JPH059858B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic recording/reproducing apparatus capable of stable high-speed reproduction of magnetic tapes having different tape speeds during recording. In recent years, magnetic recording and reproducing devices (hereinafter referred to as
(VTR) has been realized. In such a VTR, the running speed of the magnetic tape is different between short-time recording and reproduction and long-time recording and reproduction. By the way, in general, with a VTR, when you want to start playback from a desired scene in the middle of a television program recorded on magnetic tape,
The magnetic tape can be quickly run at high speed to a position where a desired scene is recorded. While the magnetic tape is running at high speed, the VTR is in playback mode, and although it is incomplete, it is possible to sequentially monitor the tape during high-speed running and to identify the desired scene. In order to further stabilize the reproduced image during high-speed running, the magnetic tape may be run at a speed that is an integral multiple of the tape speed during recording.In this case, the magnetic head crosses the recording track diagonally. The resulting noise component appears as a constant horizontal bar on the playback screen, making the playback image easier to see, and the desired scene can be searched more accurately. Capable of short-term recording/playback and long-term recording/playback
In the case of VTRs, the reproduced image when played back at high speed (hereinafter referred to as high-speed playback) is stable and easy to see, compared to magnetic tapes on which short-time recording is performed and magnetic tapes on which long-time recording is performed. To achieve this, it is necessary that the running speed of each magnetic tape be an integral multiple of the tape speed during recording. On the other hand, in order to perform such high-speed playback,
For example, if the current playback scene and the desired scene are far enough apart, the running speed of the magnetic tape is made high enough, and if the two are not far apart, the running speed is decreased. There is a need to be able to adjust the traveling speed of the vehicle, and there is a known technique in which the traveling speed can be adjusted by adjusting a lever or knob of a variable resistor. FIG. 1 is a block diagram showing an example of a conventional magnetic recording/reproducing device, in which 1 is a pulse detector, 2 is an amplifier, 3 is a frequency divider, 4 is a variable resistor, and 5 is an analog-to-digital converter ( (hereinafter referred to as an A/D converter), 6 is a frequency-to-voltage converter, 7 is a changeover switch, 8 and 9 are semi-fixed resistors, 10 is a comparator, 11
1 is a capstan motor drive circuit, and 12 is a capstan motor. Next, the operation of this prior art will be explained. In FIG. 1, a pulse detector 1 generates a pulse signal (hereinafter referred to as a rotation pulse signal) having a frequency proportional to the number of rotations of a castan motor 12.
The rotation pulse signal is amplified by amplifier 2 and sent to frequency divider 3.
supplied to The frequency divider 3 has a presettable counter,
When a magnetic tape (not shown) is run at the same tape speed during recording, the rotational pulse signal is not frequency-divided; on the other hand, when the magnetic tape is run at an integral multiple of the tape speed during recording, the rotational pulse signal is not divided. The frequency of the rotation pulse signal is divided by an integer. For this,
When the resistance value of variable resistor 4 is adjusted to the desired value,
A/D converter 5 generates a digital signal for the adjusted desired resistance value, and frequency divider 3 is preset by this digital signal to set the desired frequency division ratio. The rotation pulse signal from the frequency divider 3 is supplied to a frequency-to-voltage converter 6, and a voltage corresponding to the frequency of the rotation pulse signal is obtained. This voltage is supplied to a comparator 10 and compared with the reference voltage from the changeover switch 7. The changeover switch 7 is closed to the a side or the b side depending on the tape speed during recording of the magnetic tape.
For this purpose, the comparator 10 is equipped with a semi-fixed resistor 8 or 9 depending on the tape speed during recording of the magnetic tape.
A reference voltage obtained from Here, as a magnetic tape for short-term recording and playback, 2
A magnetic tape capable of recording and reproducing time (hereinafter referred to as 2-hour tape) and a magnetic tape capable of recording and reproducing 6 hours (hereinafter referred to as 6-hour tape) as a magnetic tape for long-term recording and reproduction will be explained. In the case of a 2-hour tape, the selector switch 7 is set to a.
