JPS63247943A - Circuit for detecting unrecorded part - Google Patents

Abstract

PURPOSE:To prevent malfunction due to noise from being generated with a simple constitution, by setting the time constant of a time constant circuit and a reference voltage for voltage detection specifically and prohibiting the generation of a detecting output by the ON and OFF of a transistor in a short time due to a reproduced amplifier output. CONSTITUTION:The transistor 104 is turned ON by a reproduced output from a recording part via an amplifier circuit 102, and is turned OFF by the reproduced output from a unrecorded part, and while it is turned ON, the charge/discharge of a capacitor in the time constant circuit where the time constant of a resistor 106 and the capacitor 105 is set at a prescribed time constant is performed. By the prescribed time constant, the detecting voltage to a voltage detection circuit 117 where the reference voltage for voltage detection is set specifically by voltage-dividing resistors 112 and 111 is prevented from being increased over the reference voltage by one or two times of the ON/OFF of the transistor 104 in a short time, and the generation of the detecting output from the circuit 117 is prohibited. And only after the OFF state of the transistor 104 being continued for a period corresponding to the time constant, the detecting output of the unrecorded part is outputted from the circuit 117, and the transistor 113 is turned ON, and a control circuit 115 is operated, thereby, it is possible to prevent the malfunction due to the noise from being generated with the simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a non-recorded portion detection circuit in an information recording/reproducing device such as a tape recorder or a video disc.

2. Description of the Related Art In general, a track interval detection circuit of a tape recorder is well known as a non-recorded portion detection circuit for detecting a non-recorded portion of two information signals on a recording medium. FIG. 3 shows a conventional tape recorder inter-track detection circuit.

In FIG. 3, when a reproduced signal from a tape recorder as shown in FIG. 4 is applied to the terminal 1, and the signal is detected by the detection circuit 2 and the amplitude is limited, a signal as shown in FIG. 4B is obtained. When this is integrated with a small capacitor, a DC voltage as shown in FIG. 2C is output to terminal 3. Then, when the signal shown in FIG. A pulse signal is generated for a certain period of time from when the recording signal disappears (no recording occurs).

This pulse signal is applied to a control circuit 8 through an amplifier or buffer 6, and the operation of the tape recorder is controlled to stop the tape recorder from normal playback or to switch from high-speed playback (referred to as cue or review) to normal playback. However, with this circuit configuration, even when noise is recorded, such as the human b signal in Figure 4, a pulse signal of k is output as shown in Figure 4, and if the operation control of the control circuit 8 is different from the desired one. There was a drawback that it made it easier.

FIG. 6 shows another conventional example. In FIG. 5, when voltage is first applied to the power supply +B, the capacitor 36 is connected to the resistor 34.
A charging current flows through the resistor 32, initially biasing the base of the transistor 33 negatively, thus turning off the transistor 33, and the base of the transistor 31 is positively biased by the resistor 32, turning on the transistor 31. Then, the collector of the transistor 26 of the flip-flop circuit 24 that operates as a memory circuit is negatively biased, so the base of the transistor 25 is negatively biased, and when the transistor 25 is turned off, the base of the transistor 26 is connected to the resistor 2.
Positively biased at 9.27 turns transistor 26 on, setting and sustaining this first state. When the capacitor 3e is charged, the transistor 33
The base of transistor 33 is turned on, transistor 31 is turned off, and flip-flop circuit 24 remains in the first state. Then, the terminal 42 which is the collector of the transistor 25 has a positive voltage, the base of the transistor 13 is positively biased by the resistor 12, and the transistor 13 is on, so that the terminal 7 is short-circuited by the transistor 13. When a reproduced signal as shown in FIG. 6 is applied to the terminal 1, it is detected by the detection circuit 2 and a DC signal as shown in FIG. 6C is outputted to the terminal 3. Since the signal shown in FIG. 6G is applied to the time constant circuit 14, when a positive DC signal is applied to the base of the transistor 16 in the time constant circuit 14 when there is a reproduction signal, the transistor 16 is turned on. The transistor 19 changes from on to off. Then, capacitor 2o has resistor 18
It is charged by a current flowing through the
The terminal 44 is gradually charged to a positive voltage as shown in FIG.
is off, the transistor 26 is turned on, and the state is reversed to the second state as shown in FIG. 6F. Then, transistor 13 is turned off. Next, when the playback signal a disappears and a non-recording section occurs, the DC signal g in FIG. 6C disappears, and the non-recording signal generating circuit 4 outputs the signal j in FIG. resistance 6
A positive pulse signal is applied to the base of the transistor 1o of the control circuit 8 via , and the transistor 1o is turned on.
By applying current to a solenoid called a plunger, you can change the operation of the tape recorder from a normal playback state to a stop state or high-speed playback (cue).

(referred to as review) state to normal playback state. Then, when there is a positive pulse of the non-recording part signal j in Figure 6, the capacitor 37 is charged, and when the positive pulse signal disappears, the capacitor 37 is discharged, and the base of the transistor 33 becomes negative. Since the transistor 33 is biased to turn off and the transistor 31 is turned on, the flip-flop circuit 24 is set to the first state and the transistor 13 is turned on. If a signal such as noise is recorded only for a short time in the non-recording section as shown in Figure 6 (b), the voltage at the terminal 44 of the time constant circuit 14 will be like the signal n in Figure 6 (E). , if the reproduced signal disappears before reaching the voltage of the dotted line, the transistor 16 is turned off and the transistor 19 is turned on, the voltage at the terminal 44 is short-circuited by the transistor 19, and the transistors 22 and 23 remain off, and the flip-flop The circuit 24 remains in the first state and the transistor 13 also remains shorted. Therefore, when the short playback signal shown in Fig. 6 runs out, the non-recording signal generating circuit 4 is
Even if a signal is generated, since the transistor 13 is short-circuited, the control circuit 8 operates so that no pulse signal is applied. From the above, it is possible to operate only when there is no signal (non-recorded signal) after a signal has been present for a certain period of time, so that malfunctions can be prevented with short signals such as noise.

However, the one in Fig. 6 has a detection circuit of 2"1 and a time constant circuit of 14.
．． Flip-flop circuit 24 and unrecorded sound signal generation circuit 4
The complex configuration of the system eliminates noise and other malfunctions.

Problems to be Solved by the Invention However, the above-mentioned configurations have the problem that they malfunction due to noise in the non-recorded area, and require a complicated configuration if they do not malfunction.

In view of the above-mentioned problems, the present invention provides a non-recorded portion detection circuit which has a simple configuration when detecting a non-recorded portion and does not malfunction even if there is noise in the non-recorded portion.

Means for Solving the Problems In order to solve the above problems, the non-recorded portion detection circuit of the present invention includes an amplifier circuit that amplifies a reproduced signal from a recording medium, and a circuit that is turned on and off by the reproduced signal output to the amplifier. A transistor to be turned off and a time constant circuit of a resistor and a capacitor are provided at the collector of the transistor, the collector output of the transistor is connected to a voltage detection circuit, and an output signal of the voltage detection circuit is applied to a control circuit. By turning on and off once or twice, the control circuit is disabled by the output of the 'I voltage detection circuit. The configuration is such that the resistance and capacitor of the time constant circuit and the detection reference voltage of the voltage detection circuit are set.

Effect of the Invention With the above-described configuration, the present invention has a simple configuration when detecting a non-recorded area, and can prevent malfunction even if there is noise in the non-recorded area.

Embodiment Hereinafter, a non-recorded portion detection circuit according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a non-recorded portion detection circuit in an embodiment of the present invention.

In FIG. 1, 101 is an input terminal, 102 is an amplifier circuit,
104 is a transistor, 106, 106 is a time constant circuit capacitor and resistor, 117 is a voltage detection circuit, 111, 1
12 is a resistor for setting the detection reference voltage of the voltage detection circuit;
13 is a transistor, and 116 is a control circuit.

The operation of the non-recorded portion detection circuit configured as described above will be explained below with reference to FIGS. 1 and 2.

When a reproduction signal as shown in FIG. 2 from a recording medium such as a tape recorder or a disk player is applied to the terminal 1o1 and amplified by the amplifier circuit 102, it is amplified as shown in FIG. 2B, and the transistor 104 is turned on and off. Then, when the transistor 104 is turned on, the capacitor 105 of the time constant circuit is charged, and when the transistor 104 is turned off, it is discharged by the resistor 106. As the ON and OFF conditions continue, the voltage at the terminal 116 gradually decreases.

Next, when the voltage reaches the dotted line in FIG. 2C, the voltage detection circuit 117
The transistor 108 is turned on, and the transistor 109 is turned off as shown in the second diagram. This is resistance 111.11
2, the detection reference voltage is set to approximately the same voltage as the voltage indicated by the dotted line in FIG. 2C. Next, when the reproduction signal is no longer applied to the terminal 101, the transistor 104 is turned off, and the voltage charged in the capacitor at the terminal 116 is discharged by the resistor 108 of the time constant circuit, and the voltage gradually increases as shown in Figure 2C. When the terminal 116 reaches the voltage indicated by the dotted line in FIG. 2C, the transistor 108 turns off.
Transistor 109 turns on.

Transistor 113 is turned on. Then, a control circuit can control the output of the transistor 113 to stop a tape recorder or the like between songs. Also, when there is noise in the non-recorded area, as shown in Figure 2, the transistor 104 turns on for a short time, but the terminal 116 is connected to the second
As shown by J in Figure C, the voltage changes only a little but does not change to the voltage indicated by the dotted line, so there is no signal change in the output of the voltage detection circuit 117, and the circuit does not operate by mistaking noise for a signal. This is the resistor 1 of the time constant circuit that prevents the voltage at the terminal 116 from operating even if the transistor 104 is turned on once or twice.
06. This is because the capacitor 106 is set and the detection reference voltage is set by the resistors 111 and 112 so that the voltage detection circuit does not operate immediately like the voltage indicated by the dotted line in FIG. 2G.

If this detection reference voltage is set approximately halfway between one power supply VCC and ground, the time E from when a signal is applied until the transistor 113 turns off is E.

It is possible to increase the time G from when there is no signal until the transistor 113 turns on to a large value.

Another feature is that the values of E and G do not change significantly even if the power supply VCC changes slightly.

Effects of the Invention As described above, the present invention prevents the control circuit from operating due to the output of the voltage detection circuit by simply turning on and off once or twice in a short period of time the transistor provided at the output of the amplifier that amplifies the reproduced signal. , i after a certain period of time after it becomes a non-recorded area.
By setting the resistance and capacitor of the time constant circuit and the detection reference voltage of the voltage detection circuit so that the output of the lightning voltage detection circuit changes, the structure is simple and malfunctions due to noise are prevented. Can be done.

[Brief explanation of the drawing]

FIG. 1 is an electrical connection diagram of a non-recorded area detection circuit according to an embodiment of the present invention, FIG. 2 is a diagram explaining the operation of the same circuit, FIG. 3 is a block diagram of a conventional non-recorded area detection circuit, and FIG. 4 is an explanatory diagram of the operation of the same circuit, FIG. 5 is a circuit diagram of a conventional non-recorded portion detection circuit, and FIG. 6 is an explanatory diagram of the operation of the circuit of FIG. 101...Signal input terminal, 102...Amplification circuit, 104.113...Transistor, 1
05,106... Time constant circuit capacitor, resistor,
117... Voltage detection circuit, 116... Control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 117 First set of broom tips Figure 2 OFF θFF Figure 3 Figure 4 d e j Figure 6 α bC

Claims (1)

[Claims] an amplifier circuit for amplifying a playback signal from a recording medium; a transistor that is turned on and off by the playback signal output to the amplifier; and a time constant circuit of a resistor and a capacitor at the collector of the transistor, and the collector output of the transistor is It is connected to a voltage detection circuit, and the output signal of the voltage detection circuit is applied to the control circuit, and the control circuit is operated by the output of the voltage detection circuit by simply turning the transistor on and off once or twice in a short time. The resistor and capacitor of the time constant circuit and the detection reference voltage of the voltage detection circuit are set so that the output of the voltage detection circuit changes after a certain period of time after a non-recorded area is created. A non-recorded area detection circuit characterized by: