JPH0614310Y2 - Audio signal tracking display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application In the present invention, a pair of magnetic heads arranged on a rotary cylinder alternately performs helical scanning of magnetic tapes running at at least two different speeds. Accordingly, the present invention relates to an audio signal tracking display device for displaying a tracking state of the audio signal reproduced by the pair of magnetic heads in a magnetic recording / reproducing device for recording / reproducing an FM audio signal.

(B) Prior art In a magnetic recording / reproducing machine (video tape recorder) for recording / reproducing an FM audio signal by alternately helically scanning a magnetic tape by a pair of magnetic heads of a rotating cylinder, the pair of magnetic heads is used. Is a circuit for correcting the tracking state of an audio signal when the audio signal is reproduced by helically scanning a recording track, for example, Japanese Patent Laid-Open No. 60-8.
No. 7407 and the like are presented, but a conventional technique for displaying a tracking state of an audio signal will be described below.

FIG. 4 is a schematic diagram showing a state in which video and audio signals are deeply recorded on a magnetic tape, and FIG. 5 is a characteristic showing the relationship between the tracking value of the audio signal and the DC voltage for shaping the audio signal for each running speed of the magnetic tape. It is a figure, (1) is magnetic tape, (2)
(3) is a track recorded on the magnetic tape (1) by a pair of magnetic heads for recording / reproducing video signals having different azimuth angles, and (4) (5) is the track (2) (3) Is a track deeply recorded on the tracks (2) and (3) on the magnetic tape (1) by a pair of magnetic heads for recording / reproducing audio signals having different azimuth angles and different azimuth angles.

Generally, the running speed of the magnetic tape (1) has a standard mode and a long time mode in which the running speed is slower than the standard mode. Here, for the video signal recording / playback in which the magnetic tape (1) is helically scanned in the long time mode. The pair of magnetic heads has a narrower head width than that of the standard mode, and the pair of magnetic heads for recording / reproducing an audio signal is shared by both modes, so the track (2) is set for each mode. The width difference between {or (3)} and track (4) {or (5)} will be different. That is, as shown in FIG. 4, the track width of the audio signal in the standard mode is made narrower than that of the video signal, but the track width of the audio signal in the long time mode is made substantially equal to that of the video signal.

As a result, the magnetic tape (1) is momentarily moved within the width of the tracks (2) (3) so that the pair of magnetic heads for recording / reproducing the audio signal accurately scan the tracks (4) (5). Assuming that the track widths (2) and (3) in the standard and long time modes are the same as shown in Fig. 5, when tracking is performed at high speed, the tracking value of the audio signal and the audio signal in each mode are The relationship of the shaped DC voltage has the characteristics shown in a and b, respectively.

(C) Problems to be solved by the device However, when displaying the change of the DC voltage shown in FIGS. 5A and 5B on the tracking meter etc., first, the difference between the maximum value of the DC voltage in both modes, that is, the optimum tracking value is calculated. Therefore, there is a problem that tracking correction becomes troublesome. Furthermore, since the level change near the optimum tracking value in FIG. 5A is large, that is, the correction range of the optimum value is narrow, tracking is performed in the standard mode. There was a problem that could not be used as a guide for correction.

(D) Means for Solving the Problems The present invention has been made to solve the above problems, and a pair of magnetic heads disposed on a rotary cylinder travel at at least two different speeds. Recording and recording of FM audio signals
In a magnetic recording / reproducing apparatus for reproducing, an amplifying means for amplifying the audio signal reproduced by the pair of magnetic heads corresponding to different speeds of the magnetic tape, and shaping the output of the amplifying means into direct current. The shaping means, a limiter means for holding the maximum value of the DC output of the shaping means at the same level capable of tracking correction of the audio signal, regardless of the speed of the magnetic tape, and a tracking state of the audio signal are displayed. It is composed of display means.

(E) Operation According to the present invention, a pair of magnetic heads arranged on the rotating cylinder alternately record and reproduce the FM audio signal by helically scanning magnetic tapes running at least at two different speeds. In the magnetic recording / reproducing apparatus for performing the above, the maximum value of the DC output obtained by shaping the audio signal is held at the same level by which the tracking correction of the audio signal can be performed by the limiter means regardless of the running speed of the magnetic tape. ,
As a result, the correction of the tracking state displayed on the display means becomes reliable and easy.

(F) Embodiment The details of the present invention will be described in detail with reference to the illustrated embodiment.

