JPH0218740A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a satisfactory reproducing picture by providing a pulse voltage impressing time control means to change a time, in which a pulse voltage is impressed to a capstan driving means, in correspondence to the fluctuation of load, which is added to a capstan, in a pulse voltage impressing means. CONSTITUTION:When a field to be recorded to a track is reproduced by a head which is different from a heat at the time of recording, the traveling speed of a tape is changed and the track is moved to the position of the prescribed head. However, the time to impress the pulse voltage to a capstan driving means 2 is increased and decreased in correspondence to the fluctuation of the load which is added to a capstan 1. Accordingly, for the capstan 1, even when a revolving speed is fluctuated by the fluctuation of the load, the track can be moved without fail and the field can be always reproduced by the head to be same as the head at the time of the recording. Thus, the satisfactory reproducing picture can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording/reproducing device having means for controlling the running speed of a tape. This invention relates to a magnetic recording/reproducing device that can be moved to the position of the head.

[Conventional technology]

Since the beginning of VTR development, improvements have been made with emphasis on making the device smaller and lighter, easier to operate, more multifunctional, and lower in cost.
A wide variety of models have been developed.

Furthermore, in recent years, it has become technically possible to produce a small VTR with an integrated camera, which is expanding a new market. In particular, the VH3-C type VTR is
Because of its compatibility with VTRs, the scope of recording and playback on VTRs has become much wider.

By the way, VTRs such as the VH3-C type use a drum with a smaller diameter than normal VHS-type VTRs in order to make the device more compact.
In order to form a track pattern according to the HS formant, it is necessary to compensate for the decrease in relative recording speed due to the reduction in the diameter of the drum.

Therefore, as shown in FIG. 3, the drum 21 rotates 45 times per second with the tape 22 wrapped around it at 270 degrees. Moreover, the side surface of the drum 21 is
Four heads L1, L2, R1, and R2 are provided at 90 degree intervals; head L1, head L2, and head R1.
and head R2 are arranged at positions facing each other. These heads L1, I, 2, R1, and R2 record one field per track on the tape 22. At this time, the scanning order of the heads for recording fields in each track is as shown in FIG. There are two types of trace patterns, pattern 1 and pattern 2, and recording is possible with either trace pattern.

For example, in pattern 1, head L1 scans field (2), head R1 scans field (2), head L2 scans field (2), and head R2 scans field (2). Also, during reproduction, field scanning is possible with either the pattern 1 or pattern 2 heads, as in the case of recording.

However, in reality, if the mounting condition of each head differs slightly depending on the processing precision, when fields recorded on a track are reproduced by a head different from the head used for recording, the characteristics of the head during recording and playback will differ. However, the image quality deteriorates due to screen distortion. Therefore, in order to prevent deterioration in image quality, it is necessary to reproduce fields using the same head used for recording. For example, if fields are recorded in each track according to pattern 1, reproduction of these fields is better performed by pattern 1 than by pattern 2. For this reason,
When reproduction is performed according to pattern 2, a pulse voltage is applied to the capstan drive means for a certain period of time to control the rotational speed of the capstan, and the tape running speed is momentarily increased to move the track to a predetermined head. position so that playback according to pattern 1 becomes possible.

[Problem to be solved by the invention]

However, in the above-mentioned conventional magnetic recording/reproducing apparatus, when a track is moved, a pulse voltage is applied to the capstan driving means for a certain period of time. Although it is possible to increase the rotational speed to increase the tape running speed and move the track correctly, for example, if the load applied to the capstan is greater than during normal playback, the tape running speed will be lower than the capstan. decreases as the rotational speed of the head decreases, and the track returns to normal without being able to move to the predetermined head position.

As described above, conventional magnetic recording/reproducing devices have the problem that if the load applied to the capstan fluctuates, the rotation of the capstan is affected by the load fluctuation, making it difficult to move the track correctly. Was.

[Means to solve the problem]

In order to solve the above-mentioned problems, the magnetic recording and reproducing device according to the present invention includes a capstan for transporting a tape, a capstan driving means for driving the capstan, and a capstan rotation for detecting the rotational speed of the capstan. a speed detector; tape running speed control means for controlling the tape running speed according to an output signal of the capstan rotational speed detector;
When the field recorded on the track is reproduced by a head different from the head used for recording, a pulse voltage is applied to the capstan driving means so as to change the running speed of the tape and move the track to a predetermined head position. A magnetic recording and reproducing apparatus comprising a pulse voltage applying means, wherein the pulse voltage applying means changes a time period during which the pulse voltage is applied to the capstan driving means in accordance with fluctuations in a load applied to the capstan. It is characterized by the provision of means.

