JPS6313157A - Magnetic head switching signal generation device - Google Patents

Abstract

PURPOSE:To obtain a titled device easy to set a time constant by setting the time constant of a charging means by plural time constant setting means which separately act according to the running speed of plural magnetic tapes. CONSTITUTION:In a reference mode, an H signal outputted from the output terminal Q1 of a flip-flop 7 by the H signal from an input terminal 24 is charged in a capacitor 20 in the time constant set in a time constant set means 37. When in the terminal D2 of a flip-flop 35 the magnetic head switching signal for a video signal corresponding to a reference mode is inputted and in the terminal C2 the signal from the terminal Q1 of the flip-flop 7 is inputted, the magnetic head switching signal for a sound signal which is delayed in phase by a time t1 is outputted from the output terminal Q2. In a long time mode, an L signal is inputted in the input terminal 24 and the time constant of the capacitor 20 is set in a time constant set means 38.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a plurality of magnetic head pairs (the former) for recording/reproducing video signals that scan a magnetic tape, and one pair for recording/reproducing audio signals. The present invention relates to a magnetic head switching signal generation device for generating a magnetic head switching signal from the former magnetic head switching signal in a magnetic recording/reproducing machine in which the latter magnetic head pair is disposed on a rotating cylinder.

(b) Conventional technology A plurality of pairs of magnetic heads for recording/reproducing video signals for scanning a magnetic tape (the former) and a pair of magnetic heads for recording/reproducing audio signals (the latter) are arranged on a rotating cylinder. For example, Japanese Patent Application No. 1983-7753 has been proposed as a conventional device for generating the latter magnetic head switching signal from the former magnetic head switching signal in a magnetic recording/reproducing machine equipped with the same system.The technology will be explained below. .

FIG. 4 is a plan view showing the rotation and arrangement of the magnetic head on the cylinder, and FIG. 5 is a circuit diagram showing a conventional magnetic head switching signal generating device.

To explain the figure numbers and configurations of Figures 4 and 5,
(1) consists of two pairs of magnetic heads (2a), (2b), (3a), and (3b) for recording/reproducing video signals corresponding to the magnetic tape running speed (standard and long-time modes) and the magnetic tape running speed. A pair of magnetic heads (4a) and (4b) for audio signal recording/reproduction not compatible with the above are opposed at 180 degrees, and each of the magnetic heads (2g) (3a) (4a)
(2b), (3b), and (4b) are arranged at 60" intervals, and (5) is 180" apart from the rotary cylinder (1).
+ (an angle corresponding to several horizontal scanning periods), the magnetic tape (6) is connected to the data terminal of the flip-flop (7), and the power supply terminal to which DC voltage can be input, (
8) When reproducing video and audio signals, the magnetic head pair <
An input terminal (9) to which the magnetic head switching signals of 2a), (2b), and (3a) and (3b) are input is connected at its base to the input terminal (8) via a resistor (10). A transistor (11) whose emitter is grounded, its base connected to the input terminal (8) via a resistor (12) and a capacitor (13), and its collector connected to the clock terminal C8 of the flip-flop (7).
and a transistor (15) whose emitter is connected to the power supply terminal (6) and connected to the collector of the transistor (11) via a resistor (14).
), a bias resistor (16) connected between the base and emitter of the transistor (15), and the resistor (1
2) and the capacitor (13) connected between the connection point and the collector of the transistor (11).
7) a clock pulse generation circuit consisting of a resistor (18) connected between the clock terminal C8 and the ground and grounding the clock terminal C1 when its input is off;
) (20) is a resistor and a capacitor connected in series between the reset terminal RI of the flip-flop (7) and the ground, (21) and (22) are the resistors and capacitors connected in series between the output terminal Q of the flip-flop (7) and the reset terminal R8. (23) is a diode whose cathode is connected to the output terminal Q1 and whose anode is connected to the reset terminal RI; (24> is a high-level signal ( A low-level signal (hereinafter referred to as rHJ) is input during long-time mode.
An input terminal (25) to which a signal (referred to as
a transistor (28) whose emitter is grounded and whose base and emitter are connected via a bias resistor (27); the collector is connected to the reset terminal R1 via a variable resistor (30) and a resistor (31);
and a transistor (33) whose emitter is connected to the power supply terminal (6) and whose base is connected via a bias resistor (32);
20) a control circuit that controls a time constant until the charging voltage reaches the threshold voltage of the reset terminal R8;
(34) is the input terminal (8) and the flip-flop (
A resistor connected between the data terminals of (35) and (36)
is an output terminal - which is connected to the output terminal Q of the flip-flop (35) and outputs a magnetic head switching signal for the magnetic head pair (4a) (4b). Note that the output terminal ζ1 of the flip-flop 7) and the clock terminal C2 of the flip-flop (35) are disconnected, and the set terminal S1 of the flip-flop (7), the set terminal S of the flip-flop (35>), and the reset terminal R1 is grounded.

