JP2001150343A - Grinding method for substrate peripheral edge for hard disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a quality and productivity by eliminating variations in the cutting speed caused by the difference among operators and prevent a defective work from being generated and a grinding wheel grinding surface from being damaged by making the cutting speed proper with degradation of sharpness of the grinding wheel after the specified number or more works are ground. SOLUTION: When the peripheral edge of a substrate for a hard disk is ground by rotary grinding wheels 10, 18, the physical quantity to be changed during grinding according to grinding resistance is detected at a minute time interval, and the cutting speed is mechanically changed on the basis of the detected value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for grinding the periphery of a hard disk substrate.

[0002]

2. Description of the Related Art The periphery of a hard disk substrate is ground with a rotating wheel. In order to realize high-precision machining, the rotating wheel used in this process uses, for example, an electrodeposited wheel in which diamond grains are adhered in a single layer to the peripheral surface of a disk body. Exchanged with During the grinding, the load acting on the rotating wheel is maintained at an appropriate level by changing the cutting speed of the rotating wheel with respect to the substrate.

[0003]

The change of the cutting speed described above is actually dependent on the experience of the operator. For example, it is necessary to listen to the sound during grinding or to change the surface of the workpiece after grinding. Checking is done appropriately.

[0004] In such a process, it is difficult to achieve uniformity in the quality of the workpiece after grinding due to the individual difference of the cutting speed between the operators, and especially in the case of a workpiece of a new material or a rotating wheel, Determining the optimal cutting speed is time consuming without trial and error. In addition, if the grinding is performed more than a certain number of times, the sharpness of the rotating wheel will be greatly reduced, so it is necessary to reduce the cutting speed. , The defective workpiece is frequently generated, the grinding surface of the rotating wheel is damaged, and the life of the number of processed workpieces is shortened. An object of the present invention is to solve the above problems.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, when a peripheral edge of a substrate for a hard disk is ground with a rotary wheel, a physical quantity which varies in accordance with the magnitude of the grinding resistance is determined. Detection is performed at very small time intervals, and the cutting speed of the rotating wheel with respect to the substrate is mechanically changed based on the detected value. According to this, the grinding resistance of the rotating wheel is reduced to a time and is approximately equal to an appropriate constant value, and the peripheral edge of the hard disk substrate is ground rationally and efficiently.

According to the second aspect of the present invention, when the peripheral edge of the hard disk substrate is ground with a rotary wheel, a grinding resistance acting on the wheel or a physical quantity related thereto is not a control amount, and the substrate is hardened. By performing automatic control in which the cutting speed of the rotating wheel with respect to the operation amount is set as an operation amount, the grinding resistance is substantially matched with an appropriate constant value.
This also allows the peripheral edge of the hard disk substrate to be ground rationally and efficiently.

At this time, as described in claim 3, an indicator for displaying a numerical value related to the magnitude of the grinding force is provided, and an operation switch for changing the cutting speed to a large or small is provided. The operation command of the operation switch can be implemented in association with the operation command of the automatic control so as to be prioritized. By doing so, it is possible to operate the operation switch while looking at the display on the display, and the load of the rotating wheel can be controlled more precisely while being modified by the experience of the operator.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the periphery of a hard disk substrate (hereinafter referred to as "work") is ground using a CNC (Computer Numerical Control) automatic grinding apparatus. First, this apparatus will be described. . FIG. 1 is a plan view showing a grinding apparatus according to the present invention, FIG. 2 is a side view showing an AA section in FIG. 1, FIG. 3 is a cross-sectional view showing a main part of the grinding apparatus, and FIG. 1 shows a part of the apparatus, in which A is a partially enlarged view of a grinding wheel, and B is a partially enlarged view of a peripheral surface of the grinding wheel.

In FIGS. 1 and 2, reference numeral 1 denotes a machine base;
On this machine base 1, a first grinding wheel base 2, a second grinding wheel base 3, and a work gripping moving base 4 are provided.

The first grinding wheel base 2 is capable of moving in the vertical direction X via a track member 5 on the machine base 1, and has a motor 6 and an outer diameter to which rotation is transmitted from the motor 6. A shaft 7 is provided. At this time, the outer diameter grinding shaft 7 is rotatable at a specific position via a ball bearing 8 as shown in FIG. 3, and a pulley 9 to which the rotation of the motor 6 is input is fixed to one end, and the other end. And a large-diameter wheel 10 is fixed. Reference numeral 7A denotes a bearing case portion rotatably supporting the outer diameter of the grinding shaft 7, which is fixed to the main body portion of the first grinding wheel base 2 by bolts so that the vertical and horizontal positions can be finely adjusted.

The fixing structure of the wheel 10 is as follows. That is, a radial surface portion 7a and a tapered surface portion 7b are provided at the front end of the outer diameter wheel shaft 7, while a tapered hole 10a is provided at a rotation center portion of the wheel 10, and the taper hole 10a is orthogonal to the center line c1 of the tapered hole 10a. Wheel 10
In addition to forming one side end face 10b, a nut hole 10d is provided in the other side end face 10c of the wheel 10. A fastening means 11 is formed at the tip of the outer diameter grinding shaft 7, and the fastening means 11 is engaged with a male screw 12 formed at the tip of the outer diameter grinding shaft 7 and the male screw 12. And a nut body 13 to be formed. Then, the nut body 13 is fastened in a state where the tapered hole 10a is fitted to the tapered surface portion 7b so that the tapered hole 10a is brought into contact with the tapered surface portion 7b in a condensed manner by elastic deformation and the side end surface 10b is connected to the radial surface portion 7a. Pressure contact. As a result, the tapered hole 10a comes into contact with the tapered surface portion 7b with an appropriate pressure and is firmly supported, and the position of the side end surface 10b in the direction of the outer diameter grinding shaft 7 is accurately specified by pressure contact with the radial surface portion 7a.

On the outer peripheral surface 10e of the wheel 10,
As shown in FIG. 4A, a plurality of annular ground portions m1 and m2 are formed. Each annular grinding portion is concentric with the center line c1 of the tapered hole 10a, and each section is formed as a trapezoidal groove as shown in FIG. 4B. Of these annular grinding parts m1 and m2, the five left-hand parts a, b, c, d, and e are for rough grinding, and the five right-hand parts f, g, h, i, and j are for finish grinding. . Each annular grinding part a, b, c, d, e, f, g,
Nickel plating is electrodeposited on the surfaces of h, i, and j, and through this plating layer, an electrodeposited wheel in which diamond grains are fixed in a single layer is formed.

The second grinding wheel base 3 is movable in the lateral direction Y via a lower race member 14 on the machine base 1 and is supported by the lower race member 14 via an upper race member 15. It is movable in the vertical direction X, and is equipped with a motor 16 and an inner diameter wheel 17 which is rotated by a rotation of the motor 16 and rotates at a specific position. A small-diameter grinding wheel 18 is fixed to the inner diameter grinding shaft 17. The grinding wheel 18 has substantially the same configuration as the above-mentioned grinding wheel 10 and is simply reduced in diameter. Wheel 10
Is fixed to the rotary drive shaft 17 by a structure corresponding to the above case.

The work holding and moving table 4 is capable of moving in the lateral direction Y via a track member 23 on the machine base 1. On the moving table 4, a spindle motor 24 and a motor A rotating spindle 25 to which rotation is transmitted is provided. A disk-shaped workpiece gripper 26 is fixed to the tip of the rotary spindle 25. The workpiece gripper 26 has an outer end surface serving as a workpiece gripping surface, and a concave hole is formed in the rotation center of the gripping surface. A plurality of suction holes (not shown) to which a vacuum pressure is applied are formed in an annular end face portion having an n and surrounding the concave hole n. The work w gripped by the work gripping surface has a donut shape, but the diameter of the concave hole n is not larger than that of the inner hole of the work w, and the outer diameter of the work gripping surface is Smaller than that of

A work loading / unloading robot (not shown) is provided in the vicinity of the work holding portion 26 for loading a work w which has not been ground on the work holding surface or carrying out the already ground work from the work holding surface. It is provided. Reference numeral 27 denotes a servomotor for feeding and moving the first grinding wheel base 2 in the vertical direction X, and reference numeral 27a denotes an outer diameter grinding wheel that is rotationally driven by the servomotor 27. Reference numeral 28 denotes a servomotor for feeding and moving the second grinding wheel base 3 in the vertical direction X. Reference numeral 28a denotes an inner diameter and a cutting shaft which is rotationally driven by the servomotor 28.

Next, the control system will be described. FIG. 5 is a diagram showing the control system. As shown in FIG. 5, a motor 6 for rotating the outer diameter wheel 7 and the inner wheel 17 is provided. From the inverters 29 and 30 which control the rotation of the inner wheel 16 and the inner wheel 17 and the inner wheel 17
Are output as analog signals, and the output is converted to a digital signal by the A / D converter 31. The control is performed so as to be input to the CNC control device 32, and a control digital signal is output from the CNC control device 32 to the servo amplifiers 33 and 34,
The servo amplifiers 33 and 34 amplify the control digital signal, and based on the signal thus processed, the servo motor 27 for moving the first and second grinding wheel tables 2 and 3 in the X direction. 28 is operated at a specific speed and at a specific angle, and is displayed from the CNC controller 32 on a display 35 having an outer diameter wheel load indicator 35a and an inner wheel load indicator 35b. A digital signal is supplied, and a speed increasing / decreasing digital signal specified by operating the cutting speed increasing / decreasing switch 36 of the display 35 is input to the CNC controller 32. Based on the speed increasing / decreasing digital signal, the servo amplifier The control digital signals input to 33 and 34 are appropriately changed.

The analog signals output from the inverters 29 and 30 may be directly input to the CNC controller 32 without providing the A / D converter 31 in FIG. 5, and in this case, The outer diameter wheel load indicator 35a and the inner diameter wheel load indicator 35b, which are surrounded by dotted lines in FIG. 5 of the display 35, are not provided. An outer diameter wheel load indicator 37 and an inner diameter shaft load indicator 38 for inputting corresponding ones of the analog signals are provided.

The work w to be ground by the above-mentioned grinding device is formed into a donut shape by core-cutting a glass base plate or the like. For example, a work w is mounted on a 2.5-inch or 3.5-inch hard disk for a storage device. The corresponding dimensions are made.

Since the inner and outer diameter end faces of the work w immediately after the coring have large machining errors and large surface roughness, it is necessary to correct the errors and reduce the surface roughness. It is also necessary to form the end face into a specific shape.

From these necessities, the inner and outer peripheral edges of the cored workpiece w are ground by the above-mentioned grinding device. The grinding process at this time is described with reference to FIGS. 1 to 5 and FIGS. It will be explained step by step. At this time, FIG. 6 is a diagram showing the overall processing flow, FIG. 7 is a graph showing the relationship between the cutting position of the large-diameter wheel 10 being processed and the elapse of the grinding time t, and FIG. It is a figure showing a flow.

Prior to the processing, preparation is made so that the unwritable work w can be continuously supplied to the vicinity of the grinding device. Thereafter, the grinding device is brought into an operating state. This allows
The following operations are performed automatically. That is, the motors 6, 16
Rotates, and this rotation is transmitted to the outer and inner diameter wheel shafts 7 and 17, and the two wheel wheels 10 and 18 rotate around their corresponding outer and inner diameter wheel shafts 7 and 17. .

At the start of this operation, in FIG. 1, the first grinding wheel base 2 is moved upward from the grinding processing position, and the second grinding wheel base 3 is positioned below the grinding processing position and to the right in FIG. Moved by distance. Further, the work holding moving table 4 is moved to the left side of the position during the grinding process.

In this state, as shown in step 100, the work loading / unloading robot supplies the work w prepared at the specific position to the vicinity of the position during the grinding process. Next, the work holding moving table 4 moves to the right side f1 in the horizontal direction Y, and the work holding surface of the work holding portion 26 performs vacuum suction to clamp the loaded hard disk substrate w. In connection with this suction, the work plate carrying-in / out robot releases the work w and returns to the original position.

Thereafter, as shown in step 101, the operation for machining the work w starts automatically, and then the operation in step 102 is performed as follows. That is, first, the first grinding wheel base 2 is moved to the cutting start position p0 in the vertical direction X (see FIG. 7), and the work gripping moving base 4 is further moved to the right f1 as necessary.
As a result, the position of the work w adsorbed on the work holding portion 26 in the lateral direction Y is directly opposed to the center of the first annular grinding portion a for rough grinding of the large diameter wheel 10. On the other hand, the second grinding wheel base 3 is moved upward f4 and leftward f2 to reach the cutting start position, and the front end of the small-diameter grinding wheel 18 has an inner hole of the work w adsorbed on the work gripping part surface. And the first annular grinding portion for rough grinding of the small-diameter grinding wheel 18 is directly opposed to the existing position of the workpiece w in the lateral direction Y. At this point, two wheel wheels 1
Reference numerals 0 and 18 are maintained in a state where they have not yet come into contact with the outer and inner end surfaces of the work w.

Next, step 103 is performed, that is, the main shaft 25 of the work holding and moving table 4 is
, The work w is rotated in the same shape as the main shaft 25. On one hand, the servo motor 31,
7, the large-diameter grinding wheel 10 is fed from the cutting start position p0 to the lower side f3 at a relatively large cutting speed v0 to move the work w together with the first grinding wheel base 2 as shown in FIG. The outer diameter reaches the rough grinding start position p1, and together with the second grinding wheel base 3, the small diameter grinding wheel 18
Is also moved upward from the cutting start position to f4 at a relatively large cutting speed to reach the rough grinding start position of the inner diameter of the work w. Thereby, the outer diameter end face of the workpiece w abuts on the first annular grinding portion a for rough grinding of the grinding wheel 10, while the inner diameter end face of the workpiece w has the first annular grinding part for rough grinding of the grinding wheel 18. It comes into contact with the part. At this point, the rough grinding in step 103 is started.
In this rough grinding, the large-diameter grinding wheel 10 is moved downward f3 at a specific cutting speed v10 by the rotation of the servomotor 27, and the small-diameter grinding wheel 18 is moved at a specific cutting speed by the rotation of the servomotor 28. It is fed upward and moved to f4, and thereafter, both end faces of the inner and outer diameters are gradually coarsely ground.

In connection with the start of the rough grinding, the processing shown in FIG. 8 is performed simultaneously and concurrently for the outer diameter and the inner diameter of the work, that is, in step 200, the output from each of the inverters 29 and 30 is output. The analog value as a load value acting on the outer diameter wheel 7 and the inner wheel 17 is converted into a digital signal by the A / D converter 31 and taken into the CNC controller 32. At this time, the load value may be an analog signal representing the current value (unit: amperes) of the main current flowing through the motors 6 and 16 or an analog signal representing a ratio (percent) to the total load.

In step 201, the CNC controller 32
It is determined whether the actual load value captured in step 200 is larger or smaller than a preset target load value. If the actual load value is larger than the target load value, YES is determined. If smaller, NO is determined. Is determined. Here, if YES, step 20
The process proceeds to step 204, while if NO, the process proceeds to step 204.

In step 202, a quantitative and time-related operation (for example, a proportional operation or a proportional operation) is performed between a difference value obtained by subtracting the target load value from the load values of the motors 6 and 16 and the most appropriate ingress speed corresponding to the difference value. Integral operation) is specified in advance, and based on the difference value between the actual load value and the target load value, the most appropriate engagement speed corresponding to the difference value at that time is extracted. On this occasion,
The target load value is, for example, about 50 to 80% of the total load value.

Then, in step 203, step 20
The output signal which becomes the most appropriate input speed extracted in Step 2 is passed through servo amplifiers 33 and 34 to the corresponding servo motor 2.
7, 28. As a result, the outer diameter grinding shaft 7 is fed and moved to the lower side f3 at the most appropriate insertion speed, and the inner diameter grinding shaft 17 is fed and moved to the upper side f4 at the most appropriate insertion speed. As a result, the loads on the outer diameter and inner diameter grinding shafts 7 and 17 tend to approach the target load value.

In step 204, the timer counts the elapsed time from the time when the load value is fetched in step 200,
The time when a predetermined time, for example, about 1 to 2 seconds, elapses is determined, and when this time is reached, the process returns to step 200, and the same processing is repeated until the rough grinding is completed. As a result, the load value acting on each of the outer diameter wheel 7 and the inner diameter wheel 17 in the rough grinding substantially matches the target load value. In the embodiment, the timer is used, but the processing up to now may be performed without the timer.

During the rough grinding, when the position in the vertical direction X of the large diameter grinding wheel 10 reaches the rough grinding end position p2, the position in the vertical direction X of the small diameter grinding wheel 18 is When the end position is reached, each rough grinding is ended and further cutting is stopped.

After the rough grinding of the outer diameter and the inner diameter is completed, the process proceeds to step 104, in which the first grinding wheel base 2 is moved to the specific position p above the upper f4 in relation to the stop of the rough grinding.
3 and the second grinding wheel base 3 is moved to a specific position below f3.

Thereafter, the work holding and moving table 4 is moved rightward by a specific distance to the right side f1, so that the position of the work w attracted to the work holding portion 26 in the horizontal direction Y is determined by two wheel wheels. It is in a state directly facing the first annular grinding portion f for finish grinding of 10, 18.

Next, the first and second grindings are performed so that the annular grinding portions f for finish grinding of the two wheel wheels 10 and 18 abut against the inner and outer diameter end faces of the work w attracted to the work holding portion 26. The wheel bases 2 and 3 are gradually moved in the vertical direction X in the same manner as in the case of the coarse grinding, and a specific position when the rough grinding is completed (for the large diameter grinding wheel 10, P
2 position). As a result, the inner and outer diameter end faces of the work w come into contact with the two wheel wheels 10 and 18, and thereafter, the processing of step 105 is performed, that is, the two wheel wheels 10 and 18 are , 28, the specific cutting speed V2
The feed is moved at 0, and finish grinding is started.

In connection with the start of the finish grinding, FIG.
Automatic control of the cutting speed according to the operation shown in (1) is performed simultaneously and in parallel for the outer diameter and the inner diameter of the work w. As a result, even in the finish grinding, the load value acting on each of the outer diameter wheel 7 and the inner diameter wheel 17 substantially matches the target load value. At this time, the target load value may be the same as or different from that in the rough grinding.

When the large-diameter grinding wheel 10 reaches its specific position p4 in the vertical direction X, and when the small-diameter grinding wheel 18 reaches its specific position in the vertical direction X, finish grinding is completed. Then, the first and second grinding wheel stands 2, 3 are stopped from moving in the vertical direction X. Under this stopped state, spark-out of step 106, which is a process in which the work is rotated for a certain period of time, is performed, whereby the inner and outer diameter end faces of the work w are accurately finished and ground.

Thereafter, the two wheel wheels 10, 18
The first and second grinding wheel bases 2 and 3 are moved in the vertical direction X so that the second grinding wheel base 3 moves away from the inner and outer diameter end faces of the workpiece w, and the second grinding wheel base 3 is also moved to the right side f1. Then, the grinding wheel base 2 is returned to the grinding start position p0 and the grinding wheel base 3 is returned to the grinding start position to be in a stopped state, and prepares for the next grinding.

Further, the work holding moving table 4 is moved to the left f2 after the two wheel wheels 10, 18 are separated from the inner and outer diameter end faces of the work w attracted to the work holding portion 26.

Next, when the work holding and moving table 4 is moved to a specific position on the left side f2 in the lateral direction Y, it is temporarily stopped. In this stopped state, the work loading / unloading robot moves the work loading / unloading robot. The work w adsorbed by the gripper 26 is adsorbed, while the work gripper 26 releases the suction of the work w.
And then carry it out to a specific location.

After the carry-out, the work carry-in / out robot carries the work w to be ground next to the vicinity of the grinding processing position in the same manner as above. Thereafter, the work gripping moving table 4 and the first and second grinding wheel tables 2 and 3 operate in the same manner as above,
The loaded work w is ground, and then the work loading / unloading robot unloads the processed work w in the same manner as described above.

By performing such a process on a large number of works w, the grinding ability of the first annular grinding portion a of the large-diameter grinding wheel 10 or the first annular grinding portion of the small-diameter grinding wheel 18 is less than a certain level. In this case, the control of the feed movement in the lateral direction Y of the work gripping moving table 4 is changed by operating an operation panel (not shown), and this time, instead of the first annular grinding units a, f, etc. The grinding process is performed in the second annular grinding units b, g, and the like. In this process, when the grinding ability of the second annular grinding units b, g, etc. is reduced to a certain degree or less, the second annular grinding unit b, g, etc. The next grinding process is performed in the third annular grinding units c, h, etc., instead of the annular grinding units b, g, etc.

Thus, when the grinding ability of all of the first to fifth annular grinding parts is reduced to a certain level or less, the grinding wheels 10, 18 are moved from the outer diameter wheel shaft 7 or the inner diameter wheel shaft 17. Remove, new wheel 10
18 is attached. When removing the grinding wheels 10 and 18, the nut body 13 has an outer diameter of the threaded portion 12 of the grinding shaft 7.
After removing from the wheel, the wheel 10 is pulled out from the outer diameter wheel 7.

On the other hand, when the new wheel 10 is mounted, the nut 13 is screwed onto the screw 12 after the tapered hole 10a is fitted over the tapered surface 7b. On this occasion,
By the fastening of the nut body 13, the tapered hole 10a is pushed into the tapered hole 7a in the direction of the outer diameter while being elastically deformed by the mutual contact pressure in the tapered surface portion 7b.
When b is brought into contact with the radial surface portion 7a, the displacement of the tapered hole 10a in the direction of the outer diameter of the grinding shaft 7 is immediately regulated, and the grinding wheel 10 is accurately fixed at a specific position in the longitudinal direction of the outer diameter of the grinding shaft 7. Will be done.

During rough grinding or finish grinding, the outer diameter wheel load indicators 35a and 37 and the inner wheel load indicator 3 are used.
While watching the readings such as 5b and 38, the cutting speed increase / decrease operation switch 36 is operated as necessary based on the actual grinding situation. As a result, the automatically performed grinding process is corrected according to the judgment of a skilled worker, and more excellent grinding is performed.

[0045]

According to the present invention described above, since the load acting on the rotation wheel is mechanically substantially matched with the target load, it is possible to prevent the deterioration of the quality due to the loss of the work and the like, and to prevent the work from becoming excessively large. The rotation wheel can be prevented from being damaged by the pressure contact and the life of the number of grinding wheels can be prolonged, and low-load grinding can be avoided and efficient grinding can be performed. In particular, electrodeposited wheels, which are often used for grinding hard disk substrates, which are workpieces, are easily damaged by excessive pressure contact of the workpiece. The significance is even greater.

According to the second aspect, the same effect as that of the first aspect can be obtained. According to the third aspect, the cutting speed automatically determined is corrected by the operator's judgment. More excellent grinding can be performed.

[Brief description of the drawings]

FIG. 1 is a plan view showing a grinding device used in the present invention.

FIG. 2 is a side arrow view showing an AA part of FIG. 1;

FIG. 3 is a sectional view showing a main part of the grinding device.

FIG. 4 shows a part of the grinding device, wherein A is an enlarged view showing a part of a wheel, and B is a partially enlarged view of a peripheral surface of the wheel.

FIG. 5 is a diagram showing a control system of the grinding device.

FIG. 6 is a diagram showing an overall processing flow according to the present invention.

FIG. 7 is a graph showing a relationship between a cutting position of a large diameter wheel and a lapse of grinding time during processing according to the present invention.

FIG. 8 is a diagram showing a partial processing flow according to the present invention.

[Explanation of symbols]

 w Hard disk substrate (work) 10, 18 Wheel (rotary wheel) 35 Indicator 35a Outer diameter wheel load indicator 35b Inner wheel load indicator

Claims (3)

[Claims] When a peripheral edge of a hard disk substrate is ground with a rotary wheel, a physical quantity that changes in relation to the magnitude of the grinding resistance during grinding is detected at minute intervals, and cutting is performed based on the detected value. A method for grinding the periphery of a hard disk substrate, wherein the method is carried out so as to mechanically change the loading speed. 2. When grinding the periphery of a hard disk substrate with a rotary wheel, a grinding resistance acting on the wheel or a physical quantity related thereto is a control amount, and the rotary wheel is cut into the substrate. A method for grinding the periphery of a hard disk substrate, wherein the grinding resistance is substantially matched to an appropriate constant value by performing automatic control with a speed as an operation amount. 3. An indicator for displaying a numerical value related to the magnitude of the grinding resistance, and an operation switch for changing the cutting speed to a large or small value, wherein an operation command of the operation switch is automatically controlled. 3. The method for grinding a peripheral edge of a hard disk substrate according to claim 2, wherein the method is performed so as to be prioritized over an operation command.