WO2012066590A1

WO2012066590A1 - Method and device for time-division control of drying device

Info

Publication number: WO2012066590A1
Application number: PCT/JP2010/006699
Authority: WO
Inventors: 中村　義則
Original assignee: ナカンテクノ株式会社
Priority date: 2010-11-15
Filing date: 2010-11-15
Publication date: 2012-05-24
Also published as: JPWO2012066590A1; JP5130415B2; KR20130098858A; CN102869937B; CN102869937A

Abstract

Provided is a time-division control device for which the amount of electricity supplied for at least one hot plate is sufficient and an increase in the factory power-receiving equipment is not required, even if the number of drying devices increases; or, which is capable of reducing the maximum flowing current value to the current value for one heater for an existing drying device equipped with multiple heaters when said multiple heaters are heated in parallel. This time-division control device (A) supplies power by sequentially switching the supply of power to the heaters (H1)-(Hn) for multiple hot plates (HP1)-(HPn), which are connected in parallel to an alternating current main power supply (1) and which respectively heat and dry, at a prescribed temperature, multiple processing bodies (2) on which an application liquid has been applied. The time-division control device is characterized in that it comprises: the existing alternating current main power supply (1), which supplies alternating current to each of the aforementioned multiple heaters (H1)-(Hn); parallel connection lines (n1) - (nn), which branch from the alternating current main power supply (1) and respectively supply power to the heaters (H1)-(Hn), and temperature measurement instruments (THS1) - (THSn) for the heaters (H1) - (Hn) and the hot plates (HP1) - (HPn); and a power supply control circuit (K), which, with the zero cross point of the alternating current to each of the heaters (H1) - (Hn) as the power supply switching point, and until each of the hot plates (H1) - (Hn) reaches the set temperature, uses a temperature signal from the aforementioned temperature measurement instruments (THS1) - (THSn) to switch the supply of power to the next selected heater after a rest period of a half-cycle or an integer multiple thereof from said power supply switching point, with the number of hot plates being the same as or less than the number of existing hot plates when the number of hot plates is being increased and the number of hot plates being one less than the number of existing hot plates when the number of hot plates is not being increased.

Description

Time-sharing control method and apparatus for dryer

The present invention makes it possible to eliminate the need to increase the power receiving equipment of the factory in connection with the expansion of the drying equipment, or to reduce the maximum current value of the existing drying equipment even when the drying equipment is not expanded. The present invention relates to a control system, and more particularly to a time-sharing control system and apparatus for a dryer for manufacturing a flat panel display.

Currently, at the flat panel display manufacturing plant, production facilities are rapidly expanded to increase production. To that end, a new factory must be established, but future demand prediction is very difficult, and it is not possible to easily set up a new factory. For this purpose, the necessary number of factory facilities will be installed using the empty space of the existing factory.

In this situation, taking an alignment film dryer for a flat panel display as an example, this dryer is equipped with a plurality of hot plates, or a plurality of dryers equipped with one or more hot plates. In the case of full operation, all the heaters of all the hot plates must be heated at the same time in order to simultaneously dry the workpieces. For this purpose, at least the rated current consumption of the heater × the number of heaters is required. And if a dryer is newly installed, the electric power for the newly installed number will be further required, and the capacity of the power receiving equipment in the existing factory will have to be raised in accordance with the introduction of equipment. Therefore, the cost increase for that purpose and the time for equipment enhancement were needed, and the problem that it was not able to respond to the rapidly increasing demand arose.

In addition, due to the circumstances of electric power companies and the energy saving policies of the countries that have received this, the existing dryers recently want to level out the peak of power consumption in the area as much as possible in combination with the user's request. It is also necessary to make the maximum current value during operation as small as possible.

As one measure for dealing with such problems, application of the method described in Japanese Patent No. 2688628 can be considered. In this method, three heaters of a hot plate are connected to a single phase of three-phase alternating current, and the three heaters are switched at the zero cross point of each phase, and noise generation at the time of heater switching is reduced as much as possible.

