Method and device for stringing substrates together in coating systems

Abstract

A method and a device for stringing together objects in transport systems, preferably in coating systems, for adjusting the distance between two objects, preferably substrates or substrate holders, being arranged one behind the other, wherein the front object moves at a process speed v.sub.p in the transport system and the rear object is at an undefined distance from the front object. The method comprises the following steps: (a) accelerating the rear substrate to an initial speed v.sub.x>v.sub.p; (b) detecting an increase in the driving torque when the rear substrate moves against the front substrate; (c) delaying the rear substrate by a predetermined value in order to establish a predetermined distance a.sub.p from the front substrate; and (d) adjusting the speed of the rear substrate to the process speed v.sub.p.

Claims

1. A method for stringing together objects in a transport system and for adjusting an adjustable distance between two of the objects, wherein the two of the objects comprise a rear object arranged behind front object, wherein the front object moves at a speed in the transport system defined as a process speed v.sub.p, and wherein the adjustable distance between the rear object and the front object is initially an undefined distance, the method comprising the following steps: (a) accelerating a speed of the rear object to an initial speed v.sub.x, wherein v.sub.x>v.sub.p; (b) detecting a driving torque of at least one motor of the transport system; (c) detecting an increase in the driving torque when the rear object moves against the front object; (d) delaying the rear object by a predetermined value in order to establish that the adjustable distance between the front object and the rear object is a predetermined distance a.sub.p; and (e) adjusting the speed of the rear object to correspond to the process speed v.sub.p of the front object.

2. The method according to claim 1, wherein after step (a) of accelerating the speed of the rear object to the initial speed v.sub.x and before step (c) of detecting the increase in the driving torque, additionally the following steps are carried out: (a1) detecting that the adjustable distance between the front object and the rear object is a first distance a.sub.1; and (a2) reducing the speed of the rear object from the initial speed v.sub.x to a second speed v.sub.x−m, wherein v.sub.x >v.sub.x−m>v.sub.p.

3. The method according to claim 1, wherein the speed of the rear object and the speed of the front object are adjusted independently of one another by at least two successively arranged drive units, wherein each of the drive units comprises one of the at least one motors, a drive amplifier and an encoder, and wherein each drive unit drives multiple drive elements.

4. The method according to claim 3, wherein the at least two successively arranged drive units comprise a front drive unit that adjusts the speed of the front object and a rear drive unit that adjusts the speed of the rear object.

5. The method according to claim 2, wherein the first distance a.sub.1 is detected by position sensors.

6. The method according to claim 1, wherein the increase in the driving torque when the rear object moves against the front object is determined by the at least one motor, wherein the at least one motor has a drive amplifier and an encoder.

7. The method according to claim 2, wherein the predetermined distance a.sub.p is smaller than the first distance a.sub.1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically shows the basic structure of a solution of the disclosure;

(2) FIG. 2(a) shows a first step of a flow chart of a transport system in which a new substrate S4 to be processed is arranged in an initial state at the place of the drive unit;

(3) FIG. 2(b) shows a second step of the flow chart of FIG. 2(a) in which S4 is accelerated to an initial speed that is higher than a process speed of the other substrates in the transport system;

(4) FIG. 2(c) shows a third step of the flow chart of FIGS. 2(a) and 2(b) in which the speed of S4 is reduced so that it can smoothly approach substrate S3 in the transport system;

(5) FIG. 2(d) shows a fourth step of the flow chart of FIGS. 2(a), 2(b), and 2(c) in which, after the distance between S4 and S3 is the same as the distance between S3 and S2, the speed of S4 is increased to achieve the processing speed of the other substrates;

(6) FIG. 3 shows measuring curves of the speeds and the moments of M2 and M3 of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(7) In the following, the disclosure will be explained in more detail on the basis of preferred embodiments and the Figures.

(8) A preferred embodiment of the disclosure is schematically shown in FIG. 1. FIG. 1 shows a total of four chambers 60, 70, 80, 90, an object 30, position sensors 10 (e.g. end switches), a drive unit 40 and drive elements 50.

(9) The chambers 60, 70, 80, 90 are in direct contact with each other, but they can also be separated from each other by locks (e.g. in a vacuum system by vacuum locks). FIG. 1 exemplarily shows four chambers. However, it is clear that the number of chambers can be more than four and also less than four.

(10) In accordance with this embodiment, each of the chambers 60, 70, 80, 90 comprises a drive unit 40. Each of the drive units preferably comprises a motor 41 with encoder and amplifier 42. The drive unit 40 is used for driving the drive elements 50 for being able to adjust the speed in the various chambers 60, 70, 80, 90 individually. Preferably, synchronization of the different drive elements 50 is realized by means of a motion controller system. Like the chambers 60, 70, 80, 90, also the drive units 40 can be present in any desired number. However, there must be at least two drive units 40 for being able to adjust at least two different speeds. The number of chambers 60, 70, 80, 90 can of course be different from the number of drive units 40.

(11) The object 30 schematically shown in FIG. 1 is driven by the drive elements 50 in the movement direction through the different chambers 60, 70, 80, 90. In a transport system, or in a coating system, normally multiple objects are arranged one behind the other in different chambers 60, 70, 80, 90, as will be described further below.

(12) Moreover, FIG. 1 shows an exemplary drive unit comprising a motor 41 with encoder and amplifier 42, wherein the amplifier is suitable for measuring an increase in the driving torque and outputting it as measuring signal. In accordance with the disclosure, an increase in the driving torque is caused by a rear object moving against a front object.

(13) The position sensors 10 indicated in FIG. 1 are adapted for determining the position of the object. This position detection, however, is only suitable for determining a relatively rough position of the object in the transport system. The exactness substantially depends on the distance of the various position sensors 10.

(14) The object 30 can have different shapes and dimensions. Some examples for objects can be a glass with/without carrier, a substrate made of any material with/without carrier, a glass inserted in a carrier, a substrate made of any material inserted in a carrier, a glass in a substrate frame, a substrate made of any material in a substrate frame, a closed box, a glass in a closed box, a substrate made of any material in a closed box, etc.

(15) FIGS. 2(a) to 2(d) schematically show a flow chart of the preferred embodiment of the present disclosure for adjusting a distance in a transport system being as small as possible. The shown embodiment shows four moments M1 to M4 which refer to the moments of the drive elements. M1 to M4 are preferably servo drives which each drive the n rolls. The objects, or substrates (here exemplarily five substrates) are marked S1 to S5 and move one behind the other along a forward direction in the transport system.

(16) In FIG. 2(a), the substrates S3 to S1 move at a distance a.sub.p and at a process speed v.sub.p through the transport system. A substrate S4 to be newly processed is arranged in an initial state at the place of the drive unit with the moment M1 at a speed v=0 m/s and an undefined distance a.sub.0, wherein a.sub.0>a.sub.p.

(17) According to FIG. 2(b), the substrate S4 is accelerated to an initial speed v.sub.x, i.e. a defined starting moment is predetermined, wherein the speed v.sub.x is higher than the process speed v.sub.p, so that the substrate S4 can catch up with the substrate S3. By means of position sensors 10 (FIG. 1), a first rough distance a.sub.1 between the substrate S4 and the substrate S3 can be detected. The distance a.sub.1 is preferably calculated by means of the position sensors 10 and a motion controller.

(18) Then, the speed of the substrate S4 is reduced to v.sub.x−m in order to avoid a too hard approaching movement of substrate S4 against substrate S3. In order to nevertheless allow the substrate to further catch up with the substrate S3, the following must be true: v.sub.p<v.sub.x−m<v.sub.x. Thus, a smooth movement of substrate S4 against substrate S3 is achieved (FIG. 2(c)). In particular in case of very sensitive substrates, a too fast (hard) approaching movement against the substrates can damage the substrates. Therefore, a smooth start is preferred. However, this step, as well as the detection of the first distance a.sub.1 by the position sensors, can be omitted if the initial speed v.sub.x is sufficiently slow for avoiding a too hard approaching movement against the substrates or if non-sensitive substrates are used. The speeds v.sub.x and/or v.sub.x−m thus depend on the specific application and can be adjusted individually without leaving the basic idea of the disclosure.

(19) Because the substrate S4 moves smoothly against the substrate S3, there is a small increase in the driving torque which can be measured by the amplifier 42. Once the amplifier detects an increase in the driving torque, the speed of the substrate S4 is adapted (delayed) so that it is reduced by a predetermined distance a.sub.p relative to the substrate S3. The substrate S4 is delayed in that the speed is reduced for a predetermined short time period to a speed lower than v.sub.p. After the distance a.sub.p between the substrate S3 and the substrate S4 is established, the speed of substrate S4 is increased to v.sub.p. Hence, substrates S3 and S4 move synchronously with a minimum distance a.sub.p further through the transport system (FIG. 2(d)) and the method can be repeated for the following substrate S5.

(20) FIG. 3 shows several time-dependent measuring curves. The two measuring curves at the top describe the adjusted speeds for the drive units M2 (upper measuring curve) and M3 (lower measuring curve), wherein the lower one of the two measuring curves (speed of M3) corresponds to the constant process speed v.sub.p. The upper measuring curve (speed of M2) starts at v=0 m/s and is increased from a first time point t.sub.1 on to a first speed v.sub.x>0 m/s. At the time point t.sub.2, the speed of M2 is reduced to a second speed v.sub.x−m. The time point t.sub.2 is the time point at which the position sensors detect the first distance a.sub.1 described above. Moreover, at the time point t.sub.3, the speed of M2 is delayed for a short time such that the speed falls for a short time below the process speed v.sub.p. This is not reflected in FIG. 3 because of the selected scale. In the further course, the speed of M2 is adjusted to the process speed v.sub.p.

(21) The two measuring curves at the bottom describe the measured temporal course of the moment (where the moment is defined as the torque τ=Iα, where I is the moment of inertia and α is the angular acceleration) in view of M2 and M3. At the time point T.sub.1, an increase in the moment in view of M2 is measured. Hence, this increase in the moment M2 correlates with the increase in the speed of M2. Accordingly, a moment decrease in M2 is detected at the time point T.sub.2, i.e. at the time point of the speed reduction of M2. Finally, at the time point T.sub.3, a moment increase in M2 or a moment decrease in M3 is detected, wherein the movement of the rear substrate against the front substrate can be detected and subsequently the speed can be adapted as described above in order to establish the desired distance between the two substrates.

(22) Also if the moment increase in M2 has been described in the above-mentioned preferred embodiment for determining the movement of the rear substrate against the front substrate, FIG. 3 shows that also the moment decrease in M3 can be used for determining movement against a substrate.

(23) The device and the method of the present disclosure can be used for different processes in different transport systems. The method is adapted to the different conditions of the different processes in the transport systems without leaving the present disclosure. For example, when using the method of the present disclosure in a tempering process, the device is subjected to particular thermal loads. In a sputtering or vapor deposition system, the device is subjected to contamination by the coating materials. In addition, some processes take place in a vacuum or even in a gaseous environment. In order to guarantee the stringing together of objects also under extreme conditions, the components of the device of the present disclosure must be adapted accordingly. In the exemplary embodiment described above, e.g., the position sensors could be adjusted to these environmental conditions and/or the motor unit with servo amplifier and encoder could be arranged at a place that is isolated from these disadvantageous environmental conditions. In accordance with the disclosure, the roll drives should be configured such that they remain movable.

(24) Although the present disclosure has been described and shown with reference to its preferred embodiments, it is obvious to persons skilled in the art that various modifications and amendments can be made without leaving the scope of the disclosure. It is thus intended that the present disclosure covers the modifications and amendments of this disclosure as far as they are covered by the scope of protection of the attached claims and their equivalents.