ELECTRICAL DRIVING SYSTEM FOR FOLDABLE REARVIEW MIRRORS OF A MOTOR VEHICLE

Abstract: An electrical driving system for the rearview mirrors of a vehicle, wherein incorporated motors (MR, ML) are rotated normally or reversibly in response to the operation of an operational switch (10), thereby erecting or folding the mirror bodies. The system comprises a momentary operational switch (10), a relay circuit (31, 32), a group of limit switches (41L, 41R, 42L, 42R) for cutting off the relay circuit and motor circuit (35, 36), respectively, by detecting erected and folded positions of the mirror bodies, and a circuit (50) for judging a folded state. When the operational switch is pushed, any folded mirror is detected within the delay time of the circuit for judging a folded state. And only when both of the left and right mirror bodies are in the folded positions, the erecting relay (Ry1) is actuated to rotate the motors in the erecting direction.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a rearview mirror and, more particularly, to an electrical driving system for a plurality of foldable rearview mirrors of a motor vehicle, of the general kind as disclosed in JP-A 61-105247. 2. Description of the Prior Art Outer rearview mirrors are suitably folded at their mirror body to reduce their length when parking or storing motor vehicles. Recently, there have been electrically foldable rearview mirrors whose mirror body is turned from an erected position to a folded position with a reversible motor mounted in the mirror body. In a respective driving system, relays and self-holding circuits are provided to let the motors be rotated and stopped indirectly in response to the operation of a switch, instead of rotating and stopping the motors directly by operating a switch. Such an improved driving system is disclosed for example in Japanese Patent Application laid-open under No. Sho 61-113533. In this system, a motor circuit for each of the right and left mirror bodies includes an erecting relay and its holding circuit which are operated when turning the mirror body from the folded position to the erected position, as well as a folding relay and its holding circuit which are operated when turning the mirror body from the erected position to the folded position. At either of the turning ends of the mirror body, a limit switch is operated to release a self-holding state so as to stop the motor automatically. In this driving system, however, the limit switches for detecting the erected and the folded positions of the left and right mirror bodies can only put operating relays in a non-exited condition, and they can not put both relays and motors out of operation. Besides, it is necessary to provide erecting and folding relays and self-holding circuits for each of the left and right reversible motors. Therefore, the overall circuit is complicated, is inevitably large in size, requires a large number of assembling steps and dictates high cost of manufacture. In Japanese Patent published under No. Sho. 61-105247 this applicant has disclosed a driving circuit for electrically foldable rearview mirrors which comprises a single-pole momentary push button switch, erecting and folding relays operated with the said bush button switch, a plurality of reversible motors rotated by the operation of either of the said relays, a single-pole single-throw switch interlocked with the said push button switch, and a folded-state judgment circuit provided with a PNP-type transistor. This driving circuit has an operation mode in which the folding relay is preferentially operated by the operation of the momentary push button switch, it is judgmented under the "ON" condition of the folding circuit whether both of the left and right mirrors are in the folded positions, both of the left and right mirrors are erected only when they are in the folded positions, either or both of the left and right mirrors are folded when they are not in the folded positions. That is, when both of the left and right mirror bodies are in the folded positions, the folding relay is excited first by pushing the push button, then plus voltage is impressed to the emitter of the transistor through a transfer contact. Because of earth potential applied to the base of the transistor through the closed single-pole single-throw switch interlocked with the push button, the transistor is put into "ON" condition at the same time, and the erecting relay is excited. Since, the transfer contact of the folding relay changes over by the excitation of the erecting relay to demagnetize the folding relay, and since, the erecting relay is self-held with the limit switch, and so the motors of the left and right mirror bodies are rotated to an erecting side. When the mirror bodies reach the erecting ends, the limit switch is mechanically forced open, and the motors are stopped by opening the motor circuits. When one of the left and right mirror bodies is in the folded position, and the other is in the erected position or in the intermediate position between the erected and folded states, the unfolded mirror body is laid back and both of the mirror bodies are stopped in the folded position by the first operation of the push button, then the mirror bodies on both sides are turned in the erecting direction. That is, when the other mirror body is in the unfolded position, as described above, the folding relay is excited. Then the transfer contact of the folding relay changes over to impress plus voltage to the base of the PNP-type transistor through the single-pole single-throw switch interlocked with the limit switch and the push button switch on the unfolded position side. Since the transistor is not put to "ON" by this impressed voltage, the erecting relay is not excited, but because of the self-held folding relay the motor of the mirror body is turned from the unfolded position to the folded position. At one turning end of the mirror body the limit switch on the folding side is opened to stop the motor. Since a single-pole single-throw switch interlocked with the push button is provided on the base input side of the PNP-type transistor, no folding operation begins immediately as long as the next operation of the push button is not performed after the mirror body has been folded. The push button switch and the single-pole single-throw switch interlocked therewith, however, form a two-pole single-throw operational switch. Therefore, the overall circuit is complicated in construction, is low in degree of freedom of design and is large in size. It requires also a large number of wires between the switches and the control circuit as well as multi-pole connectors, and dictates high cost of manufacture. An object of the present invention is to provide a compact and cheap driving circuit operated with only one momentary single-pole single-throw switch. Another object of the present invention is to provide an electrically driving circuit for foldable rearview mirrors which ensures an accurate folding operation and can be provided at low cost. SUMMARY OF THE INVENTION The present invention is characterized in claim 1. According to the present invention, it is judgmented by plus or minus of the voltage impressed to the base of a PNP-type transistor within the delay time of a delaying circuit provided on the output side of the transistor whether the left and right mirror bodies are in folded positions, and an erecting relay is operated only when the left and right mirror bodies are in the folded positions. In one preferred embodiment of the present invention, a circuit for judging a folded state comprises a PNP-type transistor and a delaying element provided on the output side of the said transistor, and this judgment circuit is connected in series with an erecting relay. A folding relay circuit comprises a folding relay, a transfer contact of the said relay, and a self-holding circuit equipped with limit switches for detecting folded positions. In another embodiment of the present invention, a timer circuit is connected in series with the said folding and erecting relays respectively. The said timer circuits put both relays into actuation for a predetermined period of time by means of an electric charge obtained when throwing an operational switch. The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims taken in conjunction with the accompanying drawings which show by way of example preferred embodiments of the present invention and in which like components parts are designated by like reference numerals throughout the various figures. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig. 1 is a schematic front view showing an outer rearview mirror folding system embodying the present invention; Fig. 2 is a circuit diagram showing one embodiment of the system according to the present invention; Fig. 3 is a timing chart of the circuit of Fig. 2; Fig. 4 is a circuit diagram showing another embodiment of the system according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the drawings. As concerns the circuit arrangements, particular reference to the drawings is made so as not to overloaden the description. It is thus emphasized that the details of the circuit arrangements shown in the drawings are intended to be materially disclosed. Referring first to Fig. 1, there is shown a folding system of an outer rearview mirror assembly suitable to be associated with a motor vehicle. This system includes an operational switch 10 provided in a vehicle compartment, a controller 30, and left and right mirror assemblies 11 and 12. Each mirror assembly 11 or 12 includes a shaft 15 provided upright on an extension 14 of a base 13, a frame 16 rotatably supported on the shaft 15, mirror body 17, a gear box 18 provided in a rotating part of the frame 16 near the shaft, a built-in reduction gear mechanism 19 of the gear box and an electric motor 20 secured to the top of the gear box 18, for folding the mirror. The reduction gear mechanism 19, as shown in Fig. 1, consists of a reduction gear train connected to a motor output shaft worm gear 21, and to an output gear 22 which engages with a clutch gear 23 mounted on the shaft 15. The clutch gear is spring-biased by a resilient spring 24 towards a clutch retainer 25 secured to the top of the shaft. Fig. 2 shows an