FIG. 1 is a circuit diagram showing the present invention, and FIGS. 2 and 3 are characteristic diagrams of the present invention showing a relationship between a tracking value of an audio signal and a DC voltage obtained by shaping the audio signal for each running speed of a magnetic tape. , (6) and (7) are arranged on the rotary cylinder (8), and as shown in FIG. 4, the magnetic tape (1) running at different speeds in the standard and long time modes are alternately helically scanned. A pair of magnetic heads for recording / reproducing an audio signal for recording / reproducing an FM audio signal; (9) an amplifier as an amplifying means whose input end is connected to the pair of magnetic heads (6) (7); (10) is a diode whose cathode is connected to the output terminal of the amplifier (9) and whose anode is grounded, (11) is a diode whose anode is connected to the output terminal of the amplifier (9), 12) has one end connected to the cathode of the diode (11) and the other end grounded. Shaping means comprising the diodes (10), (11) and the capacitor (12), (13), (14) are connected in series, and the anode of one of the diodes is the cathode of the diode (11). Is connected to the other diode and the cathode of the other diode is grounded, for example, two diodes, (15) is an amplifier whose input end is connected to the cathode of the diode (11), and (16) is the above A tracking meter as a display means connected to the output terminal of the amplifier (15).

The operation of FIG. 1 will be described with reference to the characteristics of FIGS. 2 and 3. First, the audio signal reproduced by the pair of magnetic heads (6) and (7) is amplified by the amplifier (9) corresponding to different traveling speeds of the magnetic tape (1). The output of the amplifier (9) is rectified by the diodes (10) and (11) and smoothed by the capacitor (12) to be DC, and the relationship between the tracking value of the audio signal and the DC voltage in the standard and long-time modes. Have the characteristics shown in FIGS. 2A and 2B, respectively, as in FIG.

Furthermore, the DC voltage in both modes is the diode shown in FIG.
Due to the forward voltage characteristics of (13) and (14), the diode (13) and (14) have a rising voltage (about 1.2 V) or less, that is, the maximum value of the DC voltage in both modes is kept at the same level, and FIG. It becomes the characteristic of.

For example, as shown in FIG. 5, if the tracking display range is set to 9 levels from A to I, A is set in the standard mode.
For the display range of ~ I, in the long time mode, E ~ I of 5
It becomes a display range of stages, and the difference in display becomes large. Therefore, in this proposal, the maximum value of the DC voltage in both modes is kept at the same level by applying a limiter with the diodes (13) and (14) to the DC voltage obtained by smoothing the envelope of the audio signal, and the same display range in both modes. (5 stages from E to I).

The change in the DC voltage shown in FIGS. 3A and 3B is amplified by the amplifier 15 and displayed on the tracking meter 16.

From this, when displaying the tracking status of the audio signal on the tracking meter (16), it is possible to make the optimum tracking value in both modes the same level by adding a diode limiter circuit, making it clear that tracking correction is confirmed. Becomes Further, since the correction range x of the optimum value is widened, tracking correction becomes reliable and easy.

According to the present invention, when the tracking state of the audio signal reproduced by the pair of magnetic heads is displayed on the display means, the optimum tracking values at different speeds of the magnetic tape are at the same level. From this, the confirmation of tracking correction becomes clear, and the correction range of the optimum value further expands,
Advantages such as reliable and easy tracking correction can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing the present invention, FIGS. 2 and 3 are characteristic diagrams of the present invention showing the relationship between a tracking value of an audio signal and a DC voltage obtained by shaping the audio signal, and FIG. 4 is a video and audio signal. FIG. 5 is a schematic diagram showing a state of deep recording on a magnetic tape, and FIG. 5 is a characteristic diagram showing a relationship between a tracking value of an audio signal and a DC voltage obtained by shaping the audio signal. (1) …… Magnetic tape, (6) (7) …… Magnetic head, (8) …… Rotating cylinder, (9) …… Amplifier, (10) (11) (13) (14) …… Diode, (12) …… Condenser, (16) …… Tracking meter.

Claims (1)

[Scope of utility model registration request] 1. A magnetic recording for recording / reproducing an FM audio signal by alternately helically scanning magnetic tapes running at at least two kinds of speeds by a pair of magnetic heads arranged on a rotary cylinder. / In the reproducing device, an amplifying means for amplifying the audio signal reproduced by the pair of magnetic heads corresponding to different speeds of the magnetic tape, and a shaping means for shaping the output of the amplifying means into a direct current, Regardless of the speed of the magnetic tape, limiter means for holding the maximum value of the DC output of the shaping means at the same level capable of tracking correction of the audio signal, and the output of the limiter means is input to track the audio signal. An audio signal tracking display device comprising a display means for displaying a status.