WO2007040379A1

WO2007040379A1 - Apparatus for sensing glass substrates in a cassette

Info

Publication number: WO2007040379A1
Application number: PCT/KR2006/004051
Authority: WO
Inventors: Jung-Soo Kang; Shoichi Mitsutake
Original assignee: Jinoid Co., Ltd.; Takenaka Electronic Industrial Co., Ltd.
Priority date: 2005-10-06
Filing date: 2006-10-09
Publication date: 2007-04-12

Abstract

Provided is an apparatus for detecting substrates in a cassette. The apparatus for detecting substrates in a cassette includes: a first body fixedly placed in manufacturing equipment; and a second body fixedly placed at a position facing the first body to receive a signal sent from the first body. The first body includes: a light transmitting element composed of one or more light emitting elements, and a light transmission controller that controls operations of the light emitting elements of the light transmitting element. The second body includes: a light receiving element composed of one or more sensors that detect a signal sent from the light transmitting element, and a light receiving controller that uses signals detected by the sensors of the light receiving element to determine whether substrates are present in respective channels of the cassette and that sends resultant data of determination to an external device. Accordingly, the substrate detecting apparatus is fixedly placed in manufacturing equipment, thereby not requiring an additional driver. Further, its overall structure is simple, and an extra driving time is not consumed to move a detector into a cassette. Furthermore, since a light transmitting/receiving sensor is used, stable detection can be achieved with a transparent glass material having a high transmittance and specular reflectance.

Description

APPARATUS FOR SENSING GLASS SUBSTRATES IN A

CASSETTE

Technical Field

[1] The present invention relates to an apparatus for detecting a glass substrate in a cassette, and more particularly, to an apparatus used in a manufacturing process of a liquid crystal display (LCD) in order to determine whether glass substrates are placed in a cassette. Background Art

[2] In general, a liquid crystal display uses a glass substrate. In the process of manufacturing the liquid crystal display, a plurality of glass substrates is placed in a cassette before a next process is carried out, or a glass substrate is introduced to a process so as to perform a specific task. Further, the glass substrate which has undergone the process is also placed in the cassette and then the next process is prepared. Such process generally uses a robot arm so that the glass substrate is placed in or taken out of the cassette.

[3] Before the glass substrate is placed in or taken out of the cassette by using the robot arm or other mechanisms, the presence of the glass substrate in a corresponding channel of the cassette has to be first checked. A mapping sensor serves to detect glass substrates placed in respective channels of the cassette. The mapping sensor sends information on the presence of the glass substrates placed in the respective channels to an upper level controller. The upper level controller allows the glass substrates to be placed in or taken out of the respective channels according to this information. Due to wrong mapping information, if a glass substrate is placed in a channel where another glass substrate is already placed, damage occurs in the glass substrate. In this case, the damage occurs in not only the glass substrate but also all glass substrates placed in the cassette, which leads to a significant trouble in a manufacturing process. If a glass substrate is intended to be taken out of a channel where no glass substrate is present, time loss or mismatching takes place during the manufacturing process. Therefore, the aforementioned mapping sensor is significantly important in the process of manufacturing a thin plate such as an LCD. Further, the mapping sensor is required to have a stable detecting capability.

[4] Two types of mapping sensors have been used in the conventional LCD manufacturing line.

[5] In the early stage of the LCD manufacturing line, a method called an "elevator scheme" was widely used. In this method, one sensor using laser is moved up and down to detect a lateral surface of a glass substrate. However, the method has a drawback in that the up and down movement of sensor takes a lot of times, and in many cases, detection is instable due to vibration or the like. Moreover, it has gradually become difficult to use the method with the increase in the size of a glass substrate in an LCD. As a result, the method employing the elevator scheme has almost not been usable in a newly built LCD manufacturing line since 8 or 9 years ago.

[6] In order to solve the aforementioned problems, a mapping sensor using a comb-type sensor has been dominated. Hereinafter, the comb-type sensor dominating as a mapping sensor in the current LCD manufacturing line will be described.

[7] FIG. 1 is a front view showing a conventional substrate detecting apparatus 10 using a comb-type sensor. FIG. 2 is a cross-sectional view of FIG. 1. FIG. 3 shows a process of operating the conventional substrate detecting apparatus in order to detect substrates placed in respective channels of a cassette loaded in specific manufacturing equipment.

[8] Referring to FIGS. 1 and 2, the conventional substrate detecting apparatus 10 includes a body 1 that is movably disposed in the manufacturing equipment and has a vertical tower shape, a plurality of detectors 2 that protrude along a lateral portion of the body 1 and are fixedly disposed spaced apart from one another by a predetermined distance in up and down directions of the body 1, and an optical element 3 that emits light through an open window located at an end of an upper surface of each detector 2 and receives reflected light.

[9] Inside of the body 1 is provided with an element that provides power to each detector and an element that outputs a signal detected from each detector to each channel.

[10] The conventional substrate detecting apparatus 10 having the aforementioned structure is, as shown in FIG. 3, placed on a driver 8 of manufacturing equipment 5. When a cassette 4 in which a plurality of glass substrates 6 is placed in respective channels is loaded in the manufacturing equipment 5, the driver 8 moves in an arrow direction, and thus the substrate detecting apparatus 10 moves towards the cassette 4. Then, each detector 2 of the substrate detecting apparatus 10 enters into each channel of the cassette through an opening of a lateral portion of the cassette. As a result, each detector is located between the glass substrates 6 placed in the respective channels of the cassette 6 with a detection distance greater than a predetermined distance. In this case, due to a limit of the detection distance of a reflective sensor, a thin transparent glass substrate having a high transmittance usually has a detection distance less than 20mm.

[11] Next, the presence of substrates in the respective channels of the cassette is determined by using the optical element 3 located at the end of each detector 2. The result is sent to a controller for a substrate conveying device. After receiving the result of determining the presence of the glass substrates from the substrate detecting apparatus, the controller uses relevant information to control operations of the substrate conveying device whereby the glass substrate is placed in or taken out of a particular channel.

[12] However, in the conventional substrate detecting apparatus 10, an additional driver has to be placed in the manufacturing equipment so as to move the detector and the optical element into the cassette. Therefore, there has been a problem in that the overall structure becomes complex, and a space has to be ensured so that the driver can be moved within the manufacturing equipment. Further, since the detector and the optical element have to move back to their initial positions after moved inside the cassette and detected, a driving time has also been a problem.

[13] A detection mechanism using the aforementioned method solely depends on light quantity of reflected and incident light. Thus, there has been a concern over a false detection caused by other factors of surroundings. For example, when a glass substrate having a highly glossy surface (e.g. a sputter glass substrate) is located above a channel, it is determined that the glass substrate is present in a lower channel, resulting in a fault detection.

[14] In addition, when the substrate detecting apparatus is used for a long period of time, sensitivity of the optical sensor 3 is degraded due to deterioration of an optical cable or a surrounding environment. Thus, even if a glass substrate is present in a particular channel of the cassette, the substrate detecting apparatus cannot properly detect the glass substrate in the channel.

[15] Moreover, when a glass substrate having an extremely high specular reflectance is used, reaction becomes angle sensitive. Thus, according to conditions in an actual site such as vibration or glass bending, false detection is occasionally made. Therefore, there has long been a demand for a fixed type light transmitting/receiving type mapping sensor that can solve these problems.

[16] Since long time ago, an industrial sensor (in particular in an optical sensor field) has used two types of determination mechanisms. In the first mechanisms, a specific electrical reference level is initially set so as to determine the presence of an object according to whether its input level is higher or lower than the reference level. In the second mechanism, a sensor is installed in an actual site, and a reference level is set and stored at the time of initial setting in a manual or auto teaching manner. Further, the presence of an object is determined according to whether its input level is higher or lower than the reference level. On the basis of the types of mechanisms, precision is enhanced by adding a few additional functions. Of course, the current elevator scheme and the comb-type scheme use the two mechanisms to control an optical system or a circuit part so as to achieve a specific goal.

[17] However, the aforementioned mechanisms are all highly influenced by transmittance and reflectivity. Therefore, it has been known that it is almost impossible to manufacture a light transmitting/receiving type mapping sensor that can be used in an LCD manufacturing line. Disclosure of Invention Technical Problem

[18] In order to solve the aforementioned problems, the present invention provides a fixed type substrate detecting apparatus that has a simple structure and uses a light transmitting/receiving sensor, thereby not requiring an additional driver.

[19] The present invention also provides a substrate detecting apparatus which is less affected by an optical level of an optical sensor or deterioration of a light emitting element or a light receiving element due to a long time og use and whereby the presence of glass substrates placed in respective channels of a cassette can be accurately determined. Technical Solution

[20] According to an aspect of the present invention, there is provided an apparatus which is placed in manufacturing equipment for loading a cassette and detects substrates in respective channels of the cassette.

[21] The substrate detecting apparatus comprises: a first body fixedly placed in manufacturing equipment; and a second body fixedly placed at a position facing the first body to receive a signal sent from the first body, wherein the first body comprises a light transmitting element composed of one or more light emitting elements, and a light transmission controller that controls operations of the light emitting elements of the light transmitting element, and wherein the second body comprises a light receiving element composed of one or more sensors that detect a signal sent from the light transmitting element, and a light receiving controller that uses signals detected by the sensors of the light receiving element to determine whether substrates are present in respective channels of the cassette and that sends resultant data of determination to an external device.

[22] In the aforementioned aspect of the present invention, the light emitting elements of the first body may be sequentially placed in a lateral portion of the first body so as to be located above a portion where the glass substrates are placed in the respective channels of the cassette, the sensors of the second body may be sequentially placed at a lateral portion of the second body so as to be located below a portion where the glass substrates are placed in upper or lower portion of each channel of the cassette, and the light emitting elements of the light transmitting element may emit light in a direction passing through a specific channel to be detected by the light emitting elements, and the sensors of the light receiving element may detect signals passing through the channel.

[23] In addition, the light emitting elements constituting the light transmitting element of the first body may be placed in the lateral portion of the first body and are selectively located at the upper or lower portion of each channel of the cassette, and the sensors constituting the light receiving element of the second body may be placed in the lateral portion of the second body that can receive a signal sent from the light emitting elements of the light transmitting element and may be located at the upper or lower portion of both of the upper and lower portions where light from the light emitting elements can be received after passing through the glass substrate of the respective channels.

[24] In addition, the sensors constituting the light receiving element of the second body may be placed in the lateral portion of the second body that can receive a signal sent from the light emitting elements of the light transmitting element and may be located at both of the upper and lower portions of each channel of the cassette.

[25] In addition, the light receiving controller of the second body may independently amplify a magnitude of signal detected by a sensor of the light receiving element located at the upper portion of a specific channel of the cassette and a magnitude of signal detected by a sensor of the light receiving element located at the lower portion of the channel, compare the magnitudes of the two signals, and determine that a substrate is present in the specific channel if the comparison result shows a difference greater than a predetermined value.

Advantageous Effects

[26] Unlike the conventional substrate detecting apparatus using a reflective sensor, a substrate detecting apparatus of the present invention uses a light transmitting/ receiving sensor installed at both lateral portions of a cassette. Thus, since a sensor bracket or a sensor detector is not necessary to insert the sensor into the cassette, there is no concern over a damage in the sensor bracket or the sensor detector.

[27] In addition, since the substrate detecting apparatus of the present invention operates while being fixed in manufacturing equipment, a driver which has been used in the conventional substrate detecting apparatus is not additionally required. Therefore, with the absence of the driver, the substrate detecting apparatus of the present invention has a simple structure, and a driving time for moving the substrate detecting apparatus to a position near the cassette is not consumed. Thus, manufacturing can be rapidly carried out. Further, since the substrate detecting apparatus of the present invention operates in a fixed state, a space is not necessarily ensured to drive an additional driver in the man- ufacturing equipment. Furthermore, as a novel detecting method in which a reference signal and a data signal are compared each other is contrived, the substrate detecting apparatus of the present invention surely improves instability of detection in the conventional light transmitting/receiving type sensor. Thus, the present invention can be stably applied to a glass substrate having a transparent and specular reflection surface such as a transparent glass substrate and a sputter glass substrate. Brief Description of the Drawings

[28] FIG. 1 is a front view showing a conventional substrate detecting apparatus using a comb-type sensor.

[29] FIG. 2 is a cross-sectional view of FIG. 1.

[30] FIG. 3 shows manufacturing equipment placed with the conventional substrate detecting apparatus in order to explain operations of the substrate detecting apparatus.

[31] FIG. 4 is a perspective view showing a substrate detecting apparatus according to an embodiment of the present invention.

[32] FIG. 5 shows the substrate detecting apparatus according to an embodiment of the present invention placed in manufacturing equipment.

[33] FIG. 6 is a perspective view showing an substrate detecting apparatus according to another embodiment of the present invention.

[34] FIG. 7 shows the substrate detecting apparatus of FIG. 6 placed in manufacturing equipment. Best Mode for Carrying Out the Invention

[35] First Embodiment

[36] Hereinafter, the structure and operation of an apparatus for detecting a substrate in a cassette according to a first embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[37] FIG. 4 is a perspective view showing a substrate detecting apparatus according to a first embodiment of the present invention. FIG. 5 shows the substrate detecting apparatus placed in manufacturing equipment and a cassette loaded in the manufacturing equipment in order to explain a usage state of the substrate detecting apparatus according to the first embodiment of the present invention.

[38] Referring to FIGS. 4 and 5, the substrate detecting apparatus according to the first embodiment of the present invention is placed in manufacturing equipment 60 in which a cassette 70 is loaded so as to determine whether substrates 74 are placed in respective channels 72. The substrate detecting apparatus includes a first body 40 fixedly placed in the manufacturing equipment 60 and a second body 50 fixedly placed in a specific position where a signal sent from the first body 40 can be received.

[39] The first body 40 includes a light transmitting element 42 and a light transmission controller 44. The light transmitting element 42 is composed of one or more light emitting elements. The light transmission controller 44 controls operations of the light emitting elements of the light transmitting element. The light emitting elements of the light transmitting element 42 are disposed at the upper portion of each channel 72 of the cassette 70.

[40] The second body 50 includes a light receiving element 52 and a light receiving controller 54. The light receiving element 52 is composed of one or more sensors that detect a signal sent from the light transmitting element 42. The sensors are respectively disposed at the lower portions of the respective channels 72 of the cassette 70. The light receiving controller 54 uses a signal detected by the sensors of the light receiving element so as to determine the presence of the substrates in the respective channels. Resultant data of determination is sent to a controller of an external substrate conveying device.

[41] As shown in FIGS. 4 and 5, the light emitting elements constituting the light transmitting element 42 of the first body 40 are sequentially placed at a lateral portion of the first body 40 so as to be located at the upper portions of the respective channel 72 of the cassette 70. The sensors constituting the light receiving element 52 of the second body 50 are sequentially placed at a lateral portion of the second body so as to be located at the lower portions of the respective channels 72 of the cassette 70. A surface where the light emitting elements of the light transmitting element are placed faces a surface where the sensors of the light receiving element are placed, so that the sensors of the second body 50 of the substrate detecting apparatus can accurately detect a signal sent from the first body 40.

[42] The light transmission controller 44 of the first body 40 of the substrate detecting apparatus of the present invention sequentially operates the light emitting elements constituting the light transmitting element. In addition, the sensors of the second body 50 corresponding to the light emitting elements sequentially detect signals passing through the respective channels. Accordingly, all channels of the cassette can be sequentially examined. The light emitting elements of the light transmitting element 42 emit light in a direction passing through a channel to be detected by the light emitting elements, as indicated by an arrow direction of FIG. 5. The sensors of the light receiving element 52 detects signals passing through the respective channels.

[43] The light receiving controller of the light receiving element 52 compares a signal level detected by the sensor with a predetermined reference level. When the signal level is different from the reference level by more than a predetermined value, it is determined that a glass substrate is present in the channel. Resultant data of the determination is sent to the controller of a external substrate conveying device.

[44] Accordingly, the substrate detecting apparatus of the present invention does not require a detector which has been used for the conventional apparatus for detecting a substrate so as to insert the sensor into the cassette. In addition, since the substrate detecting apparatus of the present invention does not have to insert the detector into the cassette, the detector can be fixed in the manufacturing equipment. As a result, an additional driver for moving the detector towards the cassette is not necessary in the substrate detecting apparatus of the present invention

[45] The light transmission controller and the light receiving controller may employ a scan method whereby the controllers sequentially operate by electrical switches which are embedded to allow signals of the respective channels to sequentially emit and receive light.

[46] Meanwhile, in the substrate detecting apparatus according to this embodiment of the present invention, a light emitting sensor of the light transmitting element may be disposed at the lower portion of a channel, and a sensor of the light receiving element may be disposed at the upper portion of the channel. In this case, the operations of the light transmission controller and light receiving controller are the same as described above.

[47] Second Embodiment

[48] Hereinafter, the structure and operation of a substrate detecting apparatus according to a second embodiment of the present invention will be described. FIG. 6 is a perspective view showing an substrate detecting apparatus according to the second embodiment of the present invention. FIG. 7 shows a substrate detecting apparatus placed in manufacturing equipment in order to explain a usage state of the substrate detecting apparatus according to the second embodiment of the present invention. The same descriptions as in the aforementioned embodiment will be omitted.

[49] Light emitting elements constituting a light transmitting element 82 of a first body

80 of the substrate detecting apparatus of this embodiment are placed in a lateral portion of the first body 80 and are selectively located at the upper or lower portion of each channel of a cassette. Sensors constituting a light receiving element 92 of a second body 90 are placed in a lateral portion of the second body 90 that can receive signals sent from the light emitting elements and are located at both of the upper and lower portions of each channel of the cassette. Thus, in the substrate detecting apparatus of this embodiment, the number of the light emitting elements placed in the light transmitting element 82 is equal to the number of channels of the cassette. The number of sensors placed in the light receiving element 92 is twice of the number of channels of the cassette.

[50] As shown in FIGS. 6 and 7, in the sensors disposed at the upper and lower portions of each channel of the second body 90, with respect to light emission rays of the light emitting elements of the first body corresponding to the respective channels, an electrical signal generated from one sensor located in a position, through which the glass substrate passes, is regarded as a reference signal, whereas an electrical signal generated from one sensor located at a position, through which one sensor passes, is regarded as a data signal. The light receiving controller 94 of the second body 90 amplifies the reference signal and the data signal generated from each channel and then compares the two signals in magnitude. If the difference in magnitude of the two signals is greater than a predetermined value, it is determined that a glass substrate is present in a channel. Otherwise, it is determined that the glass substrate is not present in the channel. Thereafter, the determination result of the presence of glass substrates in the respective channels is sent to the controller for a external substrate conveying device.

[51] Third Embodiment

[52] A substrate detecting apparatus according to a third embodiment of the present invention is constructed such that a light receiving element and a light transmitting element having sensors and light emitting elements in the same number as channels of the cassette. With the substrate detecting apparatus of this embodiment, it is possible to generate the aforementioned reference and data signals for each channel by installing one light receiving element for each channel of the second body. For example, when a light emitting element of the second channel emits light, the light receiving element determines that sensing signals by the sensors of the second and third channels are regarded as a data signal and a reference signal, respectively. When a light emitting element of the third channel emits light, the sensing signals by the sensors of the third and fourth channels are used a data signal and a reference signal, respectively. Accordingly, by narrowing the gap between channels or reducing the number of light receiving elements, the sensors can be manufactured in a cost effective manner.

[53] Meanwhile, the substrate detecting apparatus according to another embodiment of the present invention uses an ultrasonic sensor that outputs an ultrasonic signal instead of a light emitting element of the light transmitting element. Further, a sensor of the light receiving element may use a sensor that detects the ultrasonic signal.