[For production]

With the above configuration, when a field recorded on a track is reproduced by a head different from the recording head, the tape running speed is changed to move the track to a predetermined head position, but the pulse voltage application time is controlled. The means increases or decreases the time during which a pulse voltage is applied to the capstan drive means in accordance with changes in the load applied to the capstan, so that the capstan can reliably move the track even if the rotational speed changes due to changes in the load. can be done. Therefore, it is possible to always reproduce a field using the same head used during recording, and a good reproduced image can be obtained.

[Example] An example of the present invention will be described below based on FIGS. 1 and 2.

As shown in FIG. 1, the magnetic recording/reproducing apparatus includes a capstan 1, a capstan driving means 2 for driving the capstan L, a capstan rotation speed detector 3, and a capstan serving as a tape running speed control means. It includes a servo circuit 4 and a pulse voltage applying means 5.

The capstan 1 is servoed by a capstan servo circuit 4 via a capstan drive means 2 in order to keep the tape traveling speed constant. The capstan drive means 2 includes a capstan motor 2a and a capstan motor drive circuit 2b,
The capstan 1 is rotated by the driving force of the capstan motor 2a. Capstan rotation speed detector 3
outputs a pulse according to the rotational speed of the capstan 1, and supplies the pulse to a capstan servo circuit 4 and a pulse voltage application time control means 7, which will be described later. The pulse voltage applying means 5 applies a pulse voltage to the capstan driving means 2 to change the rotational speed of the capstan 1 in order to move the track to a predetermined head position when the head for reproducing the field is different from the head for recording. is designed to increase.

The pulse voltage application means 5 is composed of a voltage generation circuit 6, a pulse voltage application time control means 7, and a changeover switch SW, and switches the voltage from the voltage generation circuit 6 for a time determined by the pulse voltage application time control means 7. The power is supplied to the capstan driving means 2 through the switch SW.

The pulse voltage application time control means 7 includes a system controller 8, a counter 9, a time measurement circuit 10, and an arithmetic circuit 1.
1. system controller 8
determines whether the head for reproducing the field is different from the head used for recording, and selects whether to apply normal capstan servo or apply a pulse voltage to the capstan drive means 2. conduct. The counter 9 counts up the number of output pulses from the capstan rotation speed detector 3 that detects the speed of the capstan motor 2a when the head for reproducing the field is different from the head for recording. The time measurement circuit 10 includes a counter 9
Measure the time the is running. The arithmetic circuit 11 performs a predetermined arithmetic operation based on the outputs of the counter 9 and the time measurement circuit 10, and depending on the result, switches whether to continue applying pulse voltage to the capstan driving means 2 or to switch to a normal capstan servo. This is done via switch SW.

In the above configuration, immediately after the start of playback, the selector switch SW is turned on to the terminal A, and the normal capstan servo is applied.

At this time, if the head for reproducing the field is the same as the head for recording, the system controller 8 determines that the selector switch SW remains connected to terminal A, and the capstan servo circuit 4 causes the capstan servo circuit 4 to switch to the normal capstan. Servo is maintained.

On the other hand, if the head that reproduces the field is different from the head that recorded it, the system controller 8 determines that
The changeover switch SW is turned on to the terminal B, and a voltage higher than that during normal reproduction is applied to the capstan motor drive circuit 2b from the voltage generation circuit 6. The capstan motor 2a increases its speed with the drive voltage obtained from the capstan motor drive circuit 2b, and increases the speed of the tape through the capstan 1, thereby moving the track. Simultaneously with the determination by the system controller 8, the counter 9 is reset by the system controller 8 and starts counting the number of pulses output from the capstan rotational speed detector 3, and at the same time as the counter 9 starts operating, it measures time. The circuit 10 operates and measures time. The calculation circuit 11 calculates the following formula Nc≧ based on the count value of the counter 9 and the time measured by the time measurement circuit 10.
(2+-)N, . . . performs calculation according to the first equation F.

However, the above first equation is obtained by the second equation of F. In addition, tf: 1 field scanning time of the head tc: Counter operation time N: Number of output pulses of the capstan rotation speed detector per 1 field during normal servo mode Nc: Number of pulse counts.

