Motor antenna device for use with vehicules

Abstract: A power source (RX) for a car radio receiver which is kept on-state is temporarily turned off by a starter switch (12). However, three-second timer (20) is arranged between the power source (RX) and an antenna motor (M) to keep the antenna motor (M) not driven for three seconds even when the power source (RX) is shut off. This prevents the motor antenna to be unneces­ sarily lifted and lowered every time when the starter switch is made on and off.

Description: The present invention relates to a motor antenna device for use with vehicles wherein a motor antenna is lifted and projected outside the vehicle or car when a power source for electronic appliances such as the radio receiver, for example, mounted in the car is switched on and wherein it is lowered and housed in the car body when the power source is switched off. In the case of the conventional motor antenna device for use with vehicles, the power source for accessories is switched off during the time when the engine starter is to be made operative, for the purpose of making small the load for the battery. Therefore, the motor antenna is lowered because the power source for the radio receiver is switched off. When the engine starter is made operative, the antenna is again lifted because the radio power source is switched on. The present invention provides a motor antenna device for use with an antenna rod and arranged to lift or lower the antenna rod, the device being adapted for connection to a power source and comprising: a motor capable of rotating in a forward direction and a reverse direction; a driving mechanism comprising a damper coupled to the motor and adapted to be coupled to the antenna rod whereby to transfer rotational force from the motor to the antenna rod to lift or lower the antenna rod; motor driving circuitry comprising motor polarity changeover circuitry connected in series with the motor and arranged to control the direction of current flow from the power source through the motor; motor lock detector connected in series with the motor and arranged to detect the current flowing through the motor when it is mechanically locked; and motor control circuitry arranged to cause the disconnection of the motor from the power source when a motor lock state is detected by the lock detector; characterized in that: the motor driving circuitry further comprises a motor driving device responsive to the motor control circuitry connected in series with the motor polarity changeover circuitry and arranged to turn on or off the current flowing through the motor; and the lock detector comprises a variable resistive element having a positive temperature/resistance characteristic. In prior art devices, when the engine is to be started after engine stop, for example, with the motor antenna extended, the motor antenna is lowered and then lifted although it is wished that the motor antenna be left extended. The same occurs in the case where the engine is stopped, the radio is enjoyed and the engine is then started again. In order to eliminate this drawback, it is conventionally examined on the basis of the logical condition of ignition and accessories voltages whether the starter is operated or not, and the antenna motor is stopped while the starter is being operated. Because the conventional devices need it to be determined on the basis of the logical condition whether the starter is operated or not, three control lines for detecting the radio power source, ignition and accessories voltages are needed and the control circuit for calculating the logical condition is complicated. A preferred embodiment of the present invention provides a motor antenna device for use with vehicles as defined above having a logic circuit which enables the motor antenna to be appropriately operated, associating with the power source for electronic appliances such as the radio receiver mounted in the vehicle. This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Fig. 1 is a block diagram showing an embodiment of the present invention; Fig. 2 shows the circuit in Fig. 1 in more detail; Fig. 3 is a time chart in the circuit shown in Fig. 2; Fig. 4 is a sectional view showing an antenna driving system; Fig. 5 shows how motor current changes; Fig. 6 is a circuit diagram showing another embodiment of the present invention; Fig. 7 is a time chart in the circuit shown in Fig. 6; Fig. 8 is a circuit diagram showing a further embodiment of the present invention; Fig. 9 is a time chart in the circuit shown in Fig. 8; Fig. 10 is a circuit diagram showing a still further embodiment of the present invention; Fig. 11 is a circuit diagram showing a control box for use in the circuit shown in Fig. 10; Fig. 12 is a time chart in the circuit shown in Fig. 10; and Fig. 13 is a circuit diagram showing another example of the operation panel shown in Fig. 11. Fig. 1 is a circuit diagram showing a case where the present invention is applied to the motor antenna for the radio receiver. Battery 11 is earthed at the low voltage side thereof and connected at the high voltage side thereof to one end of starter switch 12 which is associated with the engine key. Starter switch 12 has an ACC (accessories) terminal, to which the power source terminal of radio receiver 10 is connected. Voltage at the other end RX of the radio power source becomes "H" (high) in level when a radio switch (not shown) is turned on and "L" (low) in level when the radio switch is turned off. Input terminals of three-second timer 20 and antenna raising or lifting trigger circuit 32 are connected to terminal RX of radio power source and an input terminal of antenna lowering trigger circuit 31 is connected to an output terminal of three-second timer. Three-second timer 20 includes a resettable multi-vibrator and serves to output signal "H" when voltage at terminal RX of radio power source is "H" level and output signal "H" for three seconds after voltage at terminal RX of radio power source becomes "L" level. Antenna lowering trigger circuit 31 generates a trigger when the output signal of three-second timer 20 falls. Antenna lifting trigger circuit 32 generates a trigger when signal applied from terminal RX of radio power source rises. Motor polarity changeover circuit 40 changes over the polarity of antenna motor M with respect to that of the battery 11 so as to lift the motor antenna when antenna lifting trigger circuit 32 generates a trigger, but it changes over the polarity of antenna motor M so as to lower the motor antenna when no trigger is generated through circuit 32. Motor power source changeover and control circuit 50 is connected in series to antenna motor M and serves to supply power to motor M when antenna lifting or lowering trigger circuit 32 or 31 generates a trigger signal. MOtor power source changeover and control circuit 50 also detects current increase in motor M and stop power supply to motor M when the top of the motor antenna reaches its uppermost or lowermost point. Three-second timer is an example of the means for stopping the lowering of the motor antenna for a predetermined time after the radio power source is switched off. Fig. 2 is a circuit diagram showing the above-described embodiment of the present invention in more detail. Motor polarity changeover circuit 40 includes relay 41, transistor (2SC2458, for example) 42 connected in series to relay 41, and contact 43 of relay 41. Contact 43 has two points of contact and when they are connected to terminal U, motor M is rotated in forward direction to lift the motor antenna but when they are contacted with terminal D, motor M is rotated in reverse direction to lower the motor antenna. Motor power source changeover and control circuit 50 inciudes drive transistor (2SC686, for example) 51 connected in series to motor M, positive characteristic temperature/resistance element 52 such as posistor connected to the emitter of transistor 51, NAND gate 53 and RS flip-flop (F/F) 54. Transistor 51 allows current to be supplied to motor M when flip-flop 54 is set. Flip-flop 54 is set at the rising or falling of signal outputted from three-second timer 20 and re-set when NAND gate 53 generates a negative pulse. Voltage at both ends of element 52 becomes high in response to current flowing to motor M and when the top of the antenna reaches its uppermost or lowermost point, current, larger than a predetermined value, flows to motor M and voltage at both ends of element 52 becomes extremely large. NAND gate 53 generates a pulse to reset flip-flop 54 when current flowing to motor M becomes larger than the predetermined value. The rising of the output signal of three-second timer (or rising of the output signal through terminal RX of radio power source) is detected by inverter 61 for inverting the output signal of three-second timer 20, condenser 62 and resistor 63, while the falling of the output signal of three-second timer 20 (or falling of the output signal through terminal RX of radio power source) is detected by condenser 64 and resistor 65. 0.2-second timer 71 generates a negative pulse of 0.2 second when the output signal of three-second timer 20 rises or falls and this negative pulse of 0.2 second serves to set flip-flop 54 and prevent flip-flop 54 from being re-set by rush current of motor M. Ten-second timer 81 generates a negative pulse for ten seconds after the output signal of three-second timer 20 rises or falls, and condenser 82 generates a positive pulse when the output signal of ten-second timer 81 rises. This positive pulse forcedly re-sets flip-flop 54 through NAND gate 53 to stop power supply to motor M even if element 52 generates no predetermined voltage when motor M is locked. AND gate 91 and transistor (2SC2458, for example) 92 for stabilizing power source are further included. AND gate 91 serves to turn on transistor 42, excite relay 41 and connect contact 43 to terminal U while three-second timer 20 generates signal "H" and flip-flop 54 is set. Fig. 3 is a time chart showing the operation of the above-described embodiment. When the key is turned, ACC and IG switches are put on and terminal RX of radio power source is turned on at time t1. Voltage at the input terminal of three-second timer 20 is thus made "H" in level and the output