The reference voltage from the semi-fixed resistor 8 is supplied to the comparator 10, and the rotating pulse signal is not divided by the frequency divider 3 in normal so-called 1x speed playback mode. The voltage converted by the frequency-to-voltage converter 6 and the reference voltage obtained from the semi-fixed resistor 8 are compared by the comparator 10, and the resulting difference voltage (for example,
When the capstan motor 12 is rotated via the castan motor drive circuit 11 by a zero volt (hereinafter referred to as a speed control signal), the semi-fixed resistor 8 is set so that the 2-hour tape runs in the 1x speed playback mode. It has been adjusted. The semi-fixed resistor 9 is similar, and in the 1x playback mode for a 6 hour tape, the comparator 10
The semi-fixed resistor 9 is adjusted so that the tape runs at 1x speed playback mode for 6 hours. In this way, the servo loop of capstan motor 12 → pulse detector 1 → amplifier 2 → frequency divider 3 → frequency-voltage converter 6 → comparator 10 → capstan motor drive circuit 11 → capstan motor 12 is formed, and the rotational speed of the capstan motor 12 is controlled so that the speed control signal of the comparator 10 becomes a constant voltage (for example, zero volts). Therefore, when the variable resistor 4 is adjusted to set a desired high-speed reproduction, the frequency divider 3 is preset to a predetermined value via the A/D converter 5, and the rotation pulse signal is frequency-divided. Therefore, the frequency of the rotation pulse signal decreases, and the voltage obtained at the frequency-to-voltage converter 6 changes more than in the 1x speed reproduction mode. The speed control signal from the comparator 10 is varied such that its voltage is a predetermined voltage (e.g. zero volts), i.e. it increases the frequency of the rotational pulse signal from the pulse detector 1 and the frequency divider 3 The rotational speed of the capstan motor 12 is increased so that the frequency of the rotational pulse signal frequency-divided by is equal to the frequency of the rotational pulse signal obtained from the pulse detector 1 in the single-speed reproduction mode. In this way, the magnetic tape runs at a high speed that is an integral multiple of the tape speed in the 1x playback mode. By the way, for both the 2-hour tape and the 6-hour magnetic tape, the frequency divider 3 adjusts the variable resistor 4 according to the digital signal from the A/D converter 5 accompanying the adjustment of the variable resistor 4. For example, if you adjust the resistance value of the variable resistor 4 so that the 3x speed playback mode is set for a 6-hour tape, the resistance value of the variable resistor 4 will be preset to the same value according to the resistance value of the variable resistor 4. Variable resistor 4 can be set to 3x speed playback mode even for tapes.
For a certain resistance value, the same double speed playback mode is set for both the 6-hour tape and the 2-hour tape. On the other hand, the capstan motor 12 has a limit to its rotational speed, and at the maximum rotational speed, a 15x playback mode can be obtained for a 6-hour tape.
With a 2-hour tape, only 15 x 2/6 = 5x speed mode can be obtained. Therefore, even if the variable resistor 4 is adjusted to a resistance value higher than the 5x playback mode for a 2-hour tape, the rotational speed of the capstan motor 12 will not increase accordingly;
This means that only double speed playback mode is available. Now, assume that the resistance value of the variable resistor 4 can be adjusted by operating a lever, and the relationship between the displacement of the lever and the double-speed playback modes for 6-hour tapes and 2-hour tapes is shown in Figure 2. Become. In Fig. 2, the amount of lever displacement is e ₁ , e ₂ ,...
e ₈ , and to simplify the explanation, it is assumed that odd-numbered speed playback is possible. For the 6-hour tape, the amount of lever displacement is 0.
Assuming that from e ₁ is played at 1x speed, from e ₁ to e ₂ is played at 3x speed, and from e ₇ to e ₈ is played at 15x speed, for a 2-hour tape, the amount of lever displacement is 0 to e ₁ is played at 1x speed, e ₁ to e ₂ is played at 3x speed, and e ₂ to e ₈ is played at 5x speed. In this way, for a 2-hour tape, the area of the displacement of the lever (of course, it is not limited to the lever, it can also be adjusted with the knob, and in this case it will be the rotation angle of the knob) for each double speed playback is non-uniform. As a result, the resolution becomes unbalanced with respect to the setting of double-speed playback, and the adjustment means of the variable resistor 4 cannot be used effectively. Further, in the 2-hour tape, if the displacement of the lever of the variable resistor 4 is set, for example, between e ₇ and e ₈ , then at this time, the displacement of the lever of the variable resistor 4 is set between e 7 and e 8.
Since this can only take the number of revolutions at 5x speed reproduction, the frequency divider 3 will provide a rotation pulse signal with an abnormally low frequency. For this purpose, comparator 10
An abnormal voltage difference occurs from the capstan motor 1.
