JPH06176437A - Magnetic reproducing device - Google Patents

Abstract

PURPOSE:To automatically adjust a switching point for a video head changeover at the time of an adjustment mode. CONSTITUTION:The adjustment mode is set by a microcomputer 21 with a pilot signal inputted during a horizontal blanking period of a video signal from a video signal processing circuit 6. Then, a control ant. is calculated by the microcomputer for the purpose of setting a space between a vertical synchronizing signal and a video head changeover signal for 6.5H. The video head changeover signal is generated in timing corresponding to this control amt. by a servo circuit 8 based on a position detecting signal of a rotary drum 11. and hence a head changeover switch 5 is changed so as to select a video head 2a or 2b. Consequently, a circuit configuration is simplified at low cost, and moreover, durability is superior.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic reproducing apparatus such as a helical scan type VTR, and more particularly to a switching point for switching a video head.

[0002]

2. Description of the Related Art In a conventional VTR, when a joint for each field of a video signal during reproduction comes after a vertical sync signal, noise generated by switching and switching of the video head during reproduction causes a horizontal sync system of a receiver. The scanning timing is disturbed, the interlace becomes incomplete, and the drift of the drum servo causes switching noise to enter the vertical synchronizing signal, resulting in vertical shaking of the screen. Therefore, the position of this joint, that is, the timing of switching the video head is set to 6.5 of the vertical synchronization signal.
By adjusting so as to come before the horizontal scanning period (hereinafter referred to as 6.5H), the above-mentioned problems are eliminated.

FIG. 8 shows the structure of a conventional VTR video head control system. In the figure, 1 is a magnetic tape which is run by a running mechanism (not shown), 2a and 2b are video heads, and 3a and 3b are video heads. Rotary transformers 4a and 4b respectively connected to the heads 2a and 2b are head amplifiers respectively connected to the rotary transformers 3a and 3b, and 5 is a head changeover switch for switching to an output part of either of the head amplifiers 4a and 4b. is there.

Reference numeral 6 denotes a video signal processing circuit having an input terminal connected to the rotor side of the head changeover switch 5, 7 denotes a vertical synchronization signal separating circuit for extracting a vertical synchronization signal Sv from the video signal from the video signal processing circuit 6, A vertical sync signal Sv from the vertical sync signal separation circuit 7 and an adjustment signal from a switching point adjustment circuit 9 for manually adjusting the switching points are input to generate a video head switching signal Ss to the head switching switch 8. This is a servo circuit for outputting, which drives and controls a mechanism (not shown) of a servo system of the device.

Reference numeral 10 is a video output terminal, and 11 is a rotary drum. The video heads 2a and 2b are mounted at, for example, 180 ° symmetrical positions, and rotary transformers 3a and 3b and a permanent magnet 12 for position detection are mounted. . Reference numeral 13 is a position detection head for extracting a pulse signal as a position detection signal from the permanent magnet 12, and is connected to the input terminal of the switching point adjustment circuit 9.

Further, FIG. 3 shows the positions of signals such as the vertical synchronizing signal Sv on the video track, and FIG. 4 shows good timing between the video head switching signal Ss and the vertical synchronizing signal Sv.

Next, the operation of the conventional apparatus will be described with reference to FIG. During reproduction, the video signal reproduced from the magnetic tape 1 by the helical scan of the video head 2a or 2b is amplified by the head amplifier 4a or 4b via the rotary transformer 3a or 3b. The amplified video signal is input to the video signal processing circuit 6 via the head switching switch 5 which is switched field by field by the video head switching signal Ss.

The video signal processed by the video signal processing circuit 6 is output from the video output terminal 10 and
The vertical synchronizing signal separation circuit 7 receives the vertical synchronizing signal Sv.
Are separated and input to the servo circuit 8 and serve as a reference signal for the reproducing system.