If this is applied to the switching of the hot plate of the dryer, the switching at the zero cross point is not performed completely at the zero cross point due to the performance of the switching device, but is performed at or near the zero cross point. In some cases, there are moments when more than a predetermined number of heaters are energized before and after switching on and off, and this has the adverse effect of placing an excessive burden that exceeds the capacity of the existing power receiving equipment. In addition, there is a problem that the number of heaters that can be controlled is limited to three because a heater is connected to each phase of the three-phase alternating current, and there is also a problem that the power supply power to the heater is weaker than that in the case of supplying power in three phases. .

Japanese Patent No. 2688628

The present invention relates to an improvement of a conventional power supply method and apparatus for such a drying facility, and the object thereof is to increase the number of dryers without increasing the factory power receiving facility, In a plurality of hot plates, even when all or a plurality of selected hot plates are heated in parallel (not simultaneously), the energizing current value is reduced to the minimum current value for one surface of the hot plate by intermittent energization. It is possible to provide a time-sharing control system and its apparatus that are less than the capacity of existing power receiving equipment.

The invention according to claim 1
“Multiple hot plates (HP1) that are connected to the AC mains power supply (1) in parallel and heat-dry each of the workpieces (2) coated with the coating liquid (3) at a predetermined temperature. In the time-sharing control device (A) of the dryer (41) that sequentially switches the power supply to the heaters (H1) to (Hn) for (HPn) and supplies power,
An existing AC main power supply (1) for supplying an AC current to each of the plurality of heaters (H1) to (Hn);
Parallel connection lines (n1) to (nn) and heaters (H1) to (Hn) branched from the main power supply line (L) of the AC main power supply (1) to supply power to the heaters (H1) to (Hn), respectively. And hot plate (HP1)-(HPn) temperature measuring instruments (THS1)-(THSn),
Until each of the hot plates (HP1) to (HPn) reaches the set temperature, the heaters (H1) to (Hn) are heated by the temperature signals (o1) to (on) from the temperature measuring devices (THS1) to (THSn). The zero cross point of AC current to the
When adding hotplates, the number of existing hotplates should be less than
If you do not add a hot plate, the number is less than the number of existing hot plates,
And a power supply control circuit (K) for switching power supply to the next heater selected after a half cycle or an integral multiple of a pause period has elapsed from the power supply switching point. (Note that the subscript “n” of each symbol used in this specification has both the meanings of the maximum number at the time of expansion and at the time of non-expansion.)

Claim 2 is the apparatus (A) of claim 1,
`` The power supply control circuit (K)
In response to temperature signals (o1) to (on) from temperature measuring devices (THS1) to (THSn), the temperature of each hot plate (HP1) to (HPn) is detected and the temperature measuring devices (THS1) to (THSn) are detected. ) When the temperature of the hot plates (HP1) to (HPn) related to the temperature signals (o1) to (on) from) is below the set temperature, power supply to each heater (H1) to (Hn) is executed sequentially A control unit (4) for outputting time-sharing control signals (s1) to (sn) commanded to
A main opening / closing circuit provided on each of the parallel connection lines (n1) to (nn) for connecting and disconnecting the heaters (H1) to (Hn) and the AC main power source (1) using the zero cross point of the supplied AC current as a power supply switching point. Elements (SSR10) to (SSRn0),
The time division control signals (s1) to (sn) are connected to the main switching elements (SSR10) to (SSRn0) and receive the time division control signals (s1) to (sn) output from the control unit (4). The auxiliary switching elements (SSR11) to (SSR1n) for turning on the main switching elements (SSR10) to (SSRn0) according to the above.

Claim 3 relates to the energization time to each heater (H1) to (Hn) in the apparatus (A) of

claim

1 or 2,
“The energization time to each of the heaters (H1) to (Hn) is one cycle of the supplied alternating current or an integral multiple thereof”.

