JPH0333944Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a tape recorder that performs interlaced music selection, and aims to prevent malfunctions of the inter-track detection section and perform accurate interlaced music selection.

Conventionally, this type of tape recorder has often used an integrated circuit manufactured by ROHM Co., Ltd., model number BA336, in the track interval detection section, and one example of this type of tape recorder using this integrated circuit has a configuration as shown in Fig. 1. has been done.

In the figure, 1 is a recording/playback head, 2 is a first recording/playback switch whose switching piece is grounded, a recording contact r is connected to one end of the head 1, and a playback contact p is connected to the other end of the head 1. ing. 3 is a reproduction equalizer circuit whose input terminal is connected to the recording contact r, 4 is a second recording/reproduction switch whose reproduction contact p is connected to the output terminal of the reproduction equalizer circuit 3, and the line input terminal 5 is connected to the recording contact r. It is connected.
6 is a noise reduction circuit whose input terminal is connected to the switching piece of the switch 4, 7 is a third recording/reproduction switch whose recording contact r is connected to the recording output terminal of the noise reduction circuit 6, and the reproduction contact p is connected to the noise reduction circuit. It is connected to the reproduction output terminal of the circuit 6. 8 is a line output terminal connected to the switching piece of switch 7, 9 is a recording equalizer circuit whose input terminal is connected to the recording contact r of switch 7, and the output terminal is connected to the playback contact p of switch 2. . 10 is an oscillation circuit whose output terminal is connected to the regeneration contact p of switch 2;
Reference numeral 1 designates a fourth recording switch in which a recording contact r is connected to a control terminal of an oscillation circuit 10, a switching piece is grounded, and a reproduction contact p is an idle contact.

Reference numeral 12 denotes an integrated circuit manufactured by Rohm Co., Ltd., model number BA336, which is provided in the inter-song detection section 13, and the third pin, that is, the signal input pin a, is connected to the switching piece of the switch 7 via the current limiting resistor 14. . 1
5 is an input level setting resistor provided between the signal input pin a and the ground point, 16 is an operational amplifier for the preamplifier provided in the integrated circuit 12, and the non-inverting input terminal (+) is the signal input terminal. The inverting input terminal (-) is connected to the fourth pin, that is, the negative feedback pin b, via the input resistor 17. 18 is a low frequency time constant determining capacitor provided between the negative feedback pin b and the ground point; 19 is a gain setting resistor provided between the inverting input terminal (-) of the amplifier 16 and the output terminal; 20 is a first circuit whose non-inverting input terminal (+) is connected to the output terminal of the amplifier 16;
It is a comparator, and the reference voltage of the reference potential terminal 21 is applied to the inverting input terminal (-).

22 is a first NPN transistor whose collector is connected to the reference potential terminal 21 via a collector resistor 23; its emitter is grounded and its base is connected to the reference potential terminal 2 via a base resistor 24;
Connected to 1. 25 is a biasing resistor provided between the base of the transistor 22 and the 6th pin of the integrated circuit 12, that is, the muting pin c, and 26 is a muting time constant determination provided between the muting pin c and the ground point. The noise absorbing capacitor 27 has one end connected to the No. 7 pin of the integrated circuit 12, that is, the noise filter pin d, and the other end is grounded.

28 is a flip-flop whose set terminal S is connected to the output terminal of the comparator 20, and whose reset terminal R is connected to the reference potential terminal 21 via a resistor 23. The base of 29 was connected to the output terminal of comparator 20, and the emitter was grounded.
This is an NPN type second transistor and forms a semiconductor switch for charge/discharge control. 30 is a third NPN type transistor whose base is connected to the inverting output terminal of the flip-flop 28 and whose emitter is grounded.
It is a transistor and forms a charge blocking circuit together with the flip-flop 28. 31 is a first time constant capacitor whose one end is connected to the collectors of the second and third transistors 29 and 30 via the second pin of the integrated circuit 12, that is, the detection timing pin e, and whose other end is grounded. . 32 is a first time constant resistor provided between one end of the capacitor 31 and the power supply terminal (+B), and together with the capacitor 31 forms a first time constant circuit.

