JPS61284846A - Magnetic tape recording and reproducing device - Google Patents

Abstract

PURPOSE:To generate no disturbance in information even if a running direction is inverted, by inverting the running direction of a magnetic tape, based on an output from a AND circuit to which the outputs of a magnetic tape quantity detecting means and a signal level detecting means are provided. CONSTITUTION:A magnetic tape remaining quantity detecting circuit 24 detects the rotation speed of reels 12, 13, when a magnetic tape 11 runs in a direction as indicated with an arrow A1 or A2, and calculates the recordable remaining quantity of a magnetic tape 11. An output from a signal processing circuit 17 is provided to a signal level detecting circuit 25 being a signal level detecting means, and when the level of a signal which is inputted is below a level deter mined in advance, the signal level detecting circuit 25 regards it as a non-signal and the recording part becomes a non-signal part. The outputs of the magnetic tape remaining quantity detecting circuit 24 and the signal level detecting circuit 25 are provided to a AND circuit 26. In this way, when recording the magnetic tape 11, the running direction of the magnetic tape 11 is inverted in a period in which the level of the signal to be recorded is below a reference value deter mined in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic tape recording/reproducing apparatus capable of recording or reproducing data in a reciprocating direction with respect to the running direction of a magnetic tape.

BACKGROUND ART Among magnetic tape recording/reproducing apparatuses, there is known a magnetic tape recording/reproducing apparatus which automatically reverses the reciprocating direction of a magnetic tape to perform a recording operation, for example, when performing a recording operation. In such a so-called reciprocating magnetic tape recording/reproducing apparatus, the end of the magnetic tape is detected during a recording operation, the running direction of the magnetic tape is reversed, and the recording operation is continued for two times.

FIG. 3 is a block diagram of a configuration for automatically reversing the running direction of a magnetic tape (not shown) in a prior art magnetic tape recording/reproducing apparatus. In a magnetic tape recording operation, the tape end detection circuit 1 detects the end of the magnetic tape. When the tape end detection circuit 1 detects the end of the magnetic tape, it outputs a high level signal to the control circuit 2 which controls the mechanism of the magnetic tape recording/playback device. The control circuit 2 reverses the direction of rotation of a motor 3 that rotates a take-up reel (not shown) for winding a magnetic tape.

Problems to be Solved by the Invention In such prior art reciprocating magnetic tape recording/reproducing devices, when the information to be recorded is long, the running direction of the magnetic tape is reversed at an undesired point in the middle of the information. I will do it. During this reversal period, the running speed of the magnetic tape changes greatly, and until the running speed of the magnetic tape stabilizes, the sound quality may be affected, such as interruptions in the sound or the occurrence of so-called wah-7 rattling. It had deteriorated.

An object of the present invention is to provide a magnetic tape recording device for recording/reproducing data in the reciprocating direction of a magnetic tape, which prevents disturbance from occurring in recorded or reproduced information even if the running direction of the magnetic tape is reversed. / To provide a playback device.

Means for Solving Problems The present invention provides means for detecting the amount of magnetic tape on the upstream side in the running direction of the magnetic tape, and detecting a high level when the level of the recorded or reproduced signal is below a predetermined reference level. a signal level detection means for outputting a signal; an AND circuit to which respective outputs of the magnetic tape amount detection means and the easy level detection means are applied; and a running direction of the magnetic tape is reversed based on the output from the AND circuit. This is a magnetic tape recording/reproducing device characterized by including a drive circuit that performs the following steps.

Operation When the magnetic tape is running in one direction, the amount of magnetic tape on the upstream side in the running direction of this magnetic tape is detected. Further, a signal level detection means is provided for deriving a high level signal when the level of a signal recorded on or reproduced from the magnetic tape is below a predetermined reference level. Therefore, when the amount of magnetic tape is less than a predetermined value and the level of the recorded or reproduced signal is below a predetermined reference level, the magnetic tape 1 detection means
``A high level signal is derived from each OR circuit to which the output from the signal level detection means is applied.The output from the AND circuit becomes a high level and is applied to the drive circuit.At this time, the drive circuit , the running direction of the magnetic tape is reversed.The change in the running speed of the magnetic tape accompanying this reversing operation is performed within a level range where the signal level is below the predetermined reference level, and the sound quality of the recorded or reproduced signal is changed. It can prevent rice from deteriorating.

Embodiment FIG. 1 is a block diagram showing the configuration of a magnetic tape recording/reproducing apparatus 10 according to an embodiment of the present invention. The magnetic tape 11 is wound on a reel 12.13, and the arrow A1 or the arrow A
It is driven by a motor 14 to run in two directions. The output of the motor 14 is switched by a switching means 15 so that it is output to the reel 12 or reel 13 side. That is, when the magnetic tape 11 runs in the direction of arrow A1, the reel 12 is switched to be driven, and when the magnetic tape 11 runs in the direction of arrow A2, the reel 13 is switched to be driven.

A magnetic head 16 for recording or reproducing, for example, a video signal and an audio signal on the magnetic tape 11 is connected to a speaker 18 and an image display device 19 via a signal processing circuit 17. The signal processing circuit 17 processes the signal read by the magnetic head 16, generates sound from the speaker 18, and displays an image on the image display device i19. On the other hand, the operation of the motor 14 is controlled by a control circuit 20 that controls the mechanism of the magnetic tape recording/reproducing device i10.

In connection with the magnetic tape 11, end detection means 21 and 22 are provided for detecting the upstream end of the magnetic tape 11 in the running direction. The end detection means 21 and 22 include a light emitting element and a light receiving element for detecting, for example, a transparent tape portion (not shown) provided at both ends of the magnetic tape 11 in the reciprocating direction. When traveling in the direction A1, the end detection means 21 detects the transparent tape portion on the upstream side in the traveling direction, and outputs a signal to the end detection circuit 23. Such a configuration and detection operation
The same applies to the means 22, which performs an end detection operation regarding the running of the magnetic tape 11 in the direction of arrow A1.

A magnetic tape remaining amount detection circuit 24, which is a magnetic tape amount detection means for detecting the remaining amount of the magnetic tape 11, is provided in association with the reel 12, 13. Magnetic tape remaining amount detection circuit 24
detects the rotational speed of the reel 12.13 when the magnetic tape 11 is traveling in the direction of arrow A1 or A2, and calculates the remaining recordable amount of the magnetic tape 11 from this rotational speed.

The output from the signal processing circuit 17 is given to a signal level detection circuit 25 which is a signal level detection means.

The signal level detection circuit 25 is realized by, for example, a comparison circuit, and when the level of the signal inputted from the signal processing circuit 17 is below a predetermined level, it is regarded as no signal, and such a signal below a certain value is detected. The portion to be recorded is regarded as a no-signal portion.

The output of the magnetic tape remaining amount detection circuit 24 and the rising signal level detection circuit 25 is given to the AND circuit 26, and the outputs of the AND circuit 26 and the termination detection circuit 23 are sent to the OR circuit 27.
given to. The output of the OR circuit 27 is given to the control circuit 20, and the output of the OR circuit 27 is applied to the magnetic tape recording at/
Controls the mechanism of the playback device 10.

FIG. 2 is a waveform diagram illustrating the operation of the magnetic tape recording/reproducing apparatus i10. The operation of the magnetic tape recording/reproducing apparatus 10 shown in FIG. 1 will be described with reference to FIG. 1 and FIG. 2. Here, a case will be described in which the magnetic tape 11 runs in the direction of arrow A2, but the same operation is performed when it runs in the direction of arrow A1. When the magnetic tape 11 is running in the direction of arrow A2, the output of the motor 14 is applied to the reel 13 via the switching means 15, and the reel 13 functions as a take-up reel to wind up the magnetic tape 11.

The outline of the level change of the signal to be recorded is shown in the line ! in Figure 2.
1, and the change in the remaining amount of the magnetic tape 11 on the reel 12, which is the supply reel, detected by the magnetic tape remaining amount detection circuit 24 is shown by the line ! in FIG. Shown as 2. Here, the magnetic tape remaining amount detection circuit 24 derives a high-level signal when the remaining amount of magnetic tape becomes less than a preset value, for example, the remaining amount corresponding to a recordable time of 5 minutes. The reference value regarding the remaining amount of the magnetic tape 11 is
This is indicated by line 13 in FIG. 2, and its reference value is indicated by reference sign A. Also, for the sake of simplicity, the reference level in the detection operation of the signal level detection circuit 25 is set to line J!
3, and its reference level is designated by reference symbol B.

