JPS61170891A - Sensor input circuit - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to improvements in sensor input circuits.

For example, a notification device is known that detects the opening and closing of a door, etc., transmits the information via a telephone line to a receiving device installed in a remote location, and displays the information audibly or visually there.

In such a device, in order to detect the opening/closing of a door, etc., a sensor has an electrical opening/closing means, and a predetermined current is applied to the sensor to reliably detect the operating state of the electrical opening/closing means. A sensor input circuit is provided to receive the opening/closing output.

(Prior Art) In a conventional sensor input circuit, the above-mentioned energizing current is a constant value during the operation of the sensor, so in a device in which a large number of sensors are provided, the current increases in accordance with the number of sensors.

(Problems to be Solved by the Invention) Therefore, when the power source of the above-mentioned reporting device is configured with only a battery, the power consumption due to the above-mentioned energizing current becomes an important problem, and there has been a demand for power saving.

Therefore, the present invention provides a predetermined energizing current to enable reliable detection of the operation when the sensor is in operation,
After operation, the sensor input circuit is configured so that the current value is the minimum necessary, thereby saving power.

(Means for Solving the Problems) Therefore, in the present invention, either a sensor having an electrical switching means, and first and second resistors each connected in series to the sensor to form a closed circuit are provided. It is composed of a transistor that is inserted into one closed circuit to open and close the closed circuit, and a flip-flop circuit that controls the transistor.When the sensor is normally (open), the output of the flip-flop circuit turns the transistor off.
N, and by resetting the flip-flop circuit and turning off the transistor due to the output signal of the sensor during operation (closed), the current passing through the sensor after operation is reduced, and the sensor's current is reduced. The present invention is characterized in that the flip-flop circuit is inverted due to recovery, and the transistor is turned on again.

(Example) Next, the present invention will be explained in detail by referring to an example shown in the drawings. FIG. 1 is a block diagram for explaining the sensor input circuit according to the present invention, where 1 is a sensor, SI is an electrical switching means (switch) included in the sensor 1, 2 is a sensor input circuit, and 3 is a control circuit for the sensor. It is configured to send data signals etc. for visual display etc. to the above-mentioned receiving device based on the status information of No. 1 (notification operation), and is configured to include, for example, a microprocessor. The details are omitted as they are not directly related and are no different from conventional ones. -R, , R are resistors, Tit is a transistor, 4 is a flip-flop circuit, 5 to 7 are inverters, and 8 is a differential circuit. Next, the operation will be explained along with a second operation waveform diagram.

First, when the power is turned on, a set signal A is sent from the output terminal SET of the control circuit 3, and the flip-flop circuit 4 enters the set state. In other words, the voltage level of the output terminal Q becomes a low level (“0”), and the transistor TR is turned on.
state.

Therefore, when the sensor 1 responds and the switch SI closes, a predetermined current I is obtained through the resistors R1 and R2. This makes it possible to reliably detect the closing of the switch S1. By closing the switch S1, the input of the inverter 5 becomes '
0'' and its output becomes a high level (``1''), which is input to the inverter via the differentiating circuit 8, so that the starting pulse B is given to the input terminal INT of the control circuit 3.

In addition, the information at this time is also given to other input terminals P,
The state of the sensor 1 can be monitored by this input terminal PK. When a plurality of sensors 1 are provided, the input terminal INT is made common, and the input terminal P is provided corresponding to each sensor. The control circuit 3 is activated by the activation pulse B, and the input terminal P
It performs a predetermined notification operation according to the information and sends out a reset pulse C to the output terminal RESET.

As a result, the flip-flop circuit 4 enters a reset state, and its output terminal Q becomes "1", so that the transistor TR is turned off. Therefore, the current flowing I is only the current flowing through the resistor R1. Since the minimum necessary current value at this time can be made much smaller than the above-mentioned predetermined current value, the power consumption can be greatly reduced.

After that, switch S is opened (and the output of inverter 5 is 0
”, an inverted signal is applied to the input terminal CK of the flip-flop circuit 40 via the inverter 6, the flip-flop circuit 4 is inverted, and the output Q becomes “0”, so the transistor TR is turned on again. , the state is restored to the state when the power was turned on as described above, and the subsequent operation of the sensor 1 is monitored.

(Effects of the Invention) As explained above, according to the present invention, since the current flowing to the sensor l is reduced after the sensor l is operated, it is possible to save power without affecting the operation detection. Furthermore, in recent years, a microprocessor equipped with a standby function is sometimes used as the control circuit 3 in order to save power, but according to the sensor input circuit according to the present invention, the activation pulse B is input to the input terminal INT. There is an advantage that the above-mentioned control of the energizing current can be carried out even if the microprocessor enters the operating state and performs a predetermined energizing operation only when the input is received, and thereafter enters the standby state. Note that the set signal A and the reset pulse C described above do not necessarily have to be given from the control circuit 3 (for example, the set signal A may be provided with a circuit that sends out a pulse when the power is turned on, and the output thereof may be given). .

As for the reset pulse C, the signal can also be generated from the output side of the inverter 5.

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining a sensor input circuit according to the present invention, and FIG. 2 is an operational waveform diagram thereof. 1...Sensor, 2...Sensor input circuit, 3...
- Control circuit, 4... Clip-frost circuit.

Claims (1)

[Claims] a sensor having an electrical switching means; a first and second sensor each connected in series to the sensor to form a closed circuit;
, a transistor that is inserted into one of the closed circuits to open and close the closed circuit, and a flip-flop circuit that controls the transistor.When the sensor is normally (open), the flip-flop circuit is The transistor is turned on by the output, and when the sensor is operated (closed), the flip-flop circuit is reset by the output signal of the sensor and the transistor is turned off, thereby reducing the current flowing through the sensor after the sensor is operated. Further, the sensor input circuit is characterized in that the flip-flop circuit is inverted due to the restoration of the sensor, and the transistor is turned on again.