JPH0320957Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a recording medium such as a magnetic tape on which absolute addresses are recorded for each of a plurality of programs.

BACKGROUND TECHNOLOGY AND PROBLEMS There are cases where absolute addresses for cuing each program are recorded on a magnetic tape for a tape recorder, such as a music tape, on which a large number of programs are recorded. This address is usually "1" or "0"
This digital code is recorded between songs on the tape. However, the content of such address code patterns differs depending on the direction in which the tape runs. That is, for example, a code that can be read as "1100000" when the tape is running in the forward direction will be read as "0000011" when the tape is running in the reverse direction.

In a tape recorder that uses a tape with absolute addresses, the address code read from the tape is converted into a program number for use in display or other purposes. For this purpose, a memory is provided that stores program numbers corresponding to address codes. However, since the address code read out differs depending on the running direction of the tape, the memory needs to store the number of data corresponding to the running direction. That is, it is necessary to prepare this memory with a storage capacity twice as large as the number of programs.

Purpose of the invention The present invention provides a recording medium on which address signals are recorded, which can solve the above problems.

Summary of the invention The present invention provides a recording medium in which a plurality of programs and an address signal consisting of a digital code indicating a program number corresponding to each of the plurality of programs are recorded. the first program number indicated by this address signal when is moving in a first moving direction, and when the recording medium is moving in a second moving direction opposite to the first moving direction. The present invention relates to a recording medium characterized in that the sum of the address signal and the second program number indicated by the address signal is the same number for all address signals.

According to the present invention configured in this manner, the recording capacity of the memory can be halved.

Embodiment First, prior to describing an embodiment of the present invention, an embodiment of an address signal recording format to which the present invention can be applied will be described with reference to FIG.

When an address signal is recorded in a non-signal portion between programs, such as a portion between songs, it is necessary to prevent the reproduction sound of the address signal from being heard when the program is reproduced. In addition, the address signal must have a frequency that can be detected by the reproducing head even during high-speed reproducing by fast forwarding, rewinding, etc. Under these conditions, the address signal is generally selected to have a frequency of around 20Hz, which is outside the audible band.

However, when such a low frequency is selected, the waveform of the address signal that passes through the equalizer circuit is significantly distorted because the integration constant of the reproduction equalizer circuit is selected to a value suitable for the audible band, making it difficult to detect the address. You will be wrong.

This embodiment solves the above problem.

In FIG. 1, a sine wave signal of, for example, 20 Hz is recorded in the shaded area of track 1 of the magnetic tape. Furthermore, the area between each shaded area is a blank area with no signal. The numbers indicated by , in the shaded area indicate the wave number of the above-mentioned sine wave signal. In other words, the shaded areas contain 16 waves, 12 waves, and
Four waves of signals are recorded in a burst manner (hereinafter the shaded area will be referred to as the burst section). Further, the numbers indicated by , in the blank section indicate the length corresponding to the wave number of the signal. Mark signals 2 and 3 consisting of a burst part of 16 waves and a blank part having a length of 4 waves are recorded between points a and b and between points c and d of track 1. An address signal 4 is recorded between point b and point c.

When the tape runs in the direction of arrow e, mark signal 2 indicates the start of the subsequent address signal 4, and mark signal 3 indicates the end of address signal 4. When the tape runs in the direction of arrow f, mark signal 3 indicates the start of the subsequent address signal 4, and mark signal 2 indicates the end of address signal 4. For this reason, when these signals 2 and 3 indicate the start of an address, they are sent first regardless of the tape running direction.
A burst portion of 16 waves is reproduced, and then a blank portion of 4 waves is reproduced. Furthermore, when signals 2 and 3 indicate the end of an address, the blank section of 4 waves is first played, and then the burst section of 16 waves is played back, regardless of the tape running direction. .

Next, the configuration of the address signal 4 will be described.

This address signal 4 is designed to represent the logic level of the address code depending on the length of the burst part and the blank part. That is, the burst part of 12 waves and
The 12-wave blank section represents one logic level, for example "1", and the 4-wave burst section and the 4-wave blank section represent the other logic level, for example "0". Therefore, in the case shown, e
Represents a 7-bit address code that indicates "1100000" for the direction, and "0000011" for the f direction.
This will represent the address code of . In this way, the address code changes depending on the running direction of the tape,
This will be discussed later.

This address signal 4 has the following features in addition to the above.

(1) Burst portions and blank portions are formed alternately.

(2) There is always a burst part at the beginning and end.

(3) Of the 7 bits, there are always 2 “1” bits.

FIG. 2 shows another embodiment of the address signal 4 having the above characteristics, in which the address code represents "0001010" in the e direction and "0101000" in the f direction. ing.

Note that track 1 in FIGS. 1 and 2 may be a track on which a program is recorded.
Alternatively, it may be a track provided exclusively for address signals.

Since the address signal 4 according to this embodiment is configured as described above, there will be no error in address detection.
That is, when a sine wave signal recorded on a magnetic recording medium is generally reproduced by a reproducing head, the reproduced waveform becomes a differentiated sine wave. By integrating this differential waveform with a reproduction equalizer circuit, the original sine waveform can be obtained. However, address signal 4
Since the frequency is low in the case of , the waveform will be distorted if it passes through the equalizer circuit as described above. When observing this waveform, among the signal waveforms consisting of several waves, the level of approximately one wave at both the front and rear end portions may become low, or may be missing altogether. That is, the two waves at both ends of the address signal waveform that have passed through the equalizer circuit are extremely uncertain, which causes false detection.

