Patent Application
20120045975
The present invention relates to a highly versatile lens-processing device that can polish, cut, or otherwise process a lens surface using a variety of processing methods.
Well-known conventional methods for processing lens surfaces include Oscar-type, inclined-axis-type, spherical-oscillation-type, and planetary-oscillation-type methods. The optimal processing method is chosen from among these processing methods according to the shape, material, and other properties of the lens; and the lens surface is processed using a lens-processing device that is specialized for processing using the selected processing method. Conventionally, lens-processing devices of various formats must therefore be separately prepared, and problems are accordingly presented in that equipment costs and installation space increase, which presents economic drawbacks.
In Patent Document 1 (Japanese Patent No. 3981326), the present applicants proposed a lens-processing device that can precisely move a plate-shaped or cup-shaped lens-processing tool along a desired trajectory without using a cam mechanism, and that can process a lens surface using a variety of processing formats. In this lens-processing device, the downward-oriented processing surface of a lens-processing tool is pressed against the lens to be processed from below, and processing is performed. The lens is held horizontally by suction on a downward-oriented lens-holding surface of a lens holder and is held from above with respect to the processing surface of the upward-oriented lens-processing tool. The movement of the lens-processing tool in a Z-axis direction (vertical direction), the movement in an X-axis direction (horizontal direction), and swiveling about a θ-axis that is perpendicular to the Z-axis and the X-axis are controlled, whereby the lens surface can be processed using a variety of lens-processing methods.
In Oscar-type, inclined-axis-type, and planetary-oscillation-type lens-processing devices that are conventionally used for processing curved lens surfaces, the lens cannot be maintained in a horizontal state when the axis of rotation of the lens-processing tool and the lens holder shaft are inclined at a predetermined angle. During processing, the lens moves in a rotary fashion following the rotation of the lens-processing tool, and a force for returning the lens to the horizontal state is always in effect due to the inertial force resulting from the rotation. The pressing stress that is generated between the lens and the lens-processing tool is therefore not uniform, and the processing precision of the lens-processing surface is reduced.
During replacement of the lens, when the axis of rotation of the lens-processing tool and the lens holder shaft are inclined, the lens may fall from the processing surface of the lens-processing tool and break when pressure on the lens holder shaft is released, and the pressing force of the lens on the lens-processing tool is removed.
If the orientation of the lens at the completion of processing is not fixed, difficulties will be encountered in attaching or detaching the lens using automatic conveying devices, and the lens will inevitably have to be replaced by hand. Automating lens replacement and increasing the efficiency of the operation is therefore impossible.
In light of the above, it is an object of the present invention to allow a curved lens surface to be processed using a variety of processing formats while always maintaining the lens in a horizontal state in a lens-processing device in which the lens is held by suction on a lens holder that is supported so as to allow rotation and oscillation interposed by a pivot bearing on a distal end of the lens holder shaft, and in which the lens and a lens-processing tool are made to move relative to each other; and the curved lens surface is processed in a state in which the lens-processing tool is pressed against the lens.
In order to solve the aforementioned problems, a lens-processing device of the present invention is characterized in comprising:
a lens-holder shaft extending in a vertical direction;
a lens holder capable of rotating and oscillating about a pivot bearing, the lens holder being attached coaxially and in a downward orientation to a lower end of the lens-holder shaft interposed by the pivot bearing;
a Z-axis movement mechanism for moving the lens-holder shaft in a Z-axis direction, the Z-axis direction being the vertical direction;
an X-axis movement mechanism for moving the lens-holder shaft in an X-axis direction, the X-axis direction being a horizontal direction;
a lens-processing tool having a convex or concave circular-arc shaped processing surface positioned in an upward orientation for processing a lens held by the lens holder;
a θ-axis-swiveling mechanism for causing the lens-processing tool to swivel about a θ-axis, the θ-axis extending in a horizontal direction perpendicular to the X-axis;
a lens-processing-tool-rotating mechanism of the lens-processing tool for causing the lens-processing tool to rotate about a center axis, the center axis passing through the θ-axis;
drive-control means for controlling driving of the X-axis movement mechanism, the Z-axis movement mechanism, and the θ-axis-swiveling mechanism; and controlling movement in the X-axis direction of the lens holder attached to the lens-holder shaft, movement of the lens holder in the Z-axis direction, and swiveling of the lens-processing tool about the θ-axis, whereby a plurality of types of lens-processing modes are executed.
The lens-processing device of the present invention is characterized in that the lens-processing modes of the drive-control means includes a lens-processing mode for controlling driving of the X-axis movement mechanism, the Z-axis movement mechanism, and the θ-axis-swiveling mechanism so that the lens to be processed is pressed from above in a horizontal state onto the circular-arc-shaped processing surface of the lens-processing tool, the lens being held on a lens-holding surface of the lens holder, and the lens-processing tool swiveling about the θ-axis.
In the lens-processing device of the present invention, an operation for feeding the lens holder in two perpendicular directions (the Z-axis and X-axis directions) can be used to move a lens to be processed along a desired trajectory on a vertical plane that includes the Z-axis and the X-axis. The lens is held by suction on the lens holder. The circular-arc-shaped processing surface of the lens-processing tool can also be made to swivel along a circular trajectory about the θ-axis on the vertical plane. Lens-processing modes can therefore be implemented in which the lens surface is processed while the lens is maintained pressing from above in a horizontal state on the circular-arc-shaped processing surface of the lens-processing tool.
