Power supply apparatus with automatic reconnection after power source failure

Abstract: A fabrication apparatus including an emergency stop circuit which is an emergency stop switch has a first electromagnetic switch for supplying and shutting off power to the apparatus and a second electromagnetic switch for controlling power supply to an electromagnetic coil of the first electromagnetic switch. Power is supplied to the electromagnetic coil of the first electromagnetic switch from the primary side of the first electromagnetic switch via a contact of the second electromagnetic switch. An uninterruptible power source supplies power to an electromagnetic coil of the second electromagnetic switch via the emergency stop circuit. This emergency stop switch is inserted midway along a power line to the electromagnetic coil of the second electromagnetic switch. This allows safe emergency stop of the fabrication apparatus for semiconductors and the like. When the operation of the fabrication apparatus stops due to stoppage of power, the apparatus is automatically reactivated after the power is recovered. This increases the productivity.

Description: FIELD OF THE INVENTION The present invention relates to a power supply system for supplying power to an apparatus, see e.g. US-A-5,412,528. DESCRIPTION OF THE RELATED ART A semiconductor fabrication plant for fabricating semiconductor devices has a clean room containing a number of fabrication apparatuses, e.g., various processing apparatuses for fabrication steps such as lithography, testing apparatuses, and transfer apparatuses. The plant also has a power supply system for supplying power for operating these various apparatuses. This power supply system includes an installed power source for transforming commercial electric power supplied from an electric power company outside the plant and supplying the transformed power into the plant. Normally, to start the operation of a fabrication apparatus, an operator (machine operator) operates a power ON switch to start supplying power to the fabrication apparatus to activate it. To stop the operation, the operator operates a power OFF switch to stop the supply of power from the installed power source to the fabrication apparatus to thereby stop the apparatus. When the plant is in operation, however, troubles rarely occur to make it necessary to urgently stop the operation of a fabrication apparatus. As a means for urgently stopping a fabrication apparatus, therefore, an emergency stop switch operable by an operator is usually arranged near the apparatus. When the operator operates this switch, an emergency stop circuit (EMO) operates to shut off power supply from the installed power source to all apparatuses such as a fabrication apparatus, air conditioner, and light source, thereby urgently stopping these apparatuses. However, if power supply to all apparatuses is abruptly shut off, the system may run away from the control when reactivated. When the plant is in operation, supply of power sometimes stops owing to an unexpected power failure (including an instantaneous power failure) such as the power failure of a commercial power source or failure of a power source in the plant. If this is the case, power supply to the emergency stop circuit also stops, and a fail safe function of the emergency stop circuit sets the same state as when the emergency stop switch is pressed, thereby shutting off power supply from the installed power source. To restart the operation of an apparatus , it is necessary to wait until an operator turns on the power switch after the installed power source is recovered. That is, even when an apparatus stops due to an instantaneous power failure, the operation of the apparatus cannot be restarted without the operation by an operator. When a large number of fabrication apparatuses are installed in the plant, it takes a long time for the operator to turn on the power sources of all fabrication apparatuses. This interferes with an increase in productivity. SUMMARY OF THE INVENTION The present invention has been made in consideration of the above situation, and is concerned to provide fabrication arrangements capable of achieving high safety and high productivity at the same time. It is another concern of the present invention to urgently and safely stop an apparatus in operation and, when the apparatus stops due to, e.g., a power failure or power source failure, reduce the time required to reactivate the apparatus, thereby increasing the productivity. To address the above concerns, a power supply apparatus according to claim 1 is provided. Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. Fig. 1 is a view showing the whole configuration of a semiconductor fabrication apparatus according to an embodiment of the present invention; Fig. 2 is a block diagram showing the arrangement of a power supply system according to the embodiment; Fig. 3 is a block diagram showing the arrangement of a power supply system according to a modification of the embodiment; Fig. 4 is a flow chart showing an embodiment of device fabrication; Fig. 5 is a flow chart showing a wafer process; Fig. 6 is a block diagram showing the configuration of a main body controller according to the embodiment; Fig. 7 is a flow chart for explaining the operation of the main body controller according to the embodiment; and Fig. 8 is a flow chart for explaining the operation of a power source controller according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings. <First Embodiment> Fig. 1 is a view showing the arrangement of a semiconductor device fabrication apparatus according to the first embodiment of the