JPH05211642A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To perform the program searching retrieval by the intermittent recording part of a video signal when fast forwarding and rewinding are performed. CONSTITUTION:This device is equipped with a capstan motor 2 to performs the intermittent feed of a magnetic tape 1, an AC head 3, an FG head 4 to read a signal magnetized on the circumference of the capstan motor 2, a CTL control circuit 5 to control the read/write of the control pulse of the AC head 3, a drive circuit 6 to drive the capstan motor 2, an FG amplifier circuit 7, a control circuit 8 to control the intermittent feed of the capstan motor, a one-field counter 9 to count an FG pulse by one field, a positive polarity counter 10 for counting the FG pulse to generate a control pulse of positive polarity, a negative polarity counter 11 for counting the FG pulse to generate a control pulse of negative polarity, and a comparator 12 for comparing the counted value of the positive polarity counter 10 and that of the negative polarity counter 11 with an arbitrary value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time-lapse VT which enables recording for a long time by intermittently step-moving a magnetic tape and recording a video signal by dropping a frame.
The present invention relates to a magnetic recording / reproducing device called R.

[0002]

2. Description of the Related Art Time-lapse VTR has been used as a monitoring VTR for in-store security (security) in banks, supermarkets, markets, etc., and for many purposes such as recording educational observation data of educational institutions and laboratories, or image files. It was On the other hand, in recent years, due to the change in the industrial structure from the secondary to the tertiary, the business hours of the commerce and service industries are gradually extended,
Due to a chronic labor shortage, the needs for time-lapse VTR as video security are increasing in various small stores.

An example of a cue signal writing method for the conventional time-lapse VTR described above will be described below with reference to the drawings. FIG. 3 shows a block diagram of recording control writing. In FIG. 3, 1 is a magnetic tape, 2 is a capstan motor, 3 is an AC head (control head) capable of reading and writing control pulses, and 5 is CTL recording / reproducing for controlling reading and writing of control pulses in the AC head 3. Circuit, 1
Reference numeral 8 is an input terminal for inputting a recording control signal from the servo circuit, 19 is a control duty changeover switch, 20 is a rising edge detector, and 21 is a mono-multi which creates a pulse width at a ratio of 3: 7. Further, FIG. 4 shows signal waveforms of respective parts. 3 and 4, h is a recording control signal which is an input from the servo circuit, i is a differentiated rising pulse which is an output of the rising detector 20, and j is a recording control pulse created by the monomulti 21. ..

The operation of the conventional cueing signal writing method configured as described above will be described below. The time-lapse VTR normally performs intermittent recording by intermittently driving the capstan motor 2 and recording video signals on the magnetic tape 1 by dropping frames. The duty of the recording control signal h which is an input from the servo circuit has a ratio of 6 to 4. If something goes wrong during monitoring,
There is a mode called alarm recording in which continuous recording at standard speed is performed in conjunction with abnormality information. During the first 2 seconds of this alarm recording, the control duty changeover switch 19 is connected to the rising edge detector 20, and the recording control signal h having a control duty ratio of 6 to 4 is differentiated by the rising edge detector 20 and a rising pulse is generated. i and output to the monomulti 21. A recording control pulse j having a ratio of 3: 7 is created from the rising pulse i by the monomulti 21, and is written on the magnetic tape 1 via the AC head 3 by the CTL recording / reproducing circuit 5.

[0005]

However, in the above-mentioned configuration, the duty of the recording control pulse cannot be changed during intermittent recording, and therefore the change of the reproduction control pulse width is detected during fast forward and rewind, and the head is not detected. However, there is a problem in that the detection that can be performed cannot be handled by the intermittent recording portion.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a magnetic recording / reproducing apparatus capable of searching for a cue in an intermittently recorded portion of a video signal during fast-forwarding and rewinding.

