Heater system and method for measuring heater current

Abstract

The present invention relates to a heater system and a method for measuring a heater current, and more particularly, to a heater system and a method for measuring a heater current, the heater system comprising a plurality of heaters; a sensing section that measures a current of each of the plurality of heaters and is provided at a single site; a plurality of connection parts for switching on / off each of the plurality of heaters; and a plurality of heater control units that control the operation of the plurality of connection units, respectively. According to the present invention, current is measured for a plurality of heaters using a sensing unit provided at a single portion, thereby reducing cost increase of equipment, reducing component mounting space, and further improving process efficiency and economy.

Description

Technical Field

[0001] The present invention relates to a heater system and a method for measuring heater current. More specifically, the present invention relates to a heater system and a method for measuring heater current that can sequentially measure the currents of multiple heaters by using a sensing unit provided at a single location to confirm whether there is a disconnection of the heater. Background Art

[0002] In semiconductor manufacturing processes, multiple processes including a process of forming a film on a substrate, a process of hardening a photoresist composition coated on the substrate, or a process of removing a photoresist film are generally performed with the substrate heated to a high temperature state. At this time, temperature control can be an important factor.

[0003] For example, in order to form a thin film on a substrate, various deposition processes such as Atomic Layer Deposition (ALD), Plasma Enhanced Atomic Layer Deposition (PEALD), Chemical Vapor Deposition (CVD), and Plasma Enhanced Chemical Vapor Deposition (PECVD) can be implemented. In such deposition processes, the deposition rate is greatly affected by the substrate temperature, so it is important to ensure the uniformity of the substrate surface temperature.

[0004] Generally, heaters are used as heat sources in a wide range of fields including such semiconductor manufacturing processes. In most cases, the heater may be composed of an array in which multiple heaters are connected. Each of the heaters has a heating element. For example, when a power source is applied to both ends of a resistor, Joule heat is generated by the current flowing through both ends of the heating element. As described above, the heating elements constituting the heater may cause problems such as disconnection, failure, and operation error due to external shock, aging, or current exceeding the capacity.

[0005] When problems such as disconnection occur, the heater cannot perform its function as a heat source. Therefore, it is necessary to detect problems such as disconnection of the heater and perform work such as replacement. The disconnection detection of the heater can be achieved by measuring the current of the heater.

[0006] Figure 1 To briefly show a schematic diagram of a heater system according to the prior art.

[0007] Refer to Figure 1 , a conventional heater system includes a circuit breaker 10, a connection part 20, a sensing part 30, a heater 40, and a heater control part 50.

[0008] The heater 40 serves as a heat source. For example, in the manufacturing process of semiconductor devices, it has the function of controlling the surface temperature of the substrate by heating.

[0009] The heater 40 may be formed in an array form connected with a plurality of heaters 40-1, 40-2, 40-3,... 40-n.

[0010] The circuit breaker 10 may have the function of cutting off the main current applied to the heater system.

[0011] The connection part 20 may function as a switch for turning on / off the heater 40. The connection part 20 may include a plurality of connection parts 20-1, 20-2, 20-3,... 20-n.

[0012] Each of the plurality of heaters 40-1, 40-2, 40-3,... 40-n may be connected to each of the plurality of connection parts 20-1, 20-2, 20-3,... 20-n.

[0013] The heater control part 50 may have the function of controlling the connection part 20. The heater control part 50 may include a plurality of heater control parts 50-1, 50-2, 50-3,... 50-n.

[0014] Each of the plurality of connection parts 20-1, 20-2, 20-3,... 20-n may correspond to each of the plurality of heater control parts 50-1, 50-2, 50-3,... 50-n and may be controlled by each of the plurality of heater control parts 50-1, 50-2, 50-3,... 50-n.

[0015] The sensing part 30 may have the function of measuring the current flowing through each of the plurality of heaters 40-1, 40-2, 40-3,... 40-n. Corresponding to each of the plurality of heaters 40-1, 40-2, 40-3,... 40-n, the sensing part 30 may include a plurality of sensing parts 30-1, 30-2, 30-3,... 30-n.

[0016] That is, in the heater system according to the prior art, in order to measure the current flowing through the heater 40 to detect problems such as disconnection of the heater 40, it is necessary to separately set the plurality of current measurement sensors 30-1, 30-2, 30-3,... 30-n according to the number of the heaters to respectively correspond to the plurality of heaters 40-1, 40-2, 40-3,... 40-n.

[0017] This will lead to an increase in the cost of the semiconductor manufacturing apparatus including the heater system, thereby becoming a process burden. Also, it is necessary to secure space for arranging a plurality of current measurement sensors 30-1, 30-2, 30-3, … 30-n within the heater system. Therefore, there may be difficulties in terms of the component mounting space of the semiconductor manufacturing apparatus.

[0018] Patent Document 1 relates to a method for detecting a failure of a multiplexed heater array, and discloses a method for detecting a failure of a multi-region heating plate including a plurality of heater regions and a substrate support assembly for supporting a semiconductor substrate in a semiconductor processing apparatus. However, in the method disclosed in Patent Document 1, a current meter is also required to measure the current according to the number of heaters constituting the array.

[0019] Therefore, there is still a need for a heater system and a method for measuring heater current that can reduce the increase in equipment cost, reduce the component mounting space, and thereby further improve process efficiency and economy.

[0020] However, the above-mentioned prior art is technical information that the inventor has retained or mastered during the derivation of the present invention, and is not necessarily publicly known art that was made public to the general public before the application of the present invention.

[0021] Prior art documents

[0022] Patent documents

[0023] Patent Document 1: Korean Patent Publication No. 10-2016-0025635 (Publication Date: March 8, 2016) Summary of the Invention

[0024] Technical problem

[0025] In solving the above problems, an object of the present invention is to provide a heater system and a method for measuring heater current as follows: measuring the current of a plurality of heaters using a sensing unit provided at a single location, thereby reducing the increase in equipment cost, reducing the component mounting space, and further improving process efficiency and economy.

[0026] Also, an object of the present invention is to provide a heater system and a method for measuring heater current as follows: sequentially monitoring the current of a plurality of heaters by using a sensing unit provided at a single location, thereby effectively identifying problems such as disconnection of an individual heater.

[0027] The technical problems to be solved by the present invention are not limited to the above-mentioned problems, and those skilled in the art to which the present invention pertains can clearly understand other technical problems to be solved that are not mentioned from the following description.

[0028] Solution to the problem

[0029] A heater system according to an embodiment of the present invention includes: a plurality of heaters; a sensing unit that measures the current of each of the plurality of heaters and is provided at a single location; a plurality of connection units that switch each of the plurality of heaters on / off; and a plurality of heater control units that respectively control the operations of the plurality of connection units.

[0030] At this time, the sensing unit may include a current measurement sensor.

[0031] Moreover, the sensing unit may be provided on the main circuit to which the plurality of heaters are connected.

[0032] Furthermore, the plurality of heater control units may be configured to control the connection unit corresponding to the heater to be measured among the plurality of connection units through the heater control unit corresponding to the heater to be measured among the plurality of heater control units, so as to turn on only the heater to be measured and turn off the remaining heaters.

[0033] Also, the connection unit may include a Solid State Relay (SSR) or a Silicon Control Rectifier (SCR).

[0034] In addition, the heater system may be used in a semiconductor manufacturing apparatus for manufacturing semiconductor elements.

[0035] A method for measuring the heater current according to an embodiment of the present invention, the heater including a plurality of heaters, a sensing unit that measures the current of each of the plurality of heaters and is provided at a single location, a plurality of connection units that switch each of the plurality of heaters on / off, and a plurality of heater control units that control the operations of the plurality of connection units, the method for measuring the heater current of the heater system includes: a heater control step of turning on only the heater to be measured and turning off the remaining heaters among the plurality of heaters; a measurement step of measuring the current flowing through the heater to be measured; and a waiting step of waiting for a preset time.

[0036] At this time, the sensing unit may include a current measurement sensor, and the measurement step may be implemented by the current measurement sensor.

[0037] Moreover, the sensing unit may be provided on the main circuit to which the plurality of heaters are connected.

[0038] Also, in the heater control step, the control of the connection unit corresponding to the heater to be measured among the plurality of connection units may be performed through the heater control unit corresponding to the heater to be measured among the plurality of heater control units.

[0039] Moreover, the waiting step can be performed for 10 ms to 1000 ms.

[0040] The method for measuring the heater current according to an embodiment of the present invention may further include: a determination step of determining whether there is a disconnection of the heater to be measured based on the measured current; and a step of performing maintenance work when it is determined to be a disconnection through the determination step, or a step of re-executing the heater control step when it is determined not to be a disconnection through the determination step.

[0041] In this case, in the determination step, when the measured current deviates from a preset reference current range, it can be determined as a disconnection, and when the measured current is within the preset reference current range, it can be determined as non-disconnection.

[0042] Effects of the Invention

[0043] As described above, according to the heater system and the method for measuring the heater current of the present invention, by using the sensing unit provided at a single location to measure the current of each heater for a plurality of heaters, the cost increase of the equipment is reduced, the component installation space is reduced, and the process efficiency and economy can be further improved.

[0044] Moreover, according to the heater system and the method for measuring the heater current of the present invention, by using the sensing unit provided at a single location to sequentially monitor the current of a plurality of heaters, problems such as disconnection of individual heaters can be effectively identified.

[0045] The effects of the present invention are not limited to the above-mentioned effects, and those skilled in the art to which the present invention pertains can clearly understand other effects not mentioned from the following description. Brief Description of the Drawings

[0046] Figure 1 Schematic diagram for briefly showing a heater system according to the prior art.

[0047] Figure 2 Schematic diagram for briefly showing a heater system and a method for measuring the heater current according to an embodiment of the present invention.

[0048] Figure 3 Flowchart for briefly showing a method for measuring the heater current according to an embodiment of the present invention.

[0049] (Description of Reference Numerals)

[0050] 110: Circuit breaker

[0051] 120: Current measurement sensor

[0052] 130: Connection part

[0053] 140: Heater

[0054] 150: Heater control unit Detailed implementation manners

[0055] In the present invention, for the sake of differentiating from the prior art, clarity, and facilitating the understanding of the technology, the drawings may be exaggeratedly shown. In addition, the following terms are defined in consideration of the functions in the present invention and may vary according to the intentions or conventions of users and operators. Therefore, these terms should be defined based on the technical content throughout this specification. On the other hand, the embodiments are merely exemplary matters of the constituent elements set forth in the claimed scope of the present invention and are not used to limit the claimed scope of the present invention. The claimed scope should be interpreted based on the technical concept throughout the specification of the present invention.

[0056] Throughout the specification, when it is stated that a certain constituent "includes" a certain constituent, unless there is a particularly contrary description, it means that other constituents may be further included, rather than excluding other constituents.

[0057] In addition, when it is stated that a certain constituent "is connected", "is connected", or "is combined" to another constituent, it means that not only the cases of "direct connection", "direct connection", or "direct combination" exist, but also the cases of "being connected with other constituents intervening therebetween", "being connected with other constituents intervening therebetween", or "being combined with other constituents intervening therebetween" exist. On the contrary, when it is stated that a certain constituent "is directly connected", "is directly connected", or "is directly combined" to another constituent, it should be understood that no other constituent exists in between.

[0058] In addition, when directional terms such as "front", "rear", "upper", "lower", "left", "right", "one end", "the other end", "both ends", etc. are used, since they are terms used exemplarily with respect to the orientation of the disclosed drawings, they should not be restrictively interpreted. When terms such as "first", "second", etc. are used, they are terms for distinguishing each constituent and should not be restrictively interpreted.

[0059] To more clearly illustrate the features of the embodiments of the present invention, detailed descriptions of matters well-known to those of ordinary skill in the technical field to which the following embodiments belong are omitted. Also, detailed descriptions of parts irrelevant to the description of the embodiments will be omitted in the drawings.

[0060] Hereinafter, with reference to the drawings, embodiments of the present invention will be described in detail.

[0061] Figure 2 For briefly showing a schematic diagram of a heater system and a method for measuring heater current according to an embodiment of the present invention, Figure 3A flowchart for briefly showing a method of measuring heater current according to an embodiment of the present invention.

[0062] Referring to Figure 2 and Figure 3 According to an embodiment of the present invention, a heater system includes a sensing unit 120, a connection unit 130, a heater 140, and a heater control unit 150. The heater system according to an embodiment of the present invention further includes a circuit breaker 110. The respective configurations of the circuit breaker 110, the sensing unit 120, the connection unit 130, the heater 140, and the heater control unit 150 are known in the related art, and thus their detailed descriptions are omitted in this embodiment. The heater system according to this embodiment can be used in a semiconductor manufacturing apparatus for manufacturing semiconductor elements.

[0063] The circuit breaker 110 may have a function of cutting off the main current applied to the heater system. The current applied to the heater system may flow in the order of the circuit breaker 110, the sensing unit 120, the connection unit 130, the heater 140, and the heater control unit 150.

[0064] In Figure 2 the illustrated embodiment, one circuit breaker 110 is provided, but the number of the circuit breakers 110 may be set to multiple according to the load capacity. For example, when the load capacity is less than 500W, one main circuit breaker may be provided in combination. On the other hand, when the load capacity is 500W or more, circuit breakers may be provided separately. For example, a sub-circuit breaker may be provided under the main circuit breaker.

[0065] The heater 140 is configured to be used as a heat source. The heater 140 may have, for example, a function of applying heat to control the surface temperature of a substrate in the manufacturing process of a semiconductor device. However, in addition to the manufacturing process of semiconductor devices, the heater system according to an embodiment of the present invention can be applied to heater systems in various industrial fields.

[0066] The heater 140 may be configured to generate heat having a predetermined temperature according to the applied electric energy. As the heater 140, a heater known in the art can be adopted.

[0067] The heater 140 may be configured in an array form connected with a plurality of heaters 140-1, 140-2, 140-3,... 140-n.

[0068] In this specification, for the heater or the plurality of heaters, the reference numeral 140 and the reference numerals 140-1, 140-2, 140-3,... 140-n may be used interchangeably.

[0069] The connection part 130 is configured to switch on / off each of the plurality of heaters 140-1, 140-2, 140-3, … 140-n.

[0070] The connection part 130 may include a Solid State Relay (SSR) or a Silicon Control Rectifier (SCR).

[0071] The connection part 130 can include a plurality of connection parts 130-1, 130-2, 130-3, … 130-n in a manner corresponding to each of the plurality of heaters 140-1, 140-2, 140-3, … 140-n. That is, the number n of the connection parts 130 may be the same as the number n of the heaters 140.

[0072] In this specification, for the connection part or the plurality of connection parts, the reference numerals 130 and 130-1, 130-2, 130-3, … 130-n can be used interchangeably.

[0073] The heater control part 150 is configured to control the operation of each of the plurality of connection parts 130-1, 130-2, 130-3, … 130-n.

[0074] The heater control part 150 can include a plurality of heater control parts 150-1, 150-2, 150-3, … 150-n in a manner corresponding to each of the plurality of connection parts 130-1, 130-2, 130-3, … 130-n. That is, the number n of the heater control parts 150 may be the same as the number n of the connection parts 130 and the number n of the heaters 140.

[0075] The heater control part 150 may be configured to control the connection part corresponding to the heater to be measured among the plurality of connection parts 130-1, 130-2, 130-3, … 130-n through the heater control part corresponding to the heater to be measured among the plurality of heater control parts 150-1, 150-2, 150-3, … 150-n, so as to only turn on the heater to be measured and turn off the remaining heaters.

[0076] In this specification, for the heater control part or the plurality of heater control parts, the reference numerals 150 and 150-1, 150-2, 150-3, … 150-n can be used interchangeably.

[0077] The sensing part 120 is configured to measure the current of each of the plurality of heaters 140-1, 140-2, 140-3, … 140-n.

[0078] For Figure 1 the conventional heater system shown in Figure 1 , a plurality of sensing units 30 are separately provided corresponding to each of the plurality of heaters 40, but the heater system of the present embodiment is characterized in that, as shown in Figure 2 , the sensing unit 120 is provided at a single location. As described above, the sensing unit 120 provided at a single location can measure the current of each of the plurality of heaters 140-1, 140-2, 140-3,..., 140-n. Figure 2 As shown, the sensing unit 120 is provided at a single location. As described above, the sensing unit 120 provided at a single location can measure the current of each of the plurality of heaters 140-1, 140-2, 140-3,..., 140-n.

[0079] The installation position of the sensing unit 120 can be set to a position capable of measuring the current of each of the plurality of heaters 140-1, 140-2, 140-3,..., 140-n. For example, the sensing unit 120 can be provided in the main circuit to which the plurality of heaters 140 are connected.

[0080] The sensing unit 120 may include a current measurement sensor.

[0081] The sensing unit 120 can measure the current of the heater to be measured among the plurality of heaters 140-1, 140-2, 140-3,..., 140-n. As described above, when the connection parts 130-1, 130-2, 130-3,..., 130-n corresponding to the heater to be measured among the plurality of heater control parts 150-1, 150-2, 150-3,..., 150-n are controlled by the heater control part corresponding to the heater to be measured so that only the heater to be measured is turned on and the remaining heaters are turned off, the sensing unit 120 can measure the current of the heater to be measured in the on state. Repeating this process for each of the plurality of heater control parts 150-1, 150-2, 150-3,..., 150-n, the sensing unit 120 can sequentially measure the current of each of the plurality of heaters 140-1, 140-2, 140-3,..., 140-n.