present invention. Referring to Fig. 1, an installed power source 23 of a fabrication plant supplies power to the fabrication apparatus. This installed power source 23 includes a main power source and a backup power source. In normal operation, the main power source transforms commercial electric power supplied from an electric power company to the semiconductor fabrication plant and supplies the transformed power to individual apparatuses in the plant. When this main power source cannot supply power because of, e.g., a power failure or power source failure, the backup power source supplies power into the factory instead of the main power source. This backup power source has an independent power generator such as a diesel generator. The semiconductor fabrication apparatus is roughly divided into a fabrication apparatus main body 1, a main body power source 6, a constant temperature chamber 2, an air conditioner 3, a main body controller 4, and a power supply unit 5. The constant temperature chamber 2 contains the fabrication apparatus main body 1 and keeps it in a fixed environment. The air conditioner 3 holds the ambient temperature, gas concentration, cleanness, and the like in the constant temperature chamber 2 constant. The main body controller 4 controls operations of the fabrication apparatus main body 1 and the air conditioner 3. The power supply unit 5 supplies or shuts off power from the installed power source 23 to the main body power source 6 and the air conditioner 3. In this embodiment, the semiconductor fabrication apparatus is a semiconductor exposure apparatus for exposing a semiconductor wafer substrate. However, the present invention is similarly applicable to various processing apparatuses and testing apparatuses used in semiconductor fabrication. A light source 13 is installed separately from the chamber 2 containing the fabrication apparatus main body 1. This light source 13 supplies exposure light to the fabrication apparatus main body 1 through a beam line 20. The light source 13 is, e.g., an excimer laser source or an X-ray source (SR or plasma X-ray source). The power supply unit 6 supplies power to the light source 13 through a power cable 21. Acommunication cable 22 connects the light source 13 and the main body controller 4. Fig. 2 is a block diagram for explaining a power supply system of the power supply unit 5 in the semiconductor fabrication apparatus shown in Fig. 1. Power lines are formed from the installed power source 23 of the plant to the main body power source 6, the air conditioner 3, and the light source 13 via a main breaker 7 and a first electromagnetic switch 8 (a contactor including a contact 8a and an electromagnetic coil 8b for opening and closing the contact 8a) for turning on and off the power source. The upstream side (near the installed power source) and the down stream side (near the fabrication apparatus) of the contact 8a of the first electromagnetic switch 8 will be called a primary side and a secondary side, respectively. The primary side of the electromagnetic switch 8 is branched and connected to an overcurrent protector 9, an uninterruptible power source 10, an overcurrent protector 12, and a power source controller 11 as an emergency stop circuit in this order. The uninterruptible power source 10 incorporates an AC/DC converter, a battery, and a power failure detecting circuit 15 for detecting a power failure (an instantaneous power failure and power failure for a few seconds to a few tens of minutes). This power failure detecting circuit 15 outputs a detection signal to the main body controller 4 and the power source controller 11. The power source controller 11 is connected to a power ON switch 17a and a power OFF switch 17b. This power source controller 11 is also connected to an electromagnetic coil 14d of a second electromagnetic switch 14 (a relay including relay contacts 14a to 14c and 14e and the electromagnetic coil 14d for opening and closing these relay contacts 14a to 14c and 14e) for controlling power supply to the electromagnetic coil of the first electromagnetic switch 8. Two emergency stop switches 18a and 18b and a connecting terminal 19 to be opened and closed by an abnormal temperature detecting unit are inserted midway along the power line to the electromagnetic coil 14d. When this power line is disconnected by any of the first and second emergency stop switches 18a and 18b and the connecting terminal 19, supply of power to the electromagnetic coil 14d of the second electromagnetic switch 14 is shut off, and the relay contact 14a of the second electromagnetic switch 14 is opened. Accordingly, the first electromagnetic switch 8 is also opened. The emergency stop switches 18a and 18b are arranged in a portion of the outer wall of the constant temperature chamber 2 of the semiconductor fabrication apparatus where an operator readily accesses these switches. The second electromagnetic switch 14 has four relay contact systems (14a to 14c and 14e) to be simultaneously opened and closed. The first system (relay contact 14a) controls power supply to the electromagnetic coil of the first electromagnetic switch 8. The remaining three systems are the relay contacts 14b, 14c and 14e. The relay contact 14b supplies and shuts off electric power to the main body controller 4. The relay contact 14c connects and disconnects the signal line for transmitting a detection signal from the power failure detecting circuit 15 to the main body controller 4. The relay contact 14e is used for discriminating whether the cause of power shut down comes from an operation of the emergency stop switch or power failure. In summary, this power supply system includes the first electromagnetic switch 8 for supplying and shutting off power from the installed power source 23 to the individual apparatuses (exposure apparatus main body, air conditioner, and light source) and the second electromagnetic switch 14 for controlling power supply to the electromagnetic coil 8b of the first electromagnetic switch 8. Power is supplied to the electromagnetic coil 8b of the first electromagnetic switch 8 from the primary side of the first electromagnetic switch 8 via the relay contact 14a of the second electromagnetic switch 14. Also, power is supplied to the electromagnetic coil 14d of the second electromagnetic switch 14 via the power source controller 11 as an emergency stop circuit. The emergency stop switches 18a and 18b are inserted midway along the power line to the electromagnetic coil 14d of the second electromagnetic switch 14. The first and second electromagnetic switches 8 and 14 include the relay contacts 8a, 14a to 14c and 14e which are open when no power is supplied to the electromagnetic coils 8b and 14d and closed when power is supplied to these electromagnetic coils 8b and 14d. The emergency stop switches 18a and 18b are normally closed to supply power. When activated, these emergency stop switches 18a and 18b are opened to shut off the power supply. Fig. 2 shows the states of the electromagnetic switches when the apparatuses are stopped. The uninterruptible power source 10 converts an AC divided on the primary side of the electromagnetic switch 8 into a DC of 24 V. This power is used to charge the built-in battery and also supplied to the power source controller 11 and the main body controller 4. Fig. 6 is a block diagram showing details of the arrangement of the main body controller 4. In this main body controller 4, a CPU 41 controls, e.g., the fabrication apparatus main body 1, the air conditioner 3, the main body power supply unit 6, and the light source 13 by executing control programs stored in a ROM 42. A RAM 43 provides a work area when the CPU 41 executes these control programs. An operation unit 44 includes operation switches for, e.g., activating and stopping the fabrication apparatus, indicators for indicating the operating state of the apparatus, and the like. An I/O interface 45 transmits a driving signal from the CPU 41 to a driving apparatus. As shown in Fig. 2, the installed power source 23 supplies power to the driving system, and the power source controller 11 (the uninterruptible power source 10) supplies power to the main body controller 4. An operation of turning on the power source in the above configuration will be described below. When an operator presses the power ON switch 17a while power is supplied to the installed power source 23, the power source controller 11 supplies power to the electromagnetic coil 14d of the second electromagnetic coil 14. As a consequence, the relay contacts 14a to 14c and 14e of the second electromagnetic switch 14 are closed. Accordingly, power is supplied to the electromagnetic coil 8b of the first electromagnetic switch 8, and the relay contact 8a of the first electromagnetic switch 8 is also closed. Power supply to the main body power supply unit 6, the air conditioner 3, and the light source is thus started to perform exposure for device fabrication. To normally stop the fabrication apparatus, an operator presses the power OFF switch 17b. The operations of activating and stopping the apparatus will be described in more detail below. To activate the apparatus, an operator presses the power ON switch 17a to allow the power source controller 11 to supply power from the uninterruptible power source 10 to the coil 14d of the second electromagnetic switch 14 (relay). Since the relay contact 14a of the second electromagnetic switch 14 is closed, power is supplied to the coil 8b of the first electromagnetic switch 8. Simultaneously the relay contact 14b closes to supply power to the main body controller 4. Consequently, the relay contact 8a is closed to supply power from the installed power source 23. In this state, the operator presses the activation switch on the operation unit 44 to allow the fabrication apparatus to start operating. To stop the apparatus, the operator first presses the stop switch on the operation unit 44 to shift the apparatus from an operating state to a stop state. After that, the operator presses the power OFF switch 17b to shut off the power supply from the power source controller 11. Consequently, the relay contact 14a opens to shut off the power supply to the coil 8b of the first electromagnetic switch 8. This opens the relay contact 8a to shut off the power supply from the installed power source 23. An emergency stop operation when the emergency stop switch is pressed while the apparatus is in operation will be described below. If an operator presses (opens) the emergency stop switch 18a or 18b or the abnormal temperature detecting unit 20 detects an over-temperature indicating an apparatus error (the contact terminal 19 is open), the power supply path from the power source controller 11 to the electromagnetic coil 14b of the second electromagnetic switch 14 is disconnected. Accordingly, the relay contact 14a opens to shut off the power supply to the electromagnetic coil 8b of the first electromagnetic switch 8, and the relay contact 8a opens. This stops the power supply to the main body power supply unit 6, the air conditioner 3, and the light source 13. The power supply to the main body controller 4 is stopped when the relay contact 14b of the second electromagnetic switch 14 opens. A signal from the power failure detecting