When the record/playback button (not shown) provided on the video table fooder is turned on and video and audio signals are recorded/played, the magnetic tape (5) moves at high speed in the A direction as shown in Figure 4. It is completely wound around the rotating cylinder (1) and travels in the B direction.

When recording/reproducing video and audio signals on the magnetic tape (5) running in the standard mode, the magnetic heads (4) having 120° intervals on the rotating cylinder (1)
a) (2a), (4b) (2b) are driven, that is, the magnetic heads (4a) (4b) are driven respectively.
Prior to step b), the same track on the magnetic tape (5) is helically scanned. Also, magnetic tape (5) runs in long-time mode at a slower speed than standard mode.
When performing recording/reproduction of video and audio signals on the rotating cylinder (1), the magnetic heads (4a) (3a), (4b) (3b) having 60" intervals are fully driven,
That is, the magnetic heads (4a) and (4b) are respectively connected to the magnetic head (3).
a) Prior to (3b), the same track on the magnetic tape (5) is helically scanned. This makes it possible to record/playback superimposed video and audio signals in support of standard and long-term modes.

However, as shown in Figure 4, one of the magnetic head pairs (2
a) (3a) (4a) (or (2b) (3b) (4b
)) helically scans the magnetic tape (5), the other magnetic head pair (2b) (3b) (4b) (or (2
a) (3a) (4a) ) cannot helically scan the magnetic tape (5), especially when playing back video and audio signals, the magnetic head pairs (2a) (2b), (3a) (3b)
, (4a) and (4b), noise will be generated in the reproduced video and audio signals due to the magnetic head that cannot scan the magnetic tape (5).

Therefore, when reproducing each video and audio signal in the standard and long-time modes, the magnetic head pairs (2a) (2b), (3a)
The magnetic head switching signal (3b) and the magnetic head pair (4) having a different phase difference from the magnetic head switching signal according to each mode.
a) The magnetic head switching signal (4b) is required.

In FIG. 5, consider the time it takes for the charged WL voltage of the capacitor (20) to reach the threshold voltage of the reset terminal R1. In the standard mode, when the signal "r H" is input to the input terminal (24) and the transistors (28) and (33) are turned on, the time constant of the capacitor (20) is determined by the variable resistors (21) (30) and the resistor ( 19)(
22) Set by (31), the power supply heavy voltage and the output voltage of the output terminal Q1 can fully charge the capacitor (20).

In the long-time mode, when an "L" signal is input to the input terminal (24) and the transistors (28) and (33) are turned on, the time constant of the capacitor (20) changes to the variable resistor (21).
) and (19) (22), the output terminal Q
Only one output voltage is charged to the capacitor (20). From this, the time it takes for the charging voltage of the capacitor (20) to reach the threshold voltage of the reset terminal R8 differs depending on the standard and long-time modes, that is, the magnetic head pairs (2a), (2b), (3a) ) Magnetic head pair (4) with a different phase difference from the magnetic head switching signal of (3b)
a) (4b) magnetic head switching signal is output terminal (36)
is output from.