signal of three-second timer 20 becomes "H". The output signal of inverter 61 rises, a negative pulse is generated by a differentiation circuit comprising condenser 62 and resistor 63, and 0.2-second timer 71 generates a negative pulse of 0.2 seconds. Further, ten-second timer 81 outputs a negative signal. Therefore, flip-flop 54 is set at time t1. When flip-flop 54 is set, transistor is turned on to supply current to motor M. Output Q of flip-flop 54 is "H" and the output signal of three-second timer 20 is also "H" in this case. Therefore, the output signal of AND gate 91 becomes "H", transistor 42 is turned on, relay is excited, contact 43 is connected to terminal U and antenna motor M is rotated in such a direction (or direction shown by an arrow in Fig. 2) as to lift the motor antenna. Even when rush current flows and voltage at both ends of element 52 becomes high in an instant just after motor M starts its rotation, 0.2-second timer 71 generates a negative pulse for 0.2 seconds. Therefore, gate 53 generates no negative pulse, flip-flop 54 is not reset, and motor M is not stopped for this time period of 0.2 seconds. Because current is small in motor M after the lapse of 0.2 seconds, voltage at both ends of element 52 does not reach a predetermined value accordingly, input 2 of gate 53 does not become "H" and flip-flop 54 is not re-set for a while. Therefore, the motor antenna is gradually lifted. When the top of the motor antenna reaches its uppermost point at time t2, motor M is locked. Motor current thus becomes large and voltage at both ends of element 52 becomes larger than the predetermined value. This causes input 2 of NAND gate 53 to become "H". Input 1 of NAND gate 53 also becomes "H" at this time. Therefore, gate 53 generates a negative pulse to re-set flip-flop 54. Transistor 51 is thus turned off to stop current supply to motor M. Output Q of flip-flop 54 becomes "L" at this time. Therefore, the output of gate 91 also becomes "L", transistor 42 is turned off, relay 41 is not excited and contact 43 is connected to terminal D. When terminal RX of radio power source is put off at t3, the output signal of three-second timer 20 becomes "L" at t4 after the lapse of three seconds, the falling of this signal is detected by the differentiation circuit of condenser 64 and resistor 65, and 0.2-second timer 71 generates a negative pulse for 0.2 seconds to set flip-flop 54. Transistor 51 is thus turned on and current flows to motor M. Since contact 43 is connected to terminal D at this time, current flows to motor M in a direction reverse to the direction shown by the arrow and the motor antenna is lowered. The top of the motor antenna reaches its lowermost point, motor M is locked, current in motor M increases and voltage at both ends of element 52 becomes higher than the predetermined value at t5. Therefore, gate 53 generates a negative pulse, flip-flop 54 is re-set and transistor 51 is put off to stop current supply to motor M. The lifting and lowering of the motor antenna are repeated responsive to on and off of terminal RX of radio power source, as described above. The engine stops, for example, while the motor antenna is being lifted, and when starter St is turned at t11, terminal RX of radio power source is turned off and the input voltage of three-second timer 20 becomes "L". The engine is usually started in three seconds. Therefore, the time of holding starter St turned is also three seconds or less. When it is assumed that starter ST is turned back at t12, t13 at which delay time td in the rising of signal through terminal RX of radio power source has passed from t12 is usually in three seconds from time t11. Therefore, the output signal of three-second timer 20 is held "H" even at t13. The output of gate 91 is thus kept "H", transistor 42 is turned on and motor M is kept rotating in forward direction. Even when the starter is turned for a short time while the motor antenna is being lifted, the output of three-second timer 20 is kept "H" and transistor 42 is not turned off. Therefore, motor is not rotated in backward direction and the antenna is not lowered. At time t14 at which ten seconds have passed since time t1, the output of ten-second timer 81 rises, and a positive pulse is generated at the output terminal of condenser 82, thereby causing flip-flop 54 to be forcedly set after ten seconds. The top of the motor antenna usually reaches its uppermost point in ten seconds and when the top of the motor antenna reaches its uppermost point and current is kept flowing to motor M after the lapse of ten seconds because of the abnormality of element 52, flip-flop 54 is forcedly re-set responsive to the output signal of ten-second timer 81 to stop current supply to motor M. This guarantees high safety. Even when starter ST is turned for a short time at t21 at which the top of the motor antenna is at its uppermost point, the output signal of three-second timer 20 is kept "H" for three seconds during which t22 and delay time td in the rising of signal through terminal RX of radio power source have passed. Therefore, current is not supplied to motor M and the motor antenna is kept normal. Timer 20 has been set three seconds in the above-described embodiment, but it may be set from 2 to 10 seconds. Any means except the resettable multi-vibrator may be used instead of three-second timer 20 to prevent the antenna from being lowered for a predetermined time after the power source of the radio receiver is switched off. Further, timers 71 and 81 may be set any seconds different from 0.2 and 10 seconds. According to the above-described embodiment of the present invention, there can be provided a control device, simple in construction and kept normal even when the starter is rendered operative, wherein two control lines for detecting the states of the ignition and the accessories are not needed as the signal line for controlling the motor antenna and the control circuit for calculating the logical condition is not needed too. Although the motor has been locked when the top of the antenna is at its uppermost and lowermost points in the above-described embodiment, motor current increases rapidly at the moment when the motor is locked. It is therefore difficult to accurately detect the motor current at this moment and accurately stop the motor at a current value set. Another embodiment of the present invention which will described below includes a system for lifting and lowering a rod antenna, a shock absorber arranged between the antenna lifting and lowering system and a motor for driving the system to damp mechanical shock, and a means for generating a voltage to meet motor current. According to this embodiment, the shock absorber damps mechanical shock between the antenna lifting and lowering system and the motor. When the motor is locked, therefore, the value of voltage to meet motor current is gradually increased in the voltage generator means. As the result, motor locking current can be accurately detected, thereby preventing motor current from being wasted at the time when the motor is locked. Fig. 4 shows a rod antenna system. The lower end of the smallest diameter section of telescopically extensible rod antenna 100 is connected to the top of rack rope 105, which is engaged with gear 104. Rack rope 105 is longer than the one shown in Fig. 4. Gear 111 is attached to the rotating shaft of motor M and a coil spring 113 which serves as s shock absorber is arranged between gears 112 and 104. Control box CB houses a control circuit such as circuits 40 and 50 in Fig. 1 to control the rotation of motor M. Rack rope 105 and gear 104 are an example of the system for lifting and lowering rod antenna 100 and motor M is an example of the means for driving this system. Coil spring 113 is an example of the shock absorber for damping mechanical shock between the system and motor M. Fig. 5 shows motor current changing while motor M is started and stopped. Fig. 6 is a diagram showing an example of the control circuit housed in control box CB. Same parts in Fig. 6 as those in Fig. 2 is denoted by same reference numerals. The circuit comprises NAND gate 120, R-S flip-flop 54, AND gate 122 serving as a circuit for preventing transistor circuit 51 from being put on, transistor circuit 51 for driving motor M, positive characteristic temperature/resistance element (which will be hereinafter referred to as PTC) 52 connected in series to motor M, resistors 125 and 126 for adjusting bias at one input terminal of NAND gate 120, and diode 127 for similarly shifting bias. PTC is an example of the means for generating voltage corresponding to motor current. The circuit further includes inverter 131 for inverting the signal of ACC, NAND gate 132 for causing signal "0" to be generated when the starter is activated, gate 141, NOR gate 142 and gate 143. Gate 141 has a function of its being not delayed when signal changes from "1" to "0" but delayed when signal changes from "0" to "1" and it has also another function of inverting signal. NOR gate 142 causes a negative pulse to be generated when the power source of radio receiver RX is switched on and off. Gate 143 is a monostable multi-vibrator for causing a negative pulse (or pulse of signal "0") to be generated every time when the power source of radio receiver RX is switched on and off and when the starter is rendered operative. The width of this pulse is set about 0.1 seconds or others by means of resistor 144a and condenser 144c. Transistor 42 excites relay 41 and contact 43 serves as the one for relay 41. When relay 41 is excited, contact 43 is connected to terminal U, motor M is rotated in forward direction and rod antenna 100 is lifted. When relay 41 is not excited, contact 43 is connected to terminal D, motor M is rotated in backward direction and rod antenna 100 is lowered. Gates 120, 122, flip-flop 54 and transistor circuit 51 form an example of the means for stopping motor M when current for motor M reaches a predetermined value. When motor M is mechanically locked, PTC serves as a means for generating such a voltage as increases almost linearly. Fig. 7 is a time chart for showing the operation of the above-described embodiment. When the power source of radio receiver RX is switched on at time T1, gates 142 and 143 generate