JPH0548273Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a video tape recorder (VTR), and is particularly suitable for application to a high-fidelity VTR.

[Prior Art] In a high-speed VTR, high-speed audio signals are recorded in the helical direction of a videotape in the same way as video signals. One way to record high-speed audio signals in a helical manner is to record them deeper than the tape layer on which the video signals are recorded. It is provided separately from the video head. Moreover, the two heads have different azimuth angles so as not to adversely affect each other.

Therefore, even if the tracking of the video head is good, the tracking of the head for the high-frequency audio signal is not necessarily good. A VTR with an independent meter has already been proposed.

[Problems to be solved by the invention] By the way, in a high-speed VTR, when the tracking condition of the high-speed audio signal head deteriorates and the level of the pick-up signal is low, the normal audio signal head picks up. There is a device that switches to select the normal audio signal recorded in the longitudinal direction of the tape.

In this way, in conventional VTRs, the tracking meter continues to operate even if the signal is switched to a normal audio signal. Therefore, the needle of the tracking meter moves regardless of the state of the audio signal being played back, which may give the viewer a misunderstanding as if the tracking meter is broken. There is a risk that the signal may be misunderstood as if it were a high-speed audio signal.

This idea was created taking the above points into consideration.
A video tape recorder capable of making the audio signal being output correspond to the tracking meter display of the audio signal being recorded in the helical direction, thereby preventing the viewer from being misled about the output state and display state. This is what we are trying to provide.

[Means for Solving the Problems] In order to solve these problems, the present invention provides a tracking state of a magnetic head that scans a track formed in the helical direction of a videotape and on which a first audio signal is recorded. When the condition deteriorates, the output signal is switched to the second audio signal recorded on the audio track formed in the longitudinal direction of the video tape, and the envelope of the first audio signal picked up is changed to the tracking state of the magnetic head. In a video tape recorder equipped with a tracking meter section that displays according to the level, when the second audio signal is used as an output signal, the first audio signal is not supplied to the tracking meter section, and the tracking meter section A pointer operation control means for stopping the operation of the pointer is provided.

[Operation] The pointer operation control means does not operate the pointer of the tracking meter unit that indicates the tracking state of the first audio signal when the second audio signal is selected.

As a result, the tracking meter section does not operate when the second audio signal is selected, causing the user to misunderstand that the first audio signal is being output, or that the pointer is malfunctioning. This can be effectively avoided.

[Embodiment] Hereinafter, an embodiment of the VTR according to the present invention will be described in detail with reference to the drawings.

In FIG. 1, a pick-up signal picked up from a video tape 1 by an audio head 2 for high-fidelity audio signals is transferred to a reproduction amplifier circuit 3.
After being amplified, the signal is applied to a limiter circuit 4, an amplifier circuit 5, and an audio signal switching control circuit 6.

The limiter circuit 4 equalizes the amplitude levels of the incoming signals and supplies them to the FM demodulation circuit 7, and the FM demodulation circuit 7 FM demodulates the incoming signals using the carrier signal component assigned to the high-fidelity audio signal. The audio signal HAUD is obtained and sent to the audio signal selection circuit 8. The audio signal selection circuit 8 is also given the reproduced normal audio signal NAUD, and the audio signal selection circuit 8 selects an audio signal in accordance with the control signal CON from the audio signal switching control circuit 6 described above. being done.

The audio signal switching control circuit 6 is composed of a comparison circuit, which compares the amplified pickup signal with a reference level, and selects a logic "H" when the envelope level is smaller than the reference level, that is, when the tracking state of the head 2 is poor. On the other hand, when the envelope level is higher than the reference level, that is, when the tracking of the head 2 is good, a control signal CON which takes logic "L" is output to the audio signal selection circuit 8. Based on the control signal CON, the audio signal selection circuit 8 selects the high audio signal HAUD when the tracking is good, and selects the normal audio signal NAUD when the tracking is poor.

Further, the pickup signal amplified via the regenerative amplifier circuit 3 is amplified to the extent that it can drive the tracking meter section 9 via the amplifier circuit 5, and is given to the tracking meter section 9. The pointer is swung according to the envelope of the incoming signal so that the user can visually check the tracking state of the head 2.

In addition to the above configuration, this embodiment has a configuration in which the pointer of the tracking meter section 9 does not swing when the audio signal selection circuit 8 selects the normal audio signal NAUD. That is, an NPN transistor Q1 whose collector is connected to the output terminal of the amplifier circuit 5 and whose emitter is grounded is provided, and the control signal CON of the audio signal switching control circuit 6 mentioned above is connected to the base of this transistor Q1 through the resistor R1. The tracking meter unit 9 is short-circuited when the normal audio signal NAUD is selected.

