KR790001853Y1 - Pulse generaton circuit - Google Patents

Abstract

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Description

Pulse generator circuit

1 and 2 are waveform diagrams for explaining the present invention.

3 to 5 are connection diagrams each showing a pulse generating circuit for explanation of the present invention.

6 is a connection diagram of an example of a pulse generating circuit according to the present invention.

The present invention relates to a pulse generating circuit for use in a remote control device such as a television receiver.

If you want to remotely control the volume control, tune-in, or power on / off from the television set, install a pulse generator circuit made of a vibrator away from the unstable distance as a remote control device. one generates a pulse P _a of τ _a of the pulse width, such as, when to raise the sound volume by generating a τ _B of the pulse P _B of the pulse width as shown in the diagram B, when the channel switching is τ _C as shown in the diagram C pulse In order to generate a pulse P _C having a width and to turn on or off the power supply, a pulse width P _D having a pulse width of τ _D as in the case of the same degree D is generated. There is a way. Thus, as shown in FIG. 2, this pulse P _A -P _D is supplied to an oscillator to obtain a high frequency signal SA-SD in the pulse width section, for example, to convert it into an ultrasonic wave, and the receiver receives the ultrasonic wave to form a high frequency signal. By detecting this, the original pulse P _A -P _D is obtained, and the pulse width is detected to perform the desired control automatically.

3 is an example of a conventional pulse generating circuit for this purpose, and the transistors 1 and 2 constitute an unstable far vibrator, and the time constant transistors of the resistor 3 and the condenser 4 The off time of 2) is determined and the transistor 1 is turned off with a time constant by the selected resistors 6A-6D and the capacitor 7 by turning on any of the switches 5A-5D. The time is determined so that the pulse width of the pulse obtained at the output stage 8 derived from the collector of the transistor 1 is determined by turning on either of the switches 5A- 6D.

However, it is difficult to make the resistance value of the resistor equal to the design value. For example, in the case of using carbon film as a resistor, the resistance value is about ± 5% of the design value.

For this reason, in the above-mentioned circuit, as shown in the figure, any of the resistors 6A to 6D is used as a variable resistor, and these must be adjusted so that each resistance value becomes a predetermined value. Therefore, in this circuit, the number of adjustment points increases depending on the control object, and there is a drawback that becomes complicated in manufacturing.

On the other hand, it is conceivable that one adjustment place is configured as shown in Fig. 4 sufficiently. In other words, this means that the resistors 6A to 6D described above are all fixed resistors, and the variable resistors 9 are connected in parallel.

In this case, however, the off time of the transistor 1, i.e., the pulse width of the output pulse, is equal to any of the variable resistors 9 and the resistors 6A- 6D selected by the switches 5A- 5D. Since the resistance value of the variable resistor 9 is adjusted to a certain value, for example, the pulse width when one of the switches 5A to 5D is turned on becomes a predetermined value. It is difficult to set the pulse width to a predetermined value when the switch other than the switches 5A to 5D is turned on, and all the pulse widths of the output pulses when the switches 5A to 5D are turned on are all predetermined values. It is difficult to make it.

On the other hand, there is also a method of adjusting the pulse width by changing the value of the voltage supplied to the time constant circuit. 5 shows an example of this case, in which a series circuit of the fixed resistor 10 and the variable resistor 11 is connected between both ends of the power supply, the capacitor 12 is connected in parallel to the variable resistor 11, and the resistor 10 ) And (11) Either one of the switches 5A- 5D is selectively turned on between the base of the transistor 1 and the transistor 1, such as a series circuit of resistors 13A, 13A and 13B, resistor The series circuit of (13A)-(13C) or the series circuit of resistors (13A)-(13D) are connected.

According to this configuration, the charging voltage V _Q of the capacitor 12 can be changed by changing the resistance value of the variable resistor 11, and as the charging voltage V _Q is lowered, the pulse width of the pulse obtained at the output terminal 8 becomes Increasingly, the supply voltage is V _CC , the transistor (1) 's base and emitter forward drop voltage is V _BE , and the collector and emitter saturation suppression is V _CES , When the resistance value of the resistor connected between the base and the transistor 1 is R and the capacitance of the capacitor 7 is C, the pulse width τ of the output pulse is

Is displayed.

However, when the pulse width is changed in accordance with the control object as described above, it is required to make the change in the pulse width due to the change in the power supply voltage or the temperature change within a predetermined allowable range.

