GB1604280A

GB1604280A - Circuits for vehicle direction indicator lamps

Info

Publication number: GB1604280A
Application number: GB18972/78A
Authority: GB
Original assignee: SWF Spezialfabrik fuer Autozubehoer Gustav Rau GmbH
Current assignee: SWF Auto Electric GmbH
Priority date: 1977-05-14
Filing date: 1978-05-11
Publication date: 1981-12-09
Also published as: IT7823157A0; DE2721879A1; DE2721879C3; DE2721879B2; IT1094597B; FR2390309B3; FR2390309A1

Description

(54) IMPROVEMENTS IN OR RELATING TO CIRCUITS FOR VEHICLE DIRECTION INDICATOR LAMPS (71) We, SWFSPEZIALFABRIK FUR AUTO- ZUBEHOR GUSTAV RAU G.m.b.H. a joint stock company organised under the Laws of Germany of Stuttgarter Strasse 119, 712 Bietigheim Bissingen, Germany do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a circuit arrangement for energising the direction indicator lamps in a motor vehicle.

In modern motor vehicles the direction indicator switches are directly secured to the steering column as so-called steering column switches. The switch lever of this steering column switch can be moved to the left and to the right into an intermediate non-locking position for so-called lane change flashing of the direction indicator lamps and into a locking position for normal change of direction indicating flashing of the lamps. The switch lever is reset into its neutral position via a resetting device comprising a switching cam and a driver on the steering tube as soon as the comering is terminated. Such steering column switches are constructed by using a great number of parts as locking elements, springs, contacts and therefore are very susceptible to trouble.Further, these steering column switches are relatively voluminous which is the reason why it is sometimes difficult to arrange this steering column switch in the area of the steering column, which is necessary because of the mechanical resetting system.

The invention is based on the problem of trying to develop a circuit arrangement in away that the direction indicator switch can be installed in the motor vehicle at any desired d place, but nevertheless a resetting influenced by the steering wheel turn is possible According to the present invention there is provided circuit arrangement for energising direction indicator lamps in a motor vehicle which may be manually actuated by means of a direction indicator switch and reset by a resetting device influenced by turning the steering wheel, wherein operation of the direction indicator switch in accordance with the desired direction of travel sets one of two electric stores which connects the clock signal of a clock pulse generator to provide an energising signal for the corresponding indicator lamp via a respective gate, and wherein the resetting device releases trigger signals characterising the direction of rotation of the steering wheel for resetting the stores.

The direction indicator switch can be built up of individual non-locking switches which can be produced economically, because they only have to switch the currents necessary for controlling an electronic circuit. Also the resetting device, which has only to release signals characterising the turning direction, can be built up much simpler and above all smaller than until now. The necessary elements for realising the electrical functions will preferably be integrated in one unit, so that further space can be saved.

The unit can be a correspondingly programmed microprocessor which presently is offered in the market at a favourable price.

The invention is described below with ref- erence to the embodiment shown in the accompanying drawings whereby advantageous developments of the invention will also be described.

The drawings show in: Figure 1 a circuit diagram of a circuit arrangementaccordingtoanembodiment oftheinvention; Figure 2 a view of a switch disk of the resetting device and Figure 3 a section taken on the line Ill-Ill of Figure 2.

The circuit arrangement contains an integrated circuit 10 which, via a power rail terminal 11 a and the ignition switch 11 or the hazard warning switch 12, is connected to the positive terminal of a voltage source. Two diodes 13 and 14 are provided for decoupling the two supply current circuits. The indicator lamps 17 and 18 on the left hand and right hand sides of the vehicle are connected to output terminals 15 and 16 of the integrated circuit 10. The direction indicator switch 20 contains four simple non-locking switches with the outputs 21 and 22 for the so-called lane change flashing and the outputs 23 and 24 for the normal direction indicating flashing connected via a set of terminals to the circuit. Ail the switch outputs can be connected to earth via a common movable bridging contact 25.The bridging contact 25 is connected to a switch lever (not shown) and on both sides it is initially tensioned by springs, so that it automatically springs back to the neutral position shown in the drawing.

A switch disk 31 having an annular contact path 32 with a gap 33 is secured to the steering tube 30. On the switch disk 31 are two slidable contact springs 34 and 35 located side by side, said contact springs being connected to input terminals 36 and 37 of the integrated circuit 10. The contact path 32 is connected to the positive terminal of the voltage source, whereas in the area of the contact gap 33 ground potential may be tapped off. The disk 31 and the contact springs 34 and 35 can be designated as signal producing elements, because from each contact spring a pulse may be tapped off during the transition from the contact path 32 to the contact gap 33. In the embodiment shown the signal producing elements constitute an electromechanical device. It is, however, also possible to use electromagnetic or electro-optic signal producing elements.It is only essential that at the inputs 36,37 a pulse sequence can be tapped off which characterises the direction of rotation of the steering wheel.

The integrated circuit 10 comprises two power output stages 40 and 41 for energising the indicator lamps 17 and 18 respectively.

These power output stages would not be necessary, if in known manner the lamps were energised via relays.

A clock generator 42 produces switching pulses according to the desired flashing frequency. This clock generator could also be realised by a separate unit, especially when it is provided to control also other switching devices in a motor vehicle as a so-called central clock generator.

A first subassembly 50 of the integrated circuit 10 contains two AND-gates 51 and 52 for controlling the power output stages 40 respectively 41. To the one input of each ANDgate the clock signal of the clock generator 42 is conducted. The control inputs of these gates 51 and 52 are connected to the output of NAND- gates 53 and 54 respectively. Each of these NAND gates 53, 54 has three inputs. One input of each NANDgate is connected to the hazard warning switch 12 through an invertor 55. At the input of the invertor 55 a resistor 56 is connected to ground. A second input of each NAND gate is connected to an output 21,22 respectively of the direction indicator switch 20.The remaining inputs of the NAND gates 53, 54 are connected to the respective complementary outputs of two stores 61 or 62 of a store assembly 60.

In the rest position, all three inputs of the NAND gates 53, 54 are in the H-state, because an open input is equal to the State as this is the case with units of the TTGfamily. In the Hstate the operating voltage applied at the inputs appears at the outputs of these units.

The inputs 63, 64, which respond to negative going signals, are connected to the outputs 23, 24 respectively of the direction indicator switch 20. The inputs 65 and 66 of the stores 61,62 are connected to the respective output of an ANMgate 67 or 68 at all times. Each of these ANZgates 67, 68 has two inputs of which one is connected to the respective output 22, 21 of the direction indicator switch. A cross coupling is provided in such a manner that the left hand store 61 is cleared, when the direction indicator switch is actuated in clockwise direction, whereas the right hand store 62 is cleared, when the direction indicator switch is actuated in anticlockwise direction.The other inputs of the AND-gates 67, 68 are connected to the complementary outputs of two monostable multivibrators 71,72 of a resetting device 70, which releases trigger signals characterising the direction of rotation for resetting the stores 61,62.

In the state of rest all inputs of the AND-gates 67, 68 are in the H-state, so that operating voltage is applied also at the clear inputs 65,66 of the stores 61,62. In this state the stores 61, 62 can be clocked via the clock inputs 63, 64.

The resetting device 70 further contains two reset stores 73, 74 the outputs of which are connected to the inputs of the monostable multivibrators 71, 72. The clock input 75 of the reset store 73 and the clear input 78 are connected to the contact spring 35, whereas the clock input 76 of the reset store 74 and the clear input 77 of the reset store 73 are connected to the contact spring 34. By this cross coupling, depending on the direction of rotation of the steering wheel, the release of the trigger signals for resetting the one or other store is blocked as will be described later.

In Figure 1 within the integrated circuit 10 only the essential connections for understanding the switching functions are shown. Components serving for the purpose of eliminating trouble are not shown in the drawing for the sake of clarity.

Now the operation of the circuit arrangement will be described, starting with the initial state shown in which the steering wheel and the direction indicator switch are in the neutral position.

Upon actuating the hazard warning switch 12 the operating voltage is conducted to the integrated circuit 10 via the diode 13 and also to one input of each of the NAND gates 53, 54 which are jointly changed over from the H-state into the Gestate. At the output of both the NAND gates 53, 54 the positive operating voltage will appear and the gates 51, 52 are open. Thereby the clock pulses of the clock generator 42 are supplied to the both lamps 17, 18 via the gates 51, 52 and the power output stages 40,41. It is essential that upon actuating the warning switch 12 the gates 51,52 will be immediately opened, so that the hazard warning flashing has priority before all other switching functions. By resetting the switch 12 the gates 51, 52 are again blocked and the initial state is reached once more.

Now let it be assumed that the ignition switch 11 is closed and the bridging contact 25 is changed over to the output 21 of the direction indicator switch. One input of the NAND gate 53 is changed over from the H-state into the Upstate and gate 51 is opened, so that the left hand lamp 17 periodically flashes. Simultaneously, via the bridging contact 25 and the output 21 of the direction switch 20, the ANDgate 68 is changed over, so that now the clear input 66 of the other store 62 there is at ground potential and store 62 is thus safely held in its state of rest. Upon resetting the bridging contact 25 the gate 51 is blocked again. In this manner the socalled lane change flashing is realised during which the switched on flasher lamp only flashes as long as the switch lever is actuated.The corresponding operations are made, when the bridging contact 25 is connected to the output 22 to cause flash ingofthelamp 18.

When the bridging contact 25 however is for a short time connected to the output 23, when the ignition switch 11 is closed, the store 61 is set by a signal applied to input 63. The output of the set store 61 changes over one input of the NAND gate 53 from the H-state into the Lr state, so that the gate 51 is opened and the lamp 17 is energised. This switching state will last even if the bridging contact 25 springs back to its neutral position shown in the drawing.

The usual locking of known steering column switches in this circuit arrangement is thus realised by the store 61, which is only controlled by a short pulse. Upon further connection of the bridging contact 25 to the output 23 another signal is applied to the input 63, so,that the store 61, which is a a clocked flip-flop, is reset and the lamp is turned off. The store 61 is also reset via the clear input, when the bridging connected to to the output 22.

Below, the function of the resetting device 70 is described, starting with the store 61 set and lamp 17 flashing. Thus a cornering to the left is intended and the steering wheel is moved in an anticlockwise manner in the direction of arrow A. The one signal producing element which is constituted by the contact spring 34 emits a positive pulse as soon as said contact spring rests upon the contact path 32. Thereby the state of the two reset stores 73,74 is not changed, for the clock input 76 only responds to a negative going signal. This state is also maintained when the steering wheel is turned back, for the clear input 78 of the store 74 is blocked via the other signal producing element constituted by the contact spring 35.Upon only a slight turn of the steering wheel the resetting device 70 thus will not be operated, corresponding to what happens with conventional steering column switches having mechanical resetting systems.

When, however, the steering wheel is turned through a larger angle the state at the output of the other signal producing element constituted by the contact spring 35 changes, when said contact spring contacts the path 32. The state of the reset stores 73, 74 is not changed.

If, however, upon termination of the cornering manoeuvre the switch disk 31 is moved in the direction of arrow B the potential at the contact spring 35 is ground as soon as the contact spring again rests in the contact gap 33.

Thereby the reset store 73 is set via input 75.

This change in state, however, does not influence the behaviour of the monostable 71, because it only responds to negative slopes. If, however, the neutral position shown is reached again, the potential at the contact spring 34 will change too. Thereby the store 73 via the clear input 77 is again reset and said negative going signal triggers the monostable 71. The output of monostable changes over into the Gestate only for a short time and the clear input 65 of the store 61 is approximately at ground potential.

