JPS581867Y2 - Tape recorder's absence recording/playback circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit for a tape recorder that electronically controls a tape running system, and specifically to an absent recording/playback circuit.

Tape recorders whose tape running systems are electronically controlled not only have superior basic performance such as operability and reliability compared to mechanical control systems, but also have the feature that additional functions can be easily added.

With electronically controlled tape recorders, the absentee recording and playback functions can be easily configured using only a capacitor and a selector switch.

FIG. 1 shows a conventional circuit diagram.

Input switches 5 to 10 are for pause, recording, fast forward, stop playback, and rewind, respectively. When any switch is operated, a desired signal is input to the dedicated IC 2 for controlling the tape running system, and the IC 2 controls the tape running system according to input signals.

The change-over switch 1 is for switching the absentee recording/replay function, and switches 1a and 1b having three contacts a, b, and c operate in conjunction with each other.

When the contact of changeover switch 1 is in position a, the answering recording function works, when it is in position C, the answering playback function works, and when it is in position b, neither the answering recording nor the playback function works. .

That is, when the contact of the changeover switch 1 is in position a, the power switch (not shown) is turned on and the dedicated control IC is turned on.
2 starts operating, the capacitors 3 and 4 connected to the contact a are charged by the pull-up resistors 13 and 15 in the control IC 2, and the capacitor 3 is charged at a time constant determined by these resistance values and capacitances. The potential of and 4 increases.

Therefore, if the capacitances of capacitors 3 and 4 are determined so that the time constant is sufficiently larger than the rise time constant of the power supply voltage, the potentials at points A and B remain at a low level for a while after the power is turned on, and the control IC 2 Recording and playback input signals are input to the , and recording during an absence is started.

Note that the switch 11 is a switch for preventing erroneous recording, and is closed when the tape is correctly mounted to enable recording.

When the contact of changeover switch 1 is in position C, point B
Only the potential becomes low level, a reproduction input signal is input to the control IC 2, and reproduction while the user is away is started.

When contact 1 of the changeover switch is in position b, capacitors 3 and 4 are not connected to control IC 2, and the absent recording/playback function does not operate.

In the above-mentioned conventional example, the absentee recording and absentee recording functions can be added using only a capacitor and a changeover switch, which is very advantageous in terms of cost.

However, the conventional example described above has the following drawbacks.

That is, when the selector switch 1 is operated after the power is turned on, the absentee recording or absentee playback function is activated at that moment.

When the selector switch 1 is switched from position b to position a or C in order to set the absentee recording/playback function while the power is on, capacitors 3 and 4 are not charged, so points A, The potential of B or B becomes low level, resulting in a recording or playback state.

Therefore, the operation for recording and reproducing an absentee recording must be performed with the power switch turned off.

An object of the present invention is to provide an answering machine recording/reproducing circuit which eliminates the above-mentioned drawbacks of the prior art, does not malfunction, and is constructed at low cost.

The present invention will be explained in detail below with reference to an embodiment circuit diagram shown in FIG.

In Figure 2, selector switch 1 for recording/playback while absent.
, input switches 5 to 11 and I for controlling the tape running system.
C2 is the same as the conventional example shown in FIG. 1, 12 to 17 are pull-up resistors, and 18 to 23 are inverters.

In the embodiment of the present invention, the changeover switch 1 includes a capacitor 3,
4 and a charging circuit consisting of a resistor 24°25.

Therefore, when the power switch is turned on while the selector switch 1 is in the a or C position, the capacitors 3 and 4 connect the external resistors 24 and 25 and the pull-up resistors 13 and 15 in the control ICZ. It is possible to record and play back while you are away in the same way as in the conventional case.

On the other hand, if the power switch is already turned on, capacitors 3 and 4 are charged by the external resistor 24°25, so changeover switch 1 can be changed from b to a or c.
Even if the control IC 2 is switched to the position shown in FIG.

The resistors 24 and 25 also serve to discharge the charges in the capacitors 3 and 4 when the power switch is off.

As described above, according to the present invention, by simply adding a charging resistor, it is possible to eliminate the malfunctions that occur in the conventional example when operating the changeover switch, and to obtain an absence recording/playback circuit that operates stably. It's practical.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional absent recording/reproducing circuit, and FIG. 2 is a circuit diagram showing an embodiment of the absent recording/reproducing circuit according to the present invention. 1... Absence recording/playback selection switch, 2... Tape running system control ICl3, 4...-capacitor, 5... Pause input switch, 6... Recording input switch, 7...
・Fast forward input switch, 8... Playback manual switch, 9
...stop input switch, 10...rewind input switch, 11...misrecording prevention switch, 12-17...
Pull-up resistor, 24.25... external resistor.

Claims (1)

[Scope of utility model registration request] A recording input switch and a playback input switch are shared to a small extent, and the tape running system is controlled by a control signal obtained by opening and closing the switch, and an absent recording/reproducing switch and a capacitor are connected in parallel with the switch,
In a tape recorder in which the current flowing through the capacitor when the power is turned on starts recording or playback while the user is away, a resistor is connected to charge the capacitor while the tape recorder is in operation. When switching the above-mentioned absence recording/absence playback switch,
A tape recorder absent recording/playback circuit characterized in that the capacitor is not charged.