[0007]

In order to solve the above-mentioned problems, a magnetic recording / reproducing apparatus of the present invention generates a capstan motor for intermittently feeding a magnetic tape and an FG pulse in proportion to the rotation speed of the capstan motor. An FG pulse generator for generating, a positive polarity counter for counting FG pulses for generating a positive control pulse, a negative polarity counter for counting FG pulses for generating a negative control pulse, and an FG pulse The 1-field counter that counts the FG pulses for one field generated by the generator and alternately applies the reset pulse to the positive polarity counter and the negative polarity counter for one field, and the count value of the positive polarity counter and the count value of the negative polarity counter, respectively. A comparator that compares an arbitrary count value and the control signal to the magnetic tape according to the comparison result of the comparator. Characterized in that a control signal recording means for recording.

[0008]

According to the structure of the present invention, during the intermittent recording of the video signal by running the magnetic tape intermittently, for example, the arbitrary count value of the comparator for comparing with the count value of the negative polarity counter is set to 2
Value, that is, the control pulse duty is 6
By setting the count value of pair 4 and the count value of 3 to 7, the duty of the negative polarity control pulse of the control signal can be changed. As a result, it is possible to search for the beginning of the intermittent recording portion during fast forward and rewind.

[0009]

1 shows the structure of a magnetic recording / reproducing apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a magnetic tape, 2 is a capstan motor for intermittently feeding the magnetic tape 1, 3
AC for reading and writing control pulses
A head 4, an FG (frequnecy generator) head for reading a signal magnetized on the circumference of the capstan motor 2, a 5 for a CTL recording / reproducing circuit for controlling reading and writing of a control pulse of the AC head 3, and 6 for a cap Drive circuit for driving the stun motor 2, 7 is FG
FG amplifier circuit for amplifying the signal from the head 4, 8 is a control circuit for controlling the capstan intermittent feed, 9 is a 1-field counter for counting the FG pulse from the FG amplifier circuit 7 for 1 field, 10 is a positive control pulse A positive polarity counter that serves as a creation reference and counts FG pulses, 11 represents a negative polarity counter that serves as a creation reference and counts FG pulses, and 12 represents a count value of the positive polarity counter 10 and a negative polarity counter 1.
It is a comparator that compares the count value of 1 with an arbitrary value. The FG pulse generator is constituted by magnetizing the FG head 4, the FG amplifier circuit 7, and the capstan motor 2 on the circumference, and the control signal recording means is the AC head 2 and the CTL.
It is composed of a recording / reproducing circuit 5.

FIG. 2 shows the timing for explaining the operation during the intermittent recording of this magnetic recording / reproducing apparatus. In FIG. 2, a is a head switch pulse, b is a recording gate signal for controlling the recording current to the video head, c is a current of the capstan motor 2 (capstan current), d is a recording control signal, and e is a one-field counter. Count value of 9 (1
Field counter count value), f is the positive polarity counter 10
Is the count value (positive polarity counter count value), and g is the negative polarity counter 11 count value (negative polarity counter count value).

The magnetic recording / reproducing apparatus configured as described above employs a helical scan system in which two heads (not shown) are crossed diagonally across the magnetic tape 1 for tracking, and the capstan motor 2 is used. A time-lapse VT that can be recorded for a long time by intermittently driving each field and recording a video signal for one field during intermittent driving
R.

A method of varying the duty of the recording control pulse at the time of intermittent recording in this magnetic recording / reproducing apparatus will be described. At the time of intermittent recording, the signal magnetized on the circumference of the capstan motor 2 is read by the FG head 4, amplified by the FG amplifier circuit 7, and the waveform-shaped FG pulse is counted up by the 1-field counter 9. The positive polarity counter 10 and the negative polarity counter 11 also count up in the same manner. The control circuit 8 controls the drive circuit 6 based on the information from the 1-field counter 9 to intermittently drive the capstan motor 2 for 1 field.