In this embodiment, a minimum of four waves of signals are recorded in the burst portion of the address signal 4, so even if the preceding and following are missing, two waves remain and detection is possible. Also, while these 4 waves represent "0", 12 waves represent "1".
Therefore, even if some of the 12 waves are missing due to other reasons, there will be a large difference in the number of waves detected between "1" and "0". 0”
can be clearly identified.

This address signal 4 is detected by a detection circuit using a microcomputer, for example, and at that time, it is determined whether it is "1" or "0" based on the conditions described in sections (1), (2), and (3) above. Ru.
For example, in the case of the address code in Figure 1, it is determined that there is a burst part first, so by checking the wave number of the burst part, it is determined whether it is "1" or "0". be able to. Furthermore, since it is determined that a blank section exists after the burst section, it is possible to determine whether it is "1" or "0" by detecting the length of this blank section. If any signal is detected in this blank area, it is determined to be noise.
In this way, the burst part and the blank part are checked alternately, and by checking the wave number in the burst part and the length in the blank part, "1",
A determination of "0" can be made.

In this embodiment, "1" and "0" are distinguished between the 12-wave burst part and the 12-wave blank part, and the 4-wave burst part and the 4-wave blank part, but as described above, Since one wave at a time is missing,
A minimum of 3 waves is sufficient, and it can be distinguished from 3 waves if there are 6 waves or more, which is at least twice as many as the 3 waves. Therefore, a 3-wave:6-wave burst section or a blank section may be provided. The results of husband and husband experiments on other 4 waves: 8 waves, etc., show that 4 waves:
Good results were obtained with 12 waves.

Next, the code pattern of the address code will be explained.

As mentioned above, the address signal 4 in FIGS. 1 and 2
Since the code pattern differs depending on the tape running direction, the problem mentioned at the beginning occurs.

The table shown in FIG. 3 shows an embodiment of the present invention for assigning address codes to program numbers to solve the above problem. According to this address code, it is sufficient to prepare a memory having a capacity equal to the number of programs.

This example is a case where there are 19 programs,
Address codes are shown for programs numbered 1 to 19, respectively. The table in Figure 3 shows the address code of a certain program number n, read from the left, and the address code of program number ``20-4'', which has a complement of ``20'' with respect to that program number n. For example, the code read from the right side is made to be the same as the code read from the right side. For example, the code "1000100" for program number 4 is program number 20-
It is equivalent to selecting the code "0010001" of 4=16 from the right side.

Therefore, when the tape is running in the forward direction, the code for program number n is read from the left side, so n is detected as is, and when the tape is running in the reverse direction, it is read from the right side, so "20-n" is detected. For example, in the case of program number 4, it is detected as is when the vehicle is traveling in the forward direction, but it is detected as "16" when the vehicle is traveling in the reverse direction.
Therefore, by performing the calculation "20-16", the correct program number "4" can be obtained. The general conversion formula is as follows: n=n _F n=N−n _R n _F : Program number detected when traveling in the forward direction.

n _R : Program number detected when traveling in the opposite direction.

N: A specific number, in the case of Figure 3, N = 20, and generally it may be greater than the maximum program number.

In the case of Figure 3, the code pattern is symmetrical above and below the middle program number 10 among the 19 programs. Also, since it is related to the format of address signal 4 described in Fig. 1, 2 bits out of 7 bits are "1", but if address signal 4 in Fig. 1 is not used, 7 Three or more of the bits may be set to "1". Various other code patterns can be considered depending on the number of programs and the number of bits. In either case, the program may be divided into a first half and a second half, and the corresponding code patterns may be arranged symmetrically.

FIG. 4 shows an embodiment of the address reading device.

The address signal reproduced from the tape 5 by the reproduction head 6 is applied to a waveform shaping circuit 8 through a reproduction equalizer circuit 7, and becomes a digital signal having an address code. This signal is converted from serial data to parallel data in the digital processing circuit 9, and error correction and the like are performed thereon. Code conversion based on data indicating this converted address code
The ROM 10 reads out the corresponding program number. The switch 11 is closed to the contact FWD side by the switching signal S when the tape is running in the forward direction.
When traveling in the opposite direction, the contact is closed to the REW side. Therefore, when running in the forward direction, the program number n read out from the ROM 10 is used as is.
When traveling in the reverse direction, the read program number
_nR is subtracted by N- _nR in the subtraction circuit 12 to obtain the correct program number n.

According to the above, it is sufficient to prepare a ROM 10 having a storage capacity equal to the number of programs.

Effects of the invention The memory capacity for converting read address signals into program numbers can be reduced.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing an example of the recording format of an address signal to which the present invention can be applied, Figure 3 is a diagram showing a code pattern of an address code according to the present invention, and Figure 4 is a diagram to which the present invention is applied. 1 is a block diagram showing an embodiment of a possible address reading device; FIG. In addition, in the symbols used in the drawings, 1...
...track, 4...address signal, 5...tape.

Claims (1)

[Claims for Utility Model Registration] In a recording medium in which a plurality of programs and a plurality of address signals each consisting of a digital code indicating a program number corresponding to each of the plurality of programs are recorded, each of the above address signals is: A first program number indicated by this address signal when the recording medium is moving in the first moving direction, and a first program number indicated by the address signal when the recording medium is moving in the first moving direction.
The configuration is such that the sum with the second program number indicated by this address signal when moving in a second movement direction opposite to the movement direction of is the same number for any address signal. A recording medium characterized by.