the detection circuit 62 is supplied to the AND circuit 68, so that an output is obtained from the AND circuit 68, and this AND output causes the switch to be activated. Circuit 53 is turned off. Therefore, the count input is no longer supplied to the counter 51, and the count value of the counter 51 becomes [
01111] or [10000]. Note that in this state, the last four digits in the decoder 61 are [1
At 110, the tape 4 is at maximum speed in the forward or reverse direction, ie, in fast forward or rewind. At this time, the rotation of the knob 34 causes the arm 42 to
Since the knob 34 separates from the coupler 44 and hits the stopper 45, the knob 34 cannot be turned any further, just like when a variable resistor is turned all the way. That is, when the tape 4 is placed in a fast forward or rewind state by turning the knob 34, the knob 34 cannot be turned anymore. When the knob 34 is turned in the opposite direction from this state, the arm 42 enters the coupler 44, so the output of the coupler 44 cannot be obtained, and therefore the output of the AND circuit 68 cannot be obtained, so the switch circuit 53 is turned on. Become. Therefore, the count value of the counter 51 changes from [01111] or [10000] to the set value as the knob 34 rotates.

At this time, the detection output of the detection circuit 62 cannot be obtained, so the clutch 33
comes off. Also, the count value of the counter 51 is [00000
] As the speed of the tape 4 decreases, for example, the count value of the counter 51 decreases.

When it reaches [00000] or [11111], the tape 4 stops and enters the still playback state. In this case, when turning the knob 34 in the high-speed feed direction, the arm 42 hits the stopper 45, making the knob 34 heavy; however, when the knob 34 is turned in the opposite direction from that position, the arm 42 touches the coupler 44. Since the clutch 33 is disengaged, the rotation of the knob 34 at this time is light. Furthermore, the counter 51
The count value of

When it becomes [00000] or [11111], that is, the last four digits are [0000] in the decoder 61.
00], this is detected by the detection circuit 63, and the detection output is supplied to the clutch 33 through the OR circuit 66 and further through the amplifier 67. At this time, the tape 4 stops running and is in a still playback state. Therefore, when the knob 34 is turned to enter stay playback, the clutch 33 works to rotate the rotating shaft 41 against the spring 43, and the arm 42 hits the stopper 45, so that the rotation of the knob 34 is stopped. becomes heavy. When the knob 34 is further turned, the count value of the counter 51 changes and the detection output of the detection circuit 63 is no longer obtained, so the clutch 33 is disengaged and the rotation of the knob 34 becomes light again. Therefore, in this case, knob 3
When turning 4, knob 3 corresponding to still playback
At rotation position 4, the rotation of the knob 34 becomes slow for a moment, and it just acts like a click mechanism. Further, the output of the decoder 61 is supplied to a display device 70 to display the playback speed. That is, this display device 70 is composed of, for example, 17 light emitting diodes 71A to 71Q arranged in a line, and during still playback, only the center diode 711 lights up, and during forward playback, the light emitting diodes 71A to 71Q light up, and during playback in the forward direction, the light emitting diodes 71A to 71Q are arranged in a line, and during playback in the forward direction, the light emitting diodes 71A to 71Q are arranged in a row, and the light emitting diodes 71Q are turned on in the forward direction. from diode 711 to diode Tl
A predetermined number of diodes 711 to 71Q light up at maximum speed (fast forward), and on the other hand, when playing in the reverse direction, a predetermined number of diodes 711 to 71A light up corresponding to the playback speed. When the maximum speed (rewind) is reached, the diode 71 lights up.
~71A are all lit, thus displaying the playback speed and playback direction. Note that when the switch 23 is switched to the normal playback side, the normal playback mode is entered. Thus, according to the present invention, joystick control can be performed without using a variable resistor or a multi-contact switch, thereby improving the life and reliability. Then, when turning the knob 34 to enter still playback, a click can be obtained as the knob 34 rotates.
You can confirm that this is still playback by looking at the playback screen. In the above-described embodiment, even when switching from the playback mode using the playback button 21 to the joystick control, the playback mode continues, so operability is good and the desired edit point can be easily searched for. Furthermore, since the playback speed and direction are displayed on the display device 70, the necessary playback speed and direction can be easily obtained. In addition, in the above description, electromagnetic detection means may be used instead of the photocouplers 36, 37, and 44. Alternatively, the switch 23 may not be provided, and when the playback button 21 or the knob 34 is operated, priority is given to the operation of the operated button.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an example of the present invention, and FIG. 2 is a diagram for explaining its operation. 4 is a magnetic tape, 20 is a control circuit, 30 is a joystick control mechanism, and 51 is a presettable reversible counter.

Claims (1)

[Claims] 1. The rotation direction and rotation angle of a rotatably provided knob are detected, and a detection output of the number of pulses corresponding to the rotation angle is supplied to a reversible counter as its counting input,
A magnetic reproducing device in which a detection output of the rotational direction is supplied to the reversible counter as a control signal for the counting direction, and the magnetic tape is run at a speed corresponding to the count value of the reversible counter. A detection means for detecting that a numerical value has reached a predetermined limit value, a means for stopping counting of the reversible counter based on the output of the detection means, and a means for restricting rotation of the knob based on the output of the detection means. A magnetic reproducing device with.