negative pulses and AND gate 144 generates a negative pulse for 0.1 seconds responsive to these pulses of gates 142 and 143. Therefore, flip-flop 54 is set to output a positive signal. If the starter is not activated at this time, gate 132 outputs a positive signal. Therefore, AND gate 122 outputs a positive signal. Transistor circuit 51 is thus made operative and motor M is rotated. On the other hand, the power source of radio receiver RX is switched on. Therefore, transistor 42 is put on, relay 41 is excited, contact 43 is connected to terminal U, motor M is rotated in forward direction, and rod antenna 100 starts its lifting. As apparent from the above, rush current (or current generated at time t1 in Fig. 5) flows to motor M at the time of motor start. Voltage is increased higher than a predetermined value at both ends of PTC 52, and voltage exceeds a threshold at one input terminal 120d of NAND gate 120, which is about to output a negative signal. However, a negative pulse is applied to the other input terminal U of NAND gate 120 for 0.1 seconds. Therefore, NAND gate 120 generates no negative signal and flip-flop 54 is not re-set. Rod antenna 100 is thus gradually lifted. In other words, motor M continues to rotate in forward direction (for a time period denoted by t2 in Fig. 5). When rod antenna 100 shows almost its full length (or at T2 in Fig. 7), gear 104 begins to stop, spring 113 begins to serve as the shock absorber since then, rotation speeds of gears 112, 111 and motor M reduce gradually and motor current rises gradually (at a time period shown by t3 in Fig. 5). Therefore, voltage rises gradually at both ends of PTC 52 and becomes higher than the predetermined value at T3 in Fig. 7 and voltage becomes higher than the threshold value at input terminal 120d of NAND gate 120. Since a positive signal is applied to input terminal 120U of NAND gate 120 at this time, NAND gate 120 outputs a negative signal and flip-flop 54 is re-set. AND gate 122 thus outputs a negative signal and transistor circuit 51 is rendered inoperative. Motor M stops its rotation at this time. When the power source of radio receiver RX is then switched off (at T4 in Fig. 7), gate 143 generates a negative pulse and gate 144 also generates a negative pulse for 0.1 seconds from when the negative pulse of gate 143 rises. Flip-flop 54 is thus set again to make transistor circuit 51 operative. Since the power source of radio receiver RX is switched off this time, transistor 42 is turned off and relay 42 is not excited. Therefore, contact 43 is connected to terminal D and motor M is rotated in backward direction. Rod antenna is thus lowered gradually. When rod antenna 100 begins to be reduced to its shortest length (at T5 in Fig. 7), gear 104 begins to be mechanically locked. Spring 113 serves again as the shock absorber this time and gears 112, 111 and motor M reduce their speeds gradually. When current for motor M increases gradually and voltage also increases gradually at both ends of PTC 52 and becomes higher than the predetermined value (at T6 in Fig. 7), gate 120 generates a negative pulse, flip-flop 54 is reset, transistor circuit 51 is put off, and motor M is stopped. Shock absorber 113 is arranged between rod antenna 100 and motor M as described above. Even when the top of rod antenna 100 reaches its uppermost or lowermost point, therefore, motor current rises not rapidly but gradually and lock current for motor M can be thus detected accurately. It is therefore not caused that a large amount of motor current continues to flow at the time when motor M is locked. The shock absorber may not be spring 113 but a clutch may be employed. When the starter is activated while rod antenna 100 is being lifted or lowered, gate 132 generates a negative pulse. Therefore, gate 122 outputs a negative signal, transistor circuit 51 is put off and motor M which is rotating is stopped. When the starter is turned off, AND gate 122 output a positive signal. Therefore, transistor circuit 51 is put on, motor M continues its rotation and rod antenna 100 continues its lifting or lowering movement. Multi-vibrator 144 generates this time a negative pulse for about 0.1 seconds. Therefore, flip-flop 54 is set again, transistor circuit 51 is put on as described above, motor M is rotated, and rod antenna 100 is lifted or lowered. In other word, when the power source of radio receiver RX is switched on or off, rod antenna 10 is lifted or lowered correspondingly. It may be arranged in this embodiment that a comparator is located before NAND gate 120 to detect whether or not voltage exceeds the threshold value According to this embodiment of the present invention, motor current can be accurately detected when the motor for the motor antenna is locked. This prevents motor current from being wasted at the time of motor lock. Fig. 8 is a circuit diagram showing a further embodiment of the present invention. This circuit in Fig. 8 is different from the one shown in Fig. 6 in that timer 150 and gate 157 are added. Timer 150 comprises resistors 152, 153, 156, condensers 154, 155 and AND gate 151. This timer 150 is an example for stopping motor M through the motor stopping means after a predetermined time period, longer than a time period during which the top of rod antenna 100 moves from its uppermost point to its lowermost point or from its lowermost point to its uppermost point, has passed since motor M is started. Gate 157 serves to turn on transistor 42 after the power source of radio receiver is switched on but within a time period set on timer 150. Transistor 42 excites relay 41. Transistor 42 is an example to excite relay 41 for the time period set on timer 150. Fig. 9 is a time chart showing the operation of the embodiment. When the power source of radio receiver RX is switched on at T1, gates 142 and 143 generate negative pulses and AND gate 144 also generates a negative pulse for 0.1 seconds responsive to the negative pulses of gates 142 and 143. Therefore, flip-flop 54 is set to output a positive signal. If the starter is not activated at this time, gate 132 outputs a positive signal. Therefore, AND gate also outputs a positive signal. Transistor circuit 51 is thus put on and motor M is rotated. Timer 150 outputs a negative signal within a time period set on it but a positive signal during another time period which is except the time period set on it, and the time period set starts at T1. Since timer 150 outputs a negative signal and gate 141 also outputs a negative signal at T1, gate 157 outputs a positive signal and transistor 42 is put on at T1 when the power source of radio receiver RX is switched on. Relay 41 is excited this time, contact 43 is contacted with terminal U, motor M is rotated in forward direction, and rod antenna starts its lifting and locked similarly when the top of rod antenna 100 reaches its uppermost point. If it happens that rod antenna 100 is locked and that the resistant value of PTC 52 is fixed to one, extremely lower than its natural value, because of some reasons, voltage does not become higher than the predetermined value at input terminal 120d of NAND gate 120 and motor M cannot be stopped. In this case, however, timer 150 outputs a positive signal (at T1) when the time period set on timer 150 lapses. Therefore, flip-flop 54 is re-set, transistor circuit 51 is put off and motor M is forcedly stopped. When the power source of radio receiver is then switched off, motor M is rotated in backward direction as seen in the above-described other embodiments. Rod antenna 100 is thus lowered gradually. Timer 150 starts its counting at T4. In a case where rod antenna 10 is locked with its top held at its lowermost point and the circuit for detecting motor current is out of order, timer 150 outputs a positive signal (at Tt1) when the time period set on timer 150 lapses. Therefore, flip-flop 54 is re-set, transistor circuit 51 is put off and motor M is forcedly stopped. Even when the circuit for detecting motor current is out of order, as described above, motor M is forcedly stopped after the lapse of the time period set on timer 150. In a case where a clutch is used, therefore, the clutch is not idled to cause noises. Further, power is not wasted by the motor. Furthermore, transistor 42 excites relay 41 only for the time period set on timer 150. Therefore, power is used only for the time period set on timer 150, thereby preventing power from being wasted. In the case of the above-described embodiments, the motor antenna is automatically lifted or lowered when the power source of the radio receiver is switched on or off. In the case of a still further embodiment of the present invention which will be described below, however, it is arranged that the power source of an antenna driving motor is shut off when the top of the antenna reaches its uppermost or lowermost point, that voltage applied from the engine key is supplied to the control circuit at a neutral position of an antenna lifting/lowering switch to cause the antenna to be moved by the antenna lifting/lowering switch only when the engine key is turned on, and that antenna housing movement is done by a trigger when the engine key is turned off, said trigger serving to make zero those inputs which are applied to the control circuit. Fig. 10 is a circuit diagram showing this embodiment of the present invention. The circuit includes engine key 211, battery 212, switch 220 for lifting and lowering a motor antenna (not shown), relay 231 having contacts 230, motor M for driving the motor antenna, transistor 241 for controlling motor current, positive characteristic temperature/resistance element 242 connected in series to transistor 241, NAND gate 243, flip-flop 244 and circuit 250 for generating gate pulses. Element 242 is an example of the means for detecting that the top of the motor antenna has reached its uppermost or lowermost point while the antenna is being lifted or lowered. Flip-flop 244 and transistor 241 are examples of the means for shutting off the power source of the antenna driving motor when the top of the antenna reaches its uppermost or lowermost point. When lifting and lowering switch 220 is contacted with terminal U, relay 231 is excited to connect contacts 230 to terminals U, thereby causing motor M to be