(c) Problems to be solved by the invention In the above, since the variable resistor (21) (3Q) is connected in parallel to the capacitor (20), after adjusting the variable resistor (21), the variable resistor (3Q) ) to set the time constant of the capacitor (20) in each mode, which causes the variable resistor (21
) or damage the capacitor (
20) It becomes impossible to set the time constant of magnetic head pairs (2a) (2b), (3a) (3b) according to each mode.
) There is a problem in that it is impossible to obtain a magnetic head switching signal for the magnetic head pair (4a) (4b) which has a different phase difference from the magnetic head switching signal for the magnetic head pair (4a) and (4b).

(d) Means for Solving the Problems The present invention has been made to solve the above problems, and is a video signal recording/reproducing device that scans a magnetic tape in response to a plurality of magnetic tape running speeds. In a magnetic recording/reproducing machine in which a plurality of pairs of magnetic heads and a pair of magnetic heads for recording/reproducing audio signals for scanning the magnetic tape are disposed on a rotating cylinder, the charging means' charging pressure and Controlled by the first magnetic head switching signal of the plurality of pairs of magnetic heads, the magnetic head switching signal of the one set is delayed from the first magnetic head switching signal corresponding to the time until the charging voltage reaches a constant value. generating means for generating a second magnetic head switching signal of a pair of magnetic heads; and a generating means that operates independently corresponding to a plurality of said magnetic tape running speeds and sets a time constant until said charging voltage reaches said constant value. This configuration includes a plurality of time constant setting means for causing the generation means to generate a plurality of second magnetic head switching signals having different phase differences with respect to the first magnetic head switching signal.

(E) Effect According to the present invention, when the generation means generates the second magnetic head switching signal having a phase difference different from that of the first magnetic head switching signal in accordance with a plurality of magnetic tape running speeds, the phase difference The time constant of the charging means that determines the magnetic tape can be set independently according to a plurality of magnetic tape running speeds.

(f) Example The details of the present invention will be specifically explained with reference to illustrated embodiments.

FIG. 1 is a circuit diagram showing the present invention, and FIGS. 2 and 3 are circuit diagrams showing the present invention.
This is a timing chart showing the waveforms of each part in the figure, and (a), (donkey 8), and (d) in FIGS. 2 and 3 are the same waveform.

To explain the figure number and structure of Fig. 1, (7>(3
5) is a flip-flop as a generating means, (20) is a capacitor as a charging means, and (37) is a resistor (26).
) (27) (29) (31) (32), variable resistor (30
), a transistor (33) whose emitter is connected to the output terminal Q1 of the flip-flop (7), and a transistor (28), and r H is connected to the input terminal (24).
, a time constant setting means (38) for setting the time constant of the capacitor (20) by receiving a signal from the resistor (39).
(40>, its base is grounded, its collector is connected to the anode of the diode (23) through the variable resistor (41) and the resistor (42), and its emitter is connected to the output terminal Q. connected and resistor (43
) connected to its base via a transistor (44
), and a time constant setting means for setting the time constant of the capacitor (20) when a signal "rl," is input to the input terminal (24) connected to the connection point of the resistors (39) and (40). The same elements as in FIG. 5 are given the same figure numbers.

The operation of the circuit shown in FIG. 1 will be explained using FIGS. 2, 3, and 4. In the standard mode in which the magnetic tape (5) is completely wound around the rotating cylinder (1) and runs at a predetermined speed, the magnetic head pair (4a) ( 4b), when generating the second magnetic head switching signal (4b), the magnetic head (4a) (4b)
Since each of the magnetic heads (2a) and (2b) helically scans the same track on the magnetic tape (5), the switching signal for obtaining reproduction signals in the magnetic heads (2a) and (2b) It is only necessary to generate a switching signal for obtaining a reproduced signal in each of the magnetic heads (4a) and (4b).

