JPH03263642A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To output an excellent reproduced picture without noise in a short time from stop by controlling the traveling of a tape in a reproducing mode so that it is started based on the stored speed of the tape when the mode is shifted to the reproducing mode from a stop mode. CONSTITUTION:When the mode is shifted to the stop mode from the mode other than the stop mode, the tape 1 is made to travel in a prescribed term and the speed of the tape recorded during the traveling term of the tape is discriminated by an automatic discriminator 10. Then, the discriminated result is stored in a memory 17. Next, when the mode is shifted to the reproducing mode from the stop mode, the traveling of the tape in the reproducing mode is controlled so as to be started by a capstan servo circuit 15 based on the speed of the tape stored in the memory 17. Therefore, reproducing is executed by the recorded tape speed immediately after the reproducing mode is started. Thus, the excellent reproduced picture without the noise is outputted in a short time from the stop.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to magnetic recording that enables recording and reproducing at a plurality of different tape speeds, as employed in household helical scan type magnetic recording and reproducing devices. The present invention relates to a playback device.

In household magnetic recording and reproducing devices, the standard mode is 33.35 mm/sec, and the 3x mode is 11
．． Recording and playback are possible at two tape speeds: 12mm/sec, and generally during playback, tapes recorded in standard mode are automatically played back by automatic discrimination, and tapes recorded in 3x mode are automatically played back. It is designed to automatically play the tape in 3x mode.

FIG. 3 is a block diagram of a tape speed control system for a conventional magnetic recording/reproducing apparatus. In the figure, (1) is a magnetic tape which is pressed onto a pinch roller (2) and a capstan shaft (19) and is run at a speed proportional to the rotational speed of a capstan motor (3).

A rotating disk (4) is attached to one end of the rotating shaft of the capstan motor (3), and S-pole and NMI magnets are alternately arranged on its circumferential side. (5) is a detection head, which is provided corresponding to the rotating disk (4) and detects pulses (hereinafter referred to as capstan FG pulses) with a repetition frequency that corresponds to the rotational speed of the capstan motor (3). . (6) is a capstan FG amplifier,
Amplify the capstan FG pulse.

(7) is a control head, (8) is a switch that can be switched between playback side P and recording side R, (9) is a control signal amplifier, and (5) is a capstan servo circuit.This capstan servo circuit is used during recording. A recording control signal outputted from (15) is recorded on the magnetic tape (1) via a switch (8) and a control head (7).

(10) is an automatic discriminator to which the capstan FG pulse from the capstan FG amplifier (6) and the reproduction control signal from the control signal amplifier (9) are respectively input. (11) is a standard mode signal generator,
Outputs the standard mote tape speed. (12) is a recording mode switch, which outputs either standard mode or triple mode according to the user's selection.

(13) is a selector switch for recording, playback and standard 3.
It has three contacts R, P, and S. (14) is a system control circuit, which is the switch (8) mentioned above.

A command signal is output to (13). (16) is a capstan motor drive amplifier which amplifies the output signal from the capstan servo circuit (15) to control the rotation of the capstan motor (3).

Next, the operation of the above configuration will be explained.

In recording mode, the system control circuit (14)
Both switches (8) and (13) are switched and connected to contact R on the recording side by a command from. Here, a capstan FG pulse corresponding to the rotation speed of the capstan motor (3) is detected by a rotating disk (4) and a detection head (5) attached to one end of the rotation shaft of the capstan motor (3). After this is amplified by the capstan FG amplifier (6), it is applied to the automatic discriminator (lO) and the capstan servo circuit (15). In recording mode, the capstan servo circuit (15) is set to standard mode or 3 depending on the mode output of the recording mode switch (12).
The rotation of the capstan motor (3) is controlled via the capstan motor drive amplifier (16) so as to achieve one of the tape speeds in the double mode.

