Ribbon edge detector and system for metering flow of molten glass

A method of following the edge of a substrate advancing along a substrate path on a conductive surface, comprising the steps of:

• positioning a conductive member over the conductive surface;
• electrically connecting the conductive member and the conductive surface to a power source to provide a capacitor having an output voltage;
• monitoring the output value of the capacitor;
• and
• moving the conductive member in a first direction relative to the substrate edge when the capacitor output value is below a first predetermined value and in the second opposite direction when the capacitor output value is above a second predetermind value.

An apparatus for following the edge of a substrate advancing along a substrate path on a conductive surface, comprising:

• a conductive member;
• means for moving said member across the conductive surface;
• electrical means including a power source connected to said conductive member and the conductive surface to provide a capacitor having a first output voltage when said conductive member is over the conductive surface, second output voltage when said conductive member is over the substrate and a third output voltage when said conductive member is over a portion of the conductive surface and an edge portion of the substrate;
• and
• means responsive to the output voltage of said capacitor and acting on said moving means to move said conductive member relative to the edge of the substrate to follow the edge of the substrate.

In a method of producing a continuous glass ribbon comprising the steps of metering a predetermined amount of molten glass between a glass supporting member and a movable tweel onto a molten metal bath contained in a forming chamber, flowing the molten metal glass downstream on the molten metal while controllably cooling the glass to provide a glass ribbon of a predetermined thickness and width and removing the ribbon from the molten metal bath wherein the improvement comprises the steps of:

• positioning a first conductive member on one side of the molten glass immediately downstream of the glass supporting member and a second conductive member on the opposite side of the molten glass immediately downstream of the glass supporting member;
• electrically connecting the first and second conductive members and the molten metal bath to a power source to provide a first and second capacitor respectively each having an output voltage;
• monitoring the output voltage of the first and second capacitor;
• moving the first and second conductive member in a first direction relative to the ribbon when the capacitor output value is below a first predetermined value and in a second opposite direction when the capacitor output value is above a second predetermined value;
• determining direction and linear displacement of each conductive member from their respective capacitor output voltage;
• and
• moving the tweel to meter the flow of molten glass required to maintain a relatively constant width of molten glass.

An apparatus for making a continuous glass ribbon wherein the apparatus is of the type having a molten metal bath contained in a forming chamber;

• a glass supporting member;
• a tweel;
• means for moving the tweel toward and away from the glass supporting member to meter a predetermined amount of molten glass onto the molten metal bath;
• means for controllably cooling the molten glass as it advances downstream on the molten metal bath to provide a glass ribbon of a predetermined thickness and width;
• and means for removing the glass ribbon from the molten metal bath, comprising:
• a first conductive member;
• means for moving said first member across the molten metal bath in spaced relation thereto;
• electrical means including a power source connected to said conductive member and the molten metal bath to provide a capacitor having a first output;
• a second conductive member;
• second means for moving said second conductive member across the molten metal bath in spaced relation thereto;
• electrical means including a power source connected to said first and second conductive members and the molten metal bath to provide first and second capacitors, respectively, each of said capacitors having a first output voltage when said conductive members are over the molten metal bath, a second output voltage when said conductive members are over the glass ribbon and a third output voltage when said conductive members are over a portion of the molten metal bath and ribbon edge portions;
• means responsive to the output voltage of said first and second capacitors for moving said first and second conductive member relative to its adjacent ribbon edge to follow the ribbon edge;
• means for determining direction and linear displacement of each conductive member;
• and
• means responsive to said determining means and acting on said means for moving the tweel for metering the flow of molten glass to maintain a relatively constant width of molten glass.

An apparatus for making a continuous glass ribbon wherein the apparatus is of the type having molten metal batch contained in a forming chamber;

• a glass supporting member;
• a tweel;
• means for moving the tweel toward and away from the glass supporting member to meter a predetermined amount of molten glass onto the molten metal bath;
• means for controllably cooling the molten glass as it advances downstream on the molten metal bath to provide a glass ribbon of a predetermined thickness and width;
• and means for removing the glass ribbon from the molten metal bath, comprising:
• means for measuring linear displacement, said measuring means including a reciprocating member;
• means for mounting said measuring means to structure of the apparatus adjacent a side of the tweel;
• means for connecting said reciprocating member of said measuring means directly to the tweel to generate an output signal from said measuring means as a direct function of movement and direction of tweel displacement relative to the glass supporting member;
• and
• means for monitoring the output signal of said measuring means to determine the movement and direction of the tweel displacement relative to the glass supporting member.