JPS6132737B2 - - 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, 1 is an input terminal to which an input signal converted from a recording tape to an electrical signal via a magnetic head is applied, and 2 is a terminal that determines recording or non-recording based on whether the input signal is above a specified recording level. 3 is a circuit for detecting the time of the non-recording section; 4 is a circuit for detecting 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 song selection function is applied; 7 is a one-shot multivibrator 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. The music selection function is started by sending one reset signal to terminal 6, placing the flip-flop 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. When the detection circuit 4 detects that the recording time is greater than the specified value and sets the flip-flop circuit 5, the stop input _In2 of the detection circuit 3 is released. Until the stop input In ₂ is released, even if the input signal level determination circuit 2
Even if it is determined that there is no recording, the detection circuit 3 does not operate. 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 the specified time, the one-shot multivibrator 7 is activated and a detection signal output 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 FIG. 2, the output of the input level determination circuit 2 is connected to In ₁ , and 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 ₁ and In ₂ are not released, one or both of the transistors Q ₁ and Q ₂ is in a conductive state, the capacitor C ₁ is in a discharge state, and Out 1 is “L ₀ ”.
It is.

Both In ₁ and In ₂ are released, and transistors Q ₁ ,
When Q ₂ becomes non-conductive, 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. When the signal that has now been determined to be at the recording level by the input signal level determination circuit 2 is applied to In ₃ , the transistor Q ₃ becomes conductive, and the capacitor C ₂ is charged by the collector current I ₁ of the transistor Q ₅ . It can be done. The charging voltage is the reference voltage of the comparator 10
If transistor Q ₃ continues to conduct (i.e. the recording section continues) until V ₂ is reached, comparator 1
0 output Out2 is inverted from “L ₀ ” to “Hi”,
This means 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 erroneously with a large level of noise or the like.

The above explanation describes the operation when one song is selected, but if you connect the detection signal output to a counter and try to count the number of songs, etc.
It is necessary to reset the flip-flop circuit 5 every time a song is selected. If not reset, 2
This is because the recording section detection function does not operate after the 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-mentioned 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 C ₂ 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 the device does not function properly.

(2) At the same time as resetting the flip-flop circuit 5 by outputting the detection signal, the capacitor _C2 is discharged.

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 will be cut off midway, and the one shot time of the output will 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 a configuration example 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, in order to make the explanation easier to understand, the recording section detection circuit 4 is shown using the specific example shown in FIG. 3. The detection signal output will be explained below assuming that the one-shot multivibrator 7 outputs "Hi" for a certain period of time when it is activated. (Steady is "L ₀ ".) 11
is 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. Reference numeral 12 denotes an OR circuit for applying a reset signal for starting music selection and a reset signal from the output fall detection circuit 11 to the flip-flop circuit 5. By the time the output of the one-shot multivibrator 7 changes from "L ₀ " to "Hi", the operation of the detection circuit 4 has already been completed, so the charge in the capacitor C ₂ has become useless.

Therefore, the detection signal output is “Hi” for a certain period of time.
The charge in the capacitor C ₂ can be discharged using a certain period of time.

Here, the transistor Q ₆ is turned on through the buffer circuit 13, and the charge in the capacitor C ₂ is forcibly discharged.

As described above, according to the present invention, since a means for discharging the charge of the capacitor using the detection signal output is provided, it is possible to reliably perform the music selection operation repeatedly.

[Brief explanation of the drawing]

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, 3 is a second detection circuit, 4 is a first detection circuit, 7 is a one-shot multivibrator, and _C2 is a capacitor. In addition, the same symbols in the figure are
Indicates the same or equivalent part.

Claims (1)

[Scope of Claims] 1. A first detection circuit that detects the transition of the running of the recording tape from the non-recording section to the recording section using the charging voltage of the capacitor; A second detection circuit detects the sound, and a control signal from the first and second detection circuits causes a one-shot multivibrator circuit that outputs an output for a certain period of time between songs, and a one-shot multivibrator circuit that outputs an output for a certain period of time between songs. A recording tape track interval detection circuit comprising means for discharging the charge in the capacitance during a period of output. 2. Claim 1, characterized in that the means for discharging the charge in the capacitor is a transistor connected in parallel to the capacitor, and the transistor is made conductive by an output signal of a one-shot multivibrator circuit. The inter-track detection circuit for the recording tape described.