GB2204752A - Motor control circuit for automatic door - Google Patents

Abstract

A door (A) is driven by a motor (B) having a control circuit with: (a) speed control using a motor-speed sensor (C) providing a rectified (D) signal that is compared (E) with a reference (F): a power-control circuit (G) is thereby controlled to maintain door speed against e.g. wind resistance; and (b) overload protection using a converting circuit (I) responsive to a voltage variation from the power-control circuit (G) to derive an overload signal that is compared (J) with a reference (K), to indicate e.g. the door being blocked, whereupon a control circuit (M) is caused to open the door. <IMAGE>

Description

AN AUTOMATIC DOOR BEING CONTROLLED WITH A SERSO-CONTROLLED SAFETY PROTECTION DEVICE As a result of the continuous long strides of progress in technology, material civilization end electronic industry, all the high buildings, restaurants, hotels, banks, hospitals, grocery stores, department stores, factories end warehouse have used an automatic doors to keep the air-conditioned temperature, to prevent the sir therein from convection, to keep the noise from entering into the room, and to facilitate people to pass through the door quickly.

Almost all the conventional doors being used in a building or the like have a common problems, i.e., the doors lack repair and maintenance. The normal wear and tear or the damages caused by the sparks ( because or the existing conventional automatic doors using electric parts ) would cause the doors to have minor troubles, such as the icro-switch that controls the motor does not turn off, or any obstacle is placed on the rail to atop the door to run. Any one or the aforesaid inor troubles would cause the control disk and the rotor not to operate normally.

Finally, these minor troubles may damage the motor or the control circuit after a period of time running under an over-load condition, and a fire may be resulted thereby. The aforesaid examples are obtained from the many years or experiences or the inventor in making, installing and repairing the automatic doors; in view of the aforesaid experiences, the inventor has developed an automatic door, which is to be controlled with a servo-controlled safety protection device so as to obviate the aforesaid drawbacks in the conventional automatic doors.

This invention relates to en automatic door being controlled uith a safety protection device so as to raise the efficiency of the motor, particularly to en automatic door which is controlled with a servo-controlled safety protection device.The special features ef the device are that it has s speed sensor to rotate synchronously with a rotor, but it will generate a corresponding feed-back signal to be transferred into a control circuit to compare with a reference signal so as to form a servo-control device. During the door being opened or closed, if the door is unable to move because of an obstacle or trouble, the motor will have an overload or may be unable to run g in that case, the control circuit will cause a feedback dynamic signal to be compared uith an overload reference voltage so as to have the door opened automatically and then to cut off the power of motor tor protecting the door. During the door moving at a slow speed and upon the door being retarded by a wind force, the motor power can be regulated automatically to have the door closed steadily so that the driving power of victor can be utilized fully.

Fig. 1 illustrates the conventional control structure of an automatic door.

Fig. 2 illustrates a circuit of a conventional speed- reducing structure.

Fig. 3 is a block diagra. of the circuit of an automatic door being contolled with a servo-controlled safety protection device according to the present invention.

Fig. 4 illustrates the structure of the automatic door device according to the present invention.

Fig. 5 is the circuit No. 1 for the automatic door device according to the present invention.

Fig. 6 is the circuit No. 2 for the automatic door device according to the present invention.

Fig. 7 illustrates the operation of the automatic door device according to the present invention.

Fig. B is a diagram showing the operation of rotor at high and low speed in the present invention.

Fig. 9 illustrates the operation curves of the rotor at high and low speed.

The major object of this invention is to provide a speed sensor in the transmission mechanism of the automatic door device to rotate synchronously with the motor and to generate a corresponding feedback dynamic signal as the speed (rpa) of the ictor g the feedback signal is to be coupled into control circuit to compare with a reference signal therein so as to form a complete servo control device.The control circuit can change the driving force of the motor in accordance with the load applied to the automatic door. For example, upon the door being applied with a wind force, the driving force of the rotor will be increased automatically. Upon the door being stopped by an obstructive atter, the power supply of the motor will be cut off g in that case, the safety of the automatic door will be increased, and the door device can be protected under the overload condition, and also the motor can render its maximum operation efficiency.

