JPS647700B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a timer, and particularly relates to a timer that provides a time-up output to a control device or the like when a predetermined time has elapsed.

As is well known, a timer is used to provide a time-up output to a control device or the like when a predetermined time has elapsed, thereby automating the control device and controlling the sequence.

FIG. 1 is a circuit diagram of a conventional timer 10, and FIG. 2 is a circuit diagram of a conventional timer 20. In its configuration, timer 10 includes a half-wave voltage doubler rectifier circuit 11 . As is well known, the half-wave voltage doubler rectifier circuit 11 converts the voltage of the AC power supply 111 into capacitors 112 and 115.
This circuit uses diodes 113 and 114 to generate approximately twice the DC output voltage. A capacitor 112 and a diode 113 are connected in series to the AC power supply 111 . A series circuit including a rectifying diode 114 and a smoothing capacitor 115 is connected in parallel to the diode 113. A resistor 12 and a Zener diode 13 are connected to the capacitor 115.
The series circuit with is connected in parallel. The Zener diode 13 is a timer integrated circuit (hereinafter referred to as a timer IC).
) 14 are connected in parallel. for timer
The IC 14 is supplied with DC voltage from the half-wave voltage doubler rectifier circuit 11, and after a predetermined time, outputs a time-up output to the transistor 1, which is an example of a first switching means.
Give it to the base of 5. The collector of the transistor 15 is connected to the capacitor 11 via the coil of the relay 16.
It is connected to one electrode of No.5. The emitter of transistor 15 is connected to the other electrode of capacitor 115.

In operation, the DC voltage half-wave rectified by the half-wave voltage doubler rectifier circuit 11 is applied to the collector of the transistor 15 via the coil of the relay 16, and is stepped down by the resistor 12 to the timer IC 14.
given to. In response, the timer IC 14 provides a time-up output to the base end of the transistor 15 after a predetermined period of time has elapsed. Therefore, the transistor 15 becomes conductive. As a result, the contacts of relay 16 are closed.

However, in the conventional timer 10, the capacitor 1
Since the resistor 12 is connected between one electrode of the AC power source 115 and the timer IC 14, the impedance seen from the AC power source 111 is high until the predetermined time elapses. For this reason, when the half-wave voltage doubler rectifier circuit 11 is driven by a non-contact switch such as a phototransistor, a dark current flows into the timer IC 14, causing the timer IC 14 to malfunction.

Therefore, in order to eliminate the above-mentioned drawbacks, a timer 20 as shown in FIG. 2 can be considered. The difference between FIG. 2 and FIG. 1 is that the capacitor 115
This is because a resistor 21 is connected in parallel to the . As a result, in the timer 20, since the resistor 21 is connected in parallel to the capacitor 115, the AC power supply 111
The impedance seen from the front can be lowered.

However, in the timer 20 as shown in FIG.
Since current always flows through the resistor 21, there is a drawback that power is wasted and the temperature rise is also undesirable. Furthermore, since the timer 20 does not have a constant voltage function, it has the disadvantage that heat is generated by the resistance in proportion to the square of the input voltage, making it difficult to drive it by supplying a high input voltage.

SUMMARY OF THE INVENTION An object of the present invention is to provide a timer that includes a power supply circuit that is less prone to malfunction when input voltage is supplied by a non-contact switch and that can widen the input voltage range.

In summary, the present invention is such that one output terminal of the voltage doubler rectifier circuit is connected to the first electrode of the second switching means via the first resistor, and the output terminal of the second switching means is connected via the Zener diode. The third electrode is connected to the output end of the first switching means for closing the relay, and the other output end of the voltage doubler rectifier circuit is connected to the second electrode of the second switching means. This is a timer made up of a power supply circuit.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a circuit diagram of a timer 30 according to an embodiment of the present invention. This embodiment differs from FIGS. 1 and 2 in that a circuit A is provided. More specifically, the collector of a transistor 31, which is an example of the second switching means, is connected to one output terminal of the half-wave voltage doubler rectifier circuit 11 via a resistor 32. The base of the transistor 31 is connected to one output terminal of the half-wave voltage doubler rectifier circuit 11 via a resistor 33 and a Zener diode 34, and
It is connected to the collector of the transistor 15 via a resistor 35. The emitter of the transistor 31 is connected to the other output terminal of the half-wave voltage doubler rectifier circuit 11.

