JPS58119227A - Pulse width adjusting circuit - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution, by constituting a circuit making the pulse width narrow with a transistor (TR), a capacitor and some resistors. CONSTITUTION:When a pulse having the pulse width T is applied to a point (a) as shown in A by depressing a start key, a waveform as B is appeared at a point (b) with charge/discharge of a capacitor C1. When the potential at the point (b) reaches a prescribed potential or below, a TRQ1 turns on and an output of the pulse wave being T1 is obtained at a collector point (c). The pulse width T1 is freely changed by changing the capacitance of the capacitor C1 and also by changing a bias voltage VB through the change of resistors R3, R4. .

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse width adjustment circuit that adjusts the pulse width to a predetermined width and outputs it even when a pulse with a large pulse width is input, and in particular uses a clip-flop or the like. This makes it easier to implement than what was previously available.

In recent years, record players have been used that incorporate control (2) circuits such as PLL and perform play start, play end, etc. using an electronic device.

This type of record player is generally configured as follows.

When the start key is pressed for a short period of time to reduce the pulse width of the control caballus, the turntable will start rotating and the arm will move to the playing start position, and then the stylus will move down onto the record, and the record will start to move. The record starts playing from the beginning.

On the other hand, if you hold down the start key for a long time and input a fairly wide pulse when starting a performance, the turntable will start rotating and the arm will move toward the center of the record depending on the pulse width of the pulse. , 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 the entire LP record, the playback 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, when you finish playing, if you press the stop key for a short period of time,
The arm rises from the record and returns to the rest position, and the turntable also stops rotating, but if the start key is pressed for a long period of time, the arm rises and moves towards the rest position for the period of time when the start key is pressed. If you release the stop key midway through, the turntable will continue to rotate and only the arm will stop moving. Therefore, if you release the stop key at an appropriate point and press the cueing key,
At that position, the needle tip descends 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 is not equipped with a song selection function, since the person operating the remote control cannot follow all the tracks on the record, but instead has a start function that starts playing from the beginning of the record. It is customary to provide a stop function for ending the performance at an arbitrary point.

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, it will be difficult to keep the start key on the remote control device pressed for a long period of time. In this case, the arm simply moves toward the center of the record, but the stylus tip never descends onto the record, which is an inconvenience. In such a case, if the player wants to start playing a record, he must go to the record player and operate the cueing key.

Similar disadvantages occur not only in such record players, but also in other devices that perform desired operations when the pulse width of the input pulse is below a certain width plate.

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, 10B1. 10B2 indicates the power supply voltage, which is set here as 10B1>10B2. C1 is a capacitor, and its both ends a and b are pull-up resistors R1
, R2i via 10B1. It is connected to the 10B2 power line. RR is a voltage dividing resistor that divides the power supply voltage B2 into the voltage VB, and Ql is an NPN whose base is biased by the divided voltage VB.
) transistor, R5 and R6 are bias resistors, SW is a switch that closes in conjunction with the start or stop key provided in the record player body, and Q2 is a switch notching transistor provided in the record player body; The output of switching transistor Q2 is P
It is added to a control circuit such as a LL synthesizer integrated circuit.

One end 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 R6 and the switch SW. Needless to say, transistor Q1
Transistor Q2 turns on when its emitter potential becomes 0.6 V or more lower than VB. Transistor Q2 turns on when its base potential becomes 0.6 V or more lower than the emitter potential.

In the above configuration, when remote control is not performed, the switching transistor Q2 is turned on by pressing the start key or stop key provided on the record player body and closing the switch SW. You can switch between playing from the beginning of a record and playing from a song in the middle.

- When performing remote control, press the start key installed on the remote control device and apply a pulse with a pulse width T as shown in Figure 2 (-) to point a in Figure 1, and the capacitor C1 will be charged. Due to the discharge, a second
A waveform like the one shown in figure (b) appears. The potential at point b (that is, the emitter potential of transistor Q1) is V B −
When the voltage drops below 0.6V, transistor Q1 turns on,
At the collector point C, an output with a pulse width of T1 as shown in FIG. 2(C) is obtained. Therefore, if this pulse width T1 is set to a narrow enough width to start playing from the beginning of the record, the transistor Q2 is turned on only during that time and the playing of the record is started. The pulse width T1 can be freely changed by changing the capacitance of the capacitor C1 (increasing the capacitance increases the length), and it can also be changed by changing the bias voltage VB by changing the values of the resistors R3 and R4 (VB (The lower it is, the shorter it will be.)

Also, when performing a stop operation, the same operation can reliably stop the performance of the record.

Furthermore, if it is set lower than 10B2i+B as in this embodiment, the 0 point 9. There is.

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 an NPN transistor whose pace is biased. Even if a pulse with a large width is applied, it is possible to output a tars with a predetermined narrow pulse width to the collector of the transistor. Therefore, if you apply it to a device that performs the desired operation when the pulse width is less than a certain width,
Malfunctions of equipment can be reliably prevented. And 1
Since it can be constructed with only a stone transistor, one capacitor, and some resistors, the circuit configuration can be simplified and costs can be reduced.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a simple embodiment of the present invention, Figure 2 (a) Φ)
, CC) are waveform diagrams of various parts in FIG. 10B 10B...Power supply voltage, C...
Capacitor 1 2 1, R1, R2...Pull-up resistor, R3, R4
・・・・・・Resistance for voltage division, RR・・・・・・Resistance for bias, 1 5 SW・・・・Switch, Q ・・・・・・NPN)
Ranjisuri, Q...Switching transistor.

Claims (2)

[Claims] (1) Connect one end of a capacitor, both ends of which are connected to the power supply via a pull-up resistor, to the emitter of an NPN transistor whose base is applied with a bias voltage, and the pulse applied to the other end of the capacitor, A pulse width adjustment circuit that converts the pulse width into a predetermined pulse width and outputs the converted pulse width to the collector of the 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. .