Fig. I illustrates the conventional control structure Of an automatic door, in which the rotor 1 drives the belt pulley 3 ( or steel cable pulley ) to rotate through a speed reducer 2 The belt pulley 3 together with an idling klt pulley 4 ( or steel cable pulley ) drives a belt 5 ( or steel cable ) clockwise or counter-clockwise.The both ends of the klt 5 are mounted, with two hanging members 6 and 7 ,with tuo doors 6 and 9 respectively t the both doors era furnished with pulleys so as to move along a rail 12 . The lower ends of the doors are mounted with guide members 10 so as to have the door, move along the rail 11 The automatic door is noreally under closed position.

Upon a person passing through the door, the sensor will actuate the control circuit to have the motor I drive the doore 8 and 9 to open immediately. Upon the doors almost reaching the full open position, the door body will touch the low speed switch 13 to reduce the rotating speed of motor 1 so as to lower the moving speed of doors ss and 9 g upon the door reaching the full open position, a stop switch 14 is touched to stop the motor I to run.

Upon a person already passing through the opened door, the sensor would sense nothing, and the control circuit actuates the motor 1 to rotate quickly in opposite direction so as to drive the tuo doors ss and 9 moving toward the closed position. Upon the doors roving almost near the closed position, the door body touches the low speed switch 15 to cause the motor I to switch to the lower speed in order to reduce the moving speed of the tuo doors.

Upon the doors reaching the completely closed position, a stop switch 16 is touched to cause the motor 1 to stop.

Summing up the aforesaid description, it is noted that the conventional automatic door has some disadvantages as follows: (1) A low speed switch and a stop switch ( micro switches ) have to be installed for opening and closing the doors. According to the several hig-amperage relays and rectifiers, and the highpower rheostat used, the tour micro switches have to be installed accurately in position so as to have the doors operated precisely.

(2) The aforesaid tour micro switches have to be wired to several control disks of relays, which require higher current; therefore, the installation operation is rather cumbersome.

(3) One factor of troubles of the conventional automatic door is susceptible to m mechanical wear and fatigue of elasticity because of the four micro switches always having friction uith the doors during the opening and closing operation.

(4) Since the aforesaid four micro switches are directly connected uith A.C.( Alternating currant) power, sparks generated by the instant ON/AND current become one of its troubles.

(5) Since there is no accurate and quick safety protection device, the motor is susceptible to being burned out upon the micro switches having trouble or upon the automatic doors or rails being hindered with miscellaneous substance or other matters, (6) Whenever the weather is changed, the wind pressure applied to the door will be increased. That increased wind pressure would cause the doors to be difficult to close with the normal torsional force of the motor.

(7) In the conventional automatic door, the slow speed and retarding device usually use circuit and method shown in Fig. 2 , in which SW1 is a quick operation switch g SW2 is a slow speed and retarding switch ;; SW3 and SW4 are the forward and reverse rotation control switches respectively g nDw is a rectifier having large current output g VR1 is a speed regulating rheostat operated with a higher power. Tho aforesaid structure would cause the following drawbacks; 1) Higher power will be consumed.

2) Upon the reverse coil of the motor being used to offset the reverse lines or magnetic force to reduce the speed, vibration will be resulted, and that vibration may generate more noise.

3) During the slow speed and retarding running, the motor is subject to a high temperature.

4) Upon two opposite lines of magnetic forces being offset, the windings will generate an instant counter E.M.F. to cause sparks, which may cause damages to the contact points of the switches.

5) The serviceable life of the motor would be reduced as a result of the factors of 2) and 3) as mentioned above.

Briefly, the prime object of the present invention is to provide an improvement to the aforesaid drawbacks by means of a servo control means to obtain an automatic protection device to the door. That device will be described in detail, with reference to the accompanied drawings, as follows: : Fig. 3 is a block diagram of the servo-controlled safety protection mechanism for the automatic door according to the present invention, in which "A" stands for the load of the automatic door ( door body ), "B" stands for a motor, "C" sands for a RPM inductor, "D" stands for a rectifier, "E" stands for a voltage-comparison circuit, "F" stands for a reterence-voltage setting circuit, "C" stands for power-control circuit, "H" stands for a power supply circuit, "I" stands for a converting circuit for instantly varying voltage, "J" stands for an overload-voltage comparison and amplification circuit, "K" stands tor an overload reference voltage setting circuit, "L" stands for an overload inductive voltage locking circuit, "M" stands for operation condition control circuit, and "N" stands for switch control circuit. The reference voltage setting circuit F can determine the rotating speed of the motor, of which the rpm variation is determined by the operation condition control circuit M.The speed sensor C rotates synchronously with the motor 8 and then it generates a signal to peas through a rectification circuit to generate a D.C. signal, which indicates its synchronous rotation with the motor B t the D.C. signal is then transmitted into a voltage comparison circuit E so as to compare with the signal voltage from the reference-voltage setting circuit F. In that case, the power-control circuit C will provide the motor B with a power in accordance with the output signal of the voltage comparison circuit.The speed sensor C can still rotate at a constant speed after sensing a varied rotating speed caused by the variation of the automatic door load A to pass through the volatage-comparison circuit E . In this invention, the variation signal rill pass through the converting circuit I for instantly varying voltage to be converted into a proper varied value being fed into the overload-voltage comparison and amplification circuit 3 . In the overload reterence- voltage setting circuit K , an overload voltage is set, and is fed into the overload-voltage comparison and amplification circuit J for comparison.In the event of the door body being over loaded or king caught uithout moving, the converting circuit I for instantly varying voltage will generate an inducted signal to indicate the motor being over loaded. The signal will be fed into the overload inductive voltage locking circuit L to generate an output signal to be fed into the operation condition control circuit M to have the autos tie door open so as to prevent the motor from king overloaded. The switch control circuit N is to be controlled by the automatic door load A to generate a signal to be fad into the operation condition control circuit M.

The point "0" stands tor the input point of the trigger signal.

Fig. 4 and 5 illustrates the structure and the circuit of an automatic door that is controlled with a servo-controlled safety protecting mechanism according to the present invention, in which the switch SW1 is a control switch for opening and closing the automatic door. The reed switch SW2 is a slow speed control switch during the door being opened. The reed switch SW3 is a stop-control switch during the door being opened; the reed switch SW4 is a slow speed control switch during the door being closed ; the reed switch 5i5 is a stop-control switch during the door being closed.The reason tor using reed switch is to prevent the door bodies from mechanical rriction and elasticity fatigue during contacting each other directly. The door body is controlled with a magnet MA to form an indirect contacts upon the door being opened, the magnet MA will move together with the belt; upon the magnet touching the reed switch SW2 , the speed of the motor will be reduced, and when the magnet touches the reed switch 5W3 , the motor will be stopped.During closing the door, the magnet MA will move together with the klt in the opposite direction; upon the magnet touching the reed switch Si4, the speed of the motor will be reduced, and upon the magnet touching the reed switch SW5 , the motor will be stopped; in fact, it achieves the purpose of indirect control.The aforesaid control means ray be replaced with a photosensitive call device, and the magnet mey be replaced with a shielding means. The reed switch in the switch control circuit mey also be replaced with a photosensitive cell . Upon the belt moving the shielding means, the different positions of the shielding means will provide the photosensitive cell with an indirect control function. The signal generated will be fed into the operation condition control circuit to control the door body to move.

Fig. 4, 5 and 6 are the two embodiments of two circuits and structure being used in the automatic door and being controlled with a servo-controlled safety protection mechanism according to the present invention, and the aforesaid circuits are described in detail as follows t (1) In Fig. 5, SW1 is e switch to be triggered tor opening or closing the automatic door. Upon SW1 being in shortcircuit condition, the collector of R3 is in a high potential condition 5 the output of IC al is in a low potential condition.

C2 and R15 together with IC al , IC 2 and 02 form a monostable multivibrator. Within the RC time constant of R15 and C2 , the output ot IC 2 is in a high potential condition, which passes through R17 to OP terminal to provide an opening signal to the automatic door so as to have the door body turned in opening direction.

(2) SW2 is a alow speed reed switch to be used during opening the door. (MA) is in a magnet on the automatic door; upon the magnet (MA) reaching the position of SW2 , the reed switch SW2 will be in shortcircuit state, and the voltage 8+ uill, through R35, be applied to the input terminal of IC dl Since a locking circuit comprises IC dl, IC d2 and 021, the output of IC d2 is a high potential to pass through R37 to the input terminal of IC d4 .Since the other input terminal of IC d4 is connected with OP , the other input terminalis also in high potential state ; therefore, the output terminal of IC d4 will be in a low potential state; then, the output terminal of IC e2 is in a high potential state to be applied to SL as a signal for opening the door slowly.

(3) SW3 is a reed switch for stopping an opening door; upon the magnet (PIA) together with the door body moving to the position or SW3 , the reed in switch SW3 will be in a short circuit state to have the voltage B+ via 03 and R16 applied to the input terminal of IC a2 ; then, the input terminal of IC 2 may be changed into a high potential state depending upon R16 and R15 being connected in parallel and depending upon the value of R16 If so, the output terminal of IC a2 will be restored in a low potential state to cause OP terminal to be in a low potential state, whereby the automatic door will be stopped to move in the opening direction ;; simultaneously, since the input terminal of IC d4 is in a lou potential state, the output terminal of IC 2 to SL is also in a low potential state.

(4) As long as SWI is in ahortcircuit state, the input terminal of IC a3 is in a high potential state, which pass through 06, 18 to cause C3 to be in a lou potential state, and also passes through 07 to let the input terminal of IC b2 have a low potential state. It there is no external signal to cause SW1 to become shortcircuited, SWI will remain in open state, the collector of Q3 remains in a lou potential state, while the output of IC a3 is in a high potential state; at the same time, the lou potential of C3 will diecharge through 07, VR1 and R20 to the output terminal of IC a3.The RC time constant for the opening and stopping of the automatic door is formed with R20, LIRI and C3, and it can be adjusted with Vr1 After the RC time constant being over, the input terminal of IC b2 turns into a high potential etate, and causes the output teriinal of IC b3 to generate a high potential state being applied to CL so as to let the automatic door turn in the closed position.

(5) A monostable multivibrator is formed with IC b2, IC b3, C4, R22, 09, and R24. As described in (4) as mentioned above, after the low voltage in C3 being discharged through VRI , R20, and the output terminal or IC a3, the input terminal of IC b2 will be in a high potential state; simultaneously, the input terminal of IC b2 is changed into a low potential state, since it is still within the RC time constant formed with C4 and R22, and the input of IC b3 is also in a low potential state; at the same time, the output terminal of IC b3 is also in a high potential state, which will, through R25, be applied to CL to cause the automatic door to move in the closing direction.

Simultaneously, the high potential on CL terminal will, through R36, be applied to the input terminal of IC d3, and then the output terminal of IC d3 is changed into a low potential state, which will, through D22, cause the slow speed opening-door locking circuit to be sat in unlocking state so as to prevent the automatic door from having a high potential state on OP terminal in case of SWI being shortcircuited again X otherwise, the output terminal of IC d4 will have a slow speed signal to cause the automatic door to be opened slowly in a high speed operation area.

(6) SW4 is a reed switch for closing the door slowly.

(MA) is a magnet being mounted the belt that is driven with a motor for driving the automatic door. Upon the automatic door body moving in closing direction and reaching the position ot SW4 , the reeds of SW4 will become shortcircuited to have B+ being through R26 applied to the input terminal of IC ci . A locking circuit includes IC c1, IC c2, R28 and D15 .Upon the input terminal of IC c4 being in high potential state, the other input terminal of IC c4 ie also in a high potential state as a result of CL terminal ; then, the output terminal or IC c4 is in a low potential state, which uill, via R30, cause the output terminal of IC e2 to be in a high potential state to have the automatic door moved in closing direction slowly.

(7) SW5 ie a reed switch for the braking and stopping functions during closing the automatic door. Upon the magnet (MA) approaching SW5 at a slow speed, the reeds in SW5 must be shortcircuited through induction effect before the center part of the magnet moving to the opposite canter of SW5 ( The distance may be determined by the strength of the magnet MA );; simultaneously, the voltage B+ will , through 012 and R31, cause the input terminal of IC e3 to be in a high potential state, while the other input terminal of IC 3 will be in a high potential state via the output terminal of IC 2. The RC time constant formed with C10 and R34 can determine how long the output terminal of IC 4 can maintain a high potential state on BL. The high potential state on BL will cause the motor to change from a slow speed running state to braking and stopping condition.That step will slow doun the inertia impact effect of the door body. In that case, the voltage B+ will, via D5 , R21 and VR2 , be applied to the RC circuit formed with C4 and R22 ; also, the RC time constant of R21 and VR2 connected in series and then connected with R22 in parallel must be higher than the time constant of C10 and R34 so as to the automatic door to be able to run again at a slow speed after being braked and stopped; then, the output terminal of IC b3 is changed into a low potential state after the automatic door being closed; the CL terminal is also changed into 8 low potential state to as to atop the motor of the automatic door gain.

(8) The aforesaid four reed switches ( or photosensitive cells ), the several logic gates, the monostable multivibrator and the locking circuit are assembled together to replace the conventional four micro-switches and several power relays so as to improve the drawbacks as mentioned above in (1) to (4) (9) Fig. 6 is a circuit of the safety protection device, which is described in detail as follows : (1û) The base bias of Q2 is provided uith a pert of circuit including R21, Q4, R22, R23, Q5, R25, Q6, R26, R27, Q7, R6 and R5 . The reference voltage required by the motor speed is determined by the resistance value of the aforesaid resistors.

OP of Fig. 6 is substantially connected with the OP in Fig. 5 Upon OP being in a high potential state, the output of IC a2 will cause Q7 to become conductive, i.e., the collector and emitter of Q7 ie considered in ahortcircuit condition g the value of R26 and R27 will determine the opening speed of the automatic door, while the value of R25 will determine the closing speed of the automatic door ; the value of R23 and R22 will determine the slw speed of the door.

(11) "G" stands for a motor rpm inductor being mounted over the shaft of motor to rotate synchronously with the shaft ; the signal induced by the inductor will be rectified, through a bridge rectifier D1 , into a series of voltage values eS that is varied in proportion to the motor rpm. The voltage eS is coupled to the base of Q1.Since Q1 and Q2 form into a differential amplification circuit, it the reference voltage of the base of Q2 is set as eR, the differential voltage generated through pl and Q2 will be (eS-eR) A= eO, which is transferred to the base of Q8 (12) If the voltage on the bese of q8 is eO, the variation of eO is considered a variable internal resistance betueen the collector and the emitter of Q8; therefore, upon AC power passing through D2, Q8, RIO, C9 and Ril, the 8 terminal of the bridge rectifier D2 will show, by testing, a series of varying voltage values because of Q8 being considered at a variable resistance.It the load of motor is increased to cause its rpm to reduce, the variation will be amplified by Q1 and R2 to obtain a voltage between R3 and the ground being varied in proportion to the rotating speed of motor, i.e, the internal resistance of Q8 being varied in proportion to the rotating speed of motor, and the B terminal of the bridge rectifier 02 will heve a variable voltage.

(13) The R34 and R33 on the input terminal (+) of IC el can be set uith a series of overload reference voltage, i.e., the plus (+) terminal of the voltage comparator. Upon the automatid door being caught to cause the motor to be unable to move, the variable voltage on terminal B to the ground of the bridge rectifier 02 will ibmediately be decreased, and will through C13 be coupled to the base of 99. The resistors R28, R29 and R31 form into a network to reduce the voltage; Q9 is designed as an emitter amplifier. 06, C14 and R32 form into a rectifier.After the voltage between terminal C and the ground being decreased, it will be converted into a voltage by Q9 and being rectified through D6, C14 and R32, and then be transferred to the input terminal (-2 of IC el, i.e., the minus (-) terminal of the voltags comparator. Whenever the value of sO on the input terminal (-) is lower than the motor overload reference voltage on the input terminal (+), the output terminal of IC e1 will generate a motor overload signal voltage.

(14) A locking circuit is assembled with IC c1 , IC c2, and D15 . When the automatic door reaching the braking area, as mentioned in (7) above, D8 will generate a series of low voltages, being transferred into the locking circuit including IC dl and IC d2 so as to remove the locking effect. The locking effect is that, upon the two door bodies being almost closed together, the motor is set in an overload condition to prevent it from rotating, and IC el will generate an overload signal to be coupled to the input terminal of IC dl.Now that a series of low voltages are generated by D8 and transferred to the locking circuit including IC dl and IC d2 ( note: The value of R40 must be lower than that of R37 so as to prevent the high voltage of IC e1 from being transferred, through R37, to input terminal of IC dl , since R40 is Co designed that it would have a currantlimiting function only when C15 being discharged through D8.) , the original locking effect will be removed.The non-obstructive overload signal will automatically be removed-after the door bodies being closed together so as to lock the other logic gates permanently and to facilitate the next normal operation.

Upon the automatic door being caught with an unknown factor during moving, open the doors as shown in Fig. 7 so as to prevent the door from being damaged continuously. After the automatic door being first opened, it has to be closed. When the two door bodies are closed together, it is also considered that the automatic door is caught; therefore, it is necessary to furnish a means, whereby the aforesaid conditions are excluded from the being caught condition. The aforesaid condition may be referred to as "Dummy Catching Condition Fn. In principle, the "Dummy" Catching Condition F" area should be as minimum as possible. During the aforesaid condition in that area, a braking signal referred to as "Dummy Catching Condition F" is generated upon the magnet nA approaching the braking and stopping reed switch SW5.

Upon the SW5 reaching to the vicinity of A, the automatic door will change its slow speed ( SW4 being a slow speed reed switch, and SW5 being a braRing and stopping switch) to braking operation, of which the theory has already been mentioned in t7" above.

It a moving door is stopped with an obstacle in the caught area, the IC el shown in Fig. 6 will have a high potential output to pass through R37 and to be transferred into IC dl. A locking circuit ( in which the value of R37 must be higher than that of R40 and R41 ) includes IC dl, IC d2, R41, D9 and R40.

Simultaneously, CL terminal ( door-closing signal ) is in a high potential state, while the signal from transferred IC b3 to IC b1 is in a low potential state. Since the automatic door has not reached the position of the braking and stopping reed switch (SW5), the BL terminal ( braking signal ) is in a low potential state; then, the two input terminals of IC bl are in a lou potential state, while the output terminal must be in a high potential estate, which will pass through R38 zand R42 to be coupled to the input terminal of IC dl ; in that case, the two input terminals of IC dl are in a high potential state, and therefore, IC dl end IC d2 will provide a locking effect ( Note: the locking effect can only be furnished upon the value of R40 being lower than that of R37 ). IC d2 will provide the input terminal of IC d3 with a high potential output; then, the output terminal of IC d3 will have a low potential transferred to terminal A in Fig.5 . Since one of the input terminals of IC b2 is in a low potential state, the signal transferred to CL (door-closing signal) from the output terminal of IC b3 through R25 must be in a low potential stats, i.e, to stop the door-closing operation.

Simultaneously, a low potential is applied, through terminal A and Dl , to the base of Q3 . In that case, SWI is deemed in hort-circuited condition1 and the collector of R3 will furnish a high potential to the input terminal of IC al so as to have the monostable multivibrator ( consisting of IC al, IC a2, C2 and R15) delivered e high potential from the output terminal of IC a2 through R17 to OP terminal ( door-opening signal ).In that case, the automatic moves in the opening direction. Simulteneously, a low potential from terminal A will, through D8, be applied to the input terminal of IC b2, and the monostable multivibrator will not operate ( since the low potential an terminal A has been locked with IC d11 IC d2, R41, D9 end R40 as shown in Fig. 6 ) unless the obstacle being -removed and the main power switch being turned on again to operate the door.