For field recording, as shown in FIG. 2, it is necessary to alternately open the recording gate (video signal writing gate) by the recording gate signal b during the R'and L'sections of the head switch pulse a. First, when the L'section recording gate is opened, the capstan activation timing is set at the rising edge of the head switch pulse a, and the capstan current c is controlled to have the waveform A. At this time, the positive polarity counter 10 is reset at the point where the 1-field counter count value e and the 1-field reference count value Nt when opening the recording gate in the R'section before this feeding match. At the point I where the positive polarity counter count value f and the specific value Np of the comparator 12 match, the recording control signal d is raised, the CTL recording / reproducing circuit 5 is moved to the AC head 3
Then, a positive control pulse is written on the magnetic tape 1. With this operation, the 1-field counter 9 is reset at the point E where the 1-field counter count value e and the 1-field reference count value Nt match, and the negative polarity counter 11 is reset.

Next, when opening the R'section recording gate,
The capstan activation timing is set at the fall of the head switch pulse a, and the capstan current c is controlled so as to have the waveform B. At this time, the 1-field counter 9 is reset at the point F where the 1-field counter count value e and the 1-field reference count value Nt match, and the positive polarity counter 10 is reset. At the point K at which the negative polarity counter count value g and the specific value N1 of the comparator 12 (value at which the control duty becomes 6 to 4) match, the recording control signal d is lowered, the CTL recording / reproducing circuit 5 is turned off, and A
A negative control pulse is written on the magnetic tape 1 by the C head 3.

Next, in the waveform D of the capstan current c for writing the cue signal, the specific value of the comparator 12 is set to N2.
By setting the value (control duty becomes 3 to 7), only the negative control pulse write timing is set to the negative counter count value g and the specific value N2.
A negative control pulse can be written at a point L where is coincident with.

Thus, the control pulse can be written and the duty can be changed by an arbitrary value of the comparator 12. That is, when the magnetic tape is run intermittently and the video signal is intermittently recorded, by changing the writing duty of the control pulse as a cue signal, it is possible to perform cue search even in the intermittent recording portion during fast forward and rewind. can do.

[0017]

As described above, according to the present invention, during the intermittent recording of the video signal by running the magnetic tape intermittently, for example, an arbitrary count value of a comparator for comparing with the count value of the negative polarity counter is displayed. By setting the two values, that is, the duty ratio of the control pulse to the count value of 6: 4 and the count value of 3 to 7, the duty of the negative polarity control pulse of the control signal can be changed. As a result, it is possible to search for the beginning of the intermittent recording portion during fast forward and rewind.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart at the time of intermittent recording in one embodiment of the present invention.

FIG. 3 is a block diagram of recording control writing in a conventional time-lapse VTR.

FIG. 4 is a signal waveform diagram of each part in a conventional example.

[Explanation of symbols]

 1 magnetic tape 2 capstan motor 3 AC head 4 FG head 5 CTL recording / reproducing circuit 6 drive circuit 7 FG amplifier circuit 8 control circuit 9 1 field counter 10 positive polarity counter 11 negative polarity counter 12 comparator

Claims (1)

[Claims] 1. A magnetic recording / reproducing method in which a magnetic tape is run intermittently, and a control signal composed of a video signal and a control pulse of a positive polarity and a negative polarity indicating a start position of a recording track of the video signal is recorded on the magnetic tape. The device is a capstan motor for intermittently feeding a magnetic tape, an FG pulse generator for generating an FG pulse in proportion to the rotation speed of the capstan motor, and the FG for generating a positive control pulse. A positive polarity counter that counts pulses, a negative polarity counter that counts the FG pulses to generate negative control pulses,
FG for one field generated by the FG pulse generator
A one-field counter that counts pulses and alternately applies a reset pulse to the positive polarity counter and the negative polarity counter in one field, and compares the count value of the positive polarity counter and the count value of the negative polarity counter with arbitrary count values. And a control signal recording means for recording a control signal on the magnetic tape according to the comparison result of the comparator.