JPH07111193A - Control circuit for illuminating lamp - Google Patents

Abstract

PURPOSE:To perform stable illumination even when light quantity of a light sensor is suddenly changed by providing a hysteresis circuit and a delay circuit. CONSTITUTION:Circuit power is supplied from a battery 1, and circuit protection and action stabilization are performed by a power supply circuit 3. a current at an optical sensor 2 is converted into a voltage to be inputted to a lighting/ lighting off determination circuit 4 provided with hysteresis, and when the voltage signal is less than a specified voltage, a voltage of 0V is outputted to a delay circuit 5 to put a relay 6 on immediately for lighting an illuminating lamp 17. When the inputted voltage signal into the circuit is the specified voltage or more, a voltage of 5V is outputted to the circuit 5, and only in the case where this output continues for a specified delay time or more, the relay 6 gets off to light off the illuminating lamp 7. In the meanwhile, the set specified delay time is changed as a capacitor capacity inside the circuit 5 changes. Stable illumination is thus provided even when light quantity of a light sensor is suddenly changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit for a light and an indicator light of an automobile, and more particularly to an illumination light suitable for a device having automatic lighting.

[0002]

2. Description of the Related Art In a conventional device, as in Japanese Utility Model Laid-Open No. 4-106041, the amount of light changes around a predetermined value and the illumination is turned on and off repeatedly. When a sudden change in the amount of light exceeds the width, the illuminating lamp is repeatedly turned on and off, which causes an adverse effect on the visibility.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an analog control circuit for an illuminating lamp, which is capable of performing stable illumination even when the amount of light changes suddenly.

[0004]

In order to achieve the above object, when the light quantity of an optical sensor exceeds a predetermined value, the illumination lamp is not immediately turned off and a predetermined value has a hysteresis, and the light intensity is more than a predetermined value. The light is turned off only when the light quantity continues for a certain delay time. However, when the light quantity of the optical sensor becomes less than the predetermined value, the illumination lamp is immediately turned on.

[0005]

The control circuit of the illuminating lamp according to the present invention converts the optical sensor input signal into a signal having hysteresis and operates so that the illuminating lamp does not turn off unless the converted signal continues for a certain period of time. Stable illumination can be performed even when the light amount of the sensor changes abruptly.

[0006]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram showing an embodiment of an analog circuit according to the present invention. A battery power source 1 lights a lighting / extinction judgment circuit 4 with hysteresis for inputting a signal to an optical sensor 2 and an illuminating lamp 7. It is connected to the relay 6, the power supply circuit 3, and the delay circuit 5.

The power supply circuit 3 is a circuit for circuit protection and stable operation. Whether the illumination lamp 7 is turned on or off is determined by first converting the current of the optical sensor 2 into a voltage and outputting the voltage to the hysteresis-equipped lighting / off determination circuit 4. When the input voltage signal of the on / off determination circuit with hysteresis 4 is equal to or higher than a predetermined voltage, the relay 6 is turned on without delay time by outputting OV to the delay circuit 5, and the illumination lamp 7 is turned on. or,
When the input voltage signal of the on / off determination circuit with hysteresis 4 is less than a predetermined voltage, the relay 6 is turned off by outputting 5V to the delay circuit 5, and the illumination lamp 7 is turned off. However, the illumination lamp 8 is turned off only when the input voltage of the delay circuit 5 continues to be 5 V or more for a certain delay time or more. Here, the fixed delay time can be changed by changing the capacitor capacity of the delay circuit 5. Refer to FIG. 2 for the relationship between the input voltage and the output voltage of the ON / OFF determination circuit 4 with hysteresis.

Next, the operation of the present invention will be described with reference to the time chart of FIG.

In FIG. 3, a waveform of the delay circuit input voltage is 201, an illumination lamp ON / OFF operation waveform with a delay time td = 0 (S) is 202, and an illumination lamp ON / OFF operation with a delay time td = 1 (S) is ON / OFF.
An OFF operation waveform is shown at 203, an illumination lamp ON / OFF operation waveform at a delay time td = 2 (S) is shown at 204, and an illumination lamp ON / OFF operation waveform at a delay time td = 3 (S) is shown at 205. In the waveform 202, when the delay time td = 0 (S), the immediate illumination lamp is ON when the delay circuit input voltage is less than 5V, and the immediate illumination lamp is OFF when it is 5V or more
To do. However, when the delay time td = 1 (S) of the waveform 203, the illumination lamp is turned on immediately when the delay circuit input voltage is less than 5V, but if the delay time of 5V or more does not pass 1 (S), the illumination lamp is It does not turn off. As can be seen from this waveform 203, the delay circuit input voltage is 0 V within the delay time 1 (S),
The illumination lamp is not turned off even if 5V is repeated. The waveforms 204 and 205 also have delay times of t
When d = 2 (S) and td = 3 (S), the waveform 203
Performs the same operation as.

[0011]

According to the present invention, it is possible to perform stable illumination by the analog control circuit even if the light quantity of the photosensor changes suddenly.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a graph showing a relationship between input and output voltages of a lighting / extinguishing determination circuit with hysteresis 4.

FIG. 3 is a time chart showing the operation of the present invention.

[Explanation of symbols]

2 ... Optical sensor, 4 ... Hysteresis on / off determination circuit, 5 ... Delay circuit, 6 ... Relay, 7 ... Illumination lamp.

Claims (1)

[Claims] Claim: What is claimed is: 1. An illumination lamp control circuit for lighting an illumination lamp when the amount of light detected by the optical sensor is less than or equal to a predetermined value. An illumination lamp control circuit comprising two circuits, a hysteresis circuit and a delay circuit, so as not to repeat.