JP2611214B2 - Vehicle turn signal device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicular turning indicator equipped with a means for detecting an abnormality of a turning indicator.

(Prior Art) Conventionally, there has been known a vehicular turning indicator having a configuration in which a mechanical contact relay is turned on and off by an oscillation circuit to blink a turning indicator. In this type of apparatus, an abnormality detecting means for detecting an abnormality of the direction indicator lamp is added. As an example of this, a load current detection resistor is connected in series with a mechanical contact relay, and a device that notifies an abnormality based on a current value detected by the resistance is known. Is notified by changing the blinking cycle of.

(Problems to be Solved by the Invention) However, according to the abnormality detecting means using the load current detection resistor described above, the voltage drop of the load current detection resistor increases with an increase in the load current, and the load is consumed by the resistor. However, there is a drawback that the power to be supplied is increased, the reliability of the turn signal lamp is reduced, and the cost is high and the external shape is large.

Accordingly, an object of the present invention is to provide a vehicular turning indicator that detects an abnormality of a turning indicator without using a load current detection resistor.

(Means for Solving the Problems) In solving the above problems, in the present invention, a direction indication changeover switch, an oscillation control circuit for generating an on / off signal, and one terminal of the direction indication changeover switch are connected. A semiconductor switch that opens and closes based on an on / off signal from the oscillation control circuit in response to a direction instruction switching operation of the direction instruction switch, a direction indicator that flashes based on opening and closing of the semiconductor switch, and power supply to the semiconductor switch And a state detection circuit for detecting a state of the direction indicator lamp based on a voltage drop of a voltage generated between both terminals of the semiconductor switch, wherein the oscillation control circuit When the detection state of the state detection circuit indicates an abnormality of the turn signal lamp, the on / off signal is changed to the on / off state. Wherein the semiconductor switch changes the blinking state of the direction indicator by a change in opening and closing based on an on / off signal that changes the on / off state from the oscillation control circuit. An indicating device is provided.

(Effects) According to the present invention configured as described above, when the state detection circuit detects the abnormality of the turn signal lamp based on the voltage drop between the two terminals of the semiconductor switch, An oscillation control circuit generates an on / off signal by changing its on / off signal state.

For this reason, the semiconductor switch changes the blinking state of the turn signal lamp by a change in opening and closing based on an on / off signal that changes the on / off state from the oscillation control circuit.

As described above, when an abnormality occurs in the direction indicator, the abnormality is detected by the state detection circuit based on the voltage drop of the semiconductor switch.

In other words, the detection of the abnormality of the turn signal lamp is not performed by detecting the current flowing through the turn signal lamp and the semiconductor switch that blinks the turn signal by the load current detecting resistor, but based on the voltage drop of the semiconductor switch. The detection is performed by the detection circuit.

Therefore, when the load current detection resistor is used, the power consumption increases, and the reliability of the turn signal lamp decreases.
While preventing problems such as cost increase and size increase,
An abnormality of the turn signal lamp can be known from the change of the blinking state.

Further, since the blinking of the direction indicator can be achieved without using a mechanical contact relay, it is possible to prevent a problem such as a contact failure and the like, thereby improving the reliability and reducing the cost and size. Can be obtained.

Further, in the present invention, the semiconductor switch has a positive internal resistance temperature characteristic, the state detection circuit has a voltage dividing circuit connected between both terminals of the semiconductor switch, and the voltage dividing circuit is a voltage dividing element. And a resistive element connected in series to the voltage dividing element and having a negative resistance temperature characteristic, and divides a voltage generated between both terminals of the semiconductor switch to generate a divided voltage. If the state of the turn signal lamp is detected based on the voltage drop of the divided voltage accompanying the voltage drop of the voltage generated between both terminals of the semiconductor switch, the operating temperature based on the positive internal resistance temperature characteristic of the semiconductor switch The characteristic is canceled by the negative resistance temperature characteristic of the resistance element.
Therefore, an error due to a temperature change does not mix in the divided voltage of the voltage dividing circuit.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First
FIG. 1 is a circuit configuration diagram of a vehicular turning indicator according to the present invention. The direction indicating device includes a pair of flasher lamps (direction indicating lamps) 10a, 10b, and 10c connected in parallel so as to blink when the vehicle turns left, and a pair of parallel connected lamps that blinks when the vehicle turns right. Flasher lamps (direction indicators) 10d, 10e, 10f and the ignition switch of the vehicle
A known oscillation control circuit 20 connected to a DC power supply (power supply circuit) B via an IG, and a changeover switch 30 (turn signal switch) connected between the oscillation control circuit 20 and each of the flasher lamps 10a to 10f are provided. This changeover switch 30
Indicate that each of the flash lamps 10a to 10c
, And is grounded at its fixed contact 32 via the flasher lamps 10d to 10f. The changeover contact 33 of the changeover switch 30 has two fixed contacts 31 at its neutral position.
It is cut off from 32 and is inserted at the fixed point 31 (or 32) when switching to the left turn direction (or right turn direction). The pair of lamps on the left and right sides is the same wattage lamp, so that the internal resistance values of the flasher lamps 10a to 10f are the same.

The oscillation control circuit 20 is supplied with power from a DC power supply B via an ignition switch IG and is activated. The start terminal 21 of the oscillation control circuit 20 is connected to a changeover contact 33 of a changeover switch 30. Thus, the oscillation control circuit 20
In response to the switching contact 33 of the changeover switch 30 being applied to the fixed contact 31 (or 32), the oscillation control action is started, and a series of control pulse signals having a predetermined level and a predetermined frequency are generated from the output terminal 22. Further, the oscillation control circuit 20 receives a detection voltage generated from a semiconductor chip E constituting a main part of the present invention as described later at an input terminal 23, compares the detection voltage with a reference voltage, and compares each of the flasher lamps 10a to 10f. The presence or absence of abnormalities is notified.

The semiconductor chip E has a vertical power MOSFET (semiconductor switch) 40 and a voltage dividing circuit 50 formed in a MOS structure. The MOSFET 40 is connected at its source 41 to a DC power source B via an ignition switch IG. I have. Also this MO
The drain 42 of the SFET 40 is connected to the changeover contact 33 of the changeover switch 30, and the gate 43 of the MOSFET 40 is connected to the oscillation control circuit 20.
Are connected to the output terminal 22. And this MOSFET
40 is an output terminal 22 of the oscillation control circuit 20 at its gate 43.
And receives a series of control pulse signals from them to conduct intermittently.

The voltage dividing circuit (state detecting circuit) 50 has a pair of resistors 51 and 52 connected in series to each other. The resistor 51 is connected at one end to the source 41 of the power MOSFET 40, and is connected to the other end. And connected to the drain 42 of the power MOSFET 40 via the resistor 52. Thus, the voltage dividing circuit 50 is a power MOSF
The voltage generated between the source 41 and the drain 42 of the ET 40 is divided by the resistors 51 and 52, and the divided voltage is used as a detection voltage as a common terminal of the resistors 51 and 52 (hereinafter referred to as an output terminal 53).
And is applied to the input terminal 23 of the oscillation control circuit 20. However, the resistor 51 is formed as a P-type semiconductor resistor by uniformly implanting (doping) boron into polycrystalline silicon at a predetermined concentration. In such a case, the predetermined concentration of boron is set to −0.148 (% / ° C.) and 1.0 × 10 ^{19 to} 1.3 × 10 ¹⁹ (pieces / cm 2) in order to give the resistor 51 a negative resistance temperature characteristic.
³ ) The concentration is within.

