Method and apparatus for making prescription eyeglass lenses

A method for generating a surface on a blank having a shape corresponding to a given eyeglass prescription, said method comprising the steps of:

• (a) providing information constituting an eyeglass prescription,
• (b) converting said prescription information to point data describing a surface related to said prescription in terms of y, z and .theta. coordinates for all points of a set of points distributed over said surface,
• said y and z coordinates being linear displacements from a zero reference point measured along linear Y and Z axes intersecting one another and said .theta. coordinates being angular displacements about said Z axis from a reference plane containing said Z axis,
• (c) providing a blank,
• (d) rotating said blank continuously about said Z axis,
• (e) moving a cutting tool in cutting engagement with said blank continuously along said Y axis so that said tool follows a generally spiral cutting path relative to said blank,
• (f) repeatedly determining the instantaneous actual y and .theta. coordinates of said blank relative to said tool, and
• (g) moving said cutting tool and blank relative to one another along said Z axis in response to said instantaneous actual y and .theta. coordinates and with reference to said point data so that the z coordinate position of said blank relative to said tool takes on at each instant an actual value substantially equal to the commanded value thereof given by said point data for a point having in said point data y and .theta. coordinates substantially equal to said instantaneous actual y and .theta. coordinates so that said tool cuts a surface on said blank related to said prescription.

A method for producing a plurality of eyeglass lenses each having a lens surface shaped to give it characteristics satisfying an associated eyeglass prescription which may vary from lens to lens, said method comprising the following steps which are performed each time a new lens is wanted:

• (a) providing a lens blank,
• (b) providing a lap blank,
• (c) providing prescription information specifying characteristics wanted in the lens to be produced from said lens blank,
• (d) using said prescription information to generated on said lap blank a lap surface accurately related in shape to the reverse of a lens surface needed on said lens blank to cause said lens blank to satisfy said prescription information, and
• (e) using said lap surface to finish and polish a lens surface such as fore said on said lens blank,
• said step of providing a lap blank being performed by selecting said lap blank from a set of lap blanks, and said step of providing a lens blank being performed by selecting said lens blank from a set of lens blank, the blanks making up one of said sets being distinguishable from the blanks of the other set by virtue of each of said blanks of said one set having a feature distinguishing it from the blanks of the other set, said cutting machine being operable in response to said prescription information in either a lap blank cutting mode or a lens blank cutting mode, sensing the blank placed in said cutting machine to detect the presence or absence of said distinguishing feature on said blank, and using the results of said detection to influence the operation of said cutting machine in either said lap blank cutting mode or said lens blank cutting mode.

A method for producing a plurality of eyeglass lenses each having a lens surface shaped to give it characteristics satisfying an associated eyeglass prescription which may vary from lens to lens, said method comprising the following steps which are performed each time a new lens is wanted:

• (a) providing a lens blank,
• (b) providing a lap blank,
• (c) providing prescription information specifying characteristics wanted in the lens to be produced from said lens blank,
• (d) using said prescription information to generate on said lap blank a lap surface accurately related in shape to the reverse of a lens surface needed on said lens blank to cause said lens blank to satisfy said prescription information, and
• (e) using said lap surface to finish and polish a lens surface such as foresaid on said lens blank,
• said step of using said prescription information to generate a lap surface on said lap blank being performed by first using said prescription information to generate a gray lens surface on said lens blank having a shape causing said lens blank to satisfy, except for the quality of said gray lens surface, said prescription information, and then using said gray lens surface to form said lap surface on said lap blank.

A method for producing a plurality of eyeglass lenses each having a lens surface shaped to give it characteristics satisfying an associated eyeglass prescription which may vary from lens to lens, said method comprising the following steps which are performed each time a new lens is wanted:

