JP2692861B2 - Electronic timer - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electronic timer using an internal primary battery and an external AC power source as a power source.

[Prior Art] Conventionally, a mechanical outlet timer has been used as a timer. However, when an AC power supply fails, there is a problem that the timer operates for a time corresponding to the power failure.

In order to solve this problem, there is provided an electronic timer that combines a primary battery and a clock circuit composed of an IC. However, even with this electronic timer, the output as the opening / closing operation signal is not output at the end of the life of the primary battery,
Further, since a signal for timer start is formed by the AC power source, there is a problem that a high voltage is applied and a latch-up phenomenon occurs in the IC of the clock circuit and the IC is destroyed.

Furthermore, if the timer operation can be started by the power supply from the primary battery, there is a problem in that the electronic timer may malfunction before it is connected to the AC power supply.

[Problem to be Solved by the Invention] The present invention has been provided in view of the above points,
The purpose is to enable the clock circuit to be driven even at the end of its life, to prevent the clock circuit from being destroyed by the latch-up phenomenon, and to prevent malfunctions that may occur before the electronic timer is connected to the AC power supply. The electronic timer is provided.

[Means for Solving the Problem] The present invention provides a plug connected to an AC power source, a primary battery, a clock circuit that stores a set timer time and outputs a signal when the time is up, and a plug circuit from the plug. A power supply circuit that converts the AC power supply to a DC power supply and outputs it, a power supply circuit that outputs the output voltage of this power supply circuit as a constant low voltage, and a small voltage drop between the emitter and collector of the transistor when the AC power supply is disconnected. The primary battery is used to supply power to the clock circuit, and when AC power is connected, the current flowing from the power supply circuit to the primary battery is blocked, and
A power supply switching circuit that switches the power supply of the clock circuit from the primary battery to the power supply circuit, a switching circuit that opens and closes the AC power supply driven by the output of the clock circuit, and an outlet that is connected to the output side of the switching circuit and to which the load is connected. A timer is provided with a display section for displaying the time and the current time, and a start means for performing the timer operation of the clock circuit only from a DC voltage power supply formed by an AC power supply.

[Operation] The power supply switching circuit uses the small voltage drop between the emitter and collector of the transistor to supply power to the timepiece circuit so that the timepiece circuit can be driven even at the end of the life of the primary battery. The output voltage of the power supply circuit that rectifies the AC power supply into direct current is applied to the above-mentioned clock circuit as a power source by making it a constant voltage of a low voltage so that the breakdown due to the latch-up phenomenon does not occur in the clock circuit at a low voltage. Since the timer means of the clock circuit can be operated only by the DC voltage power supply formed by the AC power supply by the start means, it is possible to prevent the malfunction that the electronic timer works before it is connected to the AC power supply. Is.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows an overall circuit diagram, and FIGS. 2 and 3 show perspective views of an electronic timer. As shown in FIGS. 2 and 3, a plug blade 1a of a plug 1 for connecting an AC power source is provided on the rear surface of the electronic timer main body 21 and a receptacle 8 for load connection is provided on the front surface. Further, a lid 22 for replacing the primary battery is provided on the rear surface of the electronic timer main body 21, a display unit 23 made of liquid crystal for displaying the current time and the timer time on the front surface, and for setting the current time and the timer time. A "hour" set button 24 and a "minute" set button 25, a start button 26 for starting the timer operation, and a slide-type changeover switch 27 for switching the display between the current time of the display unit 23 and the timer time are set. A slide-type changeover switch 28 or the like for switching the load on, off, or continuously on after the timer time (or timer time) is provided.

Next, the circuit shown in FIG. 1 will be described. The voltage of the primary battery 2 is supplied to the timepiece circuit 3 via the power supply switching circuit 6. For power switching circuit 6 is to reduce the voltage drop, the transistor Tr ₁ of the PNP, using a base resistor R _1, by turning on the transistor Tr _1, has a voltage drop and the voltage between the emitter and collector. The power supply circuit 4 for rectifying the AC power supply is composed of a diode bridge DB, a resistor R ₃ , a capacitor C ₁ , a zener diode ZD _2, etc.
_A power supply voltage is applied to the clock circuit 3 via a power supply circuit 3 composed of ₂ and a zener diode ZD ₁ . The zener voltage of the zener diode ZD ₁ is set higher than the voltage of the primary battery 2. Further, a low constant voltage is applied to the clock circuit 3 by the Zener diode ZD ₁ . The switching circuit 7 for switching the load is a relay Ry for directly switching the load.
₁ and a relay driver circuit 11 that drives this relay Ry ₁ . The relay driver circuit 11 is the clock circuit 3
It is designed to be driven by the output of.