2 will be supplied. The purpose of the present invention is to eliminate the drawbacks of the above-mentioned prior art,
An object of the present invention is to provide a magnetic recording and reproducing device that can make the adjustment range of a variable resistor uniform for each double speed reproduction mode for magnetic tapes having different tape speeds during recording. In order to achieve this object, the present invention divides the frequency division ratio of a rotation pulse signal having a frequency proportional to the rotation speed of the capstan motor with respect to a resistance value of 1 set in a variable resistor at the time of recording. The tape speed is set to a value corresponding to each different magnetic tape. Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram showing an embodiment of the magnetic recording/reproducing apparatus according to the present invention, in which 13 is a capacitor, 14 is a control circuit, 15 is a preset value generation circuit, and 16 is an input terminal. Corresponding parts are given the same reference numerals and some explanations will be omitted. Next, the operation of this embodiment will be explained. In FIG. 3, the target magnetic tapes are a 6-hour tape and a 2-hour tape. A capacitor 13 is connected to the adjustable variable resistor 4, and the variable resistor 4 and the capacitor 13 form a time constant circuit. Further, the A/D converter 5 includes a control circuit 14 and a preset value generation circuit 15. The control circuit 14 starts operating when the variable resistor 4 is adjusted, and starts charging the capacitor 13 with the adjusted time constant of the time constant circuit. When the charging voltage reaches a preset constant threshold voltage, the capacitor 13 is instantaneously discharged. As a result of this charging and discharging, the control circuit 14 generates a gate signal having a pulse width from the charging start point to the discharging start point.
Therefore, the pulse width of the gate signal is determined by the time constant of the time constant circuit, that is, the adjusted resistance value of the variable resistor 4. The preset value generation circuit 15 receives the gate signal from the control circuit 14 and the clock pulse from the input terminal 16, counts the number of clock pulses supplied during the pulse width period of the gate signal, and holds the count. The count number is grouped into the number of double-speed playbacks that can be selected. For example, as shown in Figure 2, eight double-speed playbacks of odd-numbered speed playbacks from 1x playback to 15x playback are performed for a 6-hour tape. Where possible, they are grouped into eight pieces. A digital amount corresponds to each double speed playback, and the digital signal of the digital amount of the group corresponding to the count number is sent to the preset value generation circuit 1.
Generated from 5. On the other hand, the operation of the preset value generating circuit 15 is switched in conjunction with the switching of the changeover switch 7. That is, when recording a 6-hour tape, the count number is divided into 8 groups as described above, but when recording a 2-hour tape, the number of counts is divided into 8 groups, as described above, due to the limit of the rotational speed of the capstan motor. double speed playback,
Since only three double speed playbacks, 3x speed playback and 5x speed playback, are possible, the counts are grouped into 3 groups, and a digital amount corresponds to each double speed group. For grouping the count numbers, for example,
If a lever is used as the resistance value adjusting means of the variable resistor 4, the adjustment displacement range of the lever for each double speed playback is set to be uniform for both the 6-hour tape and the 2-hour tape. Now, the digital amount generated in the preset value generation circuit 15 for each double speed playback, that is,
Set the preset values of counter 3 to 4, A, B, C, and D.
It is assumed that the relationship between each double speed reproduction and the preset value when expressed in bits is as shown in Table 1 below.

[Table] Therefore, the number of selectable double-speed playback modes is the same for 6-hour tapes and 2-hour tapes, and 1, 7, and 15x playback modes are possible for 6-hour tapes, and , 3, and 15 times speed playback are possible. In this case, the clock pulse counts for the 6-hour tape and the 2-hour tape are divided into three groups, and each group is represented by a 2-bit digital signal P and Q. , 6-hour tape, and 2-hour tape, and their relationships with double speed playback are set as shown in Table 2 below.

[Table] The relationship between preset values and double speed playback is as shown in Table 1. FIG. 4 shows a specific example of the circuit configuration of a part of the preset value generating circuit 15 and the frequency divider 3 shown in FIG. 3, which operate as shown in Table 2. In Fig. 4, 17, 18, 19 are input terminals, 20, 21, 22 are inverters, and 23 is an input terminal.
AND circuit, 24 and 25 are OR circuits, 26 is a resistor,
27 is a transistor, 28 is an input terminal, 29 is a relay, 30 is an input terminal, 31 is a changeover switch, 3
2 is a count, 33 is an output terminal, and parts corresponding to those in FIG. 3 are given the same symbols. Next, the operation of this specific example will be explained. In Figure 4, “1” is a high level, “0”
Low level when . The P bit is supplied to the input terminal 17, the Q bit is supplied to the input terminal 18, and the input terminal 19 is supplied with the low level, that is, " A signal of "0" is supplied, and a high level, ie, a "1" signal is supplied for a 2-hour tape. The P and Q bits are inverted by inverters 20 and 21, respectively, and supplied to a NAND circuit 23. NAND
The output signal of circuit 23 turns transistor 27 on and off via resistor 26, and controls relay 29 to switch changeover switch 31. When the transistor 27 is on, the changeover switch 31 is closed to the c side, and when it is off, it is closed to the d side. The rotation pulse signal from the amplifier 2 (FIG. 3) is supplied to the input terminal 30, and the rotation pulse signal is supplied from the output terminal 33 to the frequency-to-voltage converter 6 (the third
Figure). Therefore, when the P and Q bits from the input terminals 17 and 18 are both "0", the output signal of the NAND circuit 23 is "0", so the transistor 27 is in the off state, and the changeover switch 31 is switched to the c side. close. The rotation pulse signal from the input terminal 30 does not pass through the counter 32, and therefore is directly supplied to the output terminal 33 without being frequency-divided, and as mentioned above, 1x speed reproduction is performed. In this case, since it does not matter whether the signal from the input terminal 19 is "0" or "1", 1x speed reproduction is performed for both the 6-hour tape and the 2-hour tape. Next, when either the P or Q bit from the input terminals 17, 18 is "1", the changeover switch 30 is closed to the d side and the rotation pulse signal from the input terminal 30 is supplied to the counter 32. The counter 32 receives the signal from the input terminal 28 to set the A bit, and the output signal from the OR circuit 24 to set the B bit.
The C bit is changed by the signal from the input terminal 19, and the D bit is changed by the output signal of the OR circuit 25.
Bits are set respectively, and 4 bits A, B, C, and D are preset. The signal from the input terminal 28 is always "1", the A bit is always set to "1", and the C bit is "0" for a 6-hour tape and "0" for a 2-hour tape. It is set to 1”. Also, the B bit is set to "1" when the tape is a 6-hour tape because the output signal of the inverter 22 is "1", and when the tape is a 2-hour tape, the output signal of the inverter 22 is "0" so it is set to the P bit. It is set dependently. Further, the D bit is set depending on the P bit for a 6 hour tape, and is set to "1" for a 2 hour tape. Therefore, if the P bit is "1" and the Q bit is "0", in the case of a 6-hour tape,
Preset values A, B, C, D of the counter circuit 32
is "1, 1, 0, 1", and the rotation pulse signal is frequency-divided to become the 7x speed playback mode from Table 1, and in the case of a 2-hour tape, it is "1, 1, 1, 1".
This will result in triple speed playback mode. Next, assuming that the P bit is “0” and the Q bit is “1”, in the case of a 6-hour tape, “1”,
1,0,0” and becomes 15x playback mode.
In the case of a 2-hour tape, the sequence is "1, 0, 1, 1", resulting in a 5x speed playback mode. From the above, the relationship between the displacement of the lever for adjusting the resistance value of the variable resistor 4 (Fig. 3) and each double speed playback mode for the 6-hour tape and the 2-hour tape is shown in Fig. 5. It will be as it is. For the 6-hour tape and the 2-hour tape, the range of lever displacement for each double-speed playback mode can be uniformly assigned. Note that in order to generate a digital signal consisting of P and Q bits representing each group from the count number of clock pulses, for example, multiple comparators are used to compare the count number with a reference value set for each group. All you have to do is compare. Furthermore, in the above embodiment, three double-speed playback modes have been described for both a six-hour tape and a two-hour tape, but there is no need to limit the number of double-speed playback modes to three; It can be set arbitrarily depending on the number of double-speed playback modes to be obtained. Furthermore, as shown in FIG. 6, the number of possible double-speed playback modes can be made different between the 6-hour tape and the 2-hour tape. In this case, the number of clocks counted by the preset value generating circuit 15 (FIG. 3) is grouped into eight groups, and, for example, a 3-bit digital signal is associated with each group. Using this digital signal, in the case of a 6-hour tape, the preset value generation circuit 15 generates a preset value for the frequency divider 3 for each double-speed playback mode, and in the case of a 2-hour tape, the same digital signal generates a preset value for the frequency divider 3. A logic circuit may be constructed in the preset value generation circuit 15 to generate a preset value for each double-speed reproduction mode, and such a logic circuit may be designed as appropriate. FIG. 7 is a block diagram showing another embodiment of the magnetic recording/reproducing apparatus according to the present invention, in which 34 is a magnetic tape, 35 is a control head, 36 is an amplifier, 37 is a counter, 38 is a changeover switch, and 39 is a control head.
