JPH0239893B2 - PARUSUHABA CHOSEIKAIRO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse width adjustment circuit that adjusts to a predetermined pulse width and outputs it even when a pulse with a large pulse width is input, and in particular, the present invention relates to a pulse width adjustment circuit that adjusts to a predetermined pulse width and outputs it even when a pulse with a large pulse width is input. This is something that can be easily accomplished compared to other things.

In recent years, record players have been used which incorporate a control circuit such as a PLL and which start and end a performance under electronic control.

This type of record player is generally configured as follows.

When you press the start key for a short period of time to reduce the pulse width of the control input pulse at the beginning of a performance, the turntable will start rotating, the arm will move to the performance start position, and then the stylus will move down onto the record, and the record will begin to move. Record playback starts from the beginning of the disc.

On the other hand, when you start playing, if you hold down the start key for a long time and input a pulse with a certain wide range, the turntable will start rotating and the arm will move toward the center of the record depending on the pulse width of the pulse. However, the arm stops moving when the start key is released. In this case, the arm does not descend, but remains raised and stops.
For this reason, by pressing a separately provided cueing key, the arm is lowered to start playing the record. In this way, when playing an LP record, the play start position of the record can be controlled by the length of time the star key is pressed, and a so-called song selection function can be realized.

Also, at the end of a performance, if you press the stop key for a short period of time, the arm will rise from the record and return to the rest position, and the turntable will stop rotating, but if you press the stop key for a long period of time, the arm will rise and press the stop key. While the turntable is pressed, it moves towards the rest position, and if you release the stop key midway through, only the movement of the arm will stop while the turntable continues to rotate. Therefore, by releasing the stop key at an appropriate location and pressing the cueing key, the stylus tip descends at that location and the record can begin playing. Of course, if you keep pressing the stop key and move the arm to the rest position, the turntable will stop rotating.

When remotely controlling such a record player, the remote control device cannot see between songs on the record, so the remote control device does not have a song selection function, but instead has a start function that starts playing from the beginning of the record. It is customary to provide a stop function for stopping the performance at any time.

However, if such a remote control device is provided with a start key and a stop key that have the same functions as the start key and stop key provided on the record player itself, if the start key of the remote control device is held down for a long period of time, However, even if the arm only moves toward the center of the record, the stylus tip will not descend onto the record no matter how long it takes. In such a case, if you want to start playing a record, you must go to the record player and operate the cueing keys.

Similar problems occur not only in such record players but also in devices that perform desired operations when the pulse width of the input pulse is less than a certain width.

In order to solve this problem, the present invention has a configuration in which even when a pulse with a long pulse width is input, the pulse width is adjusted to a predetermined narrow pulse width and output, and in addition, such a function is extremely simple. The present invention provides a pulse width adjustment circuit that can be realized in the following manner.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, +B ₁ and +B ₂ indicate power supply voltages, which are set to +B ₁ >+B ₂ here.
C ₁ is a capacitor, and both ends a and b thereof are connected to power supply lines +B ₁ and +B ₂ via pull-up resistors R ₁ and R ₂ . R ₃ and R ₄ are power supply voltage + B _2
Q1 is an NPN transistor whose base is biased by the divided voltage _VB , _R5 and _R6 are bias resistors _, and SW is connected to the record player body. The switch _Q2 , which closes in conjunction with the provided start or stop key, is a switching transistor provided within the record player body, and the output of this switching transistor _Q2 is applied to a control circuit such as a PLL synthesizer integrated circuit. . One end b of the capacitor _C1 is connected to the emitter of the NPN transistor _Q1 , and the collector C of the NPN transistor _Q1 is connected to the connection point between the resistor _R5 and the switch SW. Needless to say, transistor _Q1 turns on when its emitter potential becomes 0.6V or more lower than _VB , and the transistor Q1 turns on.
For Q ₂ , its base potential is 0.6V higher than the emitter potential.
It turns on when the voltage drops above or above.

In the above configuration, if remote control is not to be performed, pressing the start key or stop key provided on the record player body and closing the switch SW turns on the switching transistor _Q2 , and turns on the switch depending on the length of the on period. You can switch between playing from the beginning of a record and playing from a song in the middle.

On the other hand, when performing remote control, if you press the start key provided on the remote control device and apply a pulse with a pulse width T as shown in Figure 2 a to point a in Figure 1, the charge and discharge of capacitor _C1 will cause A waveform as shown in FIG. 2b appears at point b. The potential of this point b (i.e. the transistor
When the emitter potential of _Q1 becomes less than _VB -0.6V, the transistor _Q1 turns on, and an output with a pulse width _T1 as shown in FIG. 2c is obtained at the collector point C. Therefore, this pulse width T ₁ is
If you set the width narrow enough to start playing from the beginning of the record, transistor _Q2 will turn on during that time and start playing the record. The pulse width T ₁ can be freely changed by changing the capacitance of the capacitor C ₁ (increasing the capacitance increases the length), and by changing the bias voltage V _B by changing the values of the resistors R ₃ and R ₄ . (lower V _B will shorten it).

Furthermore, when performing a stop operation, the performance of the record can be reliably stopped by a similar operation.

Furthermore, if +B ₂ is set lower than +B ₂ as in this embodiment, the pulse level at point C can be sufficiently lowered during the time T ₁ , and the transistor
This has the advantage that Q ₂ can be turned on reliably.

As described above, in the present invention, one end of a capacitor whose both ends are connected to the power supply via a pull-up resistor is connected to the emitter of a NPN transistor whose base is biased. Even if a large pulse is applied, a pulse with a predetermined narrow pulse width can be output to the collector of the transistor. Therefore, if the pulse width is applied to a device to perform a desired operation when the pulse width is less than a certain width, malfunction of the device can be reliably prevented. Moreover, since it can be constructed with only one transistor, one capacitor, and several resistors, the circuit configuration can be simplified and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIGS. 2a, b, and c are waveform diagrams of various parts of FIG. 1. +B ₁ +B ₂ ... power supply voltage, C ₁ ... capacitor,
R ₁ , R ₂ ... Pull-up resistor, R ₃ , R ₄ ... Voltage dividing resistor, R ₄ , R ₅ ... Bias resistor, SW ... Switch, Q ₁ ... NPN transistor, Q ₂ ... Switching transistor.

Claims (1)

[Claims] 1. One end of a capacitor whose both ends are connected to a power supply via a pull-up resistor is connected to the emitter of an NPN transistor whose base is applied with a bias voltage, and a pulse applied to the other end of the capacitor is connected to the emitter of an NPN transistor whose base is applied with a bias voltage. is converted to a predetermined pulse width and the above
A pulse width adjustment circuit that outputs to the collector of an NPN transistor. 2. The pulse width adjustment circuit according to claim 1, wherein the power supply voltage applied to one end of the capacitor and the base of the transistor is lower than the power supply voltage applied to the other end of the capacitor.