The store is thereby reset and gate 51 blocked via the NAND gate 53. The negative going signal at the contact spring 34 on the other hand does not influence the reset store 74, because it is already blocked beforehand via the contact spring 35 at the clear input 78 by the potential being at ground. At the two outputs of the resetting element 70 trigger signals characterising the direction of rotation for resetting the stores 61 and 62 may be tapped off.

This is realised by the cross coupling of the two signal producing elements via the contact springs 35 and 34 to the clock and clear inputs respectively of the reset stores 73 and 74.

Because these trigger signals are conducted to the clear inputs of the respective stores 61 and 62, only the store which was previously set by actuating the direction indicator switch 20 is cleared, but no store is set. Thereby it is simultaneously ensured that if during an intended cornering to the left, the steering wheel is turned to the right when the steering wheel is returned to its neutral position, the store set once will not be cleared. The reset stores 73, 74 can only be set via the clock inputs 75 and 76 and the position of the switch at the moment of switching-on the direction indicator switch 20 does not influence the switching behaviour.

A trigger signal for resetting the stores will only be released when the store is first set and then reset.

Thus the described circuit arrangement makes possible all the switching functions which are also provided in the known circuit arrangement comprising a steering column switch with a mechanical resetting device. The invention has the advantage that the actual direction indicator switch can be arranged remote from the steering column and only low control currents have to be switched by the mechanical part of the resetting system, that is the switch disk 31 and the direction indicator switch, so that cheaper contacts can be used.

All these components at the present state of the art can be integrated into one circuit. Because the development of such a circuit is relatively expensive, preferably a microprocessor can be used which can be programmed accordingly, so that the desired switching functions can be realised. In this case the circuit design can vary from the diagram shown in Figure 1 without departing from the scope of the invention.

In the embodiment according to Figure 1 it is assumed that the switch disk 31 during the steering wheel turn from the left hand direction of travel to the right hand direction of travel will be turned less than 360". This can easily be achieved if necessary with a suitable gear. A design according to Figure 2 and 3 is, however, much simpler. Said design has spiral contact paths 90 at the upper side and at the underside in which assigned contact springs 34, 35 are guided. In this manner it is ensured that only in the neutral position of the steering wheel do the contact springs 34 and 35 rest upon the contact gap 33. Such a switch disk can be made of metallic material, with the contact paths defined by insulated strips.This is possible because in the stated circuit an open input of an element is in the Estate. In the area of the contact gap 33 the contact springs, however, via the steering tube 30 are directly connected to ground. Instead of a spiral contact path of course a helical contact path can be provided which is made by putting insulating strips round the steering tube 30. The radial extension of the mechanical part of the resetting device can thereby be reduced.

The size of the contact gap 33 depends on the desired hysteresis of the resetting device.

When the contact gap is made very small the resetting device is already operated after a small turn of the steering wheel. With a large contact gap the lamp which is on will be switched off only when the steering wheel is turned through a relatively large angle. The adaptation to the different gear ratios of the various vehicles can thereby be performed much simpler than with known mechanical resetting systems.

In the embodiment shown in the drawing it is provided, in accordance with conventional circuit arrangements, that the lane change flashing is effective as long as the direction indicator switch is actuated. It can, however, be provided that for instance upon connecting the bridging contact 25 to one of the inputs 21 and 22 one of a pair of monostable (not shown) is set, so that the lane change flashing will automatically be switched off after a certain time, e.g. after 5 seconds. The monostables suitably have to be able to be reset before this time expires, so that the indication of direction can be changed quickly, if necessary.

A similar timing element could also be used in connection with the resetting element 70 which provides that in any case the set store will always be reset after a certain time has expired or if the steering column switch is not returned to its neutral position. Such an additional equipment is desirable when the switching hysteresis of the resetting system is such that it will not respond on large-radius bends.

WHAT WE CLAIM IS: 1. Circuit arrangement for energising direction indicator lamps in a motor vehicle which may be manually actuated by means of a direction indicator switch and reset by a resetting device influenced by turning the steering wheel, wherein operation of the direction indicator switch in accordance with the desired direction of travel sets one of two electric stores which connects the clock signal of a clock pulse generator to provide an energising signal for the corresponding indicator lamp via a respective gate, and wherein the resetting device releases trigger signals characterising the direction of rotation of the steering wheel for resetting the stores.

2. Circuit arrangement according to Claim 1, wherein the resetting device has two signal producing elements which, during turning the steering device back into the neutral position, release signals in a way that the trigger signal for resetting a said store is blocked in dependence on the direction of turn of the steering wheel.

3. Circuit arrangement according to Claim 2, wherein each signal producing element is connected to the setting input of one reset store and the clear input of another reset store and that to the outputs of the reset stores a respective monostable device is connected, the output signals of which are conducted to the clear inputs of the first mentioned stores as trigger signals.

4. Circuit arrangement according to Claim 2 or 3, wherein the signal producing elements of the resetting device work on an electrosptic, electromagnetic or electromechanic basis.

5. Circuit arrangement according to Claim 4, wherein each signal producing element is equipped with a contact spring sliding on a contact path the length of which is dependent on the steering wheel movement and having a contact gap.

6. Circuit arrangement according to Claim 5, wherein the contact path is disposed on a disk secured or securable to the steering tube.

7. Circuit arrangement according to Claim 6, wherein the contact path is a spiral path in which the contact spring is guided.

8. Circuit arrangement according to any pre ceding claim wherein the direction indicator switch is provided with two switch positions at each of which by repeated actuation of the switch respective lamp circuits can be switched on and off.

9. Circuit arrangement according to Claim 8, wherein for the control signals of the switch

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

control currents have to be switched by the mechanical part of the resetting system, that is the switch disk 31 and the direction indicator switch, so that cheaper contacts can be used.

All these components at the present state of the art can be integrated into one circuit. Because the development of such a circuit is relatively expensive, preferably a microprocessor can be used which can be programmed accordingly, so that the desired switching functions can be realised. In this case the circuit design can vary from the diagram shown in Figure 1 without departing from the scope of the invention.

In the embodiment according to Figure 1 it is assumed that the switch disk 31 during the steering wheel turn from the left hand direction of travel to the right hand direction of travel will be turned less than 360". This can easily be achieved if necessary with a suitable gear. A design according to Figure 2 and 3 is, however, much simpler. Said design has spiral contact paths 90 at the upper side and at the underside in which assigned contact springs 34, 35 are guided. In this manner it is ensured that only in the neutral position of the steering wheel do the contact springs 34 and 35 rest upon the contact gap 33. Such a switch disk can be made of metallic material, with the contact paths defined by insulated strips.This is possible because in the stated circuit an open input of an element is in the Estate. In the area of the contact gap 33 the contact springs, however, via the steering tube 30 are directly connected to ground. Instead of a spiral contact path of course a helical contact path can be provided which is made by putting insulating strips round the steering tube 30. The radial extension of the mechanical part of the resetting device can thereby be reduced.

The size of the contact gap 33 depends on the desired hysteresis of the resetting device.

When the contact gap is made very small the resetting device is already operated after a small turn of the steering wheel. With a large contact gap the lamp which is on will be switched off only when the steering wheel is turned through a relatively large angle. The adaptation to the different gear ratios of the various vehicles can thereby be performed much simpler than with known mechanical resetting systems.

In the embodiment shown in the drawing it is provided, in accordance with conventional circuit arrangements, that the lane change flashing is effective as long as the direction indicator switch is actuated. It can, however, be provided that for instance upon connecting the bridging contact 25 to one of the inputs 21 and 22 one of a pair of monostable (not shown) is set, so that the lane change flashing will automatically be switched off after a certain time, e.g. after

5 seconds. The monostables suitably have to be able to be reset before this time expires, so that the indication of direction can be changed quickly, if necessary.