In the above configuration, when the tracking state of the high-frequency audio signal head 2 is good, the envelope level of the pickup signal is large, and the control signal CON of logic "L" is sent from the audio signal switching control circuit 6, and the audio signal Selection circuit 8 is high frequency audio signal
Select HAUD. At this time, transistor Q
1 is turned off, and a pick-up signal amplified via the amplifier circuit 5 is given to the tracking meter section 9, and the pointer of the tracking meter section 9 swings in accordance with the tracking state.

On the other hand, the audio signal switching control circuit 6
When the tracking condition deteriorates to such an extent that a logic "H" output is sent from the
Select NAUD. At this time, since the control signal CON is at logic "H", the transistor Q1 is turned on to short-circuit the tracking meter section 9 and prevent the output signal of the amplifier circuit 5 from being sent to the tracking meter section 9. Thus, normal audio signal
While NAUD is being output, the pointer of the tracking meter section 9 does not swing.

Therefore, according to the embodiment described above, the pointer of the tracking meter section 9 operates only when the high audio signal HAUD is being output, and the pointer of the tracking meter section 9 operates only when the normal audio signal NAUD is being output. Since the pointer is stopped, it can be made clear that the tracking meter section 9 only supports the high audio audio signal HAUD and not the normal audio signal NAUD, so as to avoid giving the user a misunderstanding about the device. can be avoided.

FIG. 2 shows a second embodiment of the present invention, and corresponding parts to those in FIG. 1 are designated by the same reference numerals. In this embodiment, as shown in FIG. 2, the detection signal DO of the dropout detection circuit 10 is used as an on/off control signal for the short circuit transistor Q1 of the tracking meter section 9. The dropout detection circuit 10 is supplied with the pick-up signal amplified through the regenerative amplifier circuit 3, compares the envelope level of the pick-up signal with a predetermined reference value, and takes logic "H" when it is smaller than the reference value. On the other hand, it is used to supply the detection signal DO which takes logic "L" when it is larger than the reference value to the FM demodulation circuit 7 and to sample and hold the previous value when a dropout occurs so that the audio signal continues. In this embodiment, the detection signal is
DO is the transistor Q1 in addition to the FM demodulation circuit 7.
It is also given to the base of

Therefore, in this embodiment, when tracking deteriorates to the extent that many dropouts occur, the tracking meter section 9 is short-circuited and the pointer comes to a halt. Here, the comparison reference value in the audio signal switching control circuit 6 is almost equal to the comparison reference value in the dropout detection circuit 10 (more precisely, the comparison reference value in the dropout detection circuit 10 is slightly higher), and therefore, the dropout detection circuit 10 has a slightly higher comparison reference value. Even if short-circuit control is performed using the signal DO, the operation of the tracking meter section 9 stops when the normal audio signal NAUD is selected, making it possible to correlate the state of the pointer with the state of the output audio signal in a good manner. and will not mislead the user.

In this second embodiment, the reason why the output of the audio signal switching control circuit 6 is not used for short-circuit control and the output of the dropout detection circuit 10 is used for short-circuit control is actually because the amplifier circuit 5 is installed. There are IC chips that are equipped with a dropout detection circuit 10 but not equipped with an audio signal switching control circuit 6.
This is because when trying to apply the present invention to an IC chip, there are various restrictions such as the number of input/output pins, so the dropout detection circuit 10 was used in place of the audio signal switching control circuit 6.

In the above embodiment, the audio signal recorded in the helical direction is a high-frequency audio signal, but the tracking meter section can also be used for a VTR recording a PCM audio signal in the helical direction. It can also be applied if it is available.

[Effects of the invention] As described above, according to the invention, when tracking deteriorates and the switch is made to an audio signal recorded in the longitudinal direction of the tape, the pointer of the tracking meter section is prevented from moving accordingly. As a result, it is possible to obtain a video tape recorder in which the meter section and the output audio signal can be appropriately matched and the user will not be misled.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of a video tape recorder according to the present invention, and FIG. 2 is a block diagram showing a second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Video tape, 2...High-speed audio signal head, 6...Audio signal switching control circuit, 8...Audio signal selection circuit, 9...
Tracking meter section, 10... Dropout detection circuit.

Claims (1)

[Claims for Utility Model Registration] Formed in the helical direction of the videotape, the first
When the tracking condition of the magnetic head that scans the track on which the audio signal is recorded deteriorates, the output signal is switched to the second audio signal recorded on the audio track formed in the longitudinal direction of the video tape, and A video tape recorder comprising a tracking meter section that displays the tracking state of the magnetic head according to the envelope level of the picked-up first audio signal, wherein when the second audio signal is used as an output signal, the A video tape recorder comprising pointer operation control means for stopping the operation of the pointer of the tracking meter section without supplying the first audio signal to the tracking meter section.