JP3432331B2 - Oxide film forming method and power supply device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing technique for general panels such as liquid crystal panels in which an oxide film needs to be formed on the surface thereof, and more particularly to a method for controlling a power supply device used in an oxidation treatment process using an electrolytic solution. It is about.

[0002]

2. Description of the Related Art For example, as one step of a liquid crystal panel manufacturing line, there is a step of forming an oxide film on the panel surface.
In this oxide film forming step, a liquid crystal panel having a metal part is placed in an electrolytic bath filled with an electrolytic solution for oxidation treatment, and the positive electrode terminal of a DC power source is electrically connected to the metal part of the liquid crystal panel to correct the metal part. While acting as an electrode, the negative electrode terminal is inserted into the electrolytic cell. Then, DC power is supplied to these electrodes to form an oxide film on the surface of the liquid crystal panel.
In this case, since the resistance value of the panel surface is low immediately after energization, constant current control is performed, and since the conductive resistance of the load increases as time passes, it is normal to shift to constant voltage control. During constant current control, the voltage value between the electrodes linearly increases from the initial value to the upper limit value with the passage of time. On the other hand, during constant voltage control, the current value flowing between the electrodes gradually decreases starting from the current upper limit value.

[0003]

By the way, when DC power is supplied to each electrode in the above-mentioned oxide film forming step, there is a case where bubbles or peeling thereof occur on the electrode surface and the conductive resistance becomes unstable. . If the constant voltage control is continued by the conventional method in such a state, there is a problem that the current suddenly rises and the oxide film formed on the panel surface becomes non-uniform. Conventionally, since no power supply device considering such load fluctuation has been proposed, the power control procedure is considerably complicated in this kind of application, and as a result, the yield rate of the panel as a product cannot be increased. It was

In view of the above background, an object of the present invention is to provide an oxidation treatment method for suppressing a sudden increase in current due to load fluctuation and increasing the yield of the panel, and a power supply device suitable for carrying out this method. is there.

[0005]

In the oxidation treatment method of the present invention, a panel to be oxidized having a metal part and a conductor are inserted into an electrolytic solution, and a DC power supply is provided between the metal part and the conductor. In the method of forming an oxide film on the surface of the oxidation target panel by selectively supplying a current and a constant voltage, the voltage value and the current value between the metal part and the conductor in the electrolytic solution are periodically changed. It is characterized by measuring and updating the upper limit value of the supply current in the constant voltage section (hereinafter, current upper limit value) every unit time according to the measured current value of the previous cycle. In this method, the current upper limit value of the supply current is updated by adding a predetermined correction value to the measured current value of the previous cycle when the measured current value of the current cycle is less than the measured current value of the previous cycle, When the measured current value of the current cycle exceeds the measured current value of the previous cycle, it is preferable to maintain the current upper limit value of the previous cycle.

Further, the power supply device of the present invention is a power supply device for supplying DC power to the metal part and the conductor of the oxidation target panel inserted in the electrolytic solution, and the DC power is supplied between the metal part and the conductor. A DC power supply having means for supplying electric power and measuring a voltage value and a current value between the metal part and the conductor in the electrolytic solution, and selectively performing constant current control and constant voltage control of the DC power supply. And a control device.
In this configuration, the control device includes a power setting unit that sets an upper limit value of a current supplied by the DC power supply, a measurement value acquisition unit that periodically acquires a voltage value and a current value measured by the power supply, and the DC power supply. And a set value updating means for updating the upper limit value of the supply current for each unit time according to the measured current value acquired from the measured value acquiring means when the constant current section changes to the constant voltage section. To do. Further, the set value updating means includes, for example, a current value comparing means for comparing the measured current value of each cycle acquired from the DC power supply, and when the measured current value of the current cycle is less than the measured current value of the previous cycle, A predetermined correction value is added to the current upper limit value of the previous cycle, and when the measured current value of the current cycle exceeds the measured current value of the previous cycle, the current set value of the previous cycle is maintained.

According to another power supply device of the present invention, the control device is configured as follows. That is, the current upper limit value storage means that stores the change gradient of the upper limit value of the supply current during constant voltage control together with the constant voltage control time elapsed information, and the current upper limit value storage means responds to the corresponding time when the constant voltage control starts. And a current upper limit value extracting means for extracting the upper limit value of the supplied current. The DC power supply is automatically adjusted to the extracted value.

[0008]

First, when DC power (current and voltage) is supplied from the power supply device of the present invention to the metal part and the conductor of the panel to be oxidized, a current flows through the electrolytic solution. Immediately after energization, constant current control is performed as in the conventional case. The DC power supply measures the current and the inter-electrode voltage at this time and sends it to the control device. An upper limit value of the supply current and a switching set voltage value for switching from constant current control to constant voltage control are set in the control device by the power setting means, and the measured voltage value acquired periodically is set by switching. When it reaches the voltage value, it switches to constant voltage control. After the transition to the constant voltage control, the measured current value for each cycle is compared. In the normal state, the measured current value decreases in each cycle, so the upper limit value of the supply current in the current cycle is updated to a value obtained by adding the correction value to the current upper limit value in the previous cycle. On the other hand, when the measured current value in the current cycle exceeds the measured current value in the previous cycle, the current upper limit value in the previous cycle is maintained as it is. As a result, even if the conductive resistance suddenly decreases, the immediately preceding current upper limit value is maintained, so that stable oxidation treatment becomes possible.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a power supply device according to an embodiment of the present invention, in which a control device 1 and a DC power supply 2 are well-known G
The P-IB interface (IEEE-488) 3 is connected to the DC power supply 2, and the positive electrode 24 is connected to the positive electrode terminal of the DC power supply 2 and the negative electrode 25 is connected to the negative electrode terminal. Of these electrodes 24, 25, the positive electrode 2
The element 4 is electrically connected to the metal portion of the panel 6 to be oxidized, or both are integrally formed. At the time of use, these electrodes 24 and 25 and the panel 6 are put in the electrolytic cell 4 together with the electrolytic solution 5.

The control device 1 includes a data input section 11 for inputting parameter setting values and predetermined commands, which will be described later, and a DC power source 2.
Of the constant current / constant voltage control and state monitoring, the display unit 12 for displaying the state monitoring information sent from the monitor control unit 15, and the upper limit value and the constant value of the current supplied to the electrodes 24, 25. Switching from current control to constant voltage control A power setting unit 13 that sets a set voltage value and sends each value to the monitoring control unit 15, and an instruction from the monitoring control unit 15 causes at least the current upper limit value to be ex-posted every unit time. And a setting value updating unit 14 for updating the setting value.

The monitoring controller 15 has a timer 151 and also manages time for constant voltage control. The monitoring controller 15 is further connected to a status register 16, an event status register 17, and an input / output interface 18 for inputting / outputting data to / from the GP-IB interface 3. Status register 16
Is for storing the state discrimination information of the DC power supply 2,
For example, information indicating a transition from a constant current state to a constant voltage state, a transition from a constant voltage state to a constant current state, an overcurrent state, and an overcurrent state (bit assignment) is stored together with the discrimination code. Event status register 17 is GP-
Control channel of IB interface 3 (1 to 12ch)
The discrimination code of is stored.

The DC power supply 2 also includes an input / output interface 21 for inputting / outputting data to / from the GP-IB interface 3, a power control unit 22 for changing a supply current value and a voltage value based on a command, and And a power measuring unit 23 for measuring a current value flowing between the electrodes 24 and 25 and a voltage value between the electrodes 24 and 25. The power control unit 2
2 is a state when one of the constant current section (section in which constant current control is performed, the same applies hereinafter) and the constant voltage section (section in which constant voltage control is applied, the same applies below) transitions from one to the other, or when an abnormality occurs The signal (SRQ signal) is output to the input / output interface 21.

Next, the procedure for forming an oxide film on the surface of the panel using the power supply device having the above-described structure will be specifically described with reference to FIGS. FIG. 2 is a processing procedure diagram in the monitor control unit 15, and FIG. 3 is a diagram showing the relationship between the output power (power supplied to the electrodes) in the DC power supply 2 and the measured value thereof. In FIG. 2, S indicates a processing step.

In this power supply device, the switching input voltage value and the initial current upper limit value (parameter setting value) are input from the data input unit 11.
Is input to the power setting unit 13. The monitoring controller 15
Each value sent from the power setting unit 13 is set as an initial parameter (S101). When the operation start command is received from the data input unit 11 (S102), the control channel selection setting (1 to 12ch) and the power output on command are set to GP.
-Send to the IB interface 3 (S103), and start constant current control in each control channel (S104).

Thereafter, the measured value read command is periodically issued to GP-
Send to DC power supply 2 via IB interface 3 (S1
05), measured current value, measured voltage value, or the above-mentioned SR
The Q signal is acquired (S106). At the same time, the monitor information is generated and displayed on the display unit 12. In this section, only the measured voltage value and the switching set voltage value may be acquired.

Whether or not the measured voltage value has reached the switching set voltage value is determined by comparison processing or based on the SRQ signal from the DC power supply 2 (S107). If not, the constant current control is continued and the next cycle is started. Is measured (S108). This state is shown in FIG. 3 (constant current section). On the other hand, when it reaches, start constant voltage control instead of constant current control, and
The timer 151 is driven (S109). At that time, the monitor control unit 15 checks which channel is in the constant voltage state as follows.

First, the status byte included in the SRQ signal, that is, the data indicating whether the cause of the SRQ signal is due to an abnormality or due to a state transition without any abnormality, is decoded and stored in the decoded data and the status register 16. It collates with the determined discrimination code. Matching result, S
When it is determined that the cause of the RQ signal has changed from the constant current state to the constant voltage state, a predetermined command is sent to the DC power supply 2 side, and the bit assignment (event status register) in the DC power supply 2 obtained by this is sent. It is determined from which control channel (1 to 12 ch) the state transition has occurred from (stored in 17). When the control channel in the constant voltage state can be identified, the current upper limit value updating process is started from the channel.

This updating process is performed in the following procedure. First, the measured value read command is periodically sent to the GP-IB interface 3
(S110), the measured current value is acquired from the DC power supply 2 and stored (S111). Then, for each unit time, the measured current value of the current cycle is compared with the measured current value of the previous cycle (S1
12). When the former is smaller than the latter (normal state), the preset current upper limit value is updated (S113). Specifically, the correction value α stored in the RAM or the like in the monitor control unit 15
Is added to the preset current upper limit value. In this case, the correction value α can be arbitrarily selected, but in this embodiment, a constant value is used during operation. On the other hand, when the measured current value of the current cycle is larger than the measured current value of the previous cycle, the conductive resistance of the electrodes 24 and 25 may be unstable, so the preset current upper limit value is left unchanged. It is maintained (S114). As a result, constant voltage control is performed according to the upper limit value set in the previous cycle. In the example of updating the current upper limit value in FIG. 3, the measured current value in the first unit time is large in the previous cycle, so the upper limit value in the constant current section is maintained as it is, and thereafter the oxidation process is normally continued. It shows an example of the case.

Such processing is repeated cyclically within the set time of the timer 151 for all control channels (S1
15; No), when the time is up (S115; Ye
s) ends the operation. Even during the constant voltage section, when the measured current value reaches the upper limit current value, constant current control may be performed again. According to the procedure described above, in the DC power supply 2, the current upper limit value is corrected over time in the constant voltage section of FIG. 3, and the current actually flowing between the electrodes 24 and 25 is exponentially gradually reduced. Therefore, when the surface of the panel 6 is oxidized by the structure shown in FIG. 1, a sudden increase in current is suppressed, and nonuniformity of the oxide film formed on the panel surface can be effectively prevented.

Although the present embodiment has been described on the premise that the measured current value is periodically obtained from the DC power supply 2 when the constant current control and the constant voltage control are selectively performed, the experiment or calculation is performed in advance. Thus, when the slope of the current upper limit value that changes with time in relation to the load is known, a group of current upper limit values for each unit time is tabulated and stored in the monitoring control unit 15 (current upper limit value storage means). ), The current upper limit value corresponding to each time elapsed from the start to the end of operation is retrieved from the table (current upper limit value extraction means) and sent to the DC power supply 2 as needed. A known data search means can be used to find the current upper limit value. With this configuration, the configuration of the control device 1 is further simplified, which is advantageous in terms of cost.

[0021]

As is apparent from the above description, according to the power supply device of the present invention, even when the current suddenly becomes excessive due to load fluctuation during constant voltage control, the immediately preceding current upper limit value is Since it is maintained, there is an effect that the change of the current actually flowing between the electrodes is suppressed. Therefore, by using the power supply device or the power control technique for the surface processing of the panel, the accuracy of the processing can be increased and the yield of the panel can be improved.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a power supply device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a processing procedure of a monitoring controller according to the present embodiment.

FIG. 3 is an explanatory diagram of power change during constant current control and constant voltage control according to the present embodiment.

[Explanation of symbols]

1 control device 2 DC power supply 3GP-IB interface 4 electrolyzer 5 Electrolyte 6 Processing target panel 11 Data input section 12 Display 13 Power setting section 14 Setting value update section 15 Monitoring and control unit 16 Status register 17 Event status register 18,21 I / O interface 22 Power output section 23 Electric power measurement unit

Claims (5)

(57) [Claims] 1. A panel to be oxidized having a metal part and a conductor are inserted into an electrolytic solution, and a constant current and a constant voltage are selectively supplied from a DC power supply between the metal part and the conductor. In the method of forming an oxide film on the surface of the oxidation target panel, a voltage value and a current value between a metal part and a conductor in the electrolytic solution are periodically measured, and an upper limit value of a supply current in a constant voltage section. Is updated every unit time according to the measured current value of the previous cycle. 2. The updating of the upper limit value of the supply current is performed by adding a predetermined correction value to the measured current value of the previous cycle when the measured current value of the current cycle is less than the measured current value of the previous cycle. The oxide film forming method according to claim 1, wherein when the measured current value of the current cycle exceeds the measured current value of the previous cycle, the upper limit value of the supply current of the previous cycle is maintained. 3. A power supply device for supplying DC power to a metal part and a conductor of a panel to be inserted into an electrolytic solution, the DC power supply being provided between the metal part and the conductor, and the electrolytic solution. A direct current power supply having a means for measuring a voltage value and a current value between the metal part and the conductor in,
And a controller for selectively performing constant current control and constant voltage control of the DC power supply, wherein the control device is a power setting unit for setting an upper limit value of a current supplied by the DC power supply, and the power supply. A measurement value acquisition unit that periodically acquires the measured voltage value and current value, and a measurement that acquires the upper limit value of the supply current from the measurement value acquisition unit when the DC power supply makes a transition from the constant current section to the constant voltage section. A power supply device comprising: a set value updating means for updating every unit time according to a current value. 4. The set value updating means includes current value comparing means for comparing the measured current values for each cycle acquired from the DC power supply, and the measured current value for the current cycle satisfies the measured current value for the previous cycle. If there is not, a predetermined correction value is added to the upper limit value of the supply current of the previous cycle, and if the measured current value of the current cycle exceeds the measured current value of the previous cycle, the upper limit value of the supply current of the previous cycle is set. The power supply device according to claim 3, wherein the power supply device is maintained. 5. A power supply device for supplying DC power to a metal part and a conductor of an oxidation target panel inserted in an electrolytic solution, wherein DC power not more than an upper limit value is supplied between the metal part and the conductor. And a DC power supply having means for measuring a voltage value and a current value between the metal part and the conductor in the electrolytic solution, and a controller for selectively performing constant current control and constant voltage control of the DC power supply. The control device comprises a current upper limit value storage unit that stores a change gradient of the upper limit value of the supply current during constant voltage control together with constant voltage control time elapsed information, and the current upper limit upon the start of constant voltage control. And a current upper limit value extracting unit for extracting an upper limit value of the supply current corresponding to the relevant time from the value storing unit.