JPH0240586Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a power supply fluctuation malfunction prevention circuit for information recording and reproducing devices such as tape decks.

In a tape deck device, an electronic control system is often employed, and a so-called electronic system controller is used to set and control the mechanical system of the device according to each operation mode. In a device using such an electronic system controller, only the system controller is electrically reset to return to an initial state (for example, STOP mode state) in order to prevent malfunctions due to external factors such as power fluctuations. In this case, even if the electronic circuit that is the system controller is instantaneously reset by the reset signal, the reaction time of the mechanical system is long, so only the electronic circuit will be in the reset state, and the mechanical system will not be able to return to its initial state. This may result in malfunction.

Furthermore, in cassette tape deck devices such as car stereos and portable radio cassettes,
When a cassette half is inserted, the device power is turned on and the cassette half loading mechanism is activated, often resulting in a half loading hold state. Even in such devices, only the electronic circuit that is the system controller is reset, and the mechanical system is not reset. Since this cannot be done forcibly, in addition to the above-mentioned drawbacks, the cassette half-ejecting operation cannot be done forcibly, which is another disadvantage.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a circuit for preventing malfunctions caused by power fluctuations in tape decks, etc., which prevents malfunctions due to power fluctuations and returns the entire device to a reset state.

The power supply fluctuation malfunction prevention circuit according to the present invention includes a power switch that turns on when a recording medium is inserted into the recording medium insertion slot and supplies power to the information recording/reproducing device, and a power switch that turns on when the recording medium is inserted into the recording medium insertion slot, and when the recording medium is not installed in the specified position. a first reset signal generating means that generates a reset signal and stops generating the reset signal when it detects that the recording medium is installed in a predetermined position; and a first reset signal generating means that generates the reset signal by detecting fluctuations in the power supply while the power switch is on. a second reset signal generation means for generating a reset signal, an operation mode control circuit that enters a reset state in response to each reset signal, and a release control circuit that generates a release command signal when generation of a reset signal is detected after a predetermined period of time has elapsed from the time when the power switch is turned on. The present invention includes a command signal generating means and a loading/holding mechanism that holds the recording medium inserted into the recording medium insertion slot at a predetermined position and releases the loading operation of the recording medium to the predetermined position in response to a release command signal. It is a feature.

The present invention will be explained below with reference to the drawings.

The figure is a circuit diagram of an embodiment in which the present invention is applied to a tape deck, in which a power switch _S1 is provided which closes and turns on the device power supply +B in response to the loading operation of a cassette half (not shown). and
This is arranged, for example, near the cassette half insertion opening. The solenoid 1 is for holding the cassette half in a loaded state, and is provided with a circuit consisting of a transistor Q ₁ and resistors R ₁ and R ₂ as its excitation circuit. Note that the diode _D1 is a so-called spark absorber for absorbing back electromotive force.

The installed power supply +B is stepped down to, for example, 10V and 5V by converters 2 and 3, respectively, and this 5V output is used as the circuit power supply +VDD of the system controller 4. This system controller 4 is a control circuit for setting and controlling the mechanical system of the apparatus into each mode in response to an operation mode command signal, and has a purely electronic configuration. The output of a time constant circuit consisting of a capacitor _C2 and a resistor _R3 is applied to the reset input A of this circuit ₄ , and this terminal A is connected to the cassette half position detection switch _S2 via a resistor R4. ing. This switch _S2 is turned off when it detects that the cassette half is properly installed in a predetermined position, and is normally in the on state, clamping the terminal A to the ground level.

In order to detect the level of this terminal A and determine that the cassette half is installed in the normal position,
A time constant circuit including transistors Q ₂ and Q ₃ , resistors R ₆ to R ₈ , and a capacitor C ₁ and a resistor R ₅ is provided. In other words, the voltage at terminal A is
It is input to the emitter of NPN transistor Q ₂ via D ₂ , and the output of the time constant circuit is applied to the base of this transistor Q ₂ . The collector output of this transistor Q ₂ is connected through resistor R ₆
This is the base input of PNP transistor _Q3 .
Resistor _R7 is a base-emitter bias resistor for transistor _Q3 . The collector output of transistor Q ₃ is derived by resistor R ₈ and is connected to the NPN transistor via diode D ₃ and resistor R ₉ .
This becomes the base control signal for _Q4 . this transistor
The emitter of _Q4 is grounded via the position detection switch _S2 , and its collector output serves as the base drive signal for the solenoid drive transistor _Q1 .

The switch _S3 is a cassette half-displacement switch, and is provided to ground the series connection circuit of the base bias resistors _R10 and _R11 of the PNP transistor _Q5 . The collector output of the transistor _Q5 serves as the base input of the transistor _Q4 , and also serves as the base input of the NPN transistor _Q6 via the resistor _R12 . Note that the resistor _R13 is for base bias of the transistor _Q6 . The output from the collector resistor _R14 of this transistor _Q6 is the eject input of the system controller 4, and when this eject input becomes low level, the system controller 4 detects this and sends a low level command signal to the eject output. Output. An NPN type switch transistor _Q7 is provided to transmit this eject output to the base of the solenoid drive transistor _Q1 , and this base is connected to a resistor _R15.
and is grounded via switch _S2 .

Furthermore, a Schmitt trigger circuit consisting of transistors Q ₈ and Q ₉ and resistors R ₁₆ to R ₁₉ is provided to detect power supply fluctuations, that is, changes in the 10V output of the converter 2, and the collector output of the transistor Q ₈ is connected to the system controller 4. Reset input A
It is becoming.

