JPH0630186B2 - Switching signal generation circuit for voice magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a video recording / reproducing apparatus in which a magnetic head pair for a video signal and a magnetic head pair for an audio signal are arranged on a rotary cylinder. Of the magnetic head switching signal generating circuit for generating the magnetic head switching signal of the magnetic head pair for the audio signal from the magnetic head switching signal of the magnetic head pair.

(B) Conventional technology Conventionally, a magnetic recording / reproducing apparatus in which two pairs of magnetic heads for video signals and one pair of magnetic heads for audio signals in each mode are arranged on a rotary cylinder at 60 ° intervals. As
For example, the technology as shown on pages 79 to 81 of "December issue of 1984 TV technology" (published by Electronic Technology Publishing Co., Ltd.) is disclosed.

Here, as shown in FIG. 3, it is used in the standard and long-time recording / reproducing modes, and is used for the video signal which is opposed at 180 °.
A pair of magnetic heads (33a) (33b), (34a) (34b) and a pair of magnetic heads (35a) (35b) for audio signals are respectively arranged on the rotary cylinder (36) at intervals of 60 °, for example. Magnetic tape (3
In a magnetic recording / reproducing apparatus in which 7) is wound around a rotating cylinder (36) by 180 ° + (an angle corresponding to several horizontal scanning periods), the magnetic head pairs (33a) (33b), (34a) (34b) Consider a generation circuit that generates a magnetic head switching signal for a pair of magnetic heads (35a) (35b) from the head switching signal. Generally, when recording video and audio signals in standard and long time modes, magnetic head pairs (33a) (33b), (34a) (34b), (35a) (35
Since a recording signal is always applied to b), the magnetic head pair
(33a) (33b), (34a) (34b), (35a) (35b) switching is unnecessary, but to prevent the occurrence of noise such as video and audio signals during playback magnetic head pair (33a) (33b), (34a) (34
b), (35a) (35b) can not always get the playback signal,
Therefore, the magnetic head pairs (33a) (33b), (34a) (34b), (35a) (35
Each is switched by the magnetic head switching signal of b).

Furthermore, since the magnetic head pair (35a) (35b) must always precede the magnetic head pair (33a) (33b), (34a) (34b) with respect to the magnetic tape (37), standard recording / Magnetic head pairs used in playback mode (35a) (33a), (35b) (33b) and magnetic heads used in long-time recording / playback mode (35a) (34b), (35b) (34b) Is different, and the magnetic head pair in each of the standard and long-time playback modes is different.
The magnetic head switching signals of the magnetic head pairs (35a) (35b) for the magnetic head switching signals of (33a) (33b), (34a) (34b) are required. Therefore, a flip-flop or multivibrator is used as a circuit to generate the magnetic head switching signal of the magnetic head pair (35a) (35b) from the magnetic head switching signal of the magnetic head pair (33a) (33b), (34a) (34b). , And magnetic head pair (33
a) As a circuit for controlling the phase of the magnetic head switching signal of the magnetic head pair (35a) (35b) with respect to the magnetic head switching signal of (33b), (34a) (34b), it is independent for each standard and long-time reproduction mode. Used a control circuit.

(C) Problems to be solved by the invention However, in the case described above, a circuit for controlling the phase of the magnetic head switching signal of the magnetic head pair (35a) (35b) is provided independently for each of the standard and long-time reproduction modes. From the fact that
There is a problem that the cost increases due to the increase in the number of parts.

(D) Means for Solving the Problems The present invention has been made to solve the above problems, and includes first and second video signals for use in the first and second recording / reproducing modes. Magnetic head pair and a third audio signal third audio signal used in the first and second recording / reproducing modes.
In a magnetic recording / reproducing apparatus in which each pair of magnetic heads is arranged on a rotating cylinder, a clock pulse is generated from a data terminal connected to a DC power supply line and the magnetic head switching signals of the first and second magnetic head pairs. A first flip-flop having a clock terminal to which a clock pulse generation circuit is connected, an output terminal thereof and a reset terminal to which a time constant circuit is connected, a data terminal to which the magnetic head switching signal is input, and the output terminal are connected. A second flip-flop having a clock terminal and a switch circuit which is controlled according to the first and second reproduction modes and is connected to a reset terminal of the first flip-flop. A magnetic head switching signal for the third magnetic head pair is generated from the output terminal of the flip-flop, and the magnetic head switching signal is generated. The switching signal generating circuit of the magnetic head for voice controlling the phase of the signal to solve the above problems.

(E) Operation According to the switching signal generating circuit of the audio magnetic head of the present invention, when the first and second magnetic head pairs for the video signal used in the first and second recording / reproducing modes are reproduced. When generating the magnetic head switching signal of the third magnetic head pair for the audio signal from the magnetic head switching signal, the third magnetic head is controlled by the same switch circuit which is controlled according to the first and second reproduction modes. The phase of the pair of magnetic head switching signals can be controlled for each mode, which reduces the number of constituent parts of the switch circuit and has the effect of reducing the cost.

(F) Examples Details of the present invention will be specifically described with reference to illustrated examples.

FIG. 1 is a circuit diagram showing an embodiment of a switching signal generation circuit for a voice magnetic head according to the present invention, and FIG. 2 is a timing chart consisting of (a) to (h) showing waveforms at respective positions in FIG. Is.

Referring to FIG. 1, the drawing number and configuration are explained. (1) is the first
Connected to the data terminal D ₁ of the flip-flop (2) of
A power supply terminal for inputting a DC voltage, (1a) is a DC power supply line, and (3) is a pair of magnetic heads used in the standard and long time modes as the first and second recording / reproducing modes shown in FIG. 33a) (33b), (34a) (34b) input terminal for inputting the magnetic head switching signal at the time of reproduction, (4) connects its base to the input terminal (3) via a resistor (5) A transistor (6) having its emitter grounded, and its base connected to the input terminal (3) via a resistor (7) and a capacitor (8), and its collector connected to the flip-flop.
A transistor (1) connected to the clock terminal C ₁ of (2) and having its emitter connected to the power supply terminal (1) and also connected to the collector of the transistor (6) through a resistor (9).
0), a bias resistor (11) connected between the emitter and base of the transistor (10), a connection point of the resistor (7) and the capacitor (8), and a collector of the transistor (6). clock pulse generating circuit consisting of a capacitor (12) has, (13) the clock terminal C ₁ and is connected between ground, resistance to ground the clock terminal C ₁ during off its input (14) of precursor flip-flop A time constant circuit consisting of a resistor (15) and a capacitor (16) connected in series between the reset terminal R ₁ of (2) and ground, (17) and (18) are respectively
The variable resistor and the resistor connected in series between the output terminal Q ₁ and the reset terminal R _{1 of the} flip-flop (2), (19) has its cathode on the output terminal Q ₁ side and its reset terminal R ₁ side on the reset terminal R ₁ side. Diode connected to the anode, (20) is a high level signal in standard mode (hereinafter referred to as "H")
Is input and a low level signal (hereinafter referred to as “L”) is input during the long time mode, (21) is a resistor (22).
A transistor (2) whose base is connected to the input terminal (20) through the emitter and whose emitter is grounded, and whose base and emitter are connected via a bias resistor (23).
4) and its base through the resistor (25)
It is connected to the collector of (24) and also has resistance (26) and variable resistance.
A transistor (29) having its collector connected to the reset terminal R ₁ via (27), its emitter connected to the power supply terminal (1), and its emitter and base connected via a bias resistor (28). ) Switch circuit,
(30) is the input terminal (3) and the second flip-flop (3
1) resistor interposed between the data terminal D ₂ of, (32) which is connected to the output terminal Q ₂ of the flip-flop (31), the magnetic head pairs shown in Figure 3 from the output terminal Q ₂ (35a ) (35b) is an output terminal for outputting the magnetic head switching signal. The output terminal of the flip-flop (2) And the clock terminal C ₂ of the flip-flop (31) is connected, the set terminal S ₂ of the flip-flop the set terminal S ₁ and flip-flops (2) _(31), a reset terminal R
₂ is grounded.

The circuit operation will be described with reference to FIGS. 1, 2, and 3. In standard mode, a magnetic head pair is used for recording / playback.
(33a) (33b), (35a) (35b) are used, and magnetic tape (3
7), the magnetic head (33a) scans the scanning track of the magnetic head (35a), and the magnetic head (33b) is the magnetic head.
Scan on the scanning track of (35b). However, when generating the magnetic head switching signal of the magnetic head pair (35a) (35b) from the magnetic head switching signal of the magnetic head pair (33a) (33b) obtained at the time of reproduction, the latter is delayed in phase than the former. Therefore, in detail, the switching signal for obtaining the reproduction signal at the magnetic head (35b) is generated from the switching signal for obtaining the reproduction signal at the magnetic head (33a), and the magnetic head (33b It is sufficient to generate the switching signal for obtaining the reproduction signal by the magnetic head (35a) from the switching signal for obtaining the reproduction signal at (). A pair of magnetic heads (35a) (35b)
Are arranged on the rotary cylinder (36) at 60 ° intervals with respect to the magnetic head pairs (33b) (33a).

First, a DC voltage of a predetermined level (for example, +5 V) is input to the power supply terminal (1), that is, the data terminal D ₁ . Further, as shown in FIG. 2 (a), a magnetic head switching signal for alternately switching the magnetic head pair (33a) and (33b) is inputted to the input terminal (3) by the "H" and "L" signals. The magnetic head switching signal is a signal (for example, +4 V) which becomes higher than the rising voltage between the base and emitter of the transistor (6) when it is "H", and the base of the transistor (6) is connected via the resistor (5). To turn on / off the transistor (6). As a result, the signal at the collector of the transistor (6) is an inverted signal of the signal shown in FIG. 2 (a) as shown in FIG. 2 (b). When the signals shown in Fig. 2 (a) and (b) are differentiated and added by the capacitor (8) and the resistor (7), the capacitor (12) and the resistor (7), respectively, the base of the transistor (10) The input becomes the signal shown in FIG. 2C, the transistor (10) is turned on by the falling portion of the signal, and the clock pulse shown in FIG. 2D is input to the clock terminal C ₁ .

On the other hand, since it is in the standard mode, a signal of "H" higher than the rising voltage between the base and emitter of the transistor (24) is input to the input terminal (20), and the signal is transmitted through the resistor (22) to the transistor ( Input to the base of 24) to turn on the transistor (24). At this time, since the collector potential of the transistor (24) drops, the base potential of the transistor (29) also drops,
The transistor (29) is also turned on.

Then although the operation of the flip-flop (2), inputs a DC voltage to the data terminal D _1, if you enter the clock pulses to the clock terminal C _1, the signal of the first "H" from the output terminal Q ₁ is output The signal is input to the time constant circuit (14) via the variable resistor (17) and the resistor (18), and the DC voltage is always on in the standard mode, and the transistor (29),
Input to the time constant circuit (14) via the variable resistor (27) and the resistor (26). And both are the resistance value of the resistor (15) and the capacitor
Depending on the charging time constant determined by the capacitance of (16), the threshold voltage of the reset terminal R _{1 can be used up to} the threshold voltage of Fig. 2 (e).
As shown in, the capacitor (16) inside the time constant circuit (14) is charged. After that, when the charging voltage of the capacitor (16) reaches the threshold voltage of the reset terminal R ₁ , the charging charge of the capacitor (16) passes through the diode (19) to the output terminal Q.
₁ is discharged by the ground, and the output terminal Q ₁ outputs the “L” signal which is the reset of the “H” signal,
The signal is held until the next clock pulse input to clock terminal C ₁ . That is, the signal shown in FIG. 2 (f) is output from the output terminal Q ₁ .

The magnetic head switching signal shown in FIG. 2 (a) is input to the data terminal D ₂ and the output terminal is input to the clock terminal C _2. 2), that is, the signal of FIG. 2 (g) which is an inverted signal of FIG. 2 (f) is input. Since the flip-flop (31) operates so as to transfer the data terminal D ₂ input in synchronization with the rising edge of the clock terminal C ₂ input, the output terminal Q ₂ receives the second signal.
As shown in FIG. 2C, the magnetic head pair (35a) (35b) whose phase is delayed by time t from the magnetic head switching signal shown in FIG. 2 (A).
The magnetic head switching signal is output and the standard reproduction mode is executed. It is also possible to finely adjust the phase of the magnetic head switching signal of the magnetic head pair (35a) (35b) by adjusting the charge amount of the capacitor (16) in the standard mode with the variable resistors (17) (27). is there.