The method of the present invention according to claim 4
“Multiple hot plates (HP1) that are connected to the AC mains power supply (1) in parallel and heat-dry each of the workpieces (2) coated with the coating liquid (3) at a predetermined temperature. A time-division power supply control method for a dryer (41) that sequentially supplies power to the heaters (H1) to (Hn) for (HPn),
When the temperatures of the hot plates (HP1) to (HPn) are detected by detecting the temperatures of the hot plates (HP1) to (HPn), respectively, the hot plates (HP1) to (HPn) Until the set temperature is reached, the zero crossing point of the feeding AC current to each heater (H1) to (Hn) is used as the feeding switching point.
When adding hotplates, the number of existing hotplates should be less than
If you do not add a hot plate, the number is less than the number of existing hot plates,
The power supply is switched from the power supply switching point to the next heater selected after the lapse of a half cycle or an integral multiple of the rest period ”.

When the number of dryers (41) is increased, if the number of existing hot plates is n and the number of newly installed hot plates is m, the required maximum current amount is m + n in the conventional simultaneous heating method. Since the capacity is not increased, the capacity of the AC main power source (1) is only n units of the existing capacity. In a situation where the capacity of such a power supply facility is not enhanced, the present invention sequentially switches power supply to the heaters of 1 to n selected hot plates among the m + n hot plates, and at least half a cycle from the zero cross point. Power is supplied with a period of downtime (time-sharing control), so the time required to raise the temperature to the specified temperature of the hot plate is longer without noise, but the maximum number of hot plates can be increased within the range of the existing power receiving facilities. Can be warmed. In other words, power can be supplied in a range that does not exceed the capacity of the existing AC main power source (1).

If the number of existing hot plates is not increased, the number of existing hot plates (n units) will be less than the number of existing hot plates (n units) and less (n-1 units). Since switching is performed sequentially and power is supplied by providing at least a half-cycle rest period from the zero cross point (time-sharing control), as described above, the temperature rise time to the predetermined temperature of the hot plate becomes longer without noise, but in this case the hot plate The maximum amount of power supplied to the power supply is (n-1) units, which can contribute to a reduction in the amount of electricity during heating.

In addition, since the heater energization switching is performed at the zero cross point as described above, no noise is generated during energization switching, and the energization to the heater is switched sequentially rather than continuously, so that rapid temperature rise is suppressed. Heating rate of the heater is not excessive, and it can be a moderate heating rate, so that full power feeding that matches the rated current of the hot plate heater can be executed just before the set temperature. Thus, when the number of operating units is m + n or n at the maximum, the temperature rise time to the set temperature is expected to increase up to m + n or n times, but for example 0.7 to 0.8 × ( The temperature raising time can be significantly shortened from the expected time such as m + n or n) times. If the heat dissipation loss at the time of non-energization is suppressed, the time can be further shortened. In addition, since the power supply to the heaters is sequentially switched in a time-sharing manner, the switching devices such as the main switching elements (SSR10) to (SSRn0) and the auxiliary switching elements (SSR11) to (SSR1n) are conventionally used for each heater. This eliminates the need for switches and breakers that were installed in the machine, and can greatly reduce the number of parts.

Circuit diagram of an embodiment of the present invention The graph explaining the implementation state of the method of the present invention Temperature increase graph of one hot plate in the implementation status of the method of the present invention Temperature increase graph of hot plate of conventional example

Hereinafter, the invention will be described in detail according to the illustrated embodiment. FIG. 1 shows that a coating liquid (3) such as an alignment film forming liquid is applied to a substrate (2) such as glass placed on a coating stage (81) in the control apparatus (A). In the drying step, an example is shown in the case of applying to the dryer (41) in the case where the object (2) to be treated is heated to dry the coating liquid (3).

In the present invention, when the power supply capacity of the AC main power supply (1) is not increased, the capacity of the dryer (41) can be increased, and when the capacity is not increased, the power supply is reduced by at least one hot plate. To do. As the dryer (41), one equipped with one or many hot plates (HP1) to (HPn) is applied, but the one equipped with only one hot plate is naturally omitted when the equipment is not enhanced. Hereinafter, the description will focus on a dryer equipped with a plurality of hot plates.

The AC main power supply (1) used is a three-phase or single-phase AC, and the waveform on the “input side of the output contact of (SSR10 to SSRn0)” in FIG. In the case of, one phase was shown in order to avoid the complexity of the figure.

As shown in FIG. 1, heaters (H1) to (Hn) that generate heat when electric current is supplied are embedded in the hot plates (HP1) to (HPn) of the dryer (41), respectively. . Examples of the heaters (H1) to (Hn) include a planar heating element having a thin heating element layer and a sheathed heater. Of course, there are those having only one hot plate. In this case, a plurality of dryers are provided.

Heaters (H1) to (Hn) (In this case, only existing heaters are included, including both existing and additional installations.) Each is a parallel connection line branched from the main power supply line (L) of the AC main power supply (1) Connected in parallel at (n1) to (nn). The parallel connection lines (n1) to (nn) have main switch elements (SSR10) to (SSRn0) for opening and closing the ammeters (61) to (6n) and the parallel connection lines (n1) to (nn). In the embodiment, a semiconductor relay is connected in series, and each of the main switch elements (SSR10) to (SSRn0) has a DC auxiliary switch element (SSR10) for controlling the AC main switch elements (SSR10) to (SSRn0). SSR11) to (SSR1n) (semiconductor relays in this embodiment) are provided, and the latter DC auxiliary switching elements (SSR11) to (SSR1n) are provided with a temperature controller (4a) of a control unit (4), which will be described later, and Control signals from the I / O unit (4b) (temperature control signals (t1) to (tn) from the temperature controller (4a) and time-division control signals (s1) to (sn) from the I / O unit (4b) ) Is getting output). That is, the temperature signals (o1) to (on) from the temperature measuring devices (THS1) to (THSn) are sent to the temperature controller (4a) as needed, and the temperature controller (4a) has a heater temperature below the set value. At this time, temperature control signals (tl) to (tn) are output to the input side of the output contacts of the auxiliary switching elements (SSR11) to (SSR1n). The I / O unit (4b) outputs time division control signals (S1) to (Sn) to the input circuits of the auxiliary switching elements (SSR11) to (SSR1n). Auxiliary switch elements (SSR11) to (SSR1n) are output contact points under the AND condition of the time division control signals (S1) to (Sn) of the input circuit and the temperature control signals (tl) to (tn) on the input side of the output contacts. A signal is output to the output side. The output side of the output contacts of the auxiliary switching elements (SSR11) to (SSR1n) outputs signals to the input circuits of the main switching elements (SSR10) to (SSRnO). That is, this signal is a signal when the time-division control signal is ON for a heater that does not reach the set temperature. An AC main power supply (1) is supplied as needed to the input side of the output contacts of the main switching elements (SSR10) to (SSRnO). The main switching elements (SSR10) to (SSRnO) have an AND condition between the input circuit signal and the AC main power supply (1) on the input side of the output contact. To be applied. When the AND condition disappears, the AC power is turned off at the next zero cross point.

The main switching elements (SSR10) to (SSRn0) switch their power supply by turning them on and off at the zero cross point for each phase in the case of three-phase alternating current in the case of single-phase alternating current. The circuit breaker (20) for overcurrent emergency shutdown from the AC main power supply (1) side to the parallel connection lines (n1) to (nn) of the main power supply line (L) of the AC main power supply (1), all A magnet conductor (21) which is an electromagnetic contactor for switching the power supply of the heaters (H1) to (Hn) is disposed. When all heaters (H1) to (Hn) are energized simultaneously as before, these circuit breakers (20) and magnet conductors (21) are required individually for all hot plates (HP1) to (HPn). .

The hot plates (HP1) to (HPn) of the dryer (41) are equipped with temperature measuring devices (THS1) to (THSn) such as thermocouples, respectively, and the hot plates (HP1) to (HPn) ) Is continuously measured and sent as a temperature signal (o1) to (on) to the temperature controller (4a) of the control unit (4) described later, and the rise of each hot plate (HP1) to (HPn) The operating temperature state is continuously monitored including the temperature state.

Hot plate (HP1), (HP2)-(HPn) auxiliary switching element (SSR11), (SSR12)-(SSRn1) output contact input side of the application state, of which hot plate to be energized from now on ( Time sharing control signals (s1) to (sn) from the I / O unit (4b) to the input circuits of the auxiliary switching elements (SSR11) and (SSR12) to (SSRn1) of HP1), (HP2) to (HPn) The temperature controller (4a) provided in the control unit (4) receives the temperature signals (o1) to (on) of the temperature measuring devices (THS1) to (THSn), When the temperature of each hot plate (HP1) to (HPn) is lower than the set temperature, the I / O unit (4b) provided in the control unit (4) for the input circuit of the auxiliary switching elements (SSR11) to (SSRn1) ) After a certain period of pause (here, 1 or an integral multiple of a half cycle), the next hot plate (HP1), (HP2) ... (HPn) and so on in time division control signal (s1) ~ (Sn) (ON signal) is output . Therefore, when it is detected that the measured temperature is the set temperature or overshoot (however, even if there is an overshoot in the method of the present invention, the hot plate (HP1), (HP2 )... (HPn) does not output the time division control signals (s1) to (sn).

Here, the number of hot plates to be selected and heated next may be one, or when multiple workpieces must be simultaneously dried, the number of workpieces is selected by the number of workpieces. However, the number of units that are energized at the same time is limited to the same or less than the number of existing hot plates when they are added, and if not added, the number is one less than the number of existing hot plates at the maximum. The hot plates are simultaneously heated.

The output time to the auxiliary switching elements (SSR11), (SSR12) to (SSRn1) = energization time is 1 cycle or an integral multiple of it to match the detected temperature of the hot plate (HP1), (HP2) to (HPn) It can be selected as appropriate. That is, the temperature rise curve is long so that it extends linearly until just before the set temperature, and then gradually decreases.After reaching the set temperature, the energization time only needs to replenish heat loss such as heat dissipation, so it is the shortest. Will be set. On the other hand, the length of the rest period is the opposite, short when the temperature rising curve extends in a straight line, gradually longer when the temperature rising curve reaches the curve, and when the set temperature is reached, the energization time is such as heat dissipation. Since it is sufficient to replenish the heat loss, it is set for the longest time. Of course, the energization time and the length of the rest period are not limited to this, and can be freely set according to the situation.

Next, the operation of the control device (A) having such a configuration will be described with reference to FIGS. The usable capacity of the main power supply equipment of the factory where the dryer (41) is installed differs from factory to factory and is not constant, but here, as described above, when the dryer (41) is added or not, This will be described separately for the case where the input current amount of the dryer (41) is reduced. First, the case of expansion will be described, and then the case of non-expansion will be described. In either case, there are a case where one hot plate is heated and a case where there are a plurality of hot plates. In the case of a plurality of units, the number of hot plates that are overlapped and fed at the time of expansion is the same as that at the time of existing installation, but at the time of non-expansion, the maximum number is one less than that at the time of installation. It should be noted that in the latter explanation that is not added, the description overlapping the former explanation that is added is omitted, and the former explanation is used. Since the existing AC mains power supply (1) will be used as it is, the new dryer (41) will increase the hot plates (HP1), (HP2) to (HPn) from the existing capacity, The capacity of the power supply facility is insufficient.

In the workpiece drying process, when the hot plates (HP1), (HP2) to (HPn) reach a predetermined temperature, the object (2) to which the coating liquid (3) is applied is transferred to the hot plates (HP1), (HP2 ) To (HPn) to dry. For this purpose, the hot plates (HP1), (HP2) to (HPn) are first heated to a predetermined temperature in an empty state. Since the method of the present invention uses the time-sharing power supply method, when there is only one hot plate, first, the time-sharing control signal (s1) is supplied to the auxiliary switching element (SSR11) of the heater (H1) of the first hot plate (HP1). ) Is input and when the input circuit of the auxiliary switching element (SSR11) is turned on, the main switching element (SSR10) to which the auxiliary switching element (SSR11) is connected detects the zero cross point. Under the AND condition of the detection signal and the time-division control signal (s1), the main switching element (SSR10) operates to energize the heater (H1) of the first hot plate (HP1) and raise the temperature.

The time division control signal (s1) can be lengthened as necessary in one cycle or an integral multiple thereof (the shortest is the time during which one cycle can be energized), and the time division control signal (s1) is cut off. The first hot plate (HP1) is turned off when the zero cross point is detected for the first time.

Then, with the shortest half-cycle down time, the same operation as described above is repeated to energize the second hot plate (HP2) from the I / O unit (4b) and raise the temperature. When this is repeated and the energization of the final hot plate (HPn) is completed, the energization is switched to the energization of the first hot plate (HP1) and repeated until the hot plate reaches a predetermined temperature.

When the hot plate reaches the vicinity of the predetermined temperature, the energization time is shortened and the temperature rising curve gradually goes to sleep. The rest period is set as necessary. When the hot plate reaches a predetermined temperature, no time division control signal is output from the I / O unit (4b) to the auxiliary opening / closing element of the hot plate, and the input circuit of the auxiliary opening / closing element is not turned on. The main switching element connected to the auxiliary switching element is not turned on and the heater is not energized.

As described above, in the time-sharing power supply method, since the temperature rise is repeated for each hot plate for a short time, the time required for raising the temperature to a predetermined temperature is longer than the case where all the heaters are raised simultaneously. However, since the rate of temperature rise is slow, there is no overshoot that greatly exceeds the set temperature, and the set temperature is reached smoothly. The heating rate of the hot plate is almost the same, but when the hot plate after the previous hot plate reaches the set temperature first, the temperature signal from the temperature detector of the subsequent hot plate will Since the time-division control signal from the I / O unit (4b) to the auxiliary switch of the hot plate is not output, the zero cross point detection signal of the main switch of the subsequent hot plate cannot be ANDed. Energization of the heater of the hot plate is passed, and after a predetermined time elapses, the temperature is switched to the next hot plate. If the next hot plate does not reach the set temperature, energization is started.

In addition, if the temperature of any hot plate falls below the set temperature during the drying process, the hot plate is heated by energization by the temperature signal from the temperature detector. In this case, the input current amount is equivalent to one hot plate.

In the case described above, the case where the hot plates are sequentially heated one by one has been shown. However, in order to shorten the temperature rising time of all the hot plates, a plurality of hot plates may be heated simultaneously. In this case, the hot plate heaters of the selected number (however, less than the number of existing hot plates) are energized for a predetermined time, followed by a rest period, and then to the same number of selected hot plates. Energization is performed for a predetermined time. As a result, the order of energization is accelerated and the temperature rise time of the hot plate is shortened accordingly.

Next, in the case of non-expansion, the heating for each hot plate is the same as the heating for each hot plate at the time of the above-mentioned expansion. Warm time is short. In addition, when heating more than one hot plate at the same time in the case of non-addition, the selected number of hot plates (up to one less than the number of existing hot plates) is energized and heated, and when energization is completed, the system stops. After the period, the next selected hot plate is energized and heated. When the number of hot plates to be heated at the same time is more than half of the number of existing hot plates, some hot plates are continuously heated by energization after the suspension period. In this case as well, the order of energization is accelerated and the temperature rise time of the hot plate is shortened accordingly.

(Experimental conditions)
FIG. 3 shows the temperature rising state of one of the four hot plates according to the time-division control method of the present invention. FIG. 4 shows the temperature rising state of the conventional method. In each graph, the vertical axis represents temperature (° C.) and the horizontal axis represents time (seconds). The experimental conditions are as follows.
AC main power supply: 50 cycles of 3-phase AC (applicable to either single phase or 60 cycles)
Hot plate heater specification; 200V at 1mm diameter, rated power consumption 10kW
Ambient temperature at the start of energization; 23 ° C
Set temperature: 80 ° C
Current-carrying condition: Always on in the conventional system, and in the system of the present invention, it is energized for 10 seconds (500 cycles) and has a rest time of 0.3 seconds (15 cycles). Temperature sampling; Temperature measurement points every second; 8 points per hot plate.

(Experimental result)
In the method of the present invention, it takes 45 minutes to reach the set temperature. In contrast, the conventional method takes 14 minutes. Since 4 hot plates are used in the experiment, it is expected that 56 minutes, which is 4 times (14 minutes x 4) of the conventional example, is required if this is sequentially energized and heated. It can be seen that the set temperature was reached in 45 minutes and reached the set temperature about 20% earlier than expected. This is because the period (B) in which the power supplied to the heater is gradually reduced as the temperature approaches the set temperature is much shorter than the period (A) in the conventional example. In other words, the temperature rise line rises linearly until the period (A) (B). This indicates that full power is supplied to the full rated power consumption of the heater until the periods (A) and (B) are reached. Since the full power supply period is longer than that of the conventional example, the heating time of the present invention can be made shorter than expected.

(A) Time-division power supply control device
(1) ・・・ AC main power supply
(3) ... Coating solution
(4) ... Control unit
(41) ..Dryers
(HP1) ～ (HPn) ・・・ Hot plate
(H1) ~ (Hn) ・・・ Heater
(L) ... Main feed line
(n1) to (nn): Parallel connection line
(THS1) ～ (THSn) ・・・ Temperature measuring instrument
(K) ... Power supply control circuit
(SSR10) to (SSRn0) ... Main switching element
(SSR11) to (SSR1n) ... Auxiliary switching elements

Claims

A dryer that is connected to an AC main power supply in parallel, and that sequentially supplies power to a plurality of hot plate heaters that heat and dry a plurality of workpieces coated with a coating liquid at a predetermined temperature. In the time-sharing control device,
An existing AC main power supply for supplying AC current to each of the plurality of heaters;
A parallel connection line that branches off from the main power supply line of the AC main power supply and supplies power to the heater, and a temperature measuring device for the heater and hot plate;
Until each hot plate reaches the set temperature, the zero cross point of the alternating current to each heater is set as a power supply switching point by the temperature signal from the temperature measuring device.
When adding hotplates, the number of existing hotplates should be less than
If you do not add a hot plate, the number is less than the number of existing hot plates,
A time-division control device for a dryer, comprising: a power supply control circuit for switching power supply to a next heater selected after a half cycle or an integral multiple of a rest period from the power supply switching point.
The time-sharing control device for a dryer according to claim 1, wherein the power supply control circuit is:
In response to a temperature signal from the temperature measuring device, the temperature of each hot plate is detected, and when the temperature of the hot plate related to the temperature signal from the temperature measuring device is equal to or lower than a set temperature, power is sequentially supplied to each heater. A control unit that outputs a time-sharing control signal to command
A main switching element that is provided in each of the parallel connection lines, and connects and disconnects the heater and the AC main power source with a zero cross point of the supplied AC current as a power supply switching point;
A dryer comprising: an auxiliary switching element that is connected to each of the main switching elements and receives a time-sharing control signal output from the control unit and turns on the main switching element according to the time-sharing control signal Time-sharing controller.
The time-sharing control device for a dryer according to claim 1 or 2, wherein the energization time to each heater is one cycle of an alternating current to be fed or an integral multiple thereof.
A dryer that is connected to an AC main power supply in parallel, and that sequentially supplies power to a plurality of hot plate heaters that heat and dry a plurality of workpieces coated with a coating liquid at a predetermined temperature. A time-sharing power supply control method,
When the temperature of the hot plate that is sequentially supplied by detecting the temperature of the hot plate is below the set temperature, the zero cross point of the AC current supplied to each heater is used as the power supply switching point until each hot plate reaches the set temperature. ,
When adding hotplates, the number of existing hotplates should be less than
If you do not add a hot plate, the number is less than the number of existing hot plates,
A time-division power supply control method for a dryer, wherein the power supply is switched to the next heater selected after a half cycle or an integral multiple of a rest period from the power supply switching point.