During recording and playback mode, the pinch roller (2) and capstan shaft (19) are pressed together via the tape (1), so the tape speed and capstan motor (3)
The rotational speeds of are in a proportional relationship, and the tape speed is fed back to the capstan servo circuit (15) in the form of capstan FG pulses.

Also, in recording mode, the capstan servo circuit (15)
The recording control signal output from the switch (8)
Tape (1) through control head (7)
recorded in Here, since the mode output of the recording mode switch (12) is configured to be selectable by the user, the tape speed during recording can be freely selected by the user.

Next, in the playback mode, the switch (8) is activated by a command from the system control circuit (14).

(13) are both switched and connected to the contact P on the playback side.

Here, the reproduction control signal reproduced from the control head (7) is amplified by the control signal amplifier (9) and then applied to the automatic discriminator (10) and the capstan servo circuit (15). Automatic classifier (l
O) also receives capstan FG pulses from the capstan FG amplifier (6), and when a certain number or more of capstan FG pulses are input during the 8 cycles of the playback control signal, it is determined that the mode is standard mode. If the number is less than a certain number, the mode is determined to be 3x mode, and the result of the determination is applied as a mode output to the capstan servo circuit (15) via the switch (13). In this example, the reason why the playback control signal is set to 8 cycles instead of 1 cycle is because if the playback control signal and capstan FG pulse are input incorrectly due to tape demagnetization or noise, the mode is set immediately. This is because it is necessary to provide an integral effect in order to prevent switching.

The capstan servo circuit (15) controls the tape speed in accordance with the mote output as in the recording mode.

Since it is generally known that the reproduction control signal is used for phase control in this capstan servo circuit (15), the explanation will be omitted here.

By the way, when switching from stop mode to play mode,
8 pulses of the playback control signal is an automatic discriminator (lO)
The automatic discriminator (10) will not complete the mode discrimination until it is manually operated by the system control circuit (10).
4), the switch (13) is connected to contact S for a certain period at the beginning of the playback mode, and during that time the output of the standard mode signal generator (11) is connected to the capstan servo circuit (15). Since it is applied, the tape (1)
is controlled to run at standard mode tape speed.

[The invention attempts to solve i! [Problem] Conventional magnetic recording and reproducing devices are configured as described above, so when transitioning from stop mode to playback mode, mode determination is not completed until a predetermined number of pulses of the playback control signal are played back, so the playback mode cannot be changed. For an initial period of time, the standard mode is forced. That is, when playing back a tape recorded in the standard mode, the tape speed V stabilizes within a short period of time, as shown in FIG. 4(a). However, when playing back a tape recorded in 3x mode, as shown in FIG. 4(b), once l1ll! The tape speed slows down after reaching the normal mode tape speed, so it takes a certain amount of time (
tl) is required. Therefore, if the playback screen is displayed before the vehicle is running stably, a noise screen will be visible.

In recent VH5 type household magnetic recording and reproducing devices, the image output time can be shortened by keeping the cylinder rotating while loading even in stop mode, but the playback screen Considering the quality of the image, there is a problem in that the time from stopping to displaying the playback screen cannot be made very fast due to the constraints caused by the noise.

This invention was made to solve the above-mentioned problems, and it is possible to output the playback screen within a short time after stopping, and even if the recording mode is standard mode, it can be used in 3x mode. An object of the present invention is to provide a magnetic recording/reproducing device that can realize a noise-free start-up of a reproduced screen even when there is noise.

[Means for Solving the Problems] A magnetic recording/reproducing device according to the present invention runs a tape for a predetermined period when transitioning from a mode other than stop to a stop mode, and adjusts the tape speed recorded during the tape running period. is automatically determined, and the determination result is stored in memory.
Next, when transitioning from the stop mode to the playback mode, control is performed to start tape running in the playback mode based on the tape speed stored in the memory.