On the other hand, the permanent magnet 12 and the position detecting head 13
Thus, the predetermined position of the rotary drum 11 that is being driven to rotate is detected. The switching point adjustment circuit 9
Based on this position detection signal, the head switching switch 5 is switched to one of the video heads 2a and 2b at a predetermined position (position 6.5H before the vertical synchronizing signal Sv; see FIGS. 3 and 4). When the adjustment volume is manually adjusted, the adjustment signal corresponding to the adjustment amount is output.

The servo circuit 8 which has received this adjustment signal uses the vertical synchronizing signal Sv as a reference, and the video head switching signal Ss.
Is generated and output to the head switching switch 5. As a result, the head changeover switch 5 is connected to the video head 2a side,
Switching to either the video head 2b side. The conventional adjustment of the regeneration switching point on the production line is performed as follows. The adjuster reproduces the standard recorded alignment tape, sets the digital tracking to the preset mode, monitors the video signal and the video head switching signal Ss on the oscilloscope, and rotates the volume to 6.5H. adjust.

Since the conventional magnetic reproducing apparatus is constructed as described above, the switching point must be manually adjusted on the production line, which is inefficient in production and requires a complicated adjusting circuit. There was a problem that led to cost increase.

Further, since the adjustment of the switching point is performed by rotating the volume, there is a problem that drift due to variations in adjustment, temperature change and the like is likely to occur.

In order to solve the above-mentioned problems, Japanese Patent Laid-Open No. 60-150208 proposes a magnetic recording / reproducing apparatus capable of automatically adjusting the switching point. This magnetic recording / reproducing apparatus compares the phase of the vertical synchronizing signal separated from the video signal with the video head switching signal generated based on the position detection signal detected from the rotating drum. The count value corresponding to this phase difference is compared with the reference phase count value corresponding to 6.5H, and an error signal corresponding to the difference between these count values is output to the up / down control circuit. The output control signal from the up / down control circuit raises or lowers the time constant data in the memory, thereby adjusting the change timing of the video head switching signal.

In the above-mentioned conventional apparatus, there are various kinds of circuits such as a vertical synchronizing signal separation circuit, a digital mono-multi circuit, a phase difference detector, a comparator, a reference phase count value setting circuit, an up / down control circuit, a memory and a system controller. Circuits are needed.

[0015]

Since the conventional magnetic reproducing apparatus is constructed as described above, the adjustment of the switching point can be automated by digital processing in order to solve the above-mentioned problems at the time of manual adjustment. However, there is a problem that the circuit configuration becomes complicated and the cost becomes high. Also, in order to constantly adjust the switching point in playback mode,
Even if the adjustment is stabilized, the same operation is repeated, there is a waste in operation, and there is a problem that the circuit deteriorates quickly because it is used frequently.

The present invention has been made to solve the above problems, and automatically shifts to the adjustment mode by reproducing a magnetic tape and detecting a single or a plurality of specific signals. An object of the present invention is to obtain a magnetic reproducing device that automatically adjusts a switching point for switching.

[0017]

In a magnetic reproducing apparatus according to the present invention, in the apparatus, a switching signal for a video head and a vertical synchronizing signal are input to a microcomputer, and the signal interval between the two is constant. The calculation means for calculating the control amount for controlling the period and the mode setting means for setting the adjustment mode when a single or a plurality of specific signals are detected are provided.

[0018]

In the magnetic reproducing apparatus according to the present invention, in the adjustment mode by the mode setting means, the calculating means calculates the control amount for keeping the interval between the vertical synchronizing signal and the video head switching signal for a constant period, and the interval is calculated. The adjustment is automatically performed within a fixed period, and when the adjustment mode is released, the control amount is not calculated and the servo system is controlled by the control amount before the release.

[0019]

【Example】

Example 1. FIG. 1 shows a control system of a video head of a magnetic reproducing apparatus according to an embodiment of the present invention, in which the same or corresponding parts are designated by the same reference numerals 1, 2a, 2b, 3a, 3b, 4 as in FIG.
a, 4b, 5-8, 10-13 are attached and the description thereof is omitted.