If the pulse width changes beyond this range, a malfunction occurs in which the volume increases, for example, when channel switching is performed. So, for example, in FIG. 1, if the design values of the pulse widths τ _A , τ _B , τ _C , τ _D of the pulses P _A , P _B , P _C , P _D are 15 mS, 30 mS, 45 mS, 65 mS, respectively, The permissible range of change is ± 5mS, ± 5mS, ± 5mS, ± 10mS, respectively. Therefore, the permissible range of the rate of change of pulse width τ _C of pulse P _C is approximately 11%. Further, in practice, the time-dependent change of the temporary circuit components and the adjustment error must also be taken into consideration. Therefore, the allowable range of the rate of change of the pulse width due to the change in the power supply voltage or the temperature change is at most several percent.

However, in the circuit of FIG. 5, when the power supply voltage changes, a change rate of the pulse width is greatly out of the range of several%, and thus there is a drawback that malfunction is likely to occur. In the circuit of FIG. 5, V _BE = 0.6V and V _CES = 0.1V, and the battery voltage in the case of varying the ratio of the power supply voltage, that is, the battery voltage V _CC and the charging voltage V _Q of the capacitor 12 in various ways The pulse width is determined when V _CC is 3V and when it is lowered to 2V.

The results shown in Table 1 were obtained to calculate how much the value of was changed. In this table, K ₃ V is the K value when V _CC is ₃ V, and K ₂ V is the K value of ₂ V around V _CC . Is a case where the power supply voltage V _CC is set as the charging voltage V _Q of the capacitor 12 without being connected to the resistor 10.

TABLE 1

As can be seen from this table, in the circuit of FIG. 5, even if the charging voltage VQ of the capacitor 12 is selected in a certain ratio with respect to the power supply voltage VCC, the pulse width is determined according to the K value when the power supply voltage VCC is 2V. When the voltage VCC is 3V, the voltage is changed from 8% around to 20% or more. Therefore, there is a risk of malfunction when the power supply voltage VCC changes.

In view of the above, the present invention can easily absorb the irregularity of the constant of a circuit product even with one adjustment point, and furthermore, the rate of change of the pulse width can fall within the allowable range even if the power supply voltage or temperature changes. A pulse generating circuit is provided, and an example of the circuit of the present invention will be described with reference to FIG.

In FIG. 6, reference numeral 20 denotes an unstable multivibrator and consists of two transistors 21 and 22, the collector of which is connected to the power source, i.e., the battery 25 through resistors 23 and 24, respectively. One end is connected to the anode, and the collector of the transistor 21 and the base of the transistor 22 are connected through the capacitor 26, and the collector of the transistor 22 and the base of the transistor 210 are connected through the capacitor 27. Then, the emitter of the transistor 21 is connected through the parallel circuit of the resistor 31 and the capacitor 32, and the emitter of the transistor 22 is connected to the other end of the direct power source 25, that is, the negative electrode. A resistor 28 is connected between the base of the power supply 25 and the positive electrode of the power supply 25, and either one of the switches 29A-29D is optional between the base of the transistor 21 and the positive electrode of the power supply 25. By turning on, for example, the series circuit of resistor 30A, resistor 30A and 30B, resistor ( A series circuit of 30A) -30C, or a series circuit of resistors 30A-30D is connected.

Further, for example, the variable resistor 34 is connected between the anodes of the power supply 25 as a variable voltage divider, and the binary voltage point, that is, the movable element 34a, is connected to the base of the separate transistor 36 through the resistor 35, The collector of this transistor 36 is connected to one end of the power supply 25, and the emitter is connected to the emitter of the transistor 21. Furthermore, the collector of the transistor 22 is connected to the oscillator 38 via the diode 37, and this oscillator in the period of the pulse width of the output pulse, that is, the transistor 21 is turned on while the transistor 21 is off. Start the oscillation operation (38).

In this circuit, the voltage of the battery 25 is V _B , the base voltage of the transistor 36 is V _C , the emitter voltages of the transistors 36 and 21 are V _B , and the transistors 36 and 21 are The forward drop voltage between the base and the emitter is V _BE and the collector of the transistor 21, respectively. When the saturation voltage between the emitters is V _CES , the resistance value of the resistor connected between the base of the transistor 21 and the positive electrode of the battery 25 is R, and the capacitance of the capacitor 27 is C, the pulse width of the output pulse, thus the transistor The period τ in which the transistor 21 is off and the transistor 22 is on,

It becomes Thus, V _C = V _C -V _BC

In this circuit, the voltage V _B of the battery 25 and the base voltage V _C of the transistor 36 are varied by varying the position of the movable element 34a of the variable resistor 34 with V _CES = 0.1 V. In the case of varying the ratio, the pulse width is determined when the voltage V _B of the battery 25 is 3V and when the voltage is lowered to 2V.