Incidentally, how to determine the boron implantation concentration in the resistor 51 of the semiconductor chip E will be described below. The DC current flowing into the semiconductor chip E is represented by I, the shunt current flowing into the voltage dividing circuit 50 is represented by Io, the resistance value of the resistor 51 is represented by Rs, and the resistance value of the low transition 52 is represented by R (invariant to temperature). ), And assuming that the internal resistance value of the power MOSFET 40 during conduction (hereinafter referred to as ON resistance value) is Ron, Io (Rs + R) = (I-Io) R
on Holds. However, Rs + R >> Ron.

Also, assuming that the terminal voltage of the resistor 51 is Vs, In addition, the ON resistance Ron of the power MOSFET 40 changes according to the concentration of the semiconductor chip E (hereinafter referred to as chip temperature t (° C.)) as shown in FIG. Is known to have a positive temperature coefficient. Accordingly, in order to keep the coefficient of I in the equation (2), that is, the current sensitivity α constant, despite the change in the chip temperature t, in other words, when I is constant,
It is understood that in order to maintain the terminal voltage Vs at the same value, in the equation (2), the resistance value Rs must have at least a negative resistance temperature characteristic (temperature coefficient). That is, it is understood that the change due to the positive temperature coefficient of Ron needs to be canceled by the negative temperature coefficient of Rs.

However, the resistance value at a certain temperature of the ON resistance value Ron is
Even if the chip temperature t is the same, there is variation among production lots due to subtle differences in production conditions, so the secondary curve X moves in the direction of the arrow shown in FIG. 2 for each production lot. However, a lot means a bundle of products manufactured under substantially the same conditions, and the variation between individual products in the same lot can be ignored. Therefore, under a constant current sensitivity α, the change range of the resistance value Rs of the resistor 51 required to maintain the terminal voltage Vs at the same value regardless of the change of the chip temperature t is
Examination of the relationship with the chip temperature t revealed that, as shown in FIG. 3, the resistance value Rs had to be changed without the region between the curves Yu and Yl. That is, the third
If the value of Rs in the area surrounded by Yu and Yl in the figure can be set arbitrarily in relation to the chip temperature, the value of α will be constant between lots even if Ron changes for each lot and depending on the temperature. You can do it. This means that α = Is understood from R constant.

However, as can be seen from FIG.
Since Yu and Yl have different rates of change with respect to the chip temperature, when determining the resistance value Rs to keep the current sensitivity α constant, the reference value of the resistance value Rs at the reference chip temperature (or a predetermined temperature, for example, 25 ° C.) Both the Rso and the negative resistance temperature characteristics of the resistance value Rs must be made different for each production lot. In other words, for each production lot, the above-described boron injection concentration must be changed and the reference value Rso must be changed by trimming or the like. This can be said to be unsuitable for mass production of the semiconductor chips E.

Therefore, based on the above examination results, the following has been found.

(1) The reference value Rso can be easily adjusted by trimming as a matter of course. Also, such adjustment is
The adjustment can also be performed by trimming the resistance value R of 52.

(2) The current sensitivity α does not need to be constant among lots. Even if the current sensitivity α differs between lots such as α ₁ , α ₂ ,..., These α ₁ , α ₂ ,. . In other words, as long as there is no temperature characteristic,
By adjusting the current determination level in the oscillation control circuit 20 for each lot (for each product), it cannot be determined whether a predetermined current is flowing.

(3) If the current sensitivity α is allowed to vary from one production lot to another, no matter how the ON resistance value Ron of the power MOSFET 40 changes according to the change in the chip temperature t, the power MOSFET 40
If the dividing ratio of the resistor 51 to the resistor 52 with respect to the drain-source voltage of the resistor 51, that is, (Rs / R) = 1 / (N-1) is made constant, the concentration of boron implanted into the resistor 51, that is, the resistor 51
It has been found that the terminal voltage Vs can be maintained at the same value while making the negative resistance temperature characteristic of all the production lots almost the same. If the boron injection concentration can be kept constant between lots, the production becomes extremely easy.

By the way, substituting Rs / R = 1 / (N-1) into the equation (2), Is obtained. Here, in order to keep α constant, N, that is, Rs may be changed as Ron changes. Therefore, in order to prevent the α of the lot from changing with the temperature and to eliminate the detection error of the terminal voltage Vs, if the value of the ON resistance Ron at the reference chip temperature (for example, 25 ° C.) is Rono, the value of 25 ° C. In this case, the sensitivity α ₂₅ is given by the following equation (4), and Rs may be changed so that α ₂₅ does not change with temperature.

That is, May be satisfied. Then, when the relationship between Rs and t was examined using N as a parameter based on the equation (5), that is, by changing N, as shown in FIG.
When 3, the curve Zu was obtained, and when N = 2, the curve Zl was obtained. The meaning of FIG. 4 is that if the value of Rs is selected from FIG. 4 as the chip temperature changes and N changes,
The current sensitivity α of the lot can be kept constant regardless of the temperature. In addition, the curves Zu and Zl have the same negative temperature characteristics, and it has been found that the Bon injection concentration may be constant. Note that, as N increases, the accuracy improves but the sensitivity decreases. Therefore, N may be reduced as much as possible within the allowable range of required accuracy. In FIG. 4, each straight line Za, Zb
Are linear approximations of the respective curves Zu and Zl with the same negative temperature coefficient of resistance, and the temperature characteristics of the resistor Rs due to the actual boron injection have this linear characteristic, but there is an error by the hatched portion. Is negligible.

As can be understood from the above description, when boron is injected into the resistor 51 of the semiconductor chip E, the current sensitivity α is allowed to vary from one production lot to another, and the total Rs / R is made constant. In the production lot, the boron injection concentration can be made substantially the same, and mass productivity can be achieved. In addition, the reference value Rso and the resistance value R of the resistance value Rs can be easily trimmed so that the division ratio with respect to Ron, that is, N = constant.

As a result, the current sensitivity itself of the product varies for each production lot, but this does not cause any problem by adjusting the determination level on the user side. Since the current sensitivity of the product does not fluctuate due to a temperature change, accurate current detection and current determination can be performed.

In the present embodiment configured as described above, if the vehicle is in a straight running state with the ignition switch IG closed, the oscillation control circuit 20 is supplied with power from the DC power source B and is in the operating state. Maintain the switching contact 33 in the neutral position and move the semiconductor chip E to each flash lamp 10.
Maintain the cut-off state from a to 10f. Therefore, even if the power is supplied from the DC power supply B to the semiconductor chip E via the ignition switch IG, the power MOSFET 40 and the voltage dividing circuit 50 are maintained in the non-ground state, so that the power MOSFET 40 and the voltage dividing circuit
No unnecessary current flows through 50.

In such a state, when the vehicle turns left, the changeover switch 30
When the switching contact 33 is switched to the fixed contact 31, the oscillation control circuit
A start terminal 21 is grounded via each of the flasher lamps 10a to 10c to start an oscillation control action, generates a series of control pulse signals from an output terminal 22, and sequentially applies the control pulse signals to the gate of the power MOSFET 40. When the power MOSFET 40 is turned on intermittently in response to the control pulse signals, a part of the DC current from the DC power supply B flows into the power MOSFET 40 as an intermittent current, and the remaining part of the DC current Flows into the resistors 51 and 52 of the voltage dividing circuit 50 in sequence, and the intermittent current flowing out of the power MOSFET 40 and the current flowing out of the resistor 52 merge and pass through the changeover switch 30 and are introduced into the flasher lamps 10a to 10c.

Thus, each of the flasher lamps 10a to 10c blinks in response to the intermittent merge current to instruct the vehicle to turn left. At this time, the voltage dividing circuit 50 generates the inflow current from the output terminal 53 as the detection voltage Vs.
Since both 0c are not disconnected, the oscillation control circuit 20 notifies that the flasher lamps 10a to 10c are normal based on the detection voltage from the voltage dividing circuit 50 and the reference voltage. In addition,
The reference voltage is appropriately determined based on the sum of the resistance value of the resistor 52 and the parallel combined internal resistance values of the flasher lamps 10a to 10c.