Reference numeral 21 denotes a microcomputer, which receives the vertical synchronizing signal Sv from the vertical synchronizing signal separation circuit 7 and the video head switching signal Ss from the servo circuit 8 and sets the interval between these signals to 6.5H (Fig. 3 and FIG. 4), the magnetic reproducing device is automatically operated when the input of the pilot signal during the horizontal blanking period of the video signal is detected from the calculation means for calculating the control amount and the video signal processing circuit 6. It has mode setting means for setting the main body to the adjustment mode and mode releasing means for canceling the adjustment mode. Reference numeral 22 is an EAROM connected to the microcomputer 21.

Each input terminal of the servo circuit 8 is connected to the vertical synchronizing signal separating circuit 7, the microcomputer 21 and the position detecting head 13, and is for video head switching generated based on the position detecting signal from the position detecting head 13. Signal Ss
According to the control amount from the microcomputer 21, its timing is changed so as to be 6.5H before the vertical synchronizing signal Sv, and is output to the head changeover switch 5 and the microcomputer 21.

Next, the operation of the first embodiment will be described mainly with reference to FIG. However, the description of the overlapping parts with the conventional example will be omitted. During reproduction, the permanent magnet 12 and the position detection head 13 detect a predetermined position of the rotary drum 11, and this position detection signal is input to the servo circuit 8. Based on this signal, the servo circuit 8 generates a video head switching signal Ss and outputs it to the head switching switch 5 and the microcomputer 21. On the other hand, the vertical synchronization signal Sv separated by the vertical synchronization signal separation circuit 7 is the microcomputer 2
1 and the servo circuit 8 are input.

As described above, the video head switching signal S
The microcomputer 21 which receives s and the vertical synchronizing signal Sv receives the video head switching signal Ss as shown in FIG.
6.5H from the rising edge of the vertical synchronizing signal Sv to the falling edge of the vertical synchronizing signal Sv.
The control amount is calculated to be (about 413 μsec), and the servo circuit 8 is controlled by this calculation result to control the timing of the video head switching signal Ss, and the reproduction switching point is automatically adjusted.

In the above operation, the pilot signal during the horizontal blanking period of the video signal is input to the microcomputer 21 from the video signal processing circuit 6, and the microcomputer 21 automatically puts the magnetic reproducing apparatus main body into the adjustment mode. Done. After that, the microcomputer 21
When the adjustment mode is released, the control amount of the servo circuit 8 calculated immediately before the release is written in the EAROM 22. And
When the adjustment mode is released, the microcomputer 21 controls the servo circuit 8 with the control amount stored in the EAROM 22 to set the switching point to 6.5H.
Hold on.

FIG. 2 shows an example of the main part of the operation procedure of the microcomputer 21. First, the microcomputer 21 determines whether it is in the adjustment mode (step S1). In this step S1, it is judged whether or not the microcomputer 21 has input the pilot signal during the horizontal blanking period of the reproduced video signal, and if it is not in the adjustment mode, the adjustment mode is set. , If no adjustment is made and the adjustment mode is entered, cancel the adjustment mode.

The microcomputer 21, which has received the video head switching signal Ss and the vertical synchronizing signal Sv (step S2), changes the vertical synchronizing signal Sv from the rising edge of the video head switching signal Ss, as shown in FIGS. In the adjustment mode, the control amount is calculated so that the fall time is 6.5 H (about 413 μsec), and the servo circuit 8 is controlled by the calculation result to control the output timing of the video head switching signal Ss. Playback switching point 6.5H
Is automatically adjusted so that (step S3).

Next, the microcomputer 21 performs the same processing as in step S1 to determine whether or not the adjustment mode is canceled (step S4). If it is not the adjustment mode but the adjustment mode, the microcomputer 21 returns to step S2 to process and cancels. Then, the calculation result of the servo control amount is written in the EAROM 22 (step S
5). When the adjustment mode is released, the microcomputer 21 controls the servo circuit 8 with the control amount stored in the EAROM 22, and sets the switching point to 6.
It is held at 5H (step S6). Even when it is determined in step S1 that the adjustment mode is not set, the microcomputer 21 performs the process of step S6.