A similar timing element could also be used in connection with the resetting element 70 which provides that in any case the set store will always be reset after a certain time has expired or if the steering column switch is not returned to its neutral position. Such an additional equipment is desirable when the switching hysteresis of the resetting system is such that it will not respond on large-radius bends.

WHAT WE CLAIM IS: 1. Circuit arrangement for energising direction indicator lamps in a motor vehicle which may be manually actuated by means of a direction indicator switch and reset by a resetting device influenced by turning the steering wheel, wherein operation of the direction indicator switch in accordance with the desired direction of travel sets one of two electric stores which connects the clock signal of a clock pulse generator to provide an energising signal for the corresponding indicator lamp via a respective gate, and wherein the resetting device releases trigger signals characterising the direction of rotation of the steering wheel for resetting the stores.
2. Circuit arrangement according to Claim 1, wherein the resetting device has two signal producing elements which, during turning the steering device back into the neutral position, release signals in a way that the trigger signal for resetting a said store is blocked in dependence on the direction of turn of the steering wheel.
3. Circuit arrangement according to Claim 2, wherein each signal producing element is connected to the setting input of one reset store and the clear input of another reset store and that to the outputs of the reset stores a respective monostable device is connected, the output signals of which are conducted to the clear inputs of the first mentioned stores as trigger signals.
4. Circuit arrangement according to Claim 2 or 3, wherein the signal producing elements of the resetting device work on an electrosptic, electromagnetic or electromechanic basis.
5. Circuit arrangement according to Claim 4, wherein each signal producing element is equipped with a contact spring sliding on a contact path the length of which is dependent on the steering wheel movement and having a contact gap.
6. Circuit arrangement according to Claim 5, wherein the contact path is disposed on a disk secured or securable to the steering tube.
7. Circuit arrangement according to Claim 6, wherein the contact path is a spiral path in which the contact spring is guided.
8. Circuit arrangement according to any pre ceding claim wherein the direction indicator switch is provided with two switch positions at each of which by repeated actuation of the switch respective lamp circuits can be switched on and off.
9. Circuit arrangement according to Claim 8, wherein for the control signals of the switch

positions, switch terminals are connected to the setting inputs of the first mentioned stores.
10. Circuit arrangement according to Claim 8 or 9, wherein upon actuation of the switch at each position the first mentioned store controlled by the other switch position is cleared.
11. Circuit arrangement according to any preceding claim, wherein for lane change flashing of the lamps the gates which are directly connected to the clock pulse generator are enabled via two intermediate switch positions of the direction indicator switch.
12. Circuit arrangement according to Claim 11, wherein for lane change flashing of the lamps the control signals of the intermediate switch positions are conducted to the clear in- puts of the first mentioned stores.
13. Circuit arrangement according to Claim 11 or 12, wherein the control signals of the intermediate switch positions for lane change flashing are conducted to the gates through further monostable devices.
14. Circuit arrangement according to Claim 13, wherein the further monostable devices are provided with means whereby the devices can reset before the monostable period has expired.
15. Circuit arrangement according to any preceding claim, wherein both gates are controllable simultaneously by a hazard warning switch.
16. Circuit arrangement according to Claim 15, wherein the operating voltage can be connected to both gates via the warning switch.
17. Circuit arrangement according to Claim 3 or any one of Claims 4-16 when dependent on Claim 3, wherein the reset stores, the monostable devices of the resetting device, the first mentioned stores and the gates, power output stages and the clock pulse generator are combined in an integrated circuit.
18. Circuit arrangement according to Claim 17, wherein the integrated circuit is constituted by a microprocessor.
19. A circuit arrangement for energizing the direction indicator lamps of motor vehicle, substantially as hereinbefore described with reference to Figure 1, or Figure 1 modified by Figures 2 and 3, of the accompanying drawings.
20. A motor vehicle having a circuit arrangement according to any of Claims 1 to 19.