JPH01318317A - Electronic timer - Google Patents

Abstract

PURPOSE:To prevent malfunction due to noise caused when the power supply to a load is interrupted by providing a specific input control circuit. CONSTITUTION:An input control circuit 14 is provided, which interrupts a detection output of a load connection detecting circuit 8 from being inputted to a timer circuit after the timer circuit 6 expires. Thus, noise is caused even when the power supply to the load B is interrupted and an erroneous detection output is caused in the load connection detection circuit 8, the detection output from the input control circuit 14 is not given to the time circuit 6. Thus, malfunction of the electronic timer due to noise at OFF state is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic timer that detects the connection state of a load and starts counting.

E. Prior Art 1 In conventional mechanical timers and electronic timers, the timer operation is started by turning on a start switch or adjusting the timer time, which poses the problem of cumbersome setting.

Therefore, an electronic timer that detects the load connection state and automatically starts counting is proposed, for example, in Japanese patent application No. 63-80707.
electronic timer) is provided. As shown in Fig. 5, this electronic timer A is equipped with a plug (or blade) 1 on the back for connecting to a power outlet 11, and a socket (or blade) on the front for connecting a load such as a ventilation fan B. 2. The front surface of the electronic timer A is equipped with a light emitting diode 4 that emits light when power is supplied to the ventilation fan B, that is, when the ventilation fan B is operating, and a changeover switch 5 that changes the timer time. .

As shown in Figure 4, this electronic timer A forms a closed circuit in which a minute current flows when ventilation fan B is connected, and detects the minute current flowing in this closed circuit to indicate that ventilation fan B is connected. A load connection detection circuit 8 that detects the load connection detection circuit 8, a timer circuit 6 that starts counting operation based on the detection output of the load connection detection circuit 8, and a timer circuit 6 that starts the counting operation based on the detection output of the load connection detection circuit 8. and a power supply control circuit 13 that stops the supply of power to the ventilation fan B based on the count-up output of the timer circuit 6. The closed circuit of the load connection detection circuit 8 includes a diode D,
,D,, consists of a capacitor C8, a resistor R1:1R1, and an outlet 2 to which ventilation fan B is connected, and the connection state of ventilation fan B is detected by a minute current flowing through this closed circuit. As the timer circuit 6, one is used which sets the timer time using a time constant of a resistor and a capacitor, and the timer time can be varied by switching the resistance value of the resistor. The power supply control circuit 13 is connected to αr,
is the relay R inserted between plug 1 and outlet 2.
y1 and the relay R according to the output of the timer circuit 6.
1'+. A light emitting diode 4 for displaying the operating status of the ventilation fan B is connected in series to the Ilh magnetic filter I-1 of the relay R1+.

When the plug 9 of the ventilation fan B is connected to the outlet 2 of the electronic timer A, the AC power supply AC is connected through the outlet 2 (ventilation JiWB), the diode D8, the capacitor Ce (and resistor R53), the resistor R1, and the current regulation diode D7. During the negative half cycle, a small current flows in the closed circuit, and a pulse output is generated across the resistor R2 by the differentiator circuit consisting of the capacitor C1 and the resistors R, , R2 of the reset circuit 8.
This pulse output is input to the reset terminal of the timer circuit 6. When the timer circuit 6 is reset, the timer circuit 6 starts counting operation. At this time, the output of the timer circuit 6 causes the drive circuit 7 to drive the relay +<y, and the contact r of the relay R1'+ closes.
The ventilation fan B is supplied with alternating current power AC. Then, when the timer circuit 6 times out, the drive circuit 7 stops driving the relay RY+ with the output at this time, contacts r of the relay RY+ open, and the ventilation fan B-3= stops.

However, the electronic timer described above has a problem in that the timer circuit 6 is reset and the electronic timer A is restarted due to the noise generated when the power supply to the ventilation fan B is cut off.

[Problem to be Solved by the Invention 1] The present invention has been made in view of the above-mentioned points, and its purpose is to solve the problem of malfunction caused by noise that occurs when the power supply to a load such as a ventilation fan is cut off. The objective is to provide an electronic timer that can prevent this.

[Means for Solving the Problems] In order to achieve the above object, the present invention requires that the detection output of the load connection detection circuit is input to the timer circuit for a predetermined period of time after the time-up output of the timer circuit occurs. Equipped with an input control circuit to prevent

(Function) As described above, the present invention includes an input control circuit that prevents the detection output of the load connection detection circuit from being input to the timer circuit for a predetermined period of time after the time-up output of the timer circuit occurs. Even if noise is generated when the power supply to the load is cut off and the load connection detection circuit generates a false detection output, the input control circuit prevents this detection output from being input to the timer circuit to prevent malfunction. It was designed to do so.

(Example) An embodiment of the present invention is shown in FIGS. 1 to 3.

In this embodiment, as shown in FIG. 1, an input control circuit 14 is provided in the conventional circuit to prevent the detection output of the load detection circuit 8 from being input to the timer circuit 6 from the outside for a predetermined period of time when the timer circuit 6 times out. It is something. A specific circuit of this embodiment is shown in FIG.