Example 2. FIG. 5 shows a video head control system of a magnetic reproducing apparatus according to a second embodiment of the present invention.
The same or corresponding parts as those in FIG.
b, 3a, 3b, 4a, 4b, 5-8, 10-13, 2
1 and 22 are attached, and the description of the same parts is omitted. In FIG. 5, the microcomputer 21 inputs the video head switching signal Ss from the servo circuit 8 and the vertical synchronization signal Sv from the vertical synchronization signal separation circuit 7, and the interval between these signals is 6.5H (FIG. 3). And FIG. 4), and a control (hereinafter abbreviated as CTL) signal is input from the servo circuit 8 and a calculating means for calculating a control amount for control, and the magnetic reproducing apparatus main body is automatically operated from the specific duty ratio. Mode setting means for setting the adjustment mode to the adjustment mode and mode releasing means for canceling the adjustment mode.

Reference numeral 23 is a CTL head for reproducing the CTL signal stored in the CTL track of the magnetic tape 1, and reference numeral 4c is a head amplifier connected to the CTL head 23. Each input terminal of the servo circuit 8 is connected to the vertical synchronizing signal separation circuit 7, the microcomputer 21, the position detecting head 13 and the head amplifier 4c, and outputs a CTL signal to the microcomputer 21, and outputs from the position detecting head 13. The video head switching signal Ss generated based on the position detection signal is changed in timing so as to be 6.5H before the vertical synchronizing signal Sv according to the control amount from the microcomputer 21, and the head switching switch is set. 5 and the microcomputer 21.

Next, the operation of the second embodiment will be described with reference to FIG. Since the microcomputer 21 automatically adjusts the reproduction switching point in the adjustment mode and controls the servo circuit 8 with the control amount stored in the EAROM 22 when the adjustment mode is released, the description thereof is the same as that of the first embodiment. Is omitted.

In the second embodiment, adjustment mode setting,
The release operation is different from that of the first embodiment. The operation is as follows. The CTL signal recorded on the CTL track of the magnetic tape 1 is reproduced by the CTL head 23 and input to the microcomputer 21 via the head amplifier 4c and the servo circuit 8. Microcomputer 21
Detects the duty ratio of the CTL signal, sets the adjustment mode if the duty ratio is a predetermined duty ratio, and cancels the adjustment mode if the duty ratio is not the predetermined duty ratio.

The main operation procedure of the microcomputer 21 is the same as that of FIG. 2, but the contents of steps S1 and S4 are different from those of the first embodiment as the above-mentioned operations.

Example 3. 6 shows a control system of a video head of a magnetic reproducing apparatus according to a third embodiment of the present invention.
The same or corresponding parts as those in FIG.
b, 3a, 3b, 4a, 4b, 5-8, 10-13, 2
1 and 22 are attached, and the description of the same parts is omitted. In FIG. 6, 24 is a linear audio head for reproducing a linear audio signal from the audio track of the magnetic tape 1, 4d is a head amplifier connected to the linear audio head 24, 25 is a linear audio signal input from the head amplifier 4d, It is an audio signal processing circuit that performs signal processing for signals.

Further, the microcomputer 21 inputs the video head switching signal Ss from the servo circuit 8 and the vertical synchronizing signal Sv from the vertical synchronizing signal separating circuit 7, and the interval between these signals is 6.5H (Fig. 3 and FIG. 4), when a pilot signal in the linear audio signal is input from the arithmetic means for calculating the control amount for controlling and the audio signal processing circuit 25, the magnetic reproducing apparatus main body is automatically set to the adjustment mode. It has a mode setting means for setting and a mode canceling means for canceling the adjustment mode when no input is made.