circuit 15 is disabled when the relay contact 14c of the second electromagnetic switch 14 opens. In the case of emergency stop, therefore, the power supply from the installed power source 23 to the apparatus is completely shut off except for the primary side of the first electromagnetic switch 8 as a power shut-off device and the power source controller 11 as an emergency stop circuit. Accordingly, high safety can be maintained. Since a relay contact 14e of the second electromagnetic switch 14 opens, the power source controller 11 can detect emergency stop. When detecting emergency stop, the power source controller 11 stops the supply from the uninterruptible power source until the start switch 17a is again pressed. Hence, when emergency stop occurs, the apparatus cannot be reactivated unless the operator again presses the power ON switch 17a to turn on the power source. Consequently, the safety can be improved. In emergency stop, the power supply to the main body controller 4 is also shut off, so the CPU 41 of the main body 4 is initialized. Therefore, a normal initialization procedure is necessary to recover the apparatus. An operation when an unexpected power failure occurs in the installed power source 23 while the apparatus is in operation will be described below. If this is the case, the power supply to the electromagnetic coil 8b of the first electromagnetic switch 8 is stopped at the same time the power supply from the installed power source 23 stops. Therefore, the relay contact 8a of the first electromagnetic switch 8 opens to disconnect the power line to the air conditioner 3, the fabrication apparatus main body 6, and the light source 13. Meanwhile, the power failure detecting circuit 15, the power source controller 11, and the main body controller 4 are held steady because the backup power supply from the uninterruptible power source 10 is maintained. A big difference from the emergency stop described above is that the relay contacts 14a to 14c and 14e of the second electromagnetic switch 14 are kept closed. The main body controller 4 receives a signal indicating a power failure of the installed power source 23 detected by the power failure detecting circuit 15 and stores operation parameters of the fabrication apparatus main body and the air conditioner. When the installed power source 23 recovers from the power failure, power is supplied to the electromagnetic coil 8b of the first electromagnetic switch 8 because the relay contact 14a of the second electromagnetic switch 14 is kept closed. Therefore, the relay contact 8a of the first electromagnetic switch 8 again is closed to restart power supply to the air conditioner 3, the main body power supply unit 6, and the light source 13. When the power supply is thus restarted, the operation starts on the basis of the operation parameters stored immediately before the power failure by the main body controller 4. Hence, the operation can be smoothly returned. The power source controller 11 and the main body controller 4 include built-in timers. If the power failure detecting circuit 15 detects recovery from a power failure within a predetermined time (e.g., seven seconds) after detecting the power failure, the apparatus is automatically reactivated. If power failure continues over the predetermined time set in the timer, the fabrication apparatus main body 1, the air conditioner 3, and the light source 13 are not automatically reactivated even when the power failure detecting circuit 15 detects recovery from the power failure after that. As when the emergency stop circuit operates, the apparatus is not reactivated unless the operator operates the power switch. The predetermined time of the timer by which whether reactivation is possible is determined can be freely set from a fraction of a second to a few tens of minutes. In reactivating the apparatus, it is also possible to first reactivate the air conditioner 3 and then automatically reactivate the semiconductor fabrication apparatus main body 1 and the light source 13. The air conditioner 3 is preferentially reactivated because this air conditioner 3 requires the longest time to return the environment in the constant temperature chamber 2 to a steady state. The operations of the main body controller 4 and the power source controller 11 will be described in more detail below with reference to flow charts in Figs. 7 and 8. Fig. 7 is a flow chart for explaining processes of activation, stop, and emergency stop. Control programs for realizing these processes are stored in the ROM 42. When an operator presses the activation switch on the operation unit 44, this apparatus is activated (steps S101 and S102). It should be evident to those skilled in the art that supply of the installed power source, initial positions of individual devices, and variation activation conditions are checked in these steps. When the apparatus is in operation, the CPU 41 monitors an operation of the stop switch on the operation unit 44 or a power failure detection signal from the power failure detecting circuit 15. If the stop switch is operated, the CPU 41 stops the apparatus (steps S103 and S109). If a power failure is detected, the CPU 41 saves operation information such as parameters of apparatuses in operation into the RAM 43 in order to prepare for automatic reactivation upon power recovery (steps S401 and S105). If the power is recovered within a predetermined time, the CPU 41 reactivates the apparatus by using the parameters saved in the RAM 43 (steps S106 to S108). If the CPU 41 reactivates the apparatus from the air conditioner as described above, the CPU 41 executes a preprogrammed predetermined reactivation process. If the power is not recovered within the predetermined time, the flow advances to the stop process (steps S106 and S109). Fig. 8 is a flow chart for explaining the operation of the power source controller. When an operator presses the power ON switch 17a, power supply to the second electromagnetic switch 14 is started (steps S201 and S202). While the power is supplied, the CPU 41 monitors the power OFF switch 17b, occurrence of emergency stop, and occurrence of a power failure. If the power OFF switch 17b is pressed or the relay contact 14e opens to detect emergency stop, the power source controller 11 stops power supply (steps S203, S204, and S208). When a power failure is detected, the power source controller 11 keeps supplying power if the power is recovered within a predetermined time (steps S206 and S207). If the power is not recovered within the predetermined time, the power source controller 11 stops power supply (steps S206, S207, and S208). The above procedure of the power source controller 11 can be realized by using relay circuits and the like or a microcomputer. In either case, the circuit configuration is obvious to those skilled in the art. The built-in battery of the uninterruptible power source 10 has enough capacity to continuously supply power to the power source controller 11 and the main body controller 4 for amaximum of 20 minutes required for the installed power source 23 to switch from the commercial power source to the independent power generator when a power failure occurs. As described at the beginning, the installed power source includes an independent power generator such as a diesel generator as a backup power source. However, a predetermined initialization time (usually about 10 minutes) is required to activate the independent power generator, so power supply is stopped during a switching period in which the power source stops and the backup power source starts supplying power. For this reason, the built-in battery of the uninterruptible power source 10 has enough capacity to supply power for a time (e.g., 20 minutes) longer than this switching period (e.g., 10 minutes). Some fabrication plants are equipped with an uninterruptible power source (DC) for a short-time power failure. Therefore, the uninterruptible power source 10 of the above embodiment can also be replaced with this uninterruptible power source of the plant. Fig. 3 shows the arrangement of this modification. The same reference numerals as in Fig. 1 denote the same parts in Fig. 3, and a detailed description thereof will be omitted. In Fig. 3, reference numeral 24 denotes an installed uninterruptible power source of a plant; and 51, an uninterruptible power source box which includes a circuit for converting a DC supplied from the installed uninterruptible power source 24 into a DC of 24 V. The above embodiment has described a semiconductor fabrication apparatus including an emergency stop circuit which is an emergency stop switch. When this semiconductor fabrication apparatus stops operating due to a power failure, a controller automatically reactivates the semiconductor fabrication apparatus after the power is recovered. If the emergency stop circuit stops the operation of the semiconductor fabrication apparatus, the controller does not automatically reactivate the semiconductor fabrication apparatus. In other words, this embodiment is a power supply apparatus of a fabrication apparatus having an emergency stop function using an emergency stop switch. When the fabrication apparatus stops operating owing to a power failure, the power supply apparatus automatically resupplies power to the fabrication apparatus after the power is recovered. If the emergency stop function stops the operation of the fabrication apparatus, the power supply apparatus does not automatically resupply power to the fabrication apparatus. This makes it possible to provide an apparatus capable of reducing the time required to restart the operation without lowering the safety even when the supply of power stops owing to an unexpected cause such as a power failure or power source failure. Also, if the emergency stop circuit urgently stops the fabrication apparatus, the apparatus is reactivated only when an operator again turns on the power source (operates the switch 17a). As a consequence, a high-safety power supply system free of apparatus runaway can be provided. That is, this system successfully achieves both safety and productivity on a high level. <Second Embodiment> A device fabrication method using the aforementioned fabrication apparatus will be described below. Fig. 4 shows the flow of fabrication of a microdevice (e.g., a semiconductor chip such as an IC or LSI, liquid crystal panel, CCD, thin-film magnetic head, or micromachine) . In step 1 (circuit design), a device pattern is designed. In step 2 (making of mask), a mask having the designed pattern is made. In step 3 (fabrication of wafer), a wafer is fabricated by using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process in which the prepared mask and wafer are used to form an actual circuit on the wafer by lithography. Step 5 is called a post-process in which the wafer fabricated in step 4 is formed into semiconductor chips. This step 5 includes steps such as an assembly step (dicing and bonding) and a packaging step (chip encapsulation). In step 6 (testing), tests such as an operation test and a durability test of the fabricated semiconductor devices are performed. The semiconductor devices are completed through these steps and shipped (step 7) . Fig. 5 shows details of the above wafer process flow. In step 11 (oxidation), the surface of a wafer is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (formation of electrodes), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist processing), the wafer is coated with a resist. In step 16 (exposure), an exposure apparatus is used to bake mask circuit patterns in a plurality of shot regions on the wafer by exposure. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions except for the developed resist image are etched away. In step 19 (resist removal), the resist which is unnecessary after the etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the wafer. When the fabrication method of this embodiment is used, high-accuracy devices which are conventionally difficult to fabricate can be fabricated with high safety, high productivity, and low cost. The present invention can achieve high safety and high productivity at the same time. For example, to urgently stop a fabrication apparatus in operation, the apparatus can be stopped while runaway of the system is prevented. Also, even when power supply is stopped owing to an unexpected cause such as a power failure or power source failure, the time required to restart the operation can be reduced without lowering the safety. As many apparently widely different embodiments of the present invention can be made without departing from the scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

Claims: An electrical power supply apparatus comprising: a first electromagnetic switch (8) for connecting and disconnecting a first electrical power source (23) to an apparatus; (3,6,13), said first electromagnetic switch comprising first contacts (8a) and a first actuator (8b) for closing the first contacts (8a) when power is supplied to the actuator (8b); and a first circuit (7, 9, 10, 14a, 51) for supplying electrical power to said first actuator (8b) of said first electromagnetic switch (8), characterized by comprising: a second electromagnetic switch (14) comprising second contacts (14a) for closing and opening said first circuit and a second actuator (14d) for closing said second contacts (14a) when power is supplied to said second actuator (14d); a second circuit (11, 51) for supplying electric power to said second actuator (14d) of said second electromagnetic switch (14) from an uninterruptible electric power source (10, 24); and a manually-operated switch (18a, 18b) for opening said second circuit. An apparatus according to claim 1, wherein said manually-operated switch (18a,18b) is normally closed, and is opened when operated manually. An apparatus according to claim 1, wherein said second circuit further comprises a contact (19) which opens when an apparatus error is detected. An apparatus according to claim 1, wherein the uninterruptible electrical power source (10, 24) comprises a battery. An apparatus according to claim 1, wherein the first electrical power source supplies AC power, and said uninterruptible electric power source is adapted to supply DC power. An apparatus according to claim 1, wherein said first circuit supplies electrical power to said first electromagnetic switch (8) from the first electrical power source (23, 7, 9, 14a, (Fig.2)). An apparatus according to claim 1, wherein each of said first and second electromagnetic switches (8, 8a, 14, 14a) is open when no electrical power is supplied to its actuator (8b, 14d) and closed when electrical power is supplied thereto. An apparatus according to claim 1, further comprising a switch (14b) interlocked with said second electromagnetic switch to connect and disconnect the uninterruptible electrical power source to a controller (4) in the apparatus. An apparatus according to claim 1, further comprising a control unit (11) for controlling electrical power supply to said second electromagnetic switch. An apparatus according to claim 9, wherein said manually-operated switch opens said second circuit between said control unit and said second electromagnetic switch. An apparatus according to claim 9, further comprising a manually-operated power ON switch (17a) and a manually-operated power OFF switch (17b), wherein said control unit controls electrical power supply to said second electromagnetic switch based on outputs of said manually-operated power ON switch and said manually-operated power OFF switch. An apparatus according to claim 9, further comprising a detecting unit (15) for detecting failure of electrical power supply from the first electrical power source, wherein said control unit keeps supplying electrical power to said second electromagnetic switch for a predetermined time after said detecting unit detects the failure (S206), and stops supplying electrical power to said second electromagnetic switch thereafter (S208). An apparatus according to claim 12, further comprising setting means for setting the predetermined time. An apparatus according to claim 12, wherein said control unit informs a controller in the apparatus that said detecting unit detects the failure. An apparatus according to claim 14, further comprising a switch (14c) interlocked with said second electromagnetic switch to open and close a signal transmission path for the information by said control unit. An apparatus according to claim 1, wherein said first circuit supplies electrical power to said first electromagnetic switch (8) from the uninterruptible electric power source (24, 7, 51 (Fig.3)).

Inventors: AOKI SHUJI, IMAI SHUNZO, AOKI, SHUJI, IMAI, SHUNZO, Aoki, Shuji, c/o Canon Kabushiki Kaisha, Imai, Shunzo, c/o Canon Kabushiki Kaisha
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1999
Main classification: H02J9
IPC codes: H01L21, H02J9, H02H1