Next, the operation will be described. First, measures against the latch-up phenomenon will be described. If the plug 1 to the AC power supply is not connected, the primary battery 2 through the resistor R _1, a base current is supplied to the transistor Tr _1, the emitter-collector of the transistor Tr ₁ is a voltage drop on less. When the transistor Tr ₁ is turned on, the voltage of the primary battery 2 is supplied to the clock circuit 3 and the clock circuit operates. Further, the Zener diode is higher than zener voltage battery 2 voltage of ZD _1, Zener diode current primary battery 2 to ZD ₁ does not flow.

Next, a case where an AC power source is connected will be described.
Now, when the primary battery 2 reaches the end of its life, the DC voltage from the AC power supply generated by the relay driver circuit 11 enters the timepiece circuit 3 without the power supply circuit 5, and is therefore applied to the timepiece circuit 3. Since the voltage is much higher than the voltage of the battery 2, the clock circuit 3 composed of the IC is destroyed by the latch-up phenomenon. However, since the power supply circuit 5 exists, the clock circuit 3 operates normally without causing the latch-up phenomenon by making the constant voltage higher and lower than the voltage of the battery 2 by the zener diode ZD _1. Keep doing In addition, since the emitter-collector voltage of the transistor Tr ₁ is a voltage generated by the power supply circuit 5, it becomes a reverse voltage, eliminating the outflow current from the primary battery 2 and relating to the power supply of the primary battery 2 when the AC power supply is connected. Instead, the clock circuit 3 is operated by the AC power supply.

Next, the timer operation will be described. First of all, regarding the general operation, when the load is turned on at the timer time by operating the changeover switch 28 for selecting whether the load is turned on or off at the timer time (or after the timer time elapses). , The output of OFF is output during the timer operation, so that the relay driver circuit 11 is turned off, and after the time is up, the relay driver circuit 11 outputs an on signal to drive the relay Ry ₁ to turn on the load. Has become.
Further, when the load is turned off at the timer time, a signal opposite to the above will be output. The start button 26 for operating the timer is provided between the power supply circuit 4 and the clock circuit 3 as shown in FIG. That is, when the start button 26 is turned on, power is applied to the LSI 3a of the timepiece circuit 3 to operate the timer. This power supply changes the voltage across the Zener diode ZD ₂ of the power supply circuit 4 to the resistors R ₄ and R _5. It is obtained from the voltage divided by and. Therefore,
The clock circuit 3 does not operate with the voltage of the primary battery 2,
It operates only when the AC power source is connected and the start button 26 is turned on. This is because the start button 26, etc. is often a push switch and is not connected to an AC power source.
This is to prevent the timer operation from operating before the electronic timer main body 21 is connected to the AC power supply without being aware of. Therefore, the timer operation starts after the electronic timer body 21 is connected to the AC power source and the start button 26 is pressed. The start button 26 connected to the power supply circuit 4 side constitutes a start means.

Further, the output of the timer circuit 3a of the LSI 3a is used, or the display of the current time is automatically switched to the timer time display during the timer by the software program of the LSI 3a, and the current time is displayed when the time is up. That is, as shown in FIG. 5 (a), if the current time before the timer start is "2:16" and the timer time is "3:00", the start button 26 is pressed to start the timer. As shown in FIG. 5 (b), the display on the display unit 23 is automatically switched to "3:00". Then, when the time is up, the current time is "3:00" as shown in FIG. 5 (c).
Is displayed, and point 23a flashes to indicate that it is the current time. When the timer is started, it is necessary to confirm the time of the timer, so that the product has such a circuit configuration in order to make the product easy to use.

FIG. 6 shows a circuit in which the output is forcibly turned off after the recovery from the power failure. Clock circuit 3 as shown
And the relay driver circuit 11 between the flip-flop 1
2, 13, resistors R ₆ and R ₇ , and capacitors C ₆ and C ₇ are provided. The operation when the changeover switch 28 for selecting the operation is connected to the side, that is, the operation when the load is turned on over time will be described. Since the AC power supply is connected and the clock circuit 3 times up and the operation is continuously on, an output for turning on the relay Ry ₁ is output from the flip-flop 12 for turning on. And if the AC power fails,
When the electric charges of the capacitors C ₆ and C ₇ are discharged, the power failure is restored and AC power is applied, the flip-flop 12 for ON is set by the charging characteristics of the capacitors C ₆ and C ₇ , and similarly for OFF. Flip-flop 13 is reset. As a result, the load is forcibly turned off after the power is restored. Although the flip-flop 12 is set, the clock circuit 3 is reset by the output of the flip-flop 13 so that the time-up signal is not output from the clock circuit 3 to the flip-flops 12 and 13, so that the load is forced off. Keep holding. The flip-flops 12, 13 and the capacitor C ₆ ,
C ₇ and resistors R ₆ and R ₇ compose the forced-off means. With such a configuration, it is possible to eliminate dangerous use after the power is restored after a time-out when the load is turned on and the person forgets to turn off the load due to a power failure after the timer has timed out.