In this embodiment, the timer circuit 6 is composed of a timer ICI 5, a transistor Q capacitor 07, and a resistor R7, and the timer time is set by the time constants of the resistors and capacitors externally connected to the terminals (1) to (4).

In addition, Zener diode ZD: l, ZD resistance R8゜R
1 and a timer IC from the power supply circuit consisting of capacitor C3.
Power is supplied to I5. The load connection detection circuit 8 includes a diode D, a capacitor C9, and a resistor R8.
~RIO, and the voltage across the resistor R9 when a load such as the ventilation fan B is connected to the outlet 2 becomes the detection output. This detection output is input to the transistor Q1 of the timer circuit 6, and when this transistor Q1 is turned on, a reset signal is input to the reset input (■ terminal) of the timer ICl3, and the timer rci 5 starts counting operation. Start. In this embodiment, the load connection detection circuit 8 has the above-mentioned circuit configuration, but it may of course have the same circuit configuration as the conventional example. The power supply control circuit 13 includes 5CRQ2 for driving the DC relay Ry11, Zener diodes ZD, , ZD2, diodes D2 . D, consists of a capacitor c;, c2, a resistor R+, and R2, and when the timer ICI 5 is reset, the high level output (■ terminal) turns on the S CRQ 2, and the relay RY is turned on.
+ is driven, contact r1 closes, and power is supplied to ventilation fan B. When the output of the timer ICI5 reaches the 4-level when the timer ICl3 times up, the charge in the capacitor C1 is discharged for about 200 seconds.
Thereafter, 5CRQ2 is turned off, contact r1 of relay Ry+ is opened, and power supply to ventilation fan B is stopped. Note that an AC relay RF2 may be used in place of the DC relay Ry (1), and the power supply control circuit 13 in this case is as shown in FIG.

By the way, if only the above circuit is used, depending on the type of relay Ryl, an inrush current will flow into the load connection detection circuit 8 at the moment the contact r1 of relay Ry1 opens, and this will generate a voltage across the resistor R5. , a reset signal may be input to the timer ICl3 in the same way as when the ventilation fan B is connected. As a result, the electronic timer that has timed out once again starts counting, causing a problem in which power continues to be supplied to the ventilation fan B.

Therefore, in this embodiment, the following input control circuit 14 is provided to prevent the output of the load connection detection circuit 8 from being input to the timer circuit 6 for a predetermined period of time after the timer circuit 6 times up. This is to prevent malfunctions caused by the above noise. This input control circuit 14 is composed of a transistor Q2, a diode D, a capacitor C9, and a resistor RIIIR12.
31 and the diode D6, and the voltage across the capacitor C7 charges the transistor Q2.
The base voltage of transistor Q is pulled to a low level while Q is conductive.

The on period of the transistor Q2 of the input control circuit 14 is, for example, about 18. Note that the circuits within the frame surrounded by the dashed-dotted line in FIG. 2 can be integrated. According to this embodiment, by providing the input control circuit 14, even if noise is generated when the power supply to the load is cut off and the load connection detection circuit 8 generates an erroneous detection output, The input control circuit 14 does not input this detection output to the timer circuit 6. Therefore, malfunction of the electronic timer due to noise during off-time can be prevented.

[Effects of the Invention] As described above, the present invention includes an input control circuit that prevents the detection output of the load connection detection circuit from being input to the timer circuit for a predetermined period of time after the time-up output of the timer circuit occurs. Therefore, even if noise is generated when the power supply to the load is cut off and the load connection detection circuit generates an erroneous detection output, the input control circuit can prevent this detection output from being input to the timer circuit. This has the effect of preventing malfunctions.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 is a specific circuit diagram of the same as above, Fig. 3 is a circuit diagram showing a power supply control circuit when an AC relay is used as a relay, and Fig. 4 is a conventional circuit diagram. An example circuit diagram, FIG. 5, is a perspective view showing the external appearance of the same. 6 is a timer circuit, 8 is a load connection detection circuit, 13 is a power supply control circuit, 14 is an input control circuit, A is an electronic timer, and B is a ventilation fan. Agent Patent attorney Ishi 1) Chief Seven-pronged amendment form (voluntary)

Claims (1)

[Claims] (1) A load connection detection circuit that forms a closed circuit through which a minute current flows when a load is connected, and detects the connection of a load by detecting the minute current flowing in this closed circuit, and this load connection detection circuit. A timer circuit that starts counting operation based on the detection output of the circuit, and a timer circuit that supplies power to the load while the output of this timer circuit during counting operation is being generated.
A power supply control circuit that stops supplying power to the load using the count-up output of the timer circuit, and a detection output of the load connection detection circuit that is input to the timer circuit for a predetermined period of time after the time-up output of the timer circuit occurs. An electronic timer comprising: an input control circuit for preventing such occurrence.