Next, in the long time mode, the magnetic head pair (34a) (34b), (35a) (35b) is used for recording / reproducing.
In contrast to (37), the magnetic head (34a) scans the scanning track of the magnetic head (35a), and the magnetic head (34b) scans the scanning track of the magnetic head (35b). However, the magnetic head pair (34
a) (34b) magnetic head switching signal to the magnetic head pair (35a) (3
When the magnetic head switching signal of 5b) is generated, the latter is delayed in phase than the former.Therefore, in detail, the switching signal for obtaining the reproduction signal at the magnetic head (34a) is used for the magnetic head. (35b) generates a switching signal for obtaining a reproduction signal, and a switching signal for obtaining a reproduction signal at the magnetic head (35a) from a switching signal for obtaining a reproduction signal at the magnetic head (34b). It should be generated. Further, the magnetic head pair (35a) (35b) is
b) It is arranged on the rotary cylinder (36) at an interval of 120 ° with respect to (34a), and this interval is the magnetic head pair (33b) (33a) with respect to the magnetic head pair (35a) (35b) in the standard mode. ) Is larger than the 60 ° interval. The phase delay amount of the magnetic head switching signal of the magnetic head pair (35b) (35a) with respect to the magnetic head switching signal of the magnetic head pair (34a) (34b) in the long time mode is larger than the magnetic head pair (33a in the standard mode. ) (33
Magnetic head pair (35b) (35b) for the magnetic head switching signal of (b)
It must be larger than the phase delay amount t of the magnetic head switching signal of a). Therefore, in the long time mode, the charging time for the capacitor (16) inside the time constant circuit (14) may be set longer, in other words, by inputting an “L” signal different from the standard mode to the input terminal (20). off transistor (24) (29), the transistor (29), a variable resistor (27) and a resistor (26) prevents the charging of the DC voltage to the capacitor (16) via an output from the output terminal Q ₁ Only the capacitor (16) needs to be charged. Then, a magnetic head switching signal for alternately switching the magnetic head pairs (34a) and (34b) is input to the input terminal (3) by the signals of "H" and "L", and output by the same circuit operation as in the standard mode. Magnetic head pair (35a) (35b) having a delay amount greater than the delay amount t in the standard mode from the terminal (32)
The magnetic head switching signal is output and the long time mode is being executed. It is also possible to finely adjust the phase of the magnetic head switching signal of the magnetic head pair (35a) (35b) by adjusting the charge amount of the capacitor (16) in the long time mode with the variable resistor (17). Also, in the standard and long time modes, in order to obtain an appropriate magnetic head switching signal of the magnetic head pair (35a) (35b) for the magnetic head switching signal of the magnetic head pair (33a) (33b), (34a) (34b). The numerical values of the components in the circuit diagram in FIG. 1 are properly determined.

(G) Effect of the Invention According to the switching signal generating circuit of the audio magnetic head of the present invention, the reproduction of the first and second magnetic head pairs for the video signal used in the first and second recording / reproducing modes is performed. At the time of generating the magnetic head switching signal of the third magnetic head pair for the audio signal from the magnetic head switching signal at the time, the third switching circuit is controlled by the same switch circuit according to the first and second reproduction modes. The phase of the magnetic head switching signal of the magnetic head pair can be controlled for each mode, which reduces the number of constituent parts of the switch circuit and has an advantage of enabling cost reduction.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a switching signal generation circuit for a voice magnetic head according to the present invention, and FIG. 2 is a timing chart consisting of (a) to (h) showing waveforms at respective positions in FIG. FIG. 3 is a plan view showing a state in which the magnetic head pair is arranged on the rotary cylinder. Description of main figure numbers (1a) …… DC power supply line, (2) (31) …… Flip-flop, (4) …… Clock pulse creation circuit, (14) …… Time constant circuit, (21) …… Switch circuit, (33a) (33b), (34a) (34
b), (35a) (35b) …… magnetic head pair, (36) …… rotating cylinder.

Claims (1)

[Claims] 1. A first and second magnetic head pair for a video signal used in first and second recording / reproducing modes, and an audio signal used in the first and second recording / reproducing modes. In the magnetic recording / reproducing apparatus in which the third magnetic head pair is disposed on each rotating cylinder, a clock pulse is generated from the data terminal connected to the DC power supply line, the magnetic head switching signal of the first and second magnetic head pairs. A first flip-flop having a clock terminal connected to a clock pulse generation circuit, an output terminal thereof and a reset terminal connected to a time constant circuit, a data terminal to which the magnetic head switching signal is input, and the output terminal And a second flip-flop having a clock terminal connected to the first flip-flop, which is controlled according to the first and second reproduction modes. A switch circuit connected to the output terminal of the second flip-flop, which generates a magnetic head switching signal of the third magnetic head pair from the output terminal of the second flip-flop and controls the phase of the magnetic head switching signal. A switching signal generation circuit for a voice magnetic head, characterized in that