33 is a Schmitt circuit whose non-inverting output terminal (+) is connected to the collectors of the second and third transistors 29 and 30, and whose inverting input terminal (-) is grounded via a level setting resistor 34. One end of 35 is the inverting input terminal (-) of the Schmitts circuit 33.
The other end is connected to the power supply terminal (+B) via the 9th pin of the integrated circuit 12, that is, the power supply pin f. 36 is a first inverter whose input terminal is connected to the output terminal of the Schmitt circuit 33; 37 is a fourth NPN transistor whose base is connected to the output terminal of the inverter 36; and whose emitter is grounded. A second constant capacitor 38 has one end connected to the collector of the transistor 37 via the No. 1 pin of the integrated circuit 12, that is, the pulse width setting pin g, and the other end is grounded. 39 is a second time constant resistor provided between the capacitor 38 and the power supply terminal (+B), and together with the capacitor 38 forms a second time constant circuit.

40, the inverting input terminal (-) is the transistor 37
The second comparator is connected to the collector of the second comparator, and its non-inverting input terminal (+) is grounded via a level setting resistor 41. 42 is an input resistor of the comparator 40 provided between the non-inverting input terminal (+) of the comparator 40 and the power supply pin f, and 43 is a NAND gate whose one input terminal is connected to the output terminal of the Schmitt circuit 33. The other input terminal is connected to the inverting input terminal (-) of the Schmitt circuit 33 and the output terminal of the comparator 40. 44 is a second inverter whose input terminal is connected to the output terminal of the NAND gate 43;
0, forms a signal generation circuit together with the NAND gate 43.

45 is an output resistor whose one end is connected to the output terminal of the inverter 44 via the No. 8 pin of the integrated circuit 12, that is, the signal output pin h, and 46 is an NPN type fifth resistor whose base is connected to the other end of the resistor 45. It is a transistor whose emitter is grounded and whose collector is connected to the power supply terminal (+
B).

Reference numeral 48 denotes a mechanism control section whose input terminal j is connected to the collector of the transistor 46, which is formed by a microcomputer and controls the mechanism section through software processing.

Note that i is the fifth pin of the integrated circuit 12, that is, the ground pin.

When the power is turned on, the flip-flop 28 is reset and a high level output signal is output from the inverting output terminal, which turns on the transistor 30 and prevents the capacitor 31 from being charged. Further, after the capacitor 26 is charged, the transistor 22 is turned on and the reference signal is applied to the inverting input terminal (-) of the comparator 20.

On the other hand, when the power is turned on, since no signal is input to the signal input pin a, the output signal of the comparator 20, that is, the comparison signal is held at a low level, and the transistor 29 is turned off.

Since the capacitor 31 is not charged, the output signal of the Schmitt circuit 33 is held at a low level, and the transistor 37 is turned on to charge the capacitor 3.
Since the capacitor 38 is not charged, the output signal of the comparator 40 is held at a high level, and the output signal of the NAND gate 43 is held at a high level.

Further, since the output signal of the NAND gate 43 is held at a high level, the signal output pin h is held at a low level, the transistor 46 is turned off, and a high level signal is input to the input terminal j of the mechanism control section 48.

Next, in order to perform skip song selection, when the mechanism section is set to song selection mode, switches 2, 4, 7, 1 are activated.
1 switches to playback contact p, the tape is played back in fast forward or rewind, and a playback signal is input to signal input pin a.

Until the first track of the playback signal is reached,
The comparison signal is held at a low level, transistor 46 remains off, and short-term noise signals are absorbed by capacitor 27, preventing the comparison signal from changing in level.

Next, when the reproduced signal reaches a high level, the comparison signal becomes high level, the capacitor 27 is charged, the flip-flop 28 is set, and the transistor 30 is turned off. At this time, the comparison signal turns on the transistor 29, and the capacitor 31
charging is prevented and transistor 46 remains off.

Furthermore, due to the change in the playback signal from a tracked state to a non-tracked state, the comparison signal changes from a high level to a low level, the transistor 29 is turned off, and the capacitor 31
is charged.

Then, by predetermined charging of the capacitor 31, the output signal of the Schmitt circuit 33 becomes high level, the transistor 37 is turned off, the capacitor 38 is charged, and the output of the NAND gate 43 is output from the predetermined charge of the capacitor 31 until the predetermined charge of the capacitor 38. Since the signal becomes low level, the signal output pin h
A high-level pulse signal is output from , the transistor 46 is turned on for a predetermined period of time, and the output signal to the input terminal j of the mechanism control section 48 becomes low level for a predetermined period of time.

Furthermore, when the playback signal changes from the next song to no song, the comparison signal changes from high level to low level, capacitors 31 and 38 are sequentially charged, transistor 46 is turned on for a predetermined period, and the input The output signal to terminal j becomes low level for a predetermined period.

After that, by repeating the same operation, the input terminal j
The output signal to becomes low level for a predetermined period of time due to the change of the playback signal from the song presence to the no song presence.

Note that if the no-music period is not a specified no-music period of 100 msec or more due to the capacitors 31, 38, etc.
No pulse signal is output from the signal output pin h.

The microcomputer of the mechanism control unit 48 increases the number of jumps set in the counter by 1 every time a low level output signal is input to the input terminal j.
When the counter value reaches zero, a music selection end command is output, the mechanism is controlled from the music selection mode to the playback mode, and the skip music selection is ended.

Note that when a low-level output signal is not input to the input terminal j and when the counter value is not zero, the mechanical section is held in the music selection mode.

By the way, the capacitor 27 is discharged through the internal circuit of the integrated circuit 12 every time the playback signal changes from a tracked state to a non-tracked state. However, because the impedance of the internal circuit is high, the capacitor 27
discharge becomes incomplete.

Since the capacitor 27 is not fully discharged, the noise filter effect that absorbs the noise signal is weakened during the second and subsequent changes in the reproduced signal from no song to a song, causing the inter-song detection section 13 to malfunction. There are drawbacks to doing so.

This idea was made with the above points in mind, and includes a song interval detection section that compares a playback signal such as a song selection with a reference signal, and determines whether the playback signal has a high level or a low level depending on whether a song is present or not. A comparator that outputs each comparison signal, a noise absorbing capacitor that is connected to the output terminal of the comparator and prevents a change in the level of the comparison signal due to a noise signal, and a capacitor that is turned on by the comparison signal at a high level and outputs a low level signal. a semiconductor switch for charge/discharge control that is turned off by the comparison signal; a first time constant capacitor that is discharged when the semiconductor switch is turned on and charged when the semiconductor switch is turned off; a charge blocking circuit that prevents charging of the first time constant capacitor; and a charge blocking circuit that prevents charging of the first time constant capacitor;
an output semiconductor switch whose output signal changes from high level to low level; and a second time constant capacitor that is charged during a predetermined charging period after the first time constant capacitor is charged.
a time constant capacitor; a signal generation circuit that outputs a high-level pulse signal from a predetermined charge of the first time constant capacitor to a predetermined charge of the second time constant capacitor; and a signal that outputs the pulse signal. A generating circuit and a discharge path semiconductor switch that is turned on by the pulse signal to short-circuit and ground the noise absorbing capacitor are provided, and the mechanism control section is configured to detect a change in the output signal from a high level to a low level. level detecting means; period measuring means for outputting a counting pulse when the low level period of the output signal is longer than a predetermined non-musical period; The present invention provides a tape recorder equipped with a microcomputer having control means for controlling the playback mode from the playback mode.

Therefore, according to the tape recorder of this invention, each time the playback signal changes from a tracked state to a non-tracked state, the semiconductor switch for the discharge path is turned on and the noise absorbing capacitor is short-circuited to ground. By discharging the battery, it is possible to prevent the inter-track detecting section from malfunctioning, and to perform accurate skip selection.

Next, this invention will be explained in detail with reference to FIG. 2 showing one embodiment thereof.

In this figure, the same symbols as those in FIG. 1 indicate the same or equivalent parts, and the differences are as follows.

That is, the base of the transistor 46 is connected to the detection timing pin e via the base resistor 46, and the semiconductor switch for discharge path, that is, NPN, is connected to the signal output pin h via the base resistor 50.
The base of the sixth transistor 51 of the same type is connected, the emitter of the transistor 51 is grounded, and the collector is connected to the noise filter pin d.

Also, the mechanism control section 5 may be replaced with the mechanism control section 48.
2 is provided, and the microcomputer of the control unit 52 detects a change in the output signal from a high level to a low level, and outputs a counting pulse if the low level period of the output signal is longer than a predetermined non-track period of 100 msec or more. Furthermore, each time a counting pulse is input, 1 is subtracted from the jump number set in the counter, and when the counter reaches zero, a song selection end command is output to control the mechanism from the song selection mode to the playback mode. This is the point I made.

Then, each time the capacitor 31 is charged to a predetermined value due to a change in the playback signal from a tracked state to a non-tracked state, the transistor 46 changes from off to on, and the output signal input to the input terminal j of the mechanism control section 52 is as follows. Changes from high level to low level.

Furthermore, each time a high-level pulse signal is output from the signal output pin h due to a change in the playback signal from non-track to track, the transistor 51 is turned on and the capacitor 27 is discharged and grounded.
is completely discharged, the noise filtering effect of the capacitor 27 is not weakened, and malfunction of the song interval detection section 13 can be prevented.

Then, the mechanism control unit 52 measures the low level period every time a low level output signal is input to the input terminal j, and sets the value of the counter to 1 only when there is no song.
When the value on the counter becomes zero and the desired number of skips is reached, the mechanism is controlled from the music selection mode to the playback mode.

Therefore, according to the embodiment, the transistor 51 and the resistors 49 and 50 are added to those shown in FIG. 1, and the software processing of the microcomputer of the mechanism control section 48 in FIG. 1 is changed to form the mechanism control section 52. By this, capacitor 2 can be installed cheaply and easily.
7 can be completely discharged to prevent deterioration of the noise filter effect and prevent malfunction of the song interval detection section 13, thereby making it possible to perform accurate skip song selection.

Note that as a simple method, the transistor 51
It is also conceivable to provide an impedance element instead.

[Brief explanation of the drawing]

Figure 1 is a wiring diagram of a conventional tape recorder, Figure 2 is a wiring diagram of a conventional tape recorder.
The figure is a wiring diagram of one embodiment of the tape recorder of this invention. 12... integrated circuit, 13... song interval detection section, 2
0, 40... Comparator, 22, 29, 30, 37,
46, 51...Transistor, 27...Noise absorption capacitor, 28...Flip-flop, 3
1, 38... Capacitor for first and second time constants, 3
3...Schmitt circuit, 52...mechanism control section.

Claims (1)

[Scope of utility model registration request] The inter-song detection section includes a comparator that compares a playback signal at the time of song selection with a reference signal and outputs high-level and low-level comparison signals depending on whether the playback signal has a song or not, and the output of the comparator. a noise absorbing capacitor connected to the terminal to prevent a level change of the comparison signal due to a noise signal; a charge/discharge control semiconductor switch that is turned on by the comparison signal at a high level and turned off by the comparison signal at a low level; a first time constant capacitor that is discharged when the semiconductor switch is turned on and charged when the semiconductor switch is turned off; and a charge blocking circuit that prevents charging of the first time constant capacitor until the comparison signal first becomes high level. and an output semiconductor switch that changes from OFF to ON by predetermined charging of the first time constant capacitor, and whose output signal changes from high level to low level, and charging after predetermined charging of the first time constant capacitor. a second time constant capacitor that is charged during a period, and a signal generation circuit that outputs a high-level pulse signal from a predetermined charge of the first time constant capacitor to a predetermined charge of the second time constant capacitor; a semiconductor switch for a discharge path that is turned on by the pulse signal to short-circuit and ground the noise absorbing capacitor; and a level detection means for detecting a change in the output signal from a high level to a low level in the mechanism control section; , a period measuring means for outputting a counting pulse when the low level period of the output signal is equal to or longer than a predetermined non-musical period; and a period measuring means for counting the counting pulse and switching the mechanical section from the song selection mode to the playback mode when a predetermined number of jumps is reached. A tape recorder equipped with a microcomputer having a control means for controlling.