[Function] According to this invention, the recorded tape speed is detected and stored in the memory before starting playback, so that a tape recorded in standard mode can be played back in standard mode, and A tape recorded in double mode starts playing back in triple mode. Therefore, even when playback of a tape recorded in the 3x mode is started, the tape runs stably in a short time, so no noise is generated, and the timing of switching to the playback screen can be significantly accelerated.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram of a tape speed control system for a magnetic recording/reproducing apparatus according to an embodiment of the present invention.
) is the same as the conventional example shown in FIG. 3, so the same reference numerals are given to the corresponding parts and detailed explanation thereof will be omitted.

In FIG. 1, (17) is a memory, and an automatic discriminator (l
The tape running mode determined by O) is stored. (
18) is a switch which is closed by a command from the system control circuit (14) only during the period when the automatic discriminator (10) determines the tape running mode.

Next, the operation of the above configuration will be explained.

The operations in the recording mode and in the reproduction mode other than immediately after the start of reproduction are the same as those in the conventional example, and therefore the description thereof will be omitted.

When transitioning from a mode other than stop to stop mode, the tape is run for a short period of time long enough to play back 8 or more pulses of the playback control signal, and during that running period, the automatic discriminator (
1O) to determine the tape running mode. Switch (18) is system control time only during this period! (
14), the mode determination result is input to and stored in the memory (17). Note that when the tape (1,) is run, the shaft (19) of the capstan motor (3) and the pinch roller (2) are pressed together via the tape (1), and the tape (1,)
) and the frequency of the capstan FG pulse are designed to have a proportional relationship.

Also, when transitioning from a mode other than stop to stop mode,
Capstan motor (3) due to reel idler swing etc.
Since it rotates, there is no loss time to stop mode by using it.

Next, when transitioning from stop mode to playback mode, the system control circuit (14) commands the switch (
3) is connected to contact S for a predetermined period. Accordingly, the capstan servo circuit (15) is connected to the memory C.
The rotation of the capstan motor (3) is controlled through the capstan motor drive amplifier (16) so that the tape running speed corresponds to the output from the capstan motor (17).

Figure 'M2 is a characteristic diagram showing the change in tape speed over time when playback is started with the magnetic recording and reproducing apparatus configured as above, and (a) and (b) of the same figure are for recording in standard mode and triple mode, respectively. It shows the change in tape speed V over time when playback of the tape started. Since tape running is more stable in the triple mode than in the conventional characteristics shown in FIG. 4, the timing of switching to the playback screen can be made earlier, as shown in FIG.

In the above embodiments, the mode is determined based on the reproduction control signal and the capstan FG signal, but other mode determination methods may be used.

Further, the automatic discriminator (10), the memory (17), and the system control circuit (14) do not need to exist separately, but may be integrated into a microcomputer and have their functions built-in, similar to the above embodiment. be effective.

[Effects of the Invention] As described above, according to the present invention, playback can be performed at the recorded tape speed immediately after the start of the playback mode, so the playback can be performed smoothly without any noise within a short time after the playback mode is started. A playback screen can be displayed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a tape speed control system for a magnetic recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a characteristic diagram showing the change in tape speed over time at the start of playback, and FIG. 3 is a diagram of a conventional magnetic recording system. FIG. 4, which is a block diagram of a tape speed control system for a reproducing apparatus, is a characteristic diagram showing temporal changes in tape speed at the start of reproduction by a conventional magnetic recording and reproducing apparatus. (1)...magnetic tape, (2)...pinch roller,
(3) Capstan motor, (10) Automatic discriminator, (14) System control circuit (
15) Capstan servo circuit, (17)...
Memory, (18)...switch. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) Recording and playback are possible at multiple different tape speeds,
A magnetic recording/reproducing device having a function of controlling the magnetic tape to run at the tape speed in the recording mode in the playback mode, and running the magnetic tape for a predetermined period when transitioning from a mode other than stop to the stop mode. a means for automatically determining the tape speed recorded during the tape running period; a means for storing the determination result; and a means for automatically determining the tape speed recorded during the tape running period; 1. A magnetic recording and reproducing apparatus comprising: means for controlling the start of the magnetic recording and reproducing apparatus.