JPH0221064B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit for detecting gaps between songs (unrecorded portions) on a recording tape.

FIG. 1 is a block diagram showing the configuration of a conventional song interval detection circuit.

In the figure, reference numeral 1 denotes an input terminal to which an input signal converted into an electrical signal from a recording tape via a magnetic head is applied. 2 is a circuit that determines recording/non-recording based on whether the input signal is above the specified recording level. 3 is a circuit that detects the time of the unrecorded portion. 4 is a circuit that detects the time of the recording section. 5 is a flip-flop circuit; 6 is a terminal to which a reset signal for controlling the operation of the music selection function is applied; 7 is for receiving the output of the detection circuit 3 and generating a detection signal output at the output terminal 8 for a certain period of time; This is a one-shot multivibrator. The music selection function is started by sending one reset signal to the terminal 6 to put the flip-flop circuit 5 in the reset state. If the input signal level determination circuit 2 determines that the input signal level is at the recording level, a signal is sent to the detection circuits 3 and 4. If the detection circuit 4 detects that the recording time is greater than the specified value and sets the flip-flop circuit 5, the detection circuit 3
The stop input In ₂ is released. Until the stop input In ₂ is released, the detection circuit 3 does not operate even if the input signal level determination circuit 2 determines that there is no recording.

After the stop input In ₂ is released, if the input signal level determination circuit 2 determines that it is at the non-recording level, the stop input In ₁ is released and the detection circuit 3 is activated.
If the unrecorded portion is longer than a specified time, the one-shot multivibrator 7 is activated and a detection signal output 8 is obtained. This means that the song interval detection has been performed.

FIG. 2 is a circuit diagram showing a specific example of the detection circuit 3.

In ₁ The output of input level judgment circuit 2 is connected,
The output of the flip-flop circuit 5 is connected to In ₂ . Out1 corresponds to the output of the detection circuit 3. If one or both of the stop inputs In and In ₂ are not released, one or both of the transistors Q ₁ and Q ₂ is conductive, the capacitor C ₁ is in the discharge state, and Out 1 is “L ₀ ”. be. When both In ₁ and In ₂ are released and the transistors Q ₁ and Q ₂ become non-conductive, the capacitor C ₁ is charged. If In ₁ and In ₂ continue to be released until this charging voltage reaches the reference voltage of comparator 9 (that is, if the non-recording period continues), Out 1 becomes "Hi" and a non-recording section is detected. It turns out.

FIG. 3 is a circuit diagram showing a specific example of the recording section detection circuit 4. As shown in FIG.

The output of the input signal level determination circuit 2 is connected to In ₃ . Out2 corresponds to the output of the detection circuit 4. Now, when the signal determined to be at the recording level by the input signal level determination circuit 2 is added to In ₃ ,
Transistor Q ₃ becomes conductive, and capacitor C ₂ is charged by collector current I ₁ of transistor Q ₅ . If the transistor Q ₃ continues to conduct (i.e. the recording section continues) until the charging voltage reaches the reference voltage V ₂ of the comparator 10, the output of the comparator 10
Out2 is inverted from "L ₀ " to "Hi", indicating that the recording section (song) has been detected.

This recording detection circuit 4 has a function required to distinguish between a piece of music (normally recorded part) and a piece of music recorded incorrectly with a large level of noise.

The above explanation has been about the operation when one song is selected, but if you want to connect the detection signal output to a counter and count the number of songs, you need to reset the flip-flop circuit every time you select one song. The need arises. If not reset,
This is because the recording section detection function does not operate after the second song. As a means for this purpose, the output terminal 8 and the reset input terminal 6 may be connected so that the flip-flop circuit 5 is reset when the one-shot output of the detection signal is completed. However, if this is done alone, charge is accumulated in the capacitor _C2 used in the recording section detection circuit 4, so the flip-flop circuit 5 is set again, and the above reset operation is not performed correctly. In order to prevent this, the following two countermeasures can be considered, but neither of them provides the optimal effect.

1) Lower the input resistance of the comparator 10 and discharge the charge in the capacitor _C2 to some extent. However, since the time error in detecting the recording section is not increased, the input resistance cannot be lowered much and the discharge time becomes longer. Therefore, if the song selection cycle becomes faster (in the case of a series of short song sections), the detection time error becomes very large and does not function properly.

2) At the same time as the flip-flop circuit 5 is reset by the detection signal output, the capacitor C ₂
discharge.

However, the flip-flop circuit 5 must be reset at the time when the one-shot output from the output terminal 8 is completed (for example, when the output falls from "Hi" to "L ₀ "). Otherwise, the output of the detection circuit 3 would be cut off midway, and the one shot time of the output 8 would change.

Therefore, it is necessary to discharge the capacitor C ₂ by inputting a pulse for a very short time, which is extremely difficult.

In addition, the capacity will be increased for a certain period of time after the output is completed.
It is conceivable to discharge _C2 , but the circuit would be complicated and would be impractical.

The present invention has been made in view of the above points.

FIG. 4 shows an example of the configuration of the present invention. In FIG. 4, numerals 1 to 8 are the same as in FIG. 1, and have the same functions. Note that the specific example shown in FIG. 3 is applied to the recording section detection circuit 4 in order to make the explanation easier to understand.

The detection signal output 8 will be explained below on the assumption that it outputs "Hi" for a certain period of time when the one-shot multivibrator 7 is activated. (Steady is "L ₀ ".) Reference numeral 11 denotes an output fall detection circuit which detects the fall portion of the detection signal output and obtains a reset signal for the flip-flop circuit 5. 12 is a reset signal for starting music selection and an output fall detection circuit 1
This is an OR circuit for applying a reset signal from 1 to the flip-flop circuit 5. When the recording section is detected and the flip-flop circuit 5 is set by the output of the detection circuit 4, the charge stored in the capacitor _C2 becomes useless. Therefore, it is sufficient to discharge the charge in the capacitor C ₂ at this point. In FIG. 4, due to the Q output of the flip-flop circuit 5,
Transistor Q ₆ is turned on, and the charge in capacitor C ₂ is forcibly discharged. This makes it possible to eliminate the drawback of the conventional method of repeatedly selecting music.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a conventional music selection circuit, FIG. 2 is a circuit diagram showing a specific example of a detection circuit, FIG. 3 is a circuit diagram showing a specific example of a recording section detection circuit, and FIG. The figure is a circuit diagram showing one embodiment of the present invention. In the figure, 4 is a detection circuit, 5 is a holding circuit,
C ₂ is the capacitance. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A determination circuit that determines recording or non-recording according to the signal level of a playback signal of a recording tape, and a charging voltage of a capacitor that allows a portion determined to be a recording section by the determination circuit to remain in a recording area for a predetermined period of time. A recording section detection circuit that outputs a recording section detection signal when the above continues, a holding circuit that is set by the recording section detection signal, and a holding circuit that has a reverse phase output and is determined to be a non-recording section by the judgment circuit. A recording tape equipped with a non-recording part detection circuit that outputs a non-recording part detection signal when the recorded part continues for a predetermined period or more, and a multi-vibrator that generates a one-shot inter-track detection signal using the non-recording part detection signal. The song-to-song detection circuit includes a falling detection circuit that resets the holding circuit when detecting a falling edge of the song-to-song detection signal, and a transistor connected in parallel to the capacitor and made conductive by the positive phase output of the holding circuit. A recording tape track interval detection circuit characterized by the following features: