JPH0596992A - 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 F or when G off, the steady diode 7 and a resistance 8 or the diode 9 and a resistance 6 are not grounded, and a negative input of the comparator COM becomes a voltage V2 or V3 divided by the resistance 6 and the resistance 10 or the resistance 6 and the resistance 8. When the resistance 8 is made equal to the resistance 10, it makes V2=V3, and the reference voltage side of the comparator COM is set between V1 and V2, and a disconnection detection signal is taken out when the semiconductor switch is off.

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 for detecting a difference in voltage drop of a semiconductor switch, and E is an oscillation circuit B according to a disconnection detection signal.
Frequency switching circuit for changing the oscillation frequency of
, G is a second semiconductor switch, H is a battery, J and K are indicator lights, 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 activated by the battery H through the indicator lights J and K. Next, the gate signals of the first and second semiconductor switches F and G are given by the oscillator circuit B at a certain cycle, the first and second semiconductor switches F and G are turned on / off, and the indicator lights J and K are turned on. Flashes. (2) Therefore, the indicator lights J and K flash at the same time.

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 in the generated voltage between the steady state and the disconnection occurs with respect to the negative input of the comparator COM,
If the plus input (or minus input) of the comparator COM, that is, the reference voltage is set so as to be between the voltage generated in the steady state and the voltage generated at the time of disconnection, it is taken out as an output of the comparator COM as a disconnection detection signal. be able to. In this 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]

It is an object of the present invention to solve the conventional drawback of requiring an adjusting resistor for setting a reference voltage and being very poor in mass productivity, and having a circuit for detecting load disconnection without adjusting resistor. The present invention provides an electronic turn signal indicator with excellent mass productivity.

[0007]

According to the present invention, the presence or absence of an indicator lamp as a load connected to a semiconductor switch is detected (3) and is 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. In this embodiment, in the disconnection detecting circuit C, the (-) or (+) input terminal of the comparator COM is connected to the (+) terminal of the battery H, and the resistor 6 is connected, and the diodes 7 and 9 are semiconductor switches, respectively. That is, the connection is made in the opposite polarity to the conduction direction of G and F.

In this operation, first, when the switch SW is closed, the power supply circuit A is activated by the battery-H via the indicator lights K and J. Next, an on / off signal is given to the semiconductor switches G and F at a certain frequency by the oscillator circuit B, and the indicator lamp J,
K flashes. Semiconductor switches F and G are periodically turned on.
Since it is off, when the semiconductor switch is on, the diode 7 and the resistor 8 and the diode 9 and the resistor 10 can be raised to the positive voltage of the battery H, so that the comparator CO
The minus input (plus input is possible) of M becomes Hi. When the semiconductor switch is off, the connection is grounded via the indicator lights J and K, so that the negative input of the comparator COM is divided by the resistor 6 and the resistors 8 and 10 in parallel (V).
Determined in 1).

Next, when one of the indicator lights J is broken for some reason, when the semiconductor switch is off, the steady-state
Since the portion where the gate 7 and the resistor 8 are grounded is broken, it is not grounded, and only the diode 9 and the resistor 10 are grounded. That is, the negative input of the comparator COM is the resistor 6
And a voltage (V2) divided by the resistor 10 is obtained. Similarly, when one of the indicator lights K is broken, the diode 9 and the resistor 10 are not grounded when the semiconductor switch is off, and the negative input of the comparator COM is divided by the resistors 6 and 8. It becomes a voltage (V3). If the resistors 8 and 10 are the same, (V2 = V3). If the reference voltage side of the comparator COM is set to be between V1 and V2 (= V3), it can be taken out as a disconnection detection signal from the comparator COM when the semiconductor switch is off. With this signal, the frequency switching circuit of E (4) changes the frequency of the oscillation circuit B to warn the disconnection.

FIG. 3 is a circuit diagram of another embodiment of the present invention, in which resistors 11 and 12 having high resistance values are connected in parallel to semiconductor switches G and F, respectively. In this operation, since the semiconductor switches F and G are synchronously turned on and off, when the semiconductor switches G and F are turned on, the diode 1 and the resistor 2 and the diode 3 and the resistor 4 are connected to the battery H. Since the potential is raised to the plus side potential, the minus input (or plus input) of the comparator COM becomes a voltage (V1) divided by the parallel resistance of the resistors 2 and 4 and the resistor 5. Further, since the impedance of the indicator lights J and K is about several tens of Ω, the resistances 11 and 12 are
Is a high resistance, when the semiconductor switches G and F are off, the diode 1 and the resistor 2 and the diode 3 and the resistor 4 are connected to the ground, and the negative input of the comparator COM is at the L0 level. Become. That is, the minus input of the comparator COM in the steady state turns on and off (V1) and (0).

In this state, if one of the indicator lamps J is broken for some reason, the stationary diode 1 and the resistor 2 are grounded via the indicator lamp J when the semiconductor switches G and F are off. Since the indicator light is disconnected at the place where it is connected, it is not grounded, and the connection is such that it is raised to the positive potential of the battery-H via the resistor 11. That is, at that time,
The minus input (plus input is also acceptable) of the comparator COM is a divided voltage (V of the series resistance of the resistors 2 and 11 and the resistor 5).
Determined in 2). Similarly, when one of the indicator lights K is disconnected, the diode 3 is turned off when the semiconductor switch is off.
The resistor 4 is not grounded, and is determined by the voltage (V3) obtained by dividing the series resistance of the resistors 4 and 12 and the resistor 5. If the resistors 2 and 4 and the resistors 11 and 12 have the same resistance, V2 = V3. Therefore, when the semiconductor switches G and F are off, they can be taken out as an output of the comparator COM as a disconnection detection signal. As a result, the frequency switching circuit E changes the frequency of the oscillation circuit B to warn the disconnection.

(5)

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 it is possible to detect the disconnection 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.

FIG. 3 is a circuit diagram of another embodiment of the present invention.

[Explanation of symbols]

 A power supply circuit B oscillator circuit C disconnection detection circuit E frequency switching circuit 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, and a disconnection detection circuit for detecting the presence or absence of a load connected to the first and second semiconductor switches, An electronic directional indicator comprising a frequency switching circuit for changing the frequency of the oscillation circuit according to the disconnection detection signal.