The level of the signal to be recorded becomes below the reference level B at time t1 in FIG. 2, and the signal level detection circuit 25 derives a high level signal. On the other hand, at this time L1, the magnetic tape remaining amount detection circuit 24 detects the magnetic tape 11 being inspected.
As is clear from FIG. 2, the remaining amount of magnetic tape exceeds the reference level A, so the output of the magnetic tape remaining amount detection circuit 24 is at a low level. Therefore, the output of the AND circuit 26 becomes low level. On the other hand, since the magnetic tape 11 has sufficient remaining capacity on the reel 12, the end detection circuit 23
The output of is low level. Therefore, the OR circuit 27
The output of the motor 14 becomes low level, and the control circuit 20 controls the motor 14.
Do not reverse the direction of rotation.

That is, before the time t2 in FIG. 2 when the remaining amount of magnetic tape becomes less than the reference value, ! The direction of rotation of the motor 14 is not reversed regardless of the level of the signal applied.

At time t2 in FIG. 2, the remaining amount of tape is at the reference value A.
The following is true. Therefore, the magnetic tape remaining amount detection circuit 24 derives a high level output. On the other hand, this time t2
In this case, since the level of the signal to be recorded exceeds the reference value B, the output of the signal level detection circuit 25 becomes a low level, and the output of the AND circuit 26 also becomes a low level. Further, when the output of the termination detection circuit 23 is at a low level, the output of the OR circuit 27 is also at a low level, and the motor 14
The direction of rotation is not reversed.

At time t3 in FIG. 2, the level of the signal to be recorded becomes below the reference level B. At this time, the remaining amount of tape is already below the reference value A. Therefore, the magnetic tape remaining amount detection circuit 24 and the signal level detection circuit 25 each derive a high level signal, and the output of the AND circuit 26 also becomes high level. At this time, regardless of the output of the termination detection circuit 23, the output of the OR circuit 27 becomes high level,
The control circuit 20 reverses the rotational direction of the motor 14 and switches the switching means 15 so that the reel 12 is used as a take-up reel and the magnetic tape 11 is wound so as to run in the direction of arrow A1.

On the other hand, after the time jflJ t 2 , if the level of the signal to be recorded remains above the reference value,
The level of the recording signal never falls below the reference value B. At this time, it is assumed that the running direction of the magnetic tape 11 is reversed according to the operation of the end detection circuit 23, but the reference value No. 3 regarding the level of the recording signal is
Since the settings can be made arbitrarily, such a possibility can be reduced as much as possible.Although this embodiment has been described in connection with a recording operation, the present invention is implemented in exactly the same way during playback.

As described above, in this embodiment, when recording on the magnetic tape 11, the running direction of the magnetic tape 11 is reversed during a period when the level of the recorded signal is below a predetermined reference value. Therefore, since the level of the recorded signal is low during this period, it is possible to prevent the viewer from perceiving an undesired change in the recorded signal at the time of reversal as much as possible.

Effects According to the present invention as described above, when the magnetic tape is traveling in one direction, the amount of magnetic tape on the upstream side of this traveling direction is detected. The signal level detection means derives a high level signal when the level of the recorded or reproduced signal is below a predetermined reference level. The outputs of the tape amount detection means and the signal level detection means are applied to an AND circuit, and the running direction of the magnetic tape is reversed based on the output from the AND circuit. Therefore, the running direction of the magnetic tape can be reversed when the amount on the upstream side in the running direction of the magnetic tape is below a certain value and the level of the recorded or reproduced signal is below the reference level. Therefore, when the magnetic tape is reversed, deterioration in sound quality can be prevented as much as possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a magnetic tape recording/reproducing apparatus 10 according to an embodiment of the present invention, FIG. 2 is a waveform diagram explaining the operation of the magnetic tape recording/reproducing apparatus 10, and FIG. 3 is a typical preceding example. FIG. 2 is a block diagram showing the configuration of the technology. DESCRIPTION OF SYMBOLS 10... Magnetic tape recording/playback device, 11... Magnetic tape, 20... Control circuit, 24... Remaining amount detection circuit, 25... Signal level detection circuit, 26... Logical product Circuit, 27...OR circuit

Claims (1)

[Claims] Means for detecting the amount of magnetic tape on the upstream side in the running direction of the magnetic tape, and a signal that outputs a high level signal when the level of the recorded or reproduced signal is below a predetermined reference level. It includes a level detection means, an AND circuit to which respective outputs of the magnetic tape amount detection means and the signal level detection means are given, and a drive circuit that reverses the running direction of the magnetic tape based on the output from the AND circuit. A magnetic tape recording/playback device characterized by: