Substrate processing system and temperature management method for substrate processing system

Abstract

This substrate processing system comprises: an electric fan that cools air in a housing; an internal air temperature measurement unit that measures the internal air temperature of the housing; and a cooling means control unit that turns on and off the electric fan on the basis of the measured internal air temperature (turns off the electric fan when the internal air temperature measured by the internal air temperature measurement unit becomes a first reference temperature (T1) or lower, and turns on the electric fan when the internal air temperature becomes a second reference temperature (T2) or higher). Data (timing data) on the on / off timing of the electric fan performed by an electric fan control unit is generated (ST3-ST14), and the generated timing data is stored in a storage unit (ST15). Thereafter, the electric fan is turned on and off on the basis of the timing data read from the storage unit (ST16-ST20).

Description

SUBSTRATE PROCESSING SYSTEM AND TEMPERATURE MANAGEMENT METHOD FOR SUBSTRATE PROCESSING SYSTEM

[0001] The present disclosure relates to a substrate processing system that performs a predetermined process on a substrate and a temperature management method thereof.

[0002]

[0003] As a substrate processing system having a substrate processing section in a housing for performing predetermined processing on a substrate, for example, a screen printing system for printing paste on a substrate and a component mounting system for mounting components on a substrate are known. In such a substrate processing system, various problems may occur if the temperature inside the housing (internal air temperature) rises excessively. For this reason, a system that provides a cooling device such as a fan in the housing to cool the air inside the housing is known (for example, Patent Document 1 listed below).

[0003] Japanese Patent Publication No. 2002-16387

[0004] However, in conventional substrate processing systems, the fan typically continues to operate even when the temperature inside the enclosure is sufficiently low, resulting in wasted power consumption and increased costs.

[0005] SUMMARY OF THE INVENTION Accordingly, an object of the present disclosure is to provide a substrate processing system and a temperature management method for the substrate processing system that can reduce the power consumption of a cooling unit while suppressing a temperature rise inside the housing.

[0006] The substrate processing system of the present disclosure includes a housing having a substrate processing unit therein that performs a predetermined process on substrates, an electrically driven cooling means that cools the air within the internal space of the housing, an internal temperature measuring unit that measures the internal temperature of the housing, a cooling means control unit that turns the cooling means on and off based on the internal temperature measured by the internal temperature measuring unit, a data generation unit that generates data on the timing of turning the cooling means on and off performed by the cooling means control unit, a memory unit that stores the data generated by the data generation unit, and an on / off control unit that reads the data stored in the memory unit and turns the cooling means on and off based on the read data.

[0007] The temperature control method for a substrate processing system disclosed herein is a temperature control method for a substrate processing system including a housing having a substrate processing unit therein that performs a predetermined process on substrates, an electrically driven cooling means that cools the air within the internal space of the housing, an internal temperature measurement unit that measures the internal temperature of the housing, and a cooling means control unit that turns the cooling means on and off based on the internal temperature measured by the internal temperature measurement unit, and includes a data generation process that generates data on the timing of turning the cooling means on and off performed by the cooling means control unit, a storage process that stores the data generated in the data generation process in a storage unit, and an on / off control process that reads out the data stored in the storage process and turns the cooling means on and off based on the read data.

[0008] According to the present disclosure, it is possible to reduce the power consumption of the cooling means while suppressing the temperature rise inside the housing.

[0009] Fig. 1 is a configuration diagram of a substrate processing system according to an embodiment of the present disclosure; Fig. 2 is a graph showing an example of a change in internal air temperature over time of a housing provided in a screen printing apparatus constituting the substrate processing system according to an embodiment of the present disclosure; Fig. 3 is a diagram showing an example of a list of timing data stored in a storage unit constituting the substrate processing system according to an embodiment of the present disclosure; Fig. 4 is a flowchart showing a flow of a temperature management operation performed by the substrate processing system according to an embodiment of the present disclosure;

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] An embodiment of the present disclosure will now be described with reference to the drawings. Fig. 1 shows a substrate processing system 10 according to one embodiment of the present disclosure. In this embodiment, the substrate processing system 10 is a screen printing system that includes a screen printing apparatus 10A as a substrate processing apparatus and a temperature control apparatus 10B that controls the temperature of the screen printing apparatus 10A.

[0011] 1, the screen printing apparatus 10A is an apparatus that performs a printing process of printing a paste Pst on a substrate KB as a predetermined process, and includes a housing 11, a substrate processing section 12, an electric fan 13, an inside air temperature measuring section 14, an outside air temperature measuring section 15, and a control device 16. The housing 11 has an internal space 11S, and the substrate processing section 12 is provided within the internal space 11S.

[0012] The substrate processing unit 12 is a printing unit in this embodiment, and includes a pair of conveyors 21 that carry the substrate KB into the internal space 11S of the housing 11 and carry the substrate KB out of the internal space 11S, a mask 22 arranged above the conveyors 21, a lifter 23 that lifts the substrate KB carried in by the conveyor 21 and brings it into contact with the mask 22, and a squeegee 24 that slides on the mask 22 with which the substrate KB has been brought into contact by the lifter 23. The squeegee 24 scrapes the paste Pst supplied onto the mask 22 over the mask 22, thereby printing the paste Pst on the top surface of the substrate KB through printing openings (not shown) formed in the mask 22.

[0013] In this embodiment, the electric fan 13 discharges the air inside the housing 11 to the outside to release heat (i.e., dissipate heat) inside the housing 11, and functions as a cooling means that is electrically driven and cools the air inside the internal space 11S of the housing 11. The internal air temperature measuring unit 14 is provided inside the housing 11 and measures the temperature inside the housing 11 (internal air temperature) in real time. The external air temperature measuring unit 15 is provided outside the housing 11 and measures the temperature outside the housing 11 (external air temperature) in real time.

[0014] The control device 16 includes an operation control unit 16a that controls the operations of the conveyor 21, lifter 23, and squeegee 24 that constitute the substrate processing unit 12, as well as an electric fan control unit 16b that serves as a cooling means control unit (FIG. 1). The electric fan control unit 16b turns the electric fan 13 on and off based on the internal temperature of the housing 11 measured by the internal temperature measurement unit 14. Specifically, the electric fan control unit 16b turns the electric fan 13 off when the internal temperature of the housing 11 measured by the internal temperature measurement unit 14 is equal to or lower than a predetermined first reference temperature (referred to as "T1"), and turns the electric fan 13 on when the internal temperature is equal to or higher than a predetermined second reference temperature (referred to as "T2") (FIG. 2).

[0015] While the electric fan 13 is on (operating), the air inside the housing 11 is exhausted to the outside by the electric fan 13, so that heat inside the housing 11 is released to the outside and the temperature inside the housing 11 drops. On the other hand, while the electric fan 13 is off (stopped operating), the operation of the screen printing apparatus 10A generates heat in the substrate processing unit 12 and the control device 16, so that the air inside the housing 11 is warmed and the temperature inside the housing 11 rises. Therefore, when the electric fan control unit 16b of the control device 16 turns the electric fan 13 on and off based on the temperature inside the housing 11 measured by the temperature measuring unit 14, the temperature inside the housing 11 rises and falls within a temperature range TR between a first reference temperature T1 and a second reference temperature T2, as shown in FIG. 2 .

[0016] As described above, by the electric fan control unit 16b controlling the on / off of the electric fan 13 based on the information on the internal temperature of the housing 11 measured by the internal temperature measurement unit 14, fluctuations in the internal temperature of the housing 11 are contained within the temperature range TR between the first reference temperature T1 and the second reference temperature T2, and the internal temperature of the housing 11 does not significantly exceed the second reference temperature T2, preventing the internal temperature of the housing 11 from becoming abnormally high and interfering with normal printing processing. Furthermore, since no power is supplied to the electric fan 13 during the period in which the internal temperature of the housing 11 rises from the first reference temperature T1 to the second reference temperature T2, costs related to the power consumption of the electric fan 13 during that period are reduced.

[0017] The rate of decrease in the air temperature inside the housing 11 while the electric fan 13 is operating and the rate of increase in the air temperature inside the housing 11 while the electric fan 13 is not operating are both affected by the relative relationship between the air temperature inside the housing 11 and the outside air temperature. In detail, the rate of increase and decrease in the air temperature inside the housing 11 per unit operating time of the electric fan 13 differ depending on the relative level between the average air temperature inside the housing 11 (for example, the intermediate temperature between the first reference temperature T1 and the second reference temperature T2) and the outside air temperature, the temperature difference between these two temperatures, and other factors.

[0018] As the electric fan control unit 16b controls the operation (on / off) of the electric fan 13, the air temperature inside the housing 11 alternately rises and falls as shown in Fig. 2, and this repeating pattern (Fig. 2) will be the same if the type (model) of the screen printing apparatus 10A and the outside temperature are the same. Therefore, if the model information and outside temperature information are obtained in advance and a known repeating pattern that matches these is already present as data, the data of that repeating pattern can be read out and mechanically repeated thereafter, thereby making it possible to keep the air temperature inside the housing 11 within the temperature range TR between the first reference temperature T1 and the second reference temperature T2 without measuring the air temperature inside the housing 11.

[0019] The repeating pattern of the inside air temperature of the housing 11 is a cycle (FIG. 2) consisting of a combination of the time elapsed since the electric fan 13 was turned off after the inside air temperature of the housing 11 dropped to the first reference temperature T1 (off duration) and the time duration since the electric fan 13 was turned on after the inside air temperature of the housing 11 rose to the second reference temperature T2. FIG. 3 shows an example of a list of data for one cycle of the on / off pattern of the electric fan 13, i.e., data on the on / off timing of the electric fan 13 (hereinafter referred to as "timing data") consisting of a combination of the off duration and the on duration of the electric fan 13, for each combination of model and outside air temperature.

[0020] As shown in FIG. 1, the temperature control device 10B provided in the substrate processing system 10 of this embodiment includes a data generating unit 31 that generates timing data on the timing of turning on and off the electric fan 13 performed by the electric fan control unit 16b (recording the timing), a memory unit 32 that stores the timing data generated by the data generating unit 31 and other information, and an on / off control unit 33 that reads the timing data from the memory unit 32 after the timing data has been stored in the memory unit 32 and turns the electric fan 13 on and off based on the read timing data.

[0021] If data of a repetitive pattern that matches the model and outside air temperature is not stored in memory unit 32 when production is started by screen printing apparatus 10A, then after production starts, timing data for one cycle of on / off is acquired by repeatedly turning electric fan 13 on and off while monitoring the inside air temperature of housing 11 measured by inside air temperature measurement unit 14. Then, by using the acquired repetitive pattern as known timing data, it is possible to subsequently turn electric fan 13 on and off without measuring the inside air temperature of housing 11, and fluctuations in the inside air temperature of housing 11 can be contained within temperature region TR between first reference temperature T1 and second reference temperature T2.

[0022] The timing data acquired as described above is stored in the storage unit 32 in association with the model and the outside air temperature. This makes the acquired timing data known data, which will be useful for subsequent temperature management control of the substrate processing system 10.

[0023] 4 is a flowchart showing the procedure for performing temperature control of the substrate processing system 10 (temperature control method) executed by the control device 16 of the substrate processing system 10. As shown in Fig. 4, the control device 16 first recognizes the model of the substrate processing apparatus (here, the screen printing apparatus 10A) that constitutes the substrate processing system 10 (step ST1), and then measures the outside air temperature of the housing 11 using the outside air temperature measurement unit 15 (step ST2), and starts measuring the inside air temperature of the housing 11 (step ST3).

[0024] After starting to measure the air temperature inside the housing 11 in step ST3, the control device 16 turns on the electric fan 13 (step ST4). When the electric fan 13 is turned on, cooling of the air inside the housing 11 begins, and the air temperature inside the housing 11 drops.

[0025] After turning on the electric fan 13, the control device 16 checks whether the memory unit 32 has known timing data (stored in the memory unit 32) that matches the model recognized in step ST1 and the outside air temperature measured in step ST2 (step ST5). If the memory unit 32 does not have timing data that matches the model and the outside air temperature, the control device 16 acquires the timing data.

[0026] In acquiring the timing data, first, it is determined whether the current inside air temperature is equal to or lower than a first reference temperature T1, which is a predetermined reference temperature (step ST6). If the inside air temperature is not equal to or lower than the first reference temperature T1 in step ST6, the determination of step ST6 is repeated at predetermined time intervals (e.g., 10 seconds). If the inside air temperature is equal to or lower than the first reference temperature T1, the electric fan 13 is turned off (step ST7). When the electric fan 13 is turned off, cooling of the air inside the housing 11 is stopped, but heat generation by the substrate processing unit 12 and the control device 16 due to operation of the screen printing apparatus 10A continues, causing the inside air temperature inside the housing 11 to rise.

[0027] After turning off the electric fan 13, the control device 16 determines whether the inside air temperature measured by the inside air temperature measuring unit 14 is equal to or higher than a second reference temperature T2, which is a predetermined reference temperature (step ST8). If the inside air temperature is not equal to or higher than the second reference temperature T2, the control device 16 repeats the determination of step ST8 at predetermined time intervals (e.g., 10 seconds), and if it detects that the inside air temperature has reached or exceeded the second reference temperature T2, it turns on the electric fan 13 (step ST9). When the electric fan 13 is turned on and cooling of the air inside the housing 11 resumes, the inside air temperature of the housing 11 begins to drop.

[0028] After turning on the electric fan 13 in step ST9, the control device 16 stores the time from step ST7 to step ST9 as the time during which the electric fan 13 was turned off (off duration) in the memory unit 32 of the temperature management device 10B (step ST10). After storing the off duration in the memory unit 32, the control device 16 determines whether the inside air temperature measured by the inside air temperature measuring unit 14 is equal to or lower than the first reference temperature T1 (step ST11).

[0029] If it is determined in step ST11 that the inside air temperature is not equal to or lower than the first reference temperature T1, the determination in step ST11 is repeated at predetermined time intervals, and if it is detected that the inside air temperature has fallen to or lower than the first reference temperature T1, the electric fan 13 is turned off (step ST12). When the electric fan 13 is turned off and cooling of the air inside the housing 11 is stopped, the inside air temperature of the housing 11 begins to rise.

[0030] After turning off the electric fan 13 in step ST12, the control device 16 stores the time between steps ST10 and ST12 as the time the electric fan 13 was on (on duration) in the memory unit 32 of the temperature management device 10B (step ST13). After storing the on duration in the memory unit 32, the data generation unit 31 of the temperature management device 10B creates timing data (step ST14) that records the timing of the on / off of the electric fan 13 performed by the electric fan control unit 16b (combination of the off duration and the on duration) based on the off duration stored in the memory unit 32 in step ST10 and the on duration stored in the memory unit 32 in step ST13. The data generation unit 31 then creates timing data and stores the data in the memory unit 32 (step ST15). This completes the acquisition of the timing data.

[0031] When the control device 16 has completed acquiring the timing data, it returns to step ST5 and accesses the memory unit 32 of the temperature management device 10B to check whether the memory unit 32 stores timing data that matches the model recognized in step ST1 and the outside air temperature measured in step ST2.

[0032] When the control device 16 returns to step ST5 after going through the processes of steps ST6 to ST15 described above, the timing data at which the model recognized in step ST1 matches the outside air temperature measured in step ST2 will have been stored in the memory unit 32. Therefore, in this case, the process proceeds from step ST5 to step ST16, and the control device 16 reads out the timing data at which the model matches the outside air temperature from the memory unit 32 (the timing data stored in the memory unit 32 in step ST15) as known timing data.

[0033] After reading the timing data in step ST16, the control device 16 determines whether the internal air temperature measured by the internal air temperature measuring unit 14 is equal to or lower than the first reference temperature T1 (step ST17). If the internal air temperature is not equal to or lower than the first reference temperature T1, the control device 16 repeats the determination in step ST17 at predetermined time intervals. If the control device 16 detects that the internal air temperature has fallen to or lower than the first reference temperature T1, the control device 16 turns off the electric fan 13 (step ST18) and then controls the electric fan 13 on and off using the timing data read in step ST16 (step ST19). This on / off control of the electric fan 13 is repeatedly performed based on the timing data read in step ST16, i.e., the data for one cycle of the on / off pattern of the electric fan 13 ( FIG. 2 ). This process continues until the processing (printing) of the substrate KB by the screen printing apparatus 10A is completed.

[0034] The control device 16 determines whether the processing (printing) operation by the screen printing device 10A has been completed (step ST20) while controlling the operation of the electric fan 13 using the read timing data. Then, when it detects that the processing operation by the screen printing device 10A has been completed, it ends the temperature management operation.

[0035] As described above, in the substrate processing system 10 (and its temperature control method) of this embodiment, the electric fan 13 is turned on when necessary (when the internal air temperature reaches or exceeds the second reference temperature T2 and is lowered to the first reference temperature T1), but is turned off when not necessary (when the internal air temperature rises from the first reference temperature T1 to the second reference temperature T2). This allows the heat inside the housing 11 to be released by the electric fan 13, suppressing the temperature rise inside the housing 11, while reducing the power consumption of the electric fan 13, which is a cooling means.

[0036] In this embodiment, after the electric fan control unit 16b generates data (timing data) on the timing of turning on and off the electric fan 13, the electric fan 13 is turned on and off based on the timing data. Therefore, once the timing data is generated, the electric fan 13 can be turned on and off without measuring the temperature inside the housing 11, thereby keeping the temperature inside the housing 11 within a certain temperature range TR, thereby simplifying temperature management of the substrate processing system 10.

[0037] The present embodiment has been described above, and includes the following techniques (substrate processing system and temperature control method therefor).

[0038] (Item 1) A substrate processing system comprising: a housing (housing 11) having therein a substrate processing section (substrate processing section 12) that performs a predetermined process (printing process) on a substrate (substrate KB); cooling means (electric fan 13) that is electrically driven to cool the air in an internal space (internal space 11S) of the housing; an internal air temperature measurement section (internal air temperature measurement section 14) that measures an internal air temperature of the housing; a cooling means control section (electric fan control section 16b) that turns on and off the cooling means based on the internal air temperature measured by the internal air temperature measurement section; a data generation section (data generation section 31) that generates data on the on / off timing of the cooling means performed by the cooling means control section; a memory section (memory section 32) that stores the data generated by the data generation section; and an on / off control section (on / off control section 33) that reads out the data stored in the memory section and turns on and off the cooling means based on the read data.

[0039] (Item 2) In the substrate processing system of item 1, the cooling means control unit turns off the cooling means when the internal air temperature measured by the internal air temperature measurement unit becomes equal to or lower than a predetermined first reference temperature (first reference temperature T1), and turns on the cooling means when the internal air temperature becomes equal to or higher than a predetermined second reference temperature (second reference temperature T2).

[0040] (Item 3) A substrate processing system according to item 1 or 2, further comprising an outside air temperature measurement unit that measures the outside air temperature of the housing, wherein the data generation unit generates the data for each outside air temperature measured by the outside air temperature measurement unit, and the on / off control unit reads out the data corresponding to the outside air temperature measured by the outside air temperature measurement unit from the memory unit and turns on / off the cooling means based on the read data.

[0041] (Item 4) A temperature management method for a substrate processing system including a housing having a substrate processing section therein that performs predetermined processing on substrates, an electrically driven cooling means that cools the air in the internal space of the housing, an internal air temperature measurement section that measures the internal air temperature of the housing, and a cooling means control section that turns the cooling means on and off based on the internal air temperature measured by the internal air temperature measurement section, the temperature management method for a substrate processing system including: a data generation process (steps ST3 to ST14) that generates data on the on / off timing of the cooling means performed by the cooling means control section; a storage process (step ST15) that stores the data generated in the data generation process; and an on / off control process (steps ST16 to ST20) that reads out the data stored in the storage process and turns the cooling means on and off based on the read data.

[0042] (Item 5) The substrate processing system according to Item 4, wherein the cooling means control unit turns off the cooling means when the internal air temperature measured by the internal air temperature measurement unit becomes equal to or lower than a predetermined first reference temperature, and turns off the cooling means when the internal air temperature becomes equal to or higher than a predetermined second reference temperature.

[0043] (Item 6) The temperature management method for a substrate processing system according to item 4 or 5, wherein the substrate processing system includes an outside air temperature measurement unit that measures the outside air temperature of the housing, and in the data generation process, the data is generated for each outside air temperature measured by the outside air temperature measurement unit, and in the on / off control process, the data corresponding to the outside air temperature measured by the outside air temperature measurement unit is read from the memory unit, and the cooling means is turned on and off based on the read data.

[0044] Although the present embodiment has been described above, the technology of the present disclosure is not limited to the above and various modifications are possible. For example, in the above embodiment, the data generation unit 31, the storage unit 32, and the on / off control unit 33 are configured to be provided in the temperature management device 10B, which is separate from the screen printing apparatus 10A serving as the substrate processing unit. However, all or part of the data generation unit 31, the storage unit 32, and the on / off control unit 33 may be configured to be provided in the screen printing apparatus 10A.

[0045] Furthermore, in the above-described embodiment, the electric fan 13 cools the air inside the housing 11 by exhausting the air inside the housing 11, but the electric fan 13 may also cool the air inside the housing 11 by introducing air from outside the housing 11. Furthermore, in the above-described embodiment, the cooling means is constituted by the electric fan 13, but the cooling means does not necessarily have to be the electric fan 13 as long as it is electrically driven and can cool the air inside the internal space 11S of the housing 11.

[0046] Furthermore, the substrate processing system 10 in the above-described embodiment was a screen printing system that prints paste Pst on the substrate KB as a predetermined process for the substrate KB, but it may also be a component mounting system that mounts components on the substrate KB as a predetermined process for the substrate KB, etc.

[0047] This application is based on a Japanese patent application (Patent Application No. 2024-155151) filed on September 9, 2024, the contents of which are incorporated herein by reference.

[0048] A substrate processing system and a temperature management method for the substrate processing system are provided that can reduce the power consumption of a cooling means while suppressing a temperature rise inside a housing.

[0049] REFERENCE SIGNS LIST 10 Substrate processing system 10A Screen printing device 10B Temperature control device 11 Housing 11S Internal space 12 Substrate processing section 13 Electric fan (cooling means) 14 Internal air temperature measuring section 15 External air temperature measuring section 16b Electric fan control section (cooling means control section) 31 Data generating section 32 Memory section 33 On / off control section TR Temperature region KB Substrate

Claims

1. A substrate processing system comprising: a housing having a substrate processing section therein that performs predetermined processing on substrates; electrically driven cooling means that cools the air within the interior space of the housing; an internal temperature measurement section that measures the internal temperature of the housing; a cooling means control section that turns the cooling means on and off based on the internal temperature measured by the internal temperature measurement section; a data generation section that generates data on the on / off timing of the cooling means performed by the cooling means control section; a memory section that stores the data generated by the data generation section; and an on / off control section that reads out the data stored in the memory section and turns the cooling means on and off based on the read out data.

2. The substrate processing system of claim 1, wherein the cooling means control unit turns off the cooling means when the internal air temperature measured by the internal air temperature measurement unit becomes equal to or lower than a predetermined first reference temperature, and turns on the cooling means when the internal air temperature becomes equal to or higher than a predetermined second reference temperature.

3. A substrate processing system as described in claim 1 or 2, further comprising an outside air temperature measuring unit that measures the outside air temperature of the housing, wherein the data generating unit generates the data for each outside air temperature measured by the outside air temperature measuring unit, and the on / off control unit reads out the data corresponding to the outside air temperature measured by the outside air temperature measuring unit from the memory unit and turns the cooling means on and off based on the read data.

4. A temperature management method for a substrate processing system including a housing having a substrate processing section therein that performs predetermined processing on substrates, electrically driven cooling means that cools the air within the interior space of the housing, an internal air temperature measurement section that measures the internal air temperature of the housing, and a cooling means control section that turns the cooling means on and off based on the internal air temperature measured by the internal air temperature measurement section, the temperature management method for a substrate processing system comprising: a data generation step that generates data on the on / off timing of the cooling means performed by the cooling means control section; a storage step that stores the data generated in the data generation step in a storage section; and an on / off control step that reads out the data stored in the storage step and turns the cooling means on and off based on the read data.

5. A temperature management method for a substrate processing system as described in claim 4, wherein the cooling means control unit turns off the cooling means when the internal air temperature measured by the internal air temperature measurement unit becomes equal to or lower than a predetermined first reference temperature, and turns on the cooling means when the internal air temperature becomes equal to or higher than a predetermined second reference temperature.

6. A temperature management method for a substrate processing system as described in claim 4 or 5, wherein the substrate processing system is provided with an outside air temperature measurement unit that measures the outside air temperature of the housing, and in the data generation process, the data is generated for each outside air temperature measured by the outside air temperature measurement unit, and in the on / off control process, the data corresponding to the outside air temperature measured by the outside air temperature measurement unit is read from the memory unit, and the cooling means is turned on and off based on the read data.

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