The results shown in Table 2 were obtained by calculating the change in the value of. In this table, K ₃ V is the K value when V _B is 3V, and K ₂ V is the K value when V _B is 2V.

TABLE 2

As is apparent from this table, according to the circuit of the present invention, the ratio of the movable element 34a of the variable resistor 34 is 0.4 to 2.6 / 3 in the ratio of the base voltage V _C of the transistor 36 to the power supply voltage V _B. When the position is selected, the pulse width changes only about 1-2% when the power supply voltage V _B is 3V, depending on the K value when the power supply voltage V _B is lowered to 2V. Therefore, since the oscillator 38 performs the oscillation operation in the period in which the transistor 22 is turned on as described above, the section in which the oscillation waveform continues is hardly changed even when the power supply voltage V _B changes.

In addition, when the power supply voltage V _B changes and the pulse width of the output pulse is extremely small in this way, even if the pulse width of the output pulse changes slightly due to temperature change, both the power voltage variation and the temperature change are caused. The rate at which the pulse width of the output pulse changes is within the allowable range of about several percent.

By adjusting the position of the movable element 34a of the variable resistor 34 within the above-mentioned wide range, even if there is a non-uniformity in the resistance values of the resistors 30A-30D, it is absorbed, and the switch 29A- ( The pulse width of the output pulse in each case of turning on 29D) can be selected to be the same as the design value. Even if there is a change in the power supply voltage or a temperature change, the pulse width changes within the allowable range, and there is a risk of malfunction.

In the above description, when the transistor 22 is turned ON, that is, the pulse width of the output pulse or the transistor 21 is turned on and the transistor 22 is turned off, Since the transistor 22 is turned on until the transistor 21 is turned on, and the base potential of the transistor 22 is V _BE , the capacitor 23 has a positive (+) side at the resistor 23 and has a resistance ( The voltage of (V _B -V _BE ) having a negative polarity at side 28 is stored. Thus, at the moment when the conduction state of the transistors 21 and 22 is reversed and the transistor 21 is turned on, the collector potential of the transistor 210 becomes V _B + V _CES , and thus the capacitor 26 and the resistor 28. ), The potential of the connection point of () is equal to the voltage of (V _B -V _BE ) than the collector potential of the transistor 21 by the charging voltage of the capacitor 26 described above.

It becomes the potential of the negative part (-). The time until the potential rises to VBE to turn on the transistor 22 is the on time of the transistor 21. The increase in the potential at the connection point of the capacitor 26 and the resistor 28 is achieved by charging the capacitor in the opposite polarity to the polarity described above through the resistor 28 at the power supply VB. And this time

It can be represented as As is apparent from the equation (7), this time is an integer determined by the resistance 28, the value of the capacitor 26, and the voltage value of VC regardless of which of the switches 29A-29D is selected.

As the voltage V _C gets closer to V _B , this time becomes shorter. This time is not very important at the time when the oscillator 38 operates by operating the transistor 22 as in the embodiment shown in FIG. 6, i.e., in a circuit in which the pulse width of the output pulse is a problem.

Thus, according to the circuit of the present invention, even if there is only one adjustment point, the redness of the constant of the circuit components can be easily absorbed, and the pulse width of the output pulse hardly changes even when the power supply voltage or the temperature change. Therefore, malfunction can be prevented.

Further, the specific structure of the variable voltage divider can be changed in various ways in addition to the example shown in the drawings. That is, a series circuit of two capacitors is connected between both ends of the power supply, and the connection points of these two capacitors are connected to the base of the transistor 360. The capacitor may be configured to change the capacitance of one of the capacitors.

Claims (1)

Collectors of the first and second transistors 21 and 22 are respectively connected to one end of the power supply through a resistor, and the emitter of the first transistor 21 is connected to the other end of the power supply through a parallel circuit of a resistor and a capacitor. An emitter of the second transistor 22 is connected to the other end of the power supply, a base of the first and second transistors is connected to one end of the power supply via a resistor, respectively; And an unstable multivibrator in which one collector of the second transistor and the base of the other end are respectively connected through a capacitor, and a variable voltage divider is connected between both ends of the power supply, and the voltage dividing point is connected to the third transistor ( 36, the collector of the third transistor is connected to one end of the power supply, the emitter is connected to the emitter of the first transistor, and the potential of the voltage dividing point is adjusted. As the pulse generating circuit to adjust the pulse width of the output pulses obtained from the non-stable multivibrator.