In such a configuration, when the cassette half is inserted, the power switch _S1 is turned on and the power supply +B is turned on.
is supplied. Then, when the cassette half is installed in the normal position, switch _S2 is switched from on to off. Therefore, the reset input A of the system controller 4 gradually rises from a low level to a high level, and is reset and activated. Also, if reset input A goes high, the transistor
Since the emitter of Q ₂ is floating due to the action of diode D ₂ , this transistor Q ₂ is off, and therefore transistor Q ₃ is also off. Also, the emitter of transistor _Q4 is at a high level, so it is off. and transistor Q ₇
Assuming that the base of the transistor is at a high level and is on, but the eject output of the system controller 4 is controlled to a high level, the transistor
Q ₇ is also off. Therefore, since the base of the solenoid drive transistor _Q1 is determined by the divided voltage of the resistors _R1 and _R2 , if it is set to be turned on at this time, the solenoid 1 will be turned on when the cassette half is properly installed. The cassette halves remain loaded.

If the cassette half is not properly installed, the switch _S2 will not turn off, so the reset terminal A of the system controller 4 will remain at a low level in the reset state and will not operate in any way. Also, since the emitter of transistor _Q2 remains clamped to a low level, the capacitor
A predetermined time after the start of charging _C1 , this transistor _Q2 is turned on and controls the transistor _Q3 to be turned on. Thus, the high level collector output of transistor _Q3 is applied to the base of transistor _Q4 , turning it on. Therefore, the collector of transistor Q ₄ becomes low level, which is supplied as a release command signal to the base of transistor Q _{1, which sets the base of transistor Q 1 to} low level and turns off transistor Q ₁ , so that solenoid 1 is deactivated. The cassette half is then ejected.

When the ejection switch _S3 is pressed, the transistor _Q5 is turned on, and the transistor _Q6 is turned on. Therefore, the eject input of the system controller 4 returns to a low level and operates to generate an eject command. This eject command sets the eject output of the circuit 4 to a low level, and this low level output is applied to the base of the transistor _Q1 via the on-transistor _Q7 . Then,
With transistor _Q1 turned off and solenoid 1 deactivated, the cassette half can be ejected.

Next, considering power supply fluctuations, when the power supply drops below the normal value and reaches the threshold of the Schmitt circuit consisting of transistors Q ₈ and Q ₉ , transistors Q ₈ and Q ₉ turn on, and the reset input of the system controller 4 is activated. Since A is forced to a low level, the electronic circuit is reset and returns to its initial state before it malfunctions. At the same time, transistor Q ₂
and _Q3 are both turned on, so the high level collector output of transistor _Q3 is applied to the base of transistor _Q4 . Since the emitter of transistor Q ₄ is at a lower level than transistor Q ₈ ,
Transistor _Q4 turns on, turning off solenoid drive transistor _Q1 , forcing the cassette half to reset and disengaging the cassette half load and hold mechanism.

By doing this, the electronic circuit is instantaneously reset due to power fluctuations, and then the cassette half loading and holding mechanism section is reset and released, so both the electronic circuit and the mechanical system can be reliably reset, and malfunctions can be prevented. . In addition, in order to detect temperature and rotation system abnormalities and perform evacuation, these abnormal signals are sent to the transistors via diodes _D4 and _D5 .
Applied to the base of Q ₄ .

In the above example, a drop in the power supply was detected, but in the case of detecting not only a drop but also a rise in the power supply, for example, the output of converter 2 may be detected by a window comparator, and the upper and lower reference levels of the window comparator may be detected. It is sufficient if the configuration is such that a low level output is generated when the range is exceeded.

In addition, mechanical parts that cannot be returned to the initial state only by resetting the electronic circuit 4, or even mechanical parts that may not be able to return to the initial state depending on the timing of resetting the electronic circuit, can be forcibly removed. Further effects can be expected if a configuration is adopted that allows the device to return to its initial state.

As described above, according to the present invention, the electronic circuit 4 is instantaneously reset upon detecting power fluctuations, and then the necessary mechanical parts are reliably reset to the initial state, thereby eliminating malfunctions. This is particularly effective for cassette decks such as car stereos where the user cannot visually confirm the cassette, since a more reliable ejecting operation is required.

[Brief explanation of the drawing]

The figure is a circuit diagram of an embodiment of the present invention. Explanation of the symbols of the main parts: 1...Solenoid for holding the cassette half loaded, 4...System controller, _Q8 , _Q9 ...Power fluctuation detection transistor.

Claims (1)

[Scope of utility model registration request] A power switch turns on when a recording medium is inserted into the recording medium insertion slot and supplies power to the information recording/reproducing device, and a power switch generates a reset signal when the recording medium is not inserted into the predetermined position and resets the recording medium. a first reset signal generating means that stops generating the reset signal when the device is detected to be attached to a predetermined position; and a second reset signal that generates the reset signal by detecting fluctuations in the power source while the power switch is on. generating means; an operation mode control circuit that enters a reset state in response to each of the reset signals; and a release command signal that generates a release command signal when generation of the reset signal is detected after a predetermined period of time has elapsed since the power switch was turned on. and a loading holding mechanism that holds the recording medium inserted into the recording medium insertion slot at the predetermined position and releases the loading operation of the recording medium to the predetermined position in response to the release command signal. A power supply fluctuation malfunction prevention circuit for an information recording/reproducing device, characterized in that: