JPH0219552B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape position display device for displaying the position of a tape in a magnetic tape device such as a tape recorder.

A tape position display device in a normal magnetic tape device, a so-called tape counter, integrates the number of revolutions of either one of a pair of reel stands that rotate integrally with the tape reel that winds the tape. , this allows the tape position to be displayed. However, the number of rotations of the reel stand depends on the diameter of the tape roll, and there is no unambiguous relationship between the amount of tape wound and the sum of the number of rotations of the reel stand, making it impossible to accurately display the tape position. Or, when the tape cassette was replaced, there was no longer any relationship between the amount of tape wound and the tape counter display.

In order to compensate for these drawbacks, the number of revolutions of each of the pair of reel stands is fixed if the tape reel hub diameter and the total length of the tape are constant. A device has been developed that displays the tape position by detecting and calculating each, but this has the disadvantage that it can only display the approximate tape position due to variations in tape reel hub diameter, tape length, etc. It was hot.

The present invention aims to provide a novel tape position display device that can accurately display the tape position.

An example in which the tape position display device according to the present invention is applied to a video recorder will be described below.

Generally, in a video tape recorder, a magnetic tape is pulled out from a cassette and run along a cylinder containing a rotating magnetic head, and video signals are exchanged between the rotating magnetic head and the magnetic tape. When fast-forwarding or rewinding the tape, transporting the magnetic tape at high speed with the magnetic tape wrapped around the cylinder will wear out the magnetic head and damage the edges of the magnetic tape, so be sure to store the magnetic tape in the cassette. Many items are being transported at high speed.

As shown in FIG. 1, the video tape recorder according to the embodiment of the present invention has a rotation detector 6 which detects the rotation of the supply reel stand 2 and the take-up reel stand 4, and is composed of, for example, a well-known magnet and reed switch. , 8, and calculates the approximate position of the tape as in the well-known means described above.

The output of the arithmetic circuit 10 is the switching means 1 which will be described later.
Since the display means 14 is controlled through the tape cassette 2, by loading the tape cassette into the video tape recorder and sending off or rewinding the tape,
The approximate position of the tape is displayed on a display means 14 using, for example, a liquid crystal. After finding the approximate position of the tape in this way, the video tape recorder is put into playback mode and the magnetic tape 16 is run along the cylinder, and the rotating magnetic head 18 records on the magnetic tape 16. Read out the signal. By pre-recording a tape position signal on the magnetic tape 16 in the form of a code, for example, during the vertical retrace period of a video signal, the rotating magnetic head 18 can read out the recorded tape position signal. The read tape position signal is converted through an amplifier 20 and a decoder 22 into a signal capable of driving the display means 14, and then supplied to the aforementioned switching means 12.

The switching means 12 is for selectively supplying the signal from the arithmetic circuit 10 and the signal from the decoder 22 to the display means 14,
When the rotary magnetic head 18 detects a tape position signal by the tape position signal detecting means 24 which detects the output of the decoder 22, the decoder 22 is automatically detected.
Since the output is switched to be supplied to the display means 14, the exact tape position recorded on the magnetic tape 16 is displayed on the display means 14.

As is clear from the above description, the tape position display device of the present invention performs interpolation by displaying the approximate tape position in the fast winding mode of the device, and performs interpolation by displaying the tape position signal recorded on the magnetic tape in the playback mode of the device. Since it is configured to read and display the tape position, it is possible to display the exact tape position.

Further, according to the present invention, since the accurate tape position can be displayed arbitrarily and immediately at any position on the tape, there are great benefits in practical use.

[Brief explanation of drawings]

The drawing is a block diagram of essential parts of an embodiment of the present invention. 6, 8... Rotation detector, 10... Arithmetic circuit, 1
2...Switching means, 14...Display means, 18...Magnetic head, 22...Decoder, 24...Tape position signal detection means.

Claims (1)

[Claims] 1. Rotation detection means for detecting rotation of the reel stand;
a calculation means for calculating an approximate tape position according to the output of the rotation detection means; a magnetic head for reading signals recorded on the magnetic tape; and a decoder for reading a tape position signal from among the signals from the magnetic head; A switching means for selectively switching and outputting either one of the output from the arithmetic means and the output from the decoder, and a display means for displaying the tape position according to the output from the switching means. . A tape position display device, wherein the switching means is configured to preferentially supply the output of the decoder to the display means when there is an output from the decoder.