Each input terminal of the servo circuit 8 is connected to the vertical synchronizing signal separating circuit 7, the microcomputer 21, and the position detecting head 13, and a video head switching circuit is generated based on the position detecting signal from the position detecting head 13. Signal Ss
According to the control amount from the microcomputer 21, its timing is changed so as to be 6.5H before the vertical synchronizing signal Sv, and is output to the head changeover switch 5 and the microcomputer 21.

Next, the operation of the third embodiment will be described with reference to FIG. Since the microcomputer 21 automatically adjusts the reproduction switching point in the adjustment mode and controls the servo circuit 8 with the control amount stored in the EAROM 22 when the adjustment mode is released, the description thereof is the same as that of the first embodiment. Is omitted.

In the third embodiment, adjustment mode setting,
The release operation is different from that of the first embodiment. The operation is as follows. The linear audio signal recorded on the magnetic tape 1 is reproduced by the linear audio head 24, amplified by the head amplifier 4d, processed by the audio signal processing circuit 25 for an audio signal, and input to the microcomputer 21. . The microcomputer 21 detects the presence / absence of the pilot signal input in the linear audio signal, and when this pilot signal is input, the magnetic reproducing apparatus main body is automatically set to the adjustment mode, and when it is not input, the adjustment mode is set. To release.

The main operation procedure of the microcomputer 21 is the same as that of FIG. 2, but the contents of steps S1 and S4 are different from those of the first embodiment as described above.

Example 4. 7 shows a control system of a video head of a magnetic reproducing apparatus according to a fourth embodiment of the present invention.
The same or corresponding parts as those in FIG.
b, 3a, 3b, 4a, 4b, 5-8, 10-13, 2
1 and 22 are attached, and the description of the same parts is omitted. In FIG. 7, reference numerals 26a and 26b are mounted on the rotary drum 11, and HiFi heads 3c and 3d for reproducing a high-fidelity (hereinafter referred to as HiFi) audio signal from a video track of the magnetic tape 1 are mounted on the rotary drum 11 and HiFi. The rotary transformers are respectively connected to the heads 26a and 26b.

4e and 4f are rotary transformers 3c and 3
Head amplifiers 27, which are respectively connected to d, are HiFi head changeover switches for selecting one of the outputs of the head amplifiers 4e, 4f, and are changed over by an audio head changeover signal output from the servo circuit 8.
Reference numeral 25 is an audio signal processing circuit for processing the HiFi audio signal selected by the HiFi head changeover switch 27 for HiFi audio and transmitting it to the microcomputer 21.

The microcomputer 21 receives the video head switching signal Ss from the servo circuit 8 and the vertical sync signal Sv from the vertical sync signal separation circuit 7, and the interval between these signals is 6.5H (FIG. 3 and FIG. 3). (See FIG. 4). When it is detected that the pilot signal in the HiFi audio signal is input from the audio signal processing circuit 25 and the arithmetic means for calculating the control amount for controlling, the magnetic reproducing apparatus main body is automatically adjusted. And a mode releasing means for releasing the adjustment mode when the pilot signal is no longer detected.

Further, the servo circuit 8 has its input terminals connected to the vertical synchronizing signal separation circuit 7, the microcomputer 21, and the position detecting head 13, and generates an image based on the position detecting signal from the position detecting head 13. The head switching signal Ss is output to the head switching switch 5 and the microcomputer 21 by changing the timing so as to be 6.5H before the vertical synchronizing signal according to the control amount from the microcomputer 21, and The audio head switching signal thus generated is output to the HiFi head switching switch 27.

Next, the operation of the fourth embodiment will be described with reference to FIG. Since the microcomputer 21 automatically adjusts the reproduction switching point in the adjustment mode and controls the servo circuit 8 with the control amount stored in the EAROM 22 when the adjustment mode is released, the description thereof is the same as that of the first embodiment. Is omitted.