Upon the automatic door entering into the "Dummy Catching Condition Area F", i.e , upon the magnet MA approaching SW5 , the SW5 will be ehortcircuited because of the strength of the line of magnetic force to cause the terminal BL ( braking signal ) shown in Fig. 6 in (7) above to be in a high potential state ; that high potential will, via R35 , be coupled to the input terminal of IC ci to have the locking circuit ( consisting of IC c1, IC c2 and 07 ) lock the braking signal t then1 the output terminal of IC ci will have a low potential to pass through D8 and R40 to be applied to the input terminal of IC d1, assuring that a "Dummy Catching Condition " F exists. It the automatic door is closed together and being caught1 the high potential output of IC al would not cause the locking circuit ( consisting of IC dl and IC d2 ) to lock the output of overload signal from IC el; in other words, after the automatic door entering into the "Dummy Catching Condition Area", the output terminal A of IC d3 will not be changed into a low potential state.

It the automatic door is not in the braking area, and the motor is caught to cause the output terminal of IC el to transfer @a signal to the locking circuit of IC dl and IC d2 ( R37 and C15 forming a delay RC circuit to confirm an overload state ), the output terminal of IC d3 will have a locking low potential transferred to the three terminals A in Fig. 5 so 55 to have every logic gate in Fig. 5 stopped to operate.In that case, the terminals of OP, CL, SL and BL will be in a low potential state permanently1 i.e., the base of Q2 shown in Fig. 6 having no reference voltage tor the running motor and therefore the automatic door being in stopped condition permanently so as to prevent the motor from being burned out because of being overloaded continuously.

(15) By means of the aforesaid description1 an automatic door can correctly be protected with a servo-control means. The object of that means is to obviate the five drawbacks mentioned above.

(16) When using the safety protection device of the present invention tor an automatic door, the following advantages will be rendered to the automatic door.

(17) According to the slow speed-reducing nethod in the conventional automatic door as shown in Fig. 2, the un-remediable drawbacks mentioned in (6) and (7) above will be resulted.

(18) In order to obviate the drawbacks mentioned in "(17)" above, the device shown in Fig. 8 should be used, instead of that in Fig. 2, to control the motor to run at a low speed; this means that the drawbacks mentioned in "(7)" above can be obviated, but no the drawback mentioned in "(6)" above because or s (19) Referring to Figs. 8 and 9 , there is shown that it SWI is turned on, the motor will rotate at full speed; if SWI is turned off, the rotating of the motor will be determined by the value of WRI1 i.e., the slow speed of the automatic door can be varied; however, the load of the automatic door is subject to variation by certein external factors, and therefore a slow speed area 8 shown with dotted line as shown in Fig. 9 will occur ( in Fig. 9, "C" stands for the high speed running area, while '0" stands for the slow speed running area ) ; the aforesaid condition is further described as follows : In order to have the motor rdn at a slower speed, a portion of AC power has to be consumed in VR1 ( which may be a circuit consisting of SCR or TRIAC ) as shown in fig. 6. It there is no such a means to have VR1 automatically ravied with the variation or the door load, the torque or the rotor at the slow speed would permanently be lower than the output torque thereof at the high speed ; the slower the speed, the lower the torque. In that case, a door running et a slow speed, rather than at a high speed, would be susceptible to being etopped by a wind pressure or the like to prevent the door from being closed together.Suppose thet the power for the motor is increased for overcoming the wind pressure or the like applied to the motor at low speed, it may also mean that the rotor running at a high speed would be a waste of power.

(20) In Fig.6, the terminal 8 of the bridge rectifier D2 has a variable voltage value1 which will vary immediately upon the door load being incrsased as e result of any external factor to cause the slow running speed of the door to reduce ; then, the network consisting of C9, R10 and DIAC will trigger TRI, and the triggering angle of TR2 will also be increased; simultaneously, the pouer applied to the motor will be increased. After the aforesaid steps of increasing the power of the motor, the speed of the automatic door will be lowered to a slow speed as designed originally. The slow speed torque of the automatic door may, it necessary, (be raised to the level being equal to that at the high speed so as to have the automatic door run steadily. According to the aforesaid description, it is apparent that not only the automatic door can be protected by the device, but also the power applied to the motor will be consumed effectively. The description in this paragraph can improve the drawbacks mentioned in "(6)" and "(7)" above.

In the servo-controlled safety device of the present invention, the circuit is an improved one of the conventional circuit,and it is considered a new disclosure in terms of space.