First, a DC voltage of a predetermined level (for example, +5 volts) is input to the %JX terminal (6), that is, the data terminal, and the magnetic head pair (2a) is connected to the input terminal (8) by the r H and r L signals. (2b) The first magnetic head switching signal shown in FIG. 2(a) that alternately switches is input. The transistor (11) is switched by this first magnetic head switching signal, and the signal at the collector of the transistor (11) becomes the signal shown in FIG. 2(b), that is, the inverted signal of FIG. 2(a). The signals in FIG. 2(b) are differentiated and moderated by a capacitor (13) and a resistor (12), a capacitor (17), and a resistor (12), respectively.

From this, the base input of the transistor (15) is shown in Figure 2 (
Since the transistor (15) turns on at the falling edge of FIG. 2 (8), the clock terminal C
The clock pulse shown in FIG. 2 (d) is input to I.

On the other hand, since it is the standard mode, the transistor (28) is turned on by the rH signal input to the input terminal (24), and the collector potential of the transistor (28), that is, the base potential of the transistor (33) decreases. The transistor (33) is also turned on.

To explain the flip-flop (7), when a DC voltage is input to the data terminal D1, the clock terminal CI
When the clock pulse shown in Fig. 2 (d) is input to the , an "H" signal is first output from the output terminal Q, and since the transistor (44) is off, the signal shown in Fig. 2 (*) is output. Similarly, the signal is charged to the capacitor (20) with a time constant determined by adjusting the variable resistor (30). After that, when the charging voltage of the capacitor (20) reaches the threshold voltage of the reset terminal R1, the charging voltage is transferred to the diode (
23> is discharged to the ground of output terminal Q, and further resets the r HJ signal from output terminal Q.
A signal is output, and this signal is held until the next clock pulse is input to the clock terminal C1. That is, the signal shown in FIG. 2 is output from the output terminal Q1.

To explain the flip-flop (35), the first magnetic head switching signal shown in FIG. 2 (A) is input to the data terminal C2, and the signal shown in FIG. ) signal is input, and the flip-flop (35) connects to the data terminal at the rising edge of the clock terminal 02 and operates to synchronize and transfer the input, so the output terminal is as shown in Figure 2 (H). Q, the second magnetic head pair (4a) (4b) whose phase is delayed by a time t from the first magnetic head switching signal in FIG. 2(a).
A magnetic head switching signal is output.

From this, the magnetic head pair (2a) (2b) is switched by the first magnetic head switching signal in FIG. 2(A), and the magnetic head pair (4a) (4b) is switched by the first magnetic head switching signal in FIG. It is switched by the magnetic head switching signal No. 2, and the video and audio signals are reproduced in the standard mode.

Next, in the long time mode in which the magnetic tape (5) is completely wound around the rotating cylinder (1) and runs at a slower speed than the standard mode, the first magnetic head switching signal of the magnetic head pair (3a) (3b) When generating the second magnetic head switching signal for the magnetic head pair (4a) (4b), the magnetic head (
Since the magnetic heads 4a and 4b helically scan the same track on the magnetic tape 5 in advance of the magnetic heads 3a and 3b, the magnetic heads 3a and 3b obtain reproduction signals. From the switching signal for the magnetic head (4a
) (4b) to generate a switching signal for obtaining a reproduction signal. Furthermore, the magnetic heads (2a), (4b), (2b) and (4a) which are driven in the standard mode each have a 60" spacing on the rotating cylinder (1), while the magnetic head (3a) which is driven in the long-term mode (4b), (3b)
(4a) each have a 120° interval on the rotating cylinder (1), so the magnetic head (4a) in the standard mode
) (4b), it is sufficient to generate a switching signal for the magnetic heads (4a) and (4b) whose phase is delayed from that of the switching signal for (4b).

First, as in the standard mode, a DC voltage is input to the data terminal C1, and the clock pulse shown in FIG. 3(D) is input to the clock terminal C1. On the other hand, since it is a long-time mode, the transistor (44) is turned on by the signal r L inputted to the input terminal (24).