rotated in such a direction that the motor antenna is lifted. When lifting and lowering switch 220 is changed over to terminal N or D, the exciting of relay 231 is stopped to switch contacts 230 to terminals D, thereby causing motor M to be rotated in such a direction that the motor antenna is lowered. When engine key 211 is turned off, keeping lifting and lowering switch connected to terminal N, flip-flop 144 is set to put on transistor 241. Gate 243 generates a re-set pulse to re-set flip-flop 244 because the voltage of element 242 becomes higher than a predetermined value when lifting and lowering switch is connected to terminals U or D, motor M is rotated, and the top of the motor antenna reaches its uppermost or lowermost point. Transistor 241 allows current to be supplied to motor M when flip-flop 244 is set, and it shuts off the power source of motor M when flip-flop 244 is re-set. Gate pulse generator circuit 250 prevents re-set pulses from being applied to flip-flop 244 even when voltage becomes higher than the predetermined value at both ends of element 242 because of rush current, in order to prevent the malfunction of the circuit caused by rush current at the time of motor start. Fig. 11 is a circuit diagram showing the above-described embodiment in more detail. Operation panel 301 is provided with a diode arranged between lifting and lowering switch 220 and ACC and a diode arranged lifting and lowering switch 220 and IG. Other components except operation panel 301 and motor M are housed in control box 302. 0.2-second timer 51 is also included as a circuit used instead of gate pulse generator circuit 250. Fig. 12 is a time chart showing the operation of this embodiment. Engine key 211 is turned on at t0 when lifting and lowering switch is at neutral position (or connected to terminal N). When lifting and lowering switch 220 is contacted with terminal U at t1, relay 231 is excited to switch contacts 230 to terminals U, so that the polarity of motor M can be set to rotate motor M in the direction in which the motor antenna is lifted. Further, terminal N for lifting and lowering switch 220 is left open and voltage becomes "L" at the terminal N this time. Therefore, flip-flop 244 is set, transistor 241 is put on, motor M starts its rotation, current flows in a direction shown by an arrow in Fig. 11 and the motor antenna is lifted. When the top of the motor antenna reaches its uppermost point at t2, voltage becomes higher than the predetermined value at both ends of element 242 and input 2 of gate 243 becomes "H" (input 1 of gate 243 has already become "H" at this time). Therefore, gate 243 outputs a negative pulse to re-set flip-flop 244 and transistor 241 is put off to stop motor M. This enables the power source of motor M to be shut off not to burn motor M even when lifting and lowering switch 220 is kept contacted with terminal U after the top of the motor antenna reaches its uppermost point. When lifting and lowering switch 220 is then switched back to the neutral position (or contacted with terminal N) at t3, the motor antenna keeps its height. Relay 231 is not excited at this time. Therefore, contacts are switched to terminals D and the polarity of motor M is inverted. When lifting and lowering switch 220 is switched to terminal D at t4, voltage becomes "L" at terminal N, flip-flop 244 is set, transistor 241 is put on and motor M starts its rotation. Relay 231 is kept not excited in this case. Therefore, contacts 230 are connected to terminals D and motor M is connected to such a polarity that the motor antenna is lowered. Current thus flows to motor M in a direction reverse to that shown by the arrow in Fig. 11, causing the motor antenna to be lowered. When lifting and lowering switch 220 is switched back to the neutral position at t11 while the motor antenna is being lowered, voltage becomes "H" at terminal N of lifting and lowering switch 220 and input 2 of gate 243 becomes "H". Output signal (or input 1 of gate 243) is "H" because 0.2-second timer 251 is not activated. Therefore, gate 243 generates a negative pulse, flip-flop 244 is re-set, transistor 241 is put off and the power source of motor M is shut off. The antenna keeps its height, accordingly. When engine key 211 is pulled out of the key hole (or turned off) at t12 under the above-described state, voltage becomes "L" at terminal N of lifting and lowering switch 220. Therefore, flip-flop 244 is set and transistor 241 is put on to supply current to motor M. Relay 231 is not excited at this time. Therefore, contacts 230 are connected to terminals D and motor current flows in a direction reverse to that shown by the arrow in Fig. 11, causing the motor antenna to be lowered. When the top of the motor antenna reaches its lowermost point at t13, motor current becomes higher than a predetermined value, voltage rises higher than the predetermined value at both ends of element 242, and input 2 of gate 243 becomes "H" (input 1 of gate 243 has already become "H"). Therefore, gate 243 generates a negative pulse to re-set flip-flop 244 and transistor 241 is put off to shut off the power source of motor M. As apparent from the above, the motor antenna can be automatically housed only by pulling the engine key out of the key hole. Therefore, the housing of the motor antenna can be easily carried out when the driver comes outside out of the car. Further, current to motor M is automatically stopped in this case when the top of the motor antenna reaches its lowermost point, thereby preventing motor M from being burned. When lifting and lowering switch 220 is changed over from terminal U to terminal N at a time between t1 and t2 in Fig. 12, the motor antenna keeps its height. When it is switched from terminal N to terminal D, the motor antenna is lowered and when it is then switched to terminal U, the motor antenna is lifted. Even when rush current is caused at the time of motor start and voltage is raised higher than the predetermined value by this rush current at both ends of element 242, 0.2-second timer 251 generates a negative pulse for 0.2 seconds. Therefore, gate 243 generates no negative pulse to mistakenly re-set flip-flop 244. The time period set on timer 251 is not limited to 0.2 seconds but it may be longer or shorter then 0.2 seconds. Fig. 13 shows a variation of the operation panel shown in Fig. 11. Two interlock switches 224a and 224b are used instead of lifting and lowering switch 220 which has the neutral contact, and resistor 223 and diode 225 are arranged between these two interlock switches. This arrangement of two interlock switches 224a and 224b is intended to achieve same function as that attained by lifting and lowering switch 220. According to the above-described embodiment, the control means for lifting and lowering the motor antenna through the lifting and lowering switch can be made simple in construction, prevent the motor from being burned, and cause the antenna to be automatically housed when the engine key is pulled out of the key hole or turned off.

Claims: A motor antenna device for use with an antenna rod and arranged to lift or lower the antenna rod, the device being adapted for connection to a power source and comprising: a motor (M) capable of rotating in a forward direction and a reverse direction; a driving mechanism (104, 105, 111, 112, 113) comprising a damper (113) coupled to the motor (M) and adapted to be coupled to the antenna rod (100) whereby to transfer rotational force from the motor (M) to the antenna rod (100) to lift or lower the antenna rod; motor driving circuitry comprising motor polarity changeover circuitry (40) connected in series with the motor (M) and arranged to control the direction of current flow from the power source through the motor (M); motor lock detector (52) connected in series with the motor (M) and arranged to detect the current flowing through the motor (M) when it is mechanically locked; and motor control circuitry (50) arranged to cause the disconnection of the motor from the power source when a motor lock state is detected by the lock detector (52); characterized in that: the motor driving circuitry further comprises a motor driving device (51) responsive to the motor control circuitry (50) connected in series with the motor polarity changeover circuitry (40) and arranged to turn on or off the current flowing through the motor (M); and the lock detector (52) comprises a variable resistive element (52) having a positive temperature/resistance characteristic. A motor antenna device according to claim 1, wherein the motor control circuitry (50) has a bias voltage generating device (125, 126, 127). A motor antenna device according to claim 2, wherein the bias voltage generating device includes a diode (127). A motor antenna device according to claim 1, further comprising antenna lowering control circuit (20, 31) arranged to delay the lowering of the antenna rod (100) for a predetermined period of time from when the power source (RX) to a radio receiver (10) is turned off. A motor antenna device according to claim 4, wherein the predetermined period of time is in the range 2 to 10 seconds. A motor antenna device according to claim 1, wherein the motor polarity changeover circuitry (40) comprises an antenna lifting and lowering switch (41, 43) for selectively rotating the motor (M) in forward and backward directions. A motor antenna device according to claim 1, wherein the motor control circuitry (50) comprises a logic circuit (53) arranged to detect when the antenna rod (100) reaches its uppermost or lowermost position and a triggering circuit (54) arranged to turn off the motor driving device (51) in response to an output from the logic circuit (53). A motor antenna device according to claim 1, wherein the motor polarity changeover circuit (40) comprises a switch (220) having antenna lifting, lowering and neutral contacts, and the lowering of the antenna rod (100) is performed when the switch (220) is connected to the neutral contact and the starter key (12) is turned off.

Inventors: MAEDA YUJI, NAKASE KAZUHIKO, SATO KAZUFUMI, YAMAMOTO YUZO, MAEDA, YUJI, NAKASE, KAZUHIKO, SATO, KAZUFUMI, YAMAMOTO, YUZO
Applicants: HARADA IND CO LTD, HARADA INDUSTRY CO., LTD.
Application year: 1988
Main classification: H01Q1
IPC codes: H01Q1