JPS62226402A - Video signal recording device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a recording omission phenomenon arising at the time of switching an analog switch by connecting a coil between two switching terminals in a single-electrode and double-head analog switch connected between a supply circuit for a video signal and a magnetic head. CONSTITUTION:The coil 3 connects the two switching terminals (a) and (b) in the single-electrode and double-head analog switch 1. Since the coil 3 connects the terminals (a) and (b), they are always held at the same potential in terms of DC. Accordingly, if the inverse of a recording control signal REC changes over the switch 1 from the terminal (a) to the terminal (b), a DC current caused by the potential difference will not flow in a head 7, and the head 7 precisely writes a video signal supplied at that time in a magnetic disk 7. Thus the phenomenon that the recording of the video signal is omitted seldom occurs, and the video signal rises in a short time and is written in the magnetic disk.

Description

DETAILED DESCRIPTION OF THE INVENTION Background of the Invention Technical Field This invention provides a recording medium such as a magnetic disk that rotates twice.
The present invention relates to a device for recording a modulated video signal.

PRIOR ART In this type of video signal recording device, there is A single-pole double-throw analog switch is provided for controlling the sending of the video signal to the magnetic head only during the video recording period (the period of approximately one rotation of the magnetic disk).

The conventional circuit surrounding this analog switch is
As shown in the figure. The analog switch IO has two switching terminals a and b, one terminal a is grounded via a capacitor 2, and the other terminal is connected to the output side of a transistor 4 that supplies a video signal to be recorded on a magnetic disk. It is connected to the. Switching from terminal a to b or vice versa is controlled by a recording control signal RFC. This switch IO has conventionally been used, for example, for video analog
Switch B A 7001 was used.

When writing a video signal to a magnetic disk, the video signal is sent out from the video signal processing circuit, and a control signal R is also sent out.
The FC switches the analog switch lO from terminal a to b. The supplied video signal passes through the analog switch IO from the transistor 4, is amplified by the buffer amplifier including the transistor 5, and the final stage amplifier 6, and is applied to the magnetic head 7, where it is written on the rotating magnetic disk. It will be done.

Now, in this conventional circuit, switch IO is connected to terminal a
When the transistor 5 is connected to the base of the transistor 5, a bias is applied to the base of the transistor 5 via the capacitor 2. A capacitor stores a certain amount of charge. On the other hand, since the terminal of the switch 10 is connected to the emitter side of the transistor 4, it has a certain DC potential. Therefore, when switch 10 is switched from terminal a to b,
Due to the potential difference between terminals a and b, a large direct current momentarily flows through the magnetic head 7. As a result, the magnetic head 7 becomes saturated, and a recording omission phenomenon occurs in which the video signal applied to the magnetic head 7 through the switch IO is not written to the magnetic disk.

OBJECTS, STRUCTURE 1 OPERATIONS AND EFFECTS OF THE INVENTION An object of the invention is to prevent the above-mentioned recording loss phenomenon that occurs when an analog switch is switched.

To achieve this object, the present invention is characterized in that a coil 3 is connected between two switching terminals a and b of a single-pole double-throw analog switch 1, as shown in FIG. . In FIG. 1, the same parts as those shown in FIG. 2 are given the same reference numerals.

Since the coil 3 is connected between the two terminals a and b of the analog switch 1, these terminals a and b are always kept at the same potential in terms of direct current.

Therefore, even if the analog switch 1 is switched from terminal a to terminal b by the recording control signal REC, no direct current based on the potential difference will flow to the magnetic head 7, and the video signal supplied at this time will be The head 7 will accurately write on the magnetic disk.

As a result, the phenomenon of video signal recording and omission almost disappears, and the video signal rises and is written to the magnetic disk within a short time.

The above-mentioned analog switch 1 is preferably configured with 0 MO8, for example, a commercially available one is 40 MO8.
There are 53.

Note that by increasing the time constant of the capacitor 2 and coil 3, almost no alternating current component, ie, the video signal, appears at terminal a.

Therefore, when the switch 1 is connected to the terminal a side, no particular problem occurs because the switch 1 performs the intended function of electrically cutting off the video signal supply side and the magnetic head side.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of the configuration of the present invention. FIG. 2 is a circuit diagram showing a conventional example. 1...Analog switch. 3...Coil. 7...Magnetic head. a, b... Analog e switch switching terminals. that's all

Claims (1)

[Claims] In a device equipped with a single-pole, double-throw analog switch connected between a video signal supply circuit and a magnetic head for writing the video signal onto a magnetic recording medium, a switch between the two switching terminals of the analog switch is provided. A video signal recording device characterized by connecting a coil.