[54] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. For example, in the exemplary embodiments of the present invention, the type of light emitting element and sensor, control algorithms of light transmitting and receiving controllers, and various display methods for indicating an operation level of a sensor may be modified so as to enhance an overall capability of the substrate detecting apparatus. Further, a lens may be placed in windows of light emitting and receiving elements so as to improve an optical characteristic of the sensor. Therefore, all differences within the scope will be construed as being included in the present invention.

Industrial Applicability

[55] A substrate detecting apparatus of the present invention is used to determine whether substrates are placed in respective channels of a cassette in semiconductor manufacturing equipment.

[56] In particular, as a novel detecting method in which a reference signal and a data signal are compared each other is contrived, the substrate detecting apparatus of the present invention certainly improves instability of detection in the conventional light transmitting/receiving type sensor. Thus, the present invention can be stably applied to a glass substrate having a transparent and specular reflection surface such as a transparent glass substrate and a sputter glass substrate.

Claims

[1] A substrate detecting apparatus for determining whether glass substrates or plane panels are placed in a cassette, comprising: a first body fixedly placed in manufacturing equipment; and a second body fixedly placed at a position facing the first body to receive a signal sent from the first body, wherein the first body comprises a light transmitting element composed of one or more light emitting elements, and a light transmission controller that controls operations of the light emitting elements of the light transmitting element, and wherein the second body comprises a light receiving element composed of one or more sensors that detect a signal sent from the light transmitting element, and a light receiving controller that uses signals detected by the sensors of the light receiving element to determine whether substrates are present in respective channels of the cassette and that sends resultant data of determination to an external device.

[2] The substrate detecting apparatus of claim 1, wherein the light emitting elements of the first body are sequentially placed in a lateral portion of the first body so as to be located at an upper or lower portion of each channel of the cassette, the sensors of the second body are sequentially placed at a lateral portion of the second body so as to be located at the upper or lower portion of each channel of the cassette, and a surface where the light emitting elements of the light transmitting element are placed faces a surface where the sensors of the light receiving element are placed.

[3] The substrate detecting apparatus of claim 2, wherein the light emitting element of the light transmitting element emit light in a direction passing through a specific channel to be detected by the light emitting element, and the sensor of the light receiving element detect signals passing through the specific channel.

[4] The substrate detecting apparatus of claim 1, wherein the light emitting elements constituting the light transmitting element of the first body are placed in a lateral portion of the first body and are selectively located at the upper or lower portion of each channel of the cassette, and the sensors constituting the light receiving element of the second body are placed in a lateral portion of the second body that can receive signals sent from the light emitting elements and are located at both of the upper and lower portions of each channel of the cassette.

[5] The substrate detecting apparatus of claim 4, wherein the light receiving controller of the second body compares a magnitude of signal detected by a sensor of the light receiving element located at the upper portion of a specific channel of the cassette with a magnitude of signal detected by a sensor of the light receiving element located at the lower portion of the channel, and determined that a substrate is present in the specific channel if the comparison result shows a difference greater than a predetermined value.

[6] The substrate detecting apparatus of claim 2, wherein the light receiving controller of the second body detects a first signal detected by a sensor for a specific channel and a second signal detected by a sensor disposed at the upper or lower portion of the sensor when the light emitting elements of the respective channels of the first body emit light, compares the detected first and second signals in magnitude, and determines that a substrate is present in the specific channel if a difference between the first and second signals is greater than a predetermined value.

[7] The substrate detecting apparatus of claim 3, wherein the light receiving controller of the second body compares a signal detected by a sensor of the specific channel with a predetermined reference signal and determines that a substrate is present in the specific channel if a difference between the detected signal and the predetermined reference signal is greater than a predetermined value.

[8] The substrate detecting apparatus of any one of claims 1 to 7, wherein the light transmission controller of the first body sequentially operates the light emitting elements of the light transmitting element so as to sequentially determine whether substrates are present in respective channels of the cassette.

[9] The substrate detecting apparatus of any one of claims 1 to 7, wherein the light emitting elements of the light transmitting element are an ultrasonic sensors that output ultrasonic signals, and the sensors of the light receiving element are sensors that detect the ultrasonic signals.