Claims (6)

1. An autometic door being controlled with r servo- controlled safety protection device, comprising ~ an automatic door body; a motor tor opening and closing the automatic door; a speed sensor rotating synchronously with said motor; a rectifying circuit tor converting the synchronous signal generated by said speed sensor into a DC signal g avoltage-comparison circuit for comparing the reference voltage of a reference voltage setting circuit with the voltage of said rectifying circuit ;; a reference voltage setting circuit for providing said voltage-comparison circuit with a reference voltage ; a motor-power control circuit to be driven by an output signal from said voltage-comparison circuit ; a power supply circuit for providing the device with power ; an inetantly varying voltage converting circuit which can pick up a varying signal voltage from the power control circuit and have said signal voltage applied to an overload-voltage conparison and amplification circuit as a comparison voltage ; an overload reference voltage setting circuit ;; an overload voltage comparison and amplification circuit for comparing the voltage between said instantly varying voltage converting circuit and said overload voltage setting circuit an overload inductive voltage locking circuit g an operation condition control circuit for controlling the operation made of said automatic door ; and a switch control circuit tor sensing the opening1 closing or stopping operation of said automatic door; and said device characterized that said speed censor that rotates synchronously with said motor can generate a dynamic signal voltage being transferred into said voltage-comparison circuit to compare with the output voltage of said reference voltage setting circuit -; then1 a corresponding dynamic signal voltage is generated therefrom , and is applied to said power control circuit so as to control the output power of said motor automatically until said dynamic signal voltage and said reference voltage being in an equal condition tor maintaining said motor to run steadily and increasing the utilizetion efficiency or said motor ;; and by another feature being that means of said instantly varying voltage converting circuit, a variable signal voltage can be picked up from said power control circuit, and then is passing through said overload-voltage comparison and amplirication circuit to compare with the output voltage from said overload reference voltage setting circuit; and when the autonatic door being overloaded, said overload inductive voltage locking circuit will, through said operation condition control circuit, cause the automatic door to be set in open position.

2. An automatic door as claimed in claim I , wherein said switch control circuit is controlled with tour reed switches that are indirectly controlled with a magnet fixedly mounted on said automatic door.

3. An automatic door as claimed in claim 1 , wherein eaid switch control circuit is controlled with four photosensitive cells thet are indirectly controlled with a shielding neans fixedly mounted on said automatic door.

4. An automatic door as claimed in claim 1, wherein the R34 and R33 on the input terminal (+) of IC el of the overload voltage comparison and application circuit is set with an overload reference voltage for the motor; and when the door body being unable to move, the instantly varying voltage on terminal B of the bridge rectifier will be increased, and will, through C13 to the base of Q9 and being rectified via 06, C14 and R32, be transferred to the input terminal (-) of IC el ; and it the voltage on the input terminal (-) is higher than that ( the overload reference voltage for the motor ) on the input terminal (+), said IC el will have en output signal to indicate that said motor has been overloeded.

5. An automatic door as claimed in claim 1 , wherein said voltage comparison circuit can compare the varied voltage picked up by the rectifying circuit generated by the speed sensor in proportion to the motor rpm, and the voltage set in the reference voltage setting circuit; and after being amplified through Q1 and R2 or the voltage comparison and amplification circuit, and through the inner resistance variation between the collector and emitter of Q8, and also through its related circuit, an instantly varying signal will be generated corresponding to the speed sensor signal ; and the power control circuit will provide the motor with a servo-controlled power in accordance with the variation of said instantly varying signal.

6. An automatic door as claimed in claim 1 , wherein said reference voltage setting circuit can have said motor stopped with a signal to pass through BL, R21, Q4 ; and said reference voltage setting circuit can have said motor run at slow speed with r signal to pass through SL, R22, R23 ,Q5, and the speed thereof may be regulated by adjusting R23 ; and said setting circuit can also control the running speed of a closing door with a signal to pass through CL, R25, Q6 ; said setting circuit can also control the running speed of an opening door with a signal to pass through OP, R27, R26 end Q7 ; and said running speed can be regulated by adjusting R26