In the fourth embodiment, adjustment mode setting,
The release operation is different from that of the first embodiment. The operation is as follows. The HiFi audio signal recorded on the video track of the magnetic tape 1 is reproduced by the helical scanning HiFi head 26a or 26b, and the head amplifier 4 via the rotary transformer 3c or 3d.
It is amplified by e or 4f. On the other hand, the servo circuit 8 generates an audio head switching signal on the basis of the signal from the position detection head 13, and the HiFi head switching switch 27.
To output one of the head amplifiers 4e and 4f. The HiFi audio signal selected by the HiFi head changeover switch 27 is subjected to predetermined signal processing by the audio signal processing circuit 25 and input to the microcomputer 21.

When the microcomputer 21 detects the pilot signal in the inputted HiFi audio signal, it automatically sets the magnetic reproducing apparatus main body to the adjustment mode. After that, the microcomputer 21 releases the adjustment mode when the pilot signal is no longer detected in the input HiFi audio signal.

The main operation procedure of the microcomputer 21 is the same as that of FIG. 2, but the contents of step S1 and step S4 are different from those of the first embodiment as described above.

In each of the above-mentioned embodiments, the mode is set and released according to the detection result of the presence or absence of one type of signal.
Mode setting according to the detection result of the presence or absence of multiple types of signals,
Even if the release is performed, the same effect as that of the above-described embodiment can be obtained. Further, the adjustment mode may be released when a predetermined time has elapsed since the mode was set.

[0048]

As described above, according to the present invention, by detecting a single signal or a plurality of specific signals, the mode automatically shifts to the adjustment mode. In the adjustment mode, the video head switching signal and the vertical synchronizing signal are changed. The control amount is calculated so that the interval becomes a predetermined period, and the switching point of the video head is automatically adjusted by this control amount, so that the circuit configuration is simple and inexpensive, and the durability is excellent. There is.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a video head control system of a magnetic reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an example of a main operation procedure of the microcomputer shown in FIG.

FIG. 3 is an explanatory diagram showing a positional relationship between a vertical synchronizing signal on a video track and a video head switching point.

FIG. 4 is a timing chart of a vertical synchronizing signal and a video head switching signal.

FIG. 5 is a configuration diagram of a video head control system of a magnetic reproducing apparatus according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram of a video head control system of a magnetic reproducing apparatus according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of a video head control system of a magnetic reproducing apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a configuration diagram of a video head control system of a conventional magnetic reproducing device.

[Explanation of symbols]

 1 magnetic tape 2a, 2b video head 3a, 3b, 3c, 3d rotary transformer 4a, 4b, 4c, 4d, 4f, 4e head amplifier 5 head switching switch 6 video signal processing circuit 7 vertical synchronization signal separation circuit 8 servo circuit 11 Rotating drum 12 Permanent magnet 13 Position detection head 21 Microcomputer 22 EAROM 23 CTL head 24 Linear audio head 25 Audio signal processing circuit 26a, 26b HIFi head 27 HIFi head changeover switch

Claims (2)

[Claims] 1. An interval between a vertical synchronizing signal in a video signal reproduced from a magnetic tape by a video head and a video head switching signal for switching the video signal reproduced by the video head is adjusted to a constant period. In the magnetic reproducing device, the vertical synchronizing signal and the video head switching signal are input to a microcomputer, and the microcomputer calculates a control amount for controlling in the fixed period in the adjustment mode; When a single or plural specific signals recorded and reproduced on the tape are detected, a mode setting means for setting the magnetic reproducing apparatus main body to the adjustment mode is provided, and the control amount calculated above is used in the adjustment mode. The magnetic reproducing device is characterized in that the switching point of the video head is automatically adjusted. 2. A control signal having a predetermined duty ratio, a pilot signal in a linear audio signal, a pilot signal in a hi-fi audio signal, and a pilot signal in a horizontal blanking period of a video signal as the one or more specific signals. 2. The magnetic reproducing apparatus according to claim 1, wherein at least one kind of signal among the above is used.