To explain the flip-flop (7), first, a signal rH is output from the output terminal Q1, and since the transistor (33) is off, the signal is passed through the variable resistor ( The capacitor (20) is charged with a time constant determined by adjusting the variable resistor (41) which can be adjusted independently of the capacitor (20). Then the capacitor (20)
When the charging voltage reaches the threshold voltage of the reset terminal R after a longer time than in the standard mode due to the setting of the time constant, the charging voltage is discharged to the ground of the output terminal Q through the diode (23). Further, a signal r L , which is a reset of the signal r HJ, is output from the output terminal Q, and this signal is held until the next clock pulse is input to the clock terminal CI. That is, the output terminal Q,
The signal shown in FIG. 3 (to) is output from.

To explain the flip-flop (35), the first magnetic head switching signal shown in FIG. 3 (a) is inputted to the data terminal, and at the same time the first magnetic head switching signal shown in FIG. ) is input, and the flip-flop (35) is connected to the clock terminal C.

Since the data terminal is connected to the rising edge of the input and operates to synchronize and transfer the input, the first magnetic head switching from the output terminal Q as shown in Figure 3 (H) to the first magnetic head in Figure 3 (A) is performed. A second magnetic head switching signal of the magnetic head pair (4a) (4b) whose phase is delayed by time 1g (>1+) from the signal is output.

From this, the magnetic head pair (3a) (3b) is shown in Figure 3 (a).
is switched by the first magnetic head switching signal, and
The magnetic head pair (4a) (4b) is switched by the second magnetic head switching signal shown in FIG.

It goes without saying that the present invention is also applicable to devices having three or more types of magnetic tape running speeds.

(G) Effects of the Invention According to the present invention, when the generation means generates a second magnetic head switching signal having a different phase difference from all one magnetic head switching signal according to a plurality of magnetic tape running speeds, The time constant of the charging means that determines the phase difference can be set independently by a plurality of time constant setting means corresponding to a plurality of magnetic tape running speeds, making it easy to set the time constant. Advantages such as that even if the setting means is damaged, other time constant setting means are not affected are obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a magnetic head switching signal generating device of the present invention, FIGS. 2 and 3 are timing charts showing waveforms of each part of FIG. 1, and FIG. 4 is a circuit diagram showing a magnetic head switching signal generator of the present invention. FIG. 5 is a plan view showing the arrangement and a circuit diagram showing a conventional magnetic head switching signal generating device. (1)--Rotating cylinder, (2a) (2b) (3a
)(3b)(4a)(4b)...magnetic head, (5
)...Magnetic tape, (7)(35)...Flip-flop, (20)...Capacitor, (37)(3B
>... Time constant setting means. Applicant Sanyo Electric Co., Ltd. and one other agent Patent attorney Kuratsugu Nishino and one other person Figure 2 (Wednesday) Figure 3 Law) Figure 4 2I-1, 2b

Claims (1)

[Claims] (1) A plurality of pairs of magnetic heads for recording/reproducing video signals that scan the magnetic tape in accordance with a plurality of running speeds of the magnetic tape, and a pair of magnetic heads for recording/reproducing audio signals that scan the magnetic tape. In a magnetic recording/reproducing machine in which magnetic head pairs are arranged on a rotating cylinder, the charging voltage is controlled by a charging voltage of a charging means and a first magnetic head switching signal of the plurality of magnetic head pairs, and the charging voltage is set at a constant value. generating means for generating a second magnetic head switching signal for the pair of magnetic heads that is delayed from the first magnetic head switching signal in accordance with the time taken to reach the plurality of magnetic tape running speeds; switching the plurality of second magnetic heads that operate correspondingly and independently and have different phase differences with respect to the first magnetic head switching signal by setting a time constant until the charging voltage reaches the constant value; A magnetic head switching signal generation device comprising a plurality of time constant setting means for generating a signal from the generation means.