[Effects of the Invention] As described above, the present invention includes a plug connected to an AC power supply, a primary battery, a time circuit that stores a set timer time and outputs a signal when the time is up, and a plug from the plug. A power supply circuit that converts the AC power supply to a DC power supply and outputs it, a power supply circuit that outputs the output voltage of this power supply circuit as a constant low voltage, and a small voltage drop between the emitter and collector of the transistor when the AC power supply is disconnected. Power is supplied from the primary battery to the clock circuit by using it, and the current flowing from the power supply circuit to the primary battery is blocked when an AC power supply is connected, and the power supply for the clock circuit is switched from the primary battery to the power supply circuit. A circuit, a switching circuit that is driven by the output of the clock circuit to open and close an AC power supply, and an outlet that is connected to the output side of the switching circuit and to which a load is connected.
Since it is equipped with a display section for displaying the timer time, the current time, etc., and a start means for performing the timer operation of the clock circuit only from the DC voltage power supply formed by the AC power supply, the emitter of the transistor is switched by the power supply switching circuit.・ Power can be supplied to the clock circuit by using a small voltage drop between the collectors so that the clock circuit can be driven even at the end of the life of the primary current, and it is possible to open and close the load without fail. , The output voltage of the power supply circuit that rectifies the AC power supply to the direct current by the power supply circuit is applied to the above clock circuit as the power supply by setting it to a low voltage constant voltage, and the low voltage causes damage to the clock circuit due to the latch-up phenomenon. Since it can be eliminated, and can be driven by one primary battery, there is an economical effect. Furthermore, since the power supply switching circuit blocks the current from the power supply circuit to the primary battery, the charging current does not flow in the primary battery,
Therefore, there is no short-term current life or rupture or destruction, and since the primary battery does not discharge due to the power switching circuit while the AC power supply is connected, the service life of the primary battery is extended, and the conventional Unlike mechanical timers,
Even if a power failure occurs due to the power supply switching circuit, power is supplied from the primary battery to the clock circuit, so that the timer time is not delayed.

Further, since the starting means for performing the timer operation of the clock circuit is provided only from the DC voltage power supply formed by the AC power supply, the timer operation is not performed when the AC power supply is not connected by the starting means, and the AC power supply is connected to the AC power supply. When the switch is not a push switch, the timer does not operate unknowingly when the switch is not pressed, and malfunctions can be prevented and the device is easy to use.

Furthermore, by providing a force-off means for detecting the power failure recovery after the time-out of the clock circuit and forcibly turning off the output of the clock circuit, after the time-up when the load is turned on after the time of the timer elapses, It is possible to eliminate dangerous use after a power failure is restored due to forgetting to turn off the load on the person due to the power failure.

[Brief description of the drawings]

1 is an overall circuit diagram of an electronic timer according to an embodiment of the present invention, FIG. 2 is a perspective view of the electronic timer as seen from the front side, FIG. 3 is a perspective view as seen from the back side of the same, and FIG. Is a circuit diagram of a main part of the above, FIGS. 5 (a) to 5 (c) are operation explanatory views of the same, and FIG. 6 is a circuit diagram in the case where the forced-off means is provided. 1 ... Plug, 2 ... Primary battery, 3 ... Clock circuit, 4 ...
Power supply circuit, 5 power supply circuit, 6 power supply switching circuit, 7 open / close circuit, 8 outlet, 23 display section.

Claims (2)

(57) [Claims] 1. A plug connected to an AC power supply, one primary battery, a clock circuit for storing a set timer time and outputting a signal when the time is up, and an AC power supply from the plug converted to a DC power supply. Power supply circuit, a power supply circuit that outputs the output voltage of this power supply circuit as a low-voltage constant power supply, and a small voltage drop between the emitter and collector of the transistor when the AC power supply is disconnected. Power is supplied to the AC power supply, and when connecting the AC power supply, the current flowing from the power supply circuit to the primary battery is blocked, and
A power supply switching circuit that switches the power supply of the clock circuit from the primary battery to the power supply circuit, a switching circuit that opens and closes the AC power supply driven by the output of the clock circuit, and an outlet that is connected to the output side of the switching circuit and to which the load is connected. An electronic timer comprising a display unit for displaying the time and the present time of the timer, and a start means for performing the timer operation of the clock circuit only from the DC voltage power supply formed by the AC power supply. 2. The electronic timer according to claim 1, further comprising a forced-off means for detecting a power failure recovery after the time-out of the clock circuit and forcibly turning off the output of the clock circuit.