JPH0596991A - Electronic direction indicating device - Google Patents

Abstract

PURPOSE:To obtain an electronic direction indicating device which has a circuit for detecting disconnection of a load without an adjusting resistance and is excellent in mass productivity by detecting presence of an indicator lamp as a load to be connected to semiconductor switches through resistances and diodes and by taking it out as a disconnection detection signal. CONSTITUTION:A resistance 6 is connected to a negative or a positive input terminal of a comparator COM and a positive terminal of a battery H, and diodes 7 and 9 are connected in the reversed polarity of the continuity direction of semiconductor switches G and F, respectively. If an indicator lamp K or J is disconnected, when the semiconductor switch or G is off, a resistance 10 or 8 and the diode 9 or 7 are not grounded, and the negative input of the comparator COM is brought to the H level. The Hi level in these two cases is taken out as a signal as an output of the comparator COM, and this disconnection detection signal is caught, and a frequency of an oscillation circuit B is changed by a frequency switching circuit E to alarm disconnection. By this, adjustment with high accuracy is made unnecessary, and disconnection can be detected with the simple constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a direction indicating drive having an alarm function for detecting a disconnection of one light of a direction indicator mounted on an automobile or the like and changing a blinking cycle of the indicator light to notify the disconnection. It relates to the device.

[0002]

2. Description of the Related Art FIG. 1 is a conventional circuit diagram in which A is a power supply circuit and B is a circuit.
Is an oscillation circuit, C is a disconnection detection circuit that detects a difference in voltage drop of a semiconductor switch, D is an inverting circuit that inverts the oscillation circuit B, E is a frequency switching circuit that changes the oscillation frequency of the oscillation circuit B by a disconnection detection signal, F is a first semiconductor switch, G is a second semiconductor switch, H is a battery, J,
K is an indicator light and SW is a switch.

The operation of this circuit is such that the switch SW is F and G.
When connected to the power source circuit A, the power source circuit A is started up by the battery H through the indicator lights J and K. Next, the gate signal of the first semiconductor switch F is given at a certain period by the oscillator circuit B, the first semiconductor switch (2) switch F is turned on and off, and the indicator lamp K blinks. Further, a signal obtained by inverting the on / off signal obtained from the oscillator circuit B by the inverting circuit D is similarly given to the second semiconductor switch G, the second semiconductor switch G is turned on / off, and the indicator lamp J blinks. Therefore, the indicator light blinks alternately.

Next, when the indicator lamp J is broken for some reason, the load current disappears, and the on-voltage generated across the semiconductor switch G disappears. Therefore, the comparator COM is connected via the diode 1 and the resistor 2. Negative input (even positive input is possible) rises more than in steady state. Similarly, when the indicator lamp K is disconnected, the minus input of the comparator COM rises more than in the steady state. That is, a difference occurs in the voltage generated in the steady state and in the disconnection with respect to the comparator COM minus input, and the comparator COM plus input (even in the minus input is possible), that is, the reference voltage is the voltage generated in the steady state and the disconnection. If the setting is made so as to be in the interval, it can be taken out as an output of the comparator COM as a disconnection detection signal. In such a manner, the disconnection detection signal is detected, the frequency of the oscillator circuit B is changed by the frequency switching circuit E, and the disconnection is warned.

[0005]

2. Description of the Related Art Since the conventional circuit detects the difference in the ON voltage of the semiconductor switch as a disconnection detection, the setting of the reference voltage is required with an error accuracy of several tens of mV level.
Adjustment resistance is required. That is, there is a drawback that mass productivity is lacking because man-hours for individual adjustment are added.

[0006]

SUMMARY OF THE INVENTION The present invention solves the conventional drawback that an adjusting resistor is required for setting a reference voltage, which is very poor in mass productivity, and has a circuit for detecting load disconnection without adjusting resistor. In addition, the present invention provides an electronic turn signal indicator with excellent mass productivity.

(3)

According to the present invention, the presence or absence of an indicator lamp as a load connected to a semiconductor switch is detected and taken out as a disconnection detection signal.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a circuit diagram of an embodiment of the present invention. As is clear from the comparison with the conventional example, the present invention connects the resistor 6 to the (−) or (+) input terminal of the comparator COM and the (+) terminal of the battery H in the disconnection detection circuit C, and The terminals 7 and 9 are connected to the semiconductor switches G and F in opposite polarities to the conducting directions.

To operate this, when the switch SW is closed, the power supply circuit A is activated by the battery-H via the indicator lights J and K. Next, the oscillating circuit B sends an ON / OFF signal at a certain frequency to the semiconductor switch (P channel MOS F
ET) F, and the indicator light K blinks. At the same time, an inversion signal from the oscillation circuit B is given from the inversion circuit D to the semiconductor switch (P-channel MOS FET) G, and the indicator light J
Flashes. Therefore, the indicator lights J and K are alternately blinking. At this time, when the semiconductor switch F is off, the indicator light K
The diode 9 and the resistor 10 are connected to each other via the. (Because the impedance of the indicator light is several tens of Ω
If the high resistance resistors 6, 8 and 10 whose resistance is negligible are selected, they are grounded. ) Therefore,
At that time, the negative input (or the positive input is possible) of the comparator COM is a voltage divided by the resistors 6 and 8. When the semiconductor switch F is on, the diode 9 and the resistor 10 are lifted to the positive side of the battery H, so that the negative input of the comparator COM is Hi. At this time, the semiconductor switch G is off, and the diode 7 and the resistor 8 are connected to the ground. Therefore, when the semiconductor switch F is on, the minus input of the comparator COM is divided by the resistors 6 and 8. It becomes a voltage. The same applies to the opposite case, and in the steady state, the voltage divided by the resistors 6 and 8 and the resistors 6 and 10 is repeated at the negative input of the comparator COM. (4) If resistors 8 and 10 are set to have the same resistance, the negative input of the comparator COM is always fixed at the same level.

When the indicator lamp K is broken for some reason, the resistor 10 and the diode 9 are no longer grounded when the semiconductor switch F is off, and the minus input of the comparator COM at that time becomes Hi level. Similarly, even when the indicator light J is broken, the resistor 8 and the diode are turned off when the semiconductor switch G is off.
The gate 7 is no longer grounded, and the minus input of the comparator COM becomes Hi level. That is, Hi in the above two cases
If the level is taken out as a signal as the output of the comparator COM, it becomes a disconnection detection signal. By catching the disconnection detection signal,
The frequency switching circuit E changes the frequency of the oscillation circuit B to warn the disconnection.

[0011]

As is apparent from the above description, according to the present invention, it is not necessary to perform highly accurate adjustment for catching the difference in the on-voltage of the semiconductor switch, and the disconnection can be detected with a very simple structure. It will be possible. That is, it is possible to provide a direction indicator having excellent mass productivity.

[Brief description of drawings]

FIG. 1 Conventional circuit diagram

FIG. 2 is a circuit diagram of an embodiment of the present invention.

[Explanation of symbols]

 A power supply circuit B oscillator circuit C disconnection detection circuit D inversion circuit E frequency switching circuit (5) F semiconductor switch G semiconductor switch H battery SW switch J indicator light K indicator light

Claims (1)

[Claims] 1. A three-terminal type turn signal device having a first semiconductor switch connected between one terminals and a second semiconductor switch connected between the other terminals, wherein the first and second semiconductor switches are provided. A power supply circuit for supplying power to the first semiconductor switch, an oscillating circuit for giving an on / off signal to the first semiconductor switch, an on / off signal of the oscillating circuit is inverted, and an on / off signal is supplied to the second semiconductor switch. An inverting circuit for giving a signal; a disconnection detection circuit for detecting the presence or absence of a load connected to the first and second semiconductor switches; and a frequency switching circuit for changing the frequency of the oscillation circuit according to the disconnection detection signal. A characteristic electronic directional indicator.