Then, when the track is moved to a predetermined head position, the pulse count number of the sales counter 9 satisfies the first equation.
When the voltage is reached, the changeover switch SW is turned on to the terminal B, and the voltage applied from the voltage generation circuit 6 to the capstan motor drive circuit 2b is cut off, and at the same time, the capstan servo is returned to the normal servo. The voltage applied by the voltage generation circuit 6 to the capstan motor drive circuit 2b is set so that the pulse count of the counter 9, 4 degrees, satisfies the first 2 degrees within one field scanning time of the head.

Here, if the load applied to the capstan 1 changes for some reason during truck movement, the number of pulses per unit time output from the capstan rotational speed detector 3 changes accordingly.

Therefore, as shown in FIG. 2(a), when the load is light, the capstan rotation speed detector 3 outputs a large number of pulses per unit time, and the number of pulses output by the capstan rotation speed detector 3 increases until the counter 9 satisfies the first equation. Since the time is shortened, the time during which voltage is applied to the capstan motor drive circuit 2b is also shortened. On the other hand, as shown in the same figure (b), in the case of heavy load, the number of pulses output by the capstan rotation speed detector 3 per unit time decreases, so the voltage is applied to the capstan motor drive circuit 2b. The time taken will be longer.

In this way, the pulse voltage application time control means 7 controls the time for applying the pulse voltage to the capstan driving means 2 in accordance with the fluctuation of the load applied to the capstan 1, thereby adjusting the trunk movement time. , the track can be correctly moved to a predetermined head position.

〔Effect of the invention〕

As described above, the magnetic recording and reproducing apparatus according to the present invention includes a capstan for transporting a tape, a capstan driving means for driving the capstan, and a capstan rotation speed detector for detecting the rotation speed of the capstan. , a tape running speed control means for controlling the running speed of the tape according to the output signal of the capstan rotational speed detector; In a magnetic recording and reproducing apparatus, the pulse voltage applying means applies a pulse voltage to the capstan driving means so as to move the trunk to a predetermined head position by changing the speed. The configuration includes a pulse voltage application time control means that changes the time during which the pulse voltage is applied to the drive means in accordance with fluctuations in the load applied to the capstan.

With this, when a field recorded on a track is reproduced by a head different from the head used for recording, the tape traveling speed is changed to move the track to a predetermined head position, but the pulse voltage application time control means Since a pulse voltage is applied to the capstan driving means for a time corresponding to fluctuations in the load applied to the capstan, it is possible to reliably move the track to a predetermined head, and the field is always recorded using the same head as when recording. This has the effect that a good reproduced image can be obtained by reproducing the image.

[Brief Description of the Drawings] Figures 1 and 2 show an embodiment of the present invention, in which Figure 1 is a block diagram showing the capstan servo control system, and Figure 2 is a block diagram showing the capstan servo control system. Fig. 2(a) is a time chart of the voltage applied to the capstan and the number of output pulses counted by the counter. It is a time chart when the load is heavy. 3 and 4 are common to the conventional example and the embodiment of the present invention. FIG. 3 is an explanatory diagram showing the arrangement of heads on the drum and the running state of the tape, and FIG. 4 is an explanatory diagram showing the recording field. FIG. 3 is an explanatory diagram showing the scanning order of the head for reproduction. 1 is a capstan, 2 is a capstan driving means, 3 is a capstan rotation speed detector, 4 is a capstan servo circuit (tape running speed control means), 5 is a pulse voltage application means, 6 is a voltage generation circuit, is a pulse This is voltage application time control means. Figure (a) Figure

Claims (1)

[Claims] 1. A capstan for transporting the tape, a capstan driving means for driving the capstan, a capstan rotation speed detector for detecting the rotation speed of the capstan, and a capstan rotation speed detector for detecting the rotation speed of the capstan. tape running speed control means for controlling the running speed of the tape according to an output signal; and a tape running speed control means for controlling the running speed of the tape according to an output signal; In a magnetic recording/reproducing apparatus, the magnetic recording/reproducing apparatus includes a pulse voltage applying means for applying a pulse voltage to the capstan driving means so as to move the head to the position of the capstan driving means, the pulse voltage applying means applying a pulse voltage to the capstan driving means. A magnetic recording/reproducing device characterized in that it is equipped with pulse voltage application time control means that changes the time according to fluctuations in the load applied to the capstan.