In such a state, if any one of the flasher lamps 10a to 10c is disconnected, the parallel combined internal resistance value increases, and the detection voltage from the voltage dividing circuit 50 rises above the reference voltage, and this abnormal The oscillation control circuit 20, which has detected the voltage, notifies the abnormality of each of the flasher lamps 10a to 10c by a change in the number of blinks, as is well known. Further, even if the disconnection of any of the flasher lamps 10a to 10c as described above occurs when the chip temperature of the semiconductor chip E is high or low, as described above, setting of the boron injection concentration to the resistor 51, Both resistances
The trimming adjustment of each resistance value of 51 and 52 is
The change in the ON resistance value with respect to the chip temperature t is accurately canceled out, so that the detection voltage from the voltage dividing circuit 50 does not cause an error due to the change in the chip temperature t.

In the above description of the operation, the case of the vehicle turning left has been described. However, the present invention is not limited to this, and substantially the same operation and effect as in the case of left turning can be achieved when the vehicle turns right.

In implementing the present invention, the dividing ratio, ie, N
(> 1) may be appropriately changed as required, and the boron implantation concentration may be from 1.0 × 10 ^{19 to} 1.3 × 10
^The temperature may be changed as appropriate within ¹⁹ (pieces / cm ³ ), and the lower the implantation concentration, the more the negative resistance temperature characteristic tends to be.

Further, in the above-described embodiment, an example in which boron is used as the injection material for the resistor 51 is described. Instead, phosphorus is used as the injection material, and the resistor 51 is formed as a P-type semiconductor resistance element. Is also good.

Further, in the embodiment of the present invention, the resistor 52 may be replaced with the resistor 52 so as to have a negative resistance temperature characteristic.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of a vehicular turning indicator according to the present invention, FIG. 2 is a graph showing a relationship between an ON resistance value Ron and a chip temperature t, and FIG. FIG. 4 is a graph showing the relationship between the resistance value Rs and the chip temperature t, and FIG. 4 shows the relationship between the resistance value Rs and the chip temperature t when the division ratio (Rs / R) of each lot is constant. It is a graph shown. Description of symbols 10a to 10f: flasher lamp, 20: oscillation control circuit (control signal generating means), 40: power MOSFET, 41: source (input terminal), 42: drain (output terminal), 43: gate (control terminal) , 50: voltage dividing circuit, 51, 52: resistor, E: semiconductor chip.

Claims (2)

(57) [Claims] 1. A direction indication changeover switch, an oscillation control circuit for generating an on / off signal, and an oscillation control circuit connected to one terminal of the direction indication changeover switch in response to a direction indication changeover operation of the direction indication changeover switch. A semiconductor switch that opens and closes based on an on / off signal from a control circuit; a direction indicator that blinks based on the opening and closing of the semiconductor switch; a power supply circuit that supplies power to the semiconductor switch; and a voltage generated between both terminals of the semiconductor switch A state detection circuit for detecting a state of the turn signal based on the voltage drop of the turn signal, wherein the oscillation control circuit detects that the state of the turn signal is detected by the state detection circuit. When indicating an abnormality, the on / off signal is generated by changing its on / off state, and the semiconductor switch is turned on and off by the oscillation control circuit.・
A vehicular turning indicator that changes the blinking state of the turn indicator light by a change in opening and closing based on an on / off signal that has been turned off. 2. The semiconductor switch has a positive internal resistance temperature characteristic, the state detection circuit includes a voltage divider connected between both terminals of the semiconductor switch, and the voltage divider includes a voltage divider. A voltage element which is connected in series with the voltage dividing element and has a negative resistance-temperature characteristic, and divides a voltage generated between both terminals of the semiconductor switch to generate a divided voltage. 2. The vehicular turning indicator according to claim 1, wherein the detection circuit detects a state of the turn indicator based on a voltage drop of the divided voltage resulting from the voltage drop.