is an input terminal, 40 is a phase comparator, 41 is an amplifier,
42 is a variable resistor, 43 is an adder, and the third
The same reference numerals are given to the parts corresponding to those in FIG. Next, the operation of this embodiment will be explained. In this embodiment, the speed of the capstan is controlled and phase control is also performed. In FIG. 7, a 30 Hz control signal (not shown) is recorded on the magnetic tape that is run by the rotation of the capstan motor 12, and this control signal is reproduced by the control head 35. The reproduced control signal is amplified by an amplifier 36 and supplied to a counter 37 and a c-side terminal of a changeover switch 38. By adjusting the variable resistor 4, when the playback mode is set to 1x speed, the preset value generating circuit 15 generates a switching signal, and this switching signal causes the switching switch 38 to close to the c side. Ori,
A 30Hz control signal is supplied to a phase comparator 40. At this time, the changeover switch 31 is closed to the c side, and as described above, the rotation pulse signal is supplied to the frequency-to-voltage converter 6 without being frequency-divided. Further, in a double speed reproduction mode other than single speed reproduction, the changeover switch 38 is closed to the d side, and the control signal frequency-divided by the counter 37 is supplied to the phase comparator 40. The counter 37 is supplied with the same preset value as the counter 32 of the frequency divider 3 from the preset value generation circuit 15.
Hz control signal is obtained. Therefore, in the phase comparator 40, the 30 Hz control signal from the changeover switch 38 and the 30 Hz reference signal from the input terminal 39 are compared in phase. The phase difference signal is amplified by an amplifier 41 whose gain is adjusted by a variable resistor 42, and then sent to an adder 4.
3 and is added to the speed control signal from the comparator 10 described in the previous embodiment to control the rotation of the capstan motor 12. However, the capstan motor 12 rotates at a predetermined number of rotations in the double-speed playback mode based on the speed control signal from the comparator 10, and its rotational phase is controlled by the phase difference signal from the amplifier 41. As a result, in any double speed playback mode,
The phase relationship between the traveling locus of the magnetic head and the magnetic tape recording track is set to the best predetermined relationship, and a reproduced image of higher quality can be obtained. In the above two embodiments, a time constant circuit was formed by the variable resistor 4 and the capacitor 13, and charging and discharging of the time constant circuit was used. It is clear that it is good. As explained above, according to the present invention, one of the variable resistors for arbitrarily setting the double speed playback mode is
With respect to the resistance value of Even in the case of magnetic tape, the adjustment range of the variable resistor for each double-speed playback mode can be made uniform, and the variable resistor can be used effectively, and the capstan motor can be prevented from abnormalities. No voltage is applied, and a magnetic recording/reproducing device with excellent functionality can be provided without the drawbacks of the prior art.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional magnetic recording/reproducing device, FIG. 2 is an explanatory diagram showing the operation of FIG. 1, and FIG. 3 is a block diagram showing an embodiment of the magnetic recording/reproducing device according to the present invention. , FIG. 4 is a block diagram showing a specific example of a part of the preset circuit and the counter shown in FIG. 3, FIG. 5 is an explanatory diagram showing an example of the operation of FIG. 3, and FIG. FIG. 7 is a block diagram showing another embodiment of the magnetic recording/reproducing apparatus according to the present invention. 1... Rotating pulse detector, 3... Frequency divider, 4...
. . . Variable resistor, 5 . . . Analog-digital converter, 6 . . . Frequency-to-voltage converter, 10 .

Claims (1)

[Scope of Claims] 1. Has a recording mode at a plurality of different tape speeds, and runs the tape at a high speed that is an arbitrary integral multiple of the respective tape speeds at the time of recording, and performs high-speed playback at a desired playback speed. In a recording/reproducing device that is capable of The first means is to divide the range in which the set value can be changed into a plurality of substantially uniform regions for each different recording mode, and to correspond to a different playback speed number for each region. and a second means for determining the area corresponding to the desired control amount and recording mode that have been set, and setting a reproduction speed number mode corresponding to the determined area. magnetic recording and reproducing device.