electronic circuit diagram of the said controller 30. This circuit diagram includes the switch 10 which is a single-pole single-throw momentary operational switch 10, an erecting relay circuit 31 comprising an erecting relay Ry1 which is closed when turning one of the mirror bodies 17 to an erected position side, a folding relay circuit 32 comprising a folding relay Ry2, motor circuits 35 and 36, limit switches 41R, 42R, 41L and 42L, and a circuit 50 for judging a folded mirror body connected in series with the erecting relay Ry1. The erecting relay circuit 31 and the folding relay circuit 32 are connected in parallel with each other. A transfer-type relay contact S1 of the erecting relay Ry1 is connected in parallel with a transfer-type relay contact S2 of the folding relay Ry2, thereby forming self-holding circuits of both relays. The limit switches 41R and 42R detect the erected and folded positions, respectively, of the right mirror body 17, and the limit switches 41L and 42L detect the erected and folded positions, respectively, of the left mirror body. These limit switches are provided, for example, on the top surface of the extension 14, but they are omitted from Fig. 1. Each pair of these limit switches is connected in series with each other in the motor circuit 35 and 36 respectively with each reversible motor MR and ML between. The motor circuits 35 and 36 include overcurrent protection posistors PR, PL comprising positive characteristic thermistors. The circuit 50 for judging a folded state includes resistors r2 and r3, a PNP-type transistor Tr1, and delaying elements (comprising a resistor r4 and capacitor C1). When the electric current flows from the terminal N to the terminal B, the reversible motors MR and ML turn the mirror bodies towards the folded position, and when it flows from the terminal B to the terminal N, they turn the mirror bodies towards the erected position. The circuit arrangement further comprises a resistor r1 and diodes D1 to D13, connected as shown in the drawing. Now, the operation of the embodiment shown in Fig. 2 will be described. First, the case where both of the left and right mirror bodies are in the folded positions will be described. When the switch 10 is pushed while the left and right mirror bodies are in the folded positions, the folding relay Ry2 is actuated first, and then the transfer contact S2 changes over to NO. Since the limit switches 42R and 42L of the folding side are in positions "OFF", and since the limit switches 41R and 41L of the erecting side are in positions "ON", minus potential is applied to the base of the transistor Tr1 through the resistors r1 and r2. The transistor Tr1 is put to "ON", but by using the delaying elements r4 and C1, the relay Ry1 is excited after a predetermined period of time t1. By means of the excited relay Ry1 the transfer relay contact S1 changes over to NO side, and simultaneously with this change-over the relay Ry1 is self-held through diodes D5 and D6, while the relay Ry2 is demagnetized by the change-over of the transfer relay contact S1, and the relay contact S2 changes over to NC side. Then the motor circuits 35 and 36 passing along the NO contact of the relay contact S1, the posistors PR and PL, the limit switches 41R and 41L, the diodes D3 and D4 as well as the NC side of the relay contact S2, are closed, and the electric current flows from the terminal B to the terminal N, rotating the motors MR and ML so that the mirror bodies are turned to the erecting side. At the beginning of the erecting operation the limit switches 42R and 42L are put to "ON". When the limit switches 41L and 41R are put to "OFF" after the mirror bodies have reached the erecting ends, the motor circuits 35 and 36 are opened to stop the motors. The timing chart of the above-described operation is shown in I of Fig. 3. When the switch 10 is pushed while both of the left and right mirrors are in the erected positions, the folding relay Ry2 is excited through the NC circuit of the transfer contact S1. By means of the excited relay Ry2 the transfer relay contact S2 changes over to NO side, and the relay Ry2 is self-held through the limit switches 42R and 42L and the diodes D7, D8 and D9, while the motor circuits 35 and 36 are closed through the motors MR and ML, the diodes D1 and D2 and the NC circuit of the transfer contact S1, and then the electric current flows from the terminal N to the terminal B, reversing the motors MR and ML so that the mirror bodies are turned towards the folded positions. At the beginning of the turning of the mirror bodies the limit switches 41R and 41L will be put to "ON". When the mirror bodies have reached the folded positions, the limit switches 42R and 42L are put to "OFF", thus turning off and stopping the motors MR and ML. At the same time minus potential is impressed to the cathode sides of the diodes D7 and D8, so that the relay Ry2 is demagnetized (see II of Fig. 3). In this process, if either of the mirror bodies, for example, the left mirror body has reached the folded position before the right mirror body, the limit switch 42L is put to "OFF", thereby stopping only the left motor ML. But since the relay Ry2 is self-held through the limit switch 42R and the diode D7, the reversible motor MR remains "ON" till the right mirror body reaches the folded position. If the right mirror body has reached the folded position before the left mirror body, the left motor ML remains "ON" till the left mirror body reaches the folded position. If overcurent flows in the motor circuits 35 and 36, the motors are stopped by means of the actuated posistors PL and PR. As described above, while either of the limit switches 42R and 42L is in position "ON", the transistor Tr1 is not put to "ON" because of the potential of "H" level impressed to the base thereof through the resistor r2. Only when both of the limit switches 42R and 42L are in position "OFF", the potential of "L" level is impressed to the base of the transistor Tr1 through the resistors r1 and r2, thereby putting the transistor to "ON". The transistor Tr1 comes into actuation when the switch 10 is put to "ON", and it judges the folded state while passing along the output delaying circuit. That is, when either of the left and right mirror bodies continues to be folded, the transistor Tr1 goes out of actuation, and when the mirror body is already in the folded position, the transistor continues to be actuated, thus exciting the relay Ry1 through the delaying circuit of the output side thereof. When the switch 10 is pushed while, as described above, one of the left and right door mirrors is in the folded position, and the other is in the non-folded position, the potential of the base of the transistor Tr1 is pulled down to "L" level by the resistor r1, thus putting the transistor Tr1 to "ON" and trying to excite the relay Ry1 after the delaying time t1 determined by the resistor r4 and the capacitor C1. But, since either of the limit switches 42R and 42L is in position "ON", the potential of the base of the transistor Tr1 is soon raised to "H" level, thus putting the transistor Tr1 to "OFF". Assuming that the period of time from "ON" to "OFF" of the transistor Tr1 is expressed as t2, a relation t2<t1 is predetermined, so that the relay Ry1 is not excited and only the relay Ry2 remains "ON", thereby folding the non-folded mirror body. Now, another embodiment of the present invention will be described with reference to Fig. 4. In this embodiment, a timer circuit 60 is additionally connected in series with each of the folding relay and the erecting relay. This timer circuit 60 comprises a charge and discharge circuit including a diode D14, resistors r5, r6 and r7, and a capacitor C2, as well as transistors Tr2 and Tr3, and diodes D15 and D16. The bases of the transistors Tr2 and Tr3 are connected in parallel with each other. The collector of the transistor Tr2 is connected in series with the erecting relay Ry1, and the collector of the transistor Tr3 is connected in series with the folding relay Ry2. The overall circuit is the same as in Fig. 2 except for that no posistors are used. When the switch 10 according to Fig. 4 is pushed, the capacitor C2 is charged through the diode D14 and the resistor r5. The electric charge accumulated in the capacitor C2 is discharged through the resistors r6 and r7, keeping the transistors Tr2 and Tr3 "ON" for a predetermined period of time and thus exciting the folding relay Ry2. When the left and right mirror bodies are in the erected positions, the relay contact S2 changes over to NO side, so that the relay Ry2 is self-held, while the erecting relay Ry1 remains non-excited since the transistor Tr1 of the circuit 50 for judging the folded state is not put to "ON". When the switch 10 is pushed while the left and right mirror bodies are in the folded positions, the relay Ry2 is not self-held because of the "OFF" positions of the limit switches 42R and 42L. As a result thereof the timer circuit 60 is actuated to close the circuit including the transistor Tr3, diode D15, limit switches 41R and 41L, diodes D5 and D6, relay Ry1, transistor Tr2, and diode D16 after a predetermined period of time, and then the electric current flows from the terminal B to the terminal N, rotating the motors MR and ML so that the mirror bodies are turned to the erected side. As in the first embodiment, the relay contact S1 changes over to NO side and is self-held by means of the excited relay Ry1. As described above, the limit switches 41R, 41L, 42R and 42L detect the folded or erected position of the mirror bodies, and then the folding relay is preferentially actuated. When the circuit 50 for judging the folded state detects the erected mirror bodies thereafter, the folding relay is kept excited, and when the circuit 50 detects the folded mirror bodies, the folding relay is put to "OFF", and the erecting relay is excited. If any of the mirror bodies is not erected or folded, by coming into contact with any other structures, the limit switch 41R, 41L, 42R or 42L is not put to "OFF" within a predetermined period of time, so that the said transistor Tr2 or Tr3 is put to "OFF", and the relay Ry1 or Ry2 is immediately unexcited. Therefore, the motors MR and ML can be protected from overcurrent without using posistors.

Claims: An electrical driving system for a plurality of foldable rearview mirrors of a motor vehicle, said mirrors each comprising a rearview mirror body (17) foldably mounted at the outer sides of the vehicle, the driving system comprising: a momentary operational switch (10) provided in the vehicle compartment, to be operated for folding or for erecting the mirror bodies (17); two parallel relay circuits (31,32) coupled in series to the momentary operational switch (10) and including respectively an erecting relay (Ry1) and a folding relay (Ry2) which are capable of being excited in response to the operation of said switch (10) for throwing over a transfer contact switch (S1,S2) each, each of the transfer contact switches comprising two stationary contacts each connected to one of the polarities of a dc current supply, and a movable contact; a plurality of motor circuits (35,36) each associated to one of the foldable mirrors and being coupled between the movable contacts of the transfer contact switches (S1,S2), each motor circuit (35,36) comprising in series for a associated foldable mirror a reversible motor (ML,MR) and two limit switches (41L,41R,42L,42R) respectively operated by the associated mirror body (17) when reaching the folded or the erected position; relay-self-holding circuits (S2-NO,D7,D8,D9,Ry2; S1-NO,D5,D6,Ry1), each comprising one of the relays (Ry2,Ry1) and in series to the relays and in parallel to each other the associated limit switches (41L,41R,42L,42R); the movable contacts in the transfer contact switches (S1,S2) being switched to the same polarity if non of the relays is excited, and being switched to the other polarity in one of the switches if the associated relay is excited; characterized in that the relay circuit (31) of the erecting relay (Ry1) for preferentially exciting the folding relay (Ry2) in response to the operation of the single momentary operational switch (10), comprises a delay means (r4,C1) which delays the operation of said erecting relay after the operation of the momentary operational switch (10), and further, for judging whether at least one of the mirror bodies (17) is not being in the folded state upon closure of the momentary operational switch (10), comprises in series with the delay means a switching element (Tr1) which interrupts the relay circuit (31) upon closure of the relay-self-holding circuit (S2-NO,D7,D8,D9,Ry2) for the folding relay (Ry2). Electric driving system according to claim 1, characterized in that the switching element is a transistor (Tr1) the base of which is connected via resistors (r1,r2) to one of the polarities of the current supply, a point intermediate these resistors being connected to the relay-self-holding circuit (S2-NO,D7,D8,D9,Ry2) at a point where the parallel branches to each of the associated limit switches (42L,42R) of the folded positions of the mirror bodies (17) have already been united via diodes. Electrical driving system according to claim 1 or 2, characterized in that each of the relay-self-holding circuits (S2-NO,D7,D8,D9,Ry2) includes one of the transfer contact switches (S1,S2) which change over from "normal close" (NC) to "normal open" (NO) when the associated relay of the circuit concerned is excited. Electrical driving system according to any of claims 1 to 3, characterized in that said operation switch (10) is a push button which is automatically reset by one-push. Electrical driving system according to any of the claims 1 to 4, characterized in that said motor circuit (35,36) includes overcurrent protection posistors (PR,PL) which are connected in series with said motors (MR,ML). Electrical driving system according to any of the claims 1 to 4, characterized in that each relay circuit (32,31) of said folding relay (Ry2) and erecting relay (Ry1) includes a timer circuit (60) which is connected in series therewith.

Inventors: NAKAYAMA, KIYOSHI
Applicants: MURAKAMI KAIMEIDO CO., LTD
Application year: 1988
Main classification: B60R1
IPC codes: B60R1