Note that the resistance value of the resistor 32 is selected to be slightly smaller than the resistance value of the coil of the relay 16 in order to absorb the voltage increase when the input voltage increases before the predetermined time of the timer IC elapses.

Next, the operation of this embodiment will be explained with reference to FIG. First, a case will be described in which the output voltage of the half-wave voltage doubler rectifier circuit 11 is lower than the predetermined voltage required to make the Zener diode 34 conductive. In this case, the DC voltage half-wave rectified by the half-wave voltage doubler rectifier circuit 11 is passed through the resistor 32 to the transistor 31.
is applied to the collector of the transistor 31 through the coil of the relay 16 and the resistor 35.
given at the base end of. Further, the DC voltage is applied to the collector of the transistor 15 via the coil of the relay 16. Furthermore, the DC voltage is resistor 12
The voltage is stepped down and applied to the timer IC 14. The timer IC 14 is configured to provide a time-up output to the base of the transistor 15 after a predetermined time has elapsed when a DC voltage is applied. Therefore, the transistor 15 is in a non-conducting state and the transistor 31 is in a conducting state until a predetermined period of time has elapsed. On the other hand, after the predetermined time has elapsed, the timer IC 14 provides a time-up output to the base of the transistor 15, so the transistor 15 becomes conductive and the contact of the relay 16 is closed. Therefore, the transistor 31 becomes non-conductive. Note that there is almost no load variation due to the resistor 32.

Next, a case where the DC voltage is higher than the predetermined voltage required to make the Zener diode 34 conductive will be described. In this case, a DC voltage makes the Zener diode 34 conductive and is applied to the base of the transistor 31 via the resistor 33. Therefore, until the predetermined time elapses, the transistor 31
becomes conductive. Furthermore, after a predetermined period of time has elapsed, the transistors 15 and 31 become conductive.
The contacts of relay 16 are closed.

As described above, in this embodiment, when the half-wave voltage doubler rectifier circuit 11 is driven by a non-contact switch, the resistor 32 is connected in parallel to the capacitor 115, so that the impedance seen from the AC power supply 111 is Can be made smaller. Make malfunctions less likely to occur. In addition, in this embodiment, even if the input voltage becomes high, the load voltage remains almost constant, so the heat generated by the resistance is reduced approximately in proportion to the first power of the input voltage, so it is possible to drive by supplying a high input voltage. I can do it.

As described above, according to the present invention, the unique effects of making malfunction less likely to occur when input power is supplied by a non-contact switch and widening the input voltage range are achieved.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional timer 10. FIG. 2 is a circuit diagram of another conventional timer 20. FIG. 3 is a circuit diagram of a timer 30 according to an embodiment of the present invention. In the figure, 11 is a half-wave voltage doubler rectifier circuit;
2, 32, 33, 35 are resistors, 13, 34 are Zener diodes, 14 is a timer IC, 15, 31
indicates a transistor.

Claims (1)

[Scope of Claims] 1. A timer for driving a first switching means to close a contact of a relay when a predetermined time has elapsed, the voltage doubler rectifier circuit having one output of the voltage doubler rectifier circuit; a first resistor, one end of which is connected to the other end, a first electrode of which is connected to the other end of the first resistor, and a second electrode of which is connected to the other output end of the voltage doubler rectifier circuit; a second switching means whose third electrode is connected to the output end of the first switching means; and a second switching means connected between the voltage doubler rectifier circuit and a third electrode of the second switching means. A timer with a zener diode.