• (a) providing first and second sets of blanks, said first set of blanks being a set of lap blanks and said second set of blanks being a set of lens blanks, the blanks of one of said first and second sets each having a central axis and a side surface which is at least substantially a surface of revolution about said central axis and also each having means providing an anomaly in said side surface at one point along a line extending circumferentially of said blank about said central axis, the blanks of the other of said first and second sets of blanks each having a central axis and a side surface which is at least substantially a surface of revolution about said central axis and each lacking an anomaly such as aforesaid in said side surface,
• (b) selecting a lap blank from said first set of blanks,
• (c) selecting a lens blank from said second set of blanks,
• (d) providing prescription information specifying characteristics wanted in the lens to be produced from said selected lens blank,
• (e) placing said selected lap blank in a data controlled cutting machine which rotates said selected lap blank about its central axis,
• (f) operating said machine under the control of said prescription information to cause said machine to cut a lap surface on said selected lap blank as said machine rotates said selected lap blank about its central axis and then removing said lap blank from said machine,
• (g) placing said selected lens blank in said data controlled cutting machine for rotation about its central axis by said cutting machine,
• (h) operating said machine under the control of said prescription information to cause said machine to generate a gray lens surface on said lens blank as said machine rotates said lens blank about its central axis and which gray lens surface has a shape causing said lens blank to satisfy, except for the surface quality of said gray lens surface, said prescription information, and then removing said lens blank from said machine,
• (i) using said lap surface of said selected lap blank to finish and polish said lens surface of said selected lens blank,
• (j) during the rotation of each of said selected lap blank and said selected lens blank about its central axis by said data controlled cutting machine sensing the blank then in said cutting machine by a sensor positioned adjacent the rotational path of tis side surface to detect the presence or absence of an anomaly such as aforesaid in the side surface of said blank then in said machine, and
• (k) using the results of said sensing step to influence the operation of said cutting machine in either said lap blank cutting step or in said lens blank cutting step.

A machine for machining a blank to produce a surface thereon related to a given eyeglass prescription, said machine comprising:

• (a) means for converting information constituting an eyeglass prescription to point data describing a surface related to said prescription in terms of Y, Z and .theta. coordinates for all points of a set of points distributed over said surface, said Y and Z coordinates being linear displacements from a zero reference point measured along linear Y and Z axes intersecting one another and said .theta. coordinates being angular displacements from a reference plane containing said Z axis,
• (b) means for rotating a blank continuously about said Z axis,
• (c) means for moving a cutting tool in cutting engagement with said blank continuously along said Y axis so that said tool follows a generally spiral cutting path relative to said blank,
• (d) means for repeatedly determining the instantaneous actual Y and .theta. coordinates of said blank relative to said tool, and
• (e) means for moving said cutting tool and blank relative to one another along said Z axis in response to said instantaneous Y and .theta. coordinates and with reference to said point data so that the Z coordinate position of said blank relative to said tool takes on at each instant an actual value substantially equal to the commanded value thereof given by said point data for a point having in said point data Y and .theta. coordinates substantially equal to said instantaneous actual Y and .theta. coordinates.

A machine for machining a blank and for use with either blanks supplied from a first set of blanks or with blanks supplied from a second set of blanks, said machine comprising:

• (a) a blank holder rotatable about a Z axis,
• (b) a tool for cutting a blank held by said holder as said holder is rotated about said Z axis,
• each of the blanks making up said first set of blanks having a central axis which becomes aligned with said Z axis when said blank is held by said holder and a side surface which is at last substantially a surface of revolution about said central axis and also having means providing an anomaly in said side surface at one point along a line extending circumferentially of said blank about said central axis, the blanks of said second set of blanks each having a central axis which becomes aligned with said Z axis when said blank is held by said holder and a side surface which is at least substantially a surface of revolution about said central axis and each lacking an anomaly such as aforesaid in said side surface, each of said blanks, of said first set being made substantially of plastic and said anomaly of each of said blanks of said first set being provided by a piece of magnetic material fixed relative to said side surface of each of said blanks, and
• (c) means including a sensor operable during the rotation of a blank as a consequence of rotation of said blank holder about said Z axis for detecting said piece of magnetic material as it moves past said sensor during the rotation of its associated blank about said Z axis by said blank holder to identify whether the blank held by said holder is one from said first set of blanks or one from said second set of blanks.

A method for machining a blank and for use with either blanks supplied from a first set of blanks or with blanks supplied from a second set of blanks, said method comprising:

• (a) providing a first set of blanks each of which has a central axis and a side surface which is at least substantially a surface of revolution about said central axis and also having means providing an anomaly in said side surface at one point along a line extending circumferentially of said blank about said central axis, each of said blanks being made substantially of plastic material and said anomaly of each of said blanks being provided by a piece of magnetic material fixed relative to said side surface of each blank,
• (b) providing a second set of blanks each having a central axis and a side surface which is at least substantially a surface of revolution about said central axis and each lacking an anomaly such as aforesaid in said side surface,
• (c) selecting a blank from one of said sets and rotating it about its central axis,
• (d) providing a magnetic sensor and using it in sensing the presence of absence of an anomaly such as aforesaid as said blank is rotated about its central axis, and
• (e) thereafter working on said blank in one way if an anomaly such as aforesaid is detected during said sensing step and working on said blank in another way if no anomaly such as aforesaid is detected during said sensing step.