[0082] The heater system according to an embodiment of the present invention is characterized in that the sensing unit 120 is provided at a single location instead of separately provided to measure the current of each of the plurality of heaters 140-1, 140-2, 140-3,..., 140-n. Therefore, according to an embodiment of the present invention, an increase in the cost of the equipment can be reduced, the component installation space can be reduced, and the process efficiency and economy can be further improved. And, according to an embodiment of the present invention, by using the sensing unit 120 provided at a single location to sequentially monitor the current of the plurality of heaters 140-1, 140-2, 140-3,..., 140-n, problems such as disconnection of a single heater can be effectively confirmed.

[0083] The method for measuring the heater current according to an embodiment of the present invention is a method for measuring the heater current of a heater system, the heater system including: a plurality of heaters; a sensing unit that measures the current of each of the plurality of heaters and is provided at a single location; a plurality of connection units that switch each of the plurality of heaters on / off; and a plurality of heater control units that respectively control the operations of the plurality of connection units. That is, the method for measuring the heater current according to an embodiment of the present invention is a method for measuring the heater current of the heater system according to an embodiment of the present invention as described above. In this embodiment, the content described about the heater system in the above embodiment is omitted from detailed description to avoid repetition.

[0084] The method for measuring the heater current according to an embodiment of the present invention includes a heater control step (S10), a measurement step (S20), and a waiting step (S30). And, the method for measuring the heater current according to an embodiment of the present invention may further include: a disconnection step (S40) of determining whether the heater to be measured exists according to the measured current; and a step of performing maintenance work (S50) or re-executing the step (S10).

[0085] The heater control step (S10) is a step of only turning on the heater to be measured among the plurality of heaters 140-1, 140-2, 140-3, … 140-n and turning off the remaining heaters.

[0086] As described above, in this embodiment, the sensing unit 120 for measuring current is provided as a single location with respect to the entire heater system, rather than being separately provided for each of the plurality of heaters 140-1, 140-2, 140-3, … 140-n. Therefore, in order to measure the current of any one heater, it is necessary to only turn on the heater to be measured and turn off the remaining heaters.

[0087] In the heater control step (S10), the connection unit corresponding to the heater to be measured among the plurality of connection units 130-1, 130-2, 130-3, … 130-n can be controlled by the heater control unit corresponding to the heater to be measured among the plurality of heater control units 150-1, 150-2, 150-3, … 150-n.

[0088] The measurement step (S20) is a step of measuring the current flowing through the heater to be measured.

[0089] The measurement of the current of the heater to be measured can be performed by the sensing unit 120. The sensing unit may include a current measurement sensor, and the measurement step (S20) can be implemented by the current measurement sensor.

[0090] As described above, the sensing unit 120 is disposed at a single position with respect to the heater system. For example, it can be disposed in the main circuit to which the plurality of heaters 140 are connected.

[0091] In the measuring step (S20), the sensing unit 120 measures the current flowing through the heater to be measured in the open state. At this time, the time when the sensing unit 120 reads the current flowing through the heater to be measured can be represented by "T" read ".

[0092] The waiting step (S30) is a step of waiting for a preset time. That is, through the waiting step (S30), after the sensing unit 120 reads the current flowing through the heater to be measured during T, it has a preset waiting time. read

[0093] Waiting for a preset time in the waiting step (S30) is to confirm that there is no problem with the heater system.

[0094] At this time, the waiting time can be set by the user to confirm that there is no problem with the heater system, so the current value measured in the measuring step (S20) is reliable. For example, the waiting step (S30) can be performed for 10 ms to 1000 ms.

[0095] The determination step (S40) is a step of determining whether there is a break in the heater to be measured based on the measured current.

[0096] In the determination step (S40), when the current measured by the sensing unit 120 deviates from the preset reference current range, it can be determined as a break, and when the measured current is within the preset reference current range, it can be determined as non - broken.

[0097] At this time, the user can set the reference current range used to determine whether there is a break in the heater to be measured based on the current value measured from a normally operating heater.

[0098] In the step (S50), when it is determined through the determination step (S40) that the heater to be measured is broken, maintenance work is performed on the heater to be measured. At this time, the maintenance work can include work such as replacement, repair, and maintenance processing of the heater determined to be broken.

[0099] On the other hand, when it is determined through the determination step (S40) that the heater to be measured is non - broken, the heater control step (S10) can be executed again to measure the current of the next heater.

[0100] A process like this can be represented as a loop respectively. To measure the currents of all the multiple heaters 140-1, 140-2, 140-3, … 140-n, n loops need to be executed, and the total time required at this time can be expressed as “T total ”.

[0101] The method for measuring the heater current according to an embodiment of the present invention is characterized in that the sensing unit 120 provided at a single location is used to sequentially measure the currents of each of the multiple heaters 140-1, 140-2, 140-3, … 140-n. Therefore, according to the embodiment of the present invention, the cost increase of the device can be reduced, the component installation space can be reduced, and the process efficiency and economy can be further improved. And, according to the embodiment of the present invention, the sensing unit 120 provided at a single location is used to sequentially monitor the currents of the multiple heaters 140-1, 140-2, 140-3, … 140-n, so that problems such as disconnection of a single heater can be effectively confirmed.

[0102] As described above, the present invention has been described with reference to the embodiments shown in the drawings, but this is only exemplary. It should be understood that various modifications and equivalent other embodiments can be made based on general knowledge in the technical field to which this technology belongs. Therefore, the true technical protection scope of the present invention should be based on the scope of the appended claims of the invention and determined based on the above specific content of the invention.

[0103] Industrial Applicability

[0104] The present invention relates to a heater system and a method for measuring a heater current, and can be used in the industrial field related to heaters.

Claims

1. A heater system, wherein: include: Multiple heaters; a sensing portion that measures a current of each of the plurality of heaters and is provided at a single location; a plurality of connection parts for switching each of the plurality of heaters on / off; and The plurality of heater control units controls the operation of each of the plurality of connection units.

2. The heater system according to claim 1, characterized in that The sensing portion includes a current measuring sensor.

3. The heater system according to claim 1, characterized in that The sensing unit is provided in a main circuit to which the plurality of heaters are connected.

4. The heater system according to claim 1, characterized in that The plurality of heater control sections are configured to control a connection section corresponding to the heater to be measured among the plurality of connection sections through a heater control section corresponding to the heater to be measured among the plurality of heater control sections so that only the heater to be measured is turned on and the remaining heaters are turned off.

5. The heater system according to claim 1, characterized in that The connecting portion includes a solid-state relay or a silicon controlled rectifier.

6. The heater system of claim 1, wherein: The heater system is used in a semiconductor manufacturing apparatus for manufacturing semiconductor elements.

7. A method for measuring heater current, the method being a method for measuring heater current of a heater system, the heater system comprising a plurality of heaters, a sensing unit for measuring the current of each of the plurality of heaters and arranged at a single location, a plurality of connecting units for switching each of the plurality of heaters on / off, and a plurality of heater control units for controlling the operation of each of the plurality of connecting units, wherein: The method comprises: a heater control step of turning on only the heater to be measured and turning off the remaining heaters among the plurality of heaters; a measuring step of measuring the current flowing through the heater to be measured; and Wait step, wait for the preset time.

8. The method for measuring heater current according to claim 7, characterized in that: The sensing portion includes a current measuring sensor, The step of measuring the current flowing through the heater to be measured is achieved by the current measuring sensor.

9. The method for measuring heater current according to claim 7, characterized in that: The sensing unit is provided on a main circuit connected to the plurality of heaters.

10. The method for measuring heater current according to claim 7, characterized in that: In the heater control step, control of a connection portion corresponding to the heater to be measured among the plurality of connection portions is performed by a heater control portion corresponding to the heater to be measured among the plurality of heater control portions.

11. The method for measuring heater current according to claim 7, characterized in that: The waiting step is performed for 10 ms to 1000 ms.

12. The method for measuring heater current according to claim 7, characterized in that: The method further comprises: a judging step, judging whether there is a disconnection of the heater to be measured according to the measured current; and A step of performing maintenance work when it is determined that the wire is broken by the determination step, or a step of executing the heater control step again when it is determined that the wire is not broken by the determination step.

13. The method for measuring heater current according to claim 12, characterized in that: In the judging step, when the measured current deviates from a preset reference current range, it is judged as a line break, and when the measured current is within the preset reference current range, it is judged as not a line break.

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