The lens-processing device of the present invention preferably comprises a Y-axis movement mechanism for moving the lens-processing tool in a direction of a Y-axis, the Y-axis being parallel to the θ-axis.
The Y-axis movement mechanism is used to hold the lens-processing tool in a desired position in the Y-axis direction. The lens holder is moved back and forth in the X-axis direction by the X-axis movement mechanism at this position, whereby the lens surface can be processed using a lens-processing mode that corresponds to a conventional Oscar format. Separately controlling the X-axis movement mechanism, the Z-axis movement mechanism, and the θ-axis-swiveling mechanism, and moving and immobilizing the lens holder and the lens-processing tool at predetermined positions allows the lens surface to be processed using a lens-processing mode that corresponds to a conventional inclined-axis-type.
According to the lens-processing device of the present invention, lens processing can be performed using lens-processing modes in which the lens surface is processed such that the lens is always maintained in a horizontal state. In these lens-processing modes, the pressing stress of the lens on the circular-arc-shaped processing surface of the lens-processing tool is uniform on all the portions of the lens surface. When the pressing force on the lens holder shaft is removed, and the lens that is held by suction on the lens holder that is supported on the end thereof is released, the lens does not fall and break along the circular-arc-shaped processing surface of the lens-processing tool. The position of the lens is always horizontal at the completion of processing, and therefore the work of replacing the lens on the lens holder can be efficiently performed using an automated conveying device.
The lens-processing device of the present invention allows processing using Oscar-type, inclined-axis-type, planetary-oscillation-type, and a variety of other types of lens-processing modes using a single machine. The lens-processing device is therefore highly versatile. Lens-processing devices of various formats therefore need not be separately prepared; therefore, equipment costs and installation space can be planned for in an extremely economical fashion.
Embodiments of a lens-processing device in which the present invention is applied will be described below with reference to the drawings.
As described in
The upper axial unit 10 holds a lens holder 12 in a downward-oriented state, where the purpose of the lens holder is to hold a lens 11 to be processed. The lower axial unit 30 holds a lens-processing tool 31 in an upward-oriented state, where the lens-processing tool is used for processing the lens surface. The conveyor unit 50 supplies the lens 11 to be processed to the lens holder 12 and retrieves the lens 11 from the lens holder 12 after the completion of processing.
The upper axial unit 10 is provided with a lens-holder shaft 13 that is positioned in the vertical direction. The lens holder 12 is attached in a downward-oriented state to a lower end of the lens-holder shaft 13 interposed by a pivot-shaft-bearing mechanism 14. The lens 11 to be processed can be, e.g., held by suction on a downward-oriented lens-holding surface 12a of the lens holder 12 using a vacuum.
The upper axial unit 10 is provided with an X-axis movement mechanism 15 for feeding the lens-holder shaft 13 along an X-axis direction that extends in a horizontal direction, and a Z-axis movement mechanism 19 for feeding the lens-holder shaft 13 along a Z-axis direction that extends in a vertical direction. In the present example, the X-axis movement mechanism 15 is provided with an X-axis guide 16 that extends in the horizontal direction; an X-axis table 16a that can slide in the X-axis direction along the X-axis guide 16; an X-axis feed screw 17 for feeding the X-axis table 16a in the X-axis direction; and an X-axis servo motor 18 that serves as a drive source. The Z-axis movement mechanism 19 is provided with a Z-axis guide 20 that extends in the vertical direction perpendicular to the X-axis and that attaches to the front surface of the X-axis table 16a; a Z-axis table 20a that can freely slide in the Z-axis direction along the Z-axis guide 20; a Z-axis feed screw 21 for feeding the Z-axis table 20a in the Z-axis direction; and a Z-axis servo motor 22 that serves as a drive source.
A holder-shaft base 23 is fixed on the Z-axis table 20a of the Z-axis movement mechanism. The holder-shaft base 23 rotatably supports the lens-holder shaft 13 in a vertical state. The lens-holder shaft 13 is always urged downward by a holder-pressing spring 24. The pressing force of the holder-pressing spring 24 can be adjusted using a pressure-adjusting bolt 25. Besides a spring, the method of pressing may also employ a weight, a pneumatic cylinder, or a hydraulic cylinder. The lens-holder shaft 13 can also be made to rotate about a center axis line 13a thereof using a holder-shaft-driving motor 26 that is mounted on the holder-shaft base 23.
Various types of structures can be employed as the pivot-shaft-bearing mechanism 14 between the lens-holder shaft 13 and the lens holder 12. The lens holder 12 should be attached in a state that allows oscillation about a back-surface position 12b that is supported by the lens-holder shaft 13 and that allows rotation about the center axis line 13a. When the lens 11 is held on the lens-holding surface 12a of the lens holder 12 by suction using a vacuum, the vacuum-suction line for applying vacuum suction to the lens 11 must be formed to pass through the lens-holder shaft 13 and the pivot-shaft-bearing mechanism 14 and open on the lens-holding surface 12a of the lens holder 12. The pivot-shaft-bearing mechanism 14 that is employed should be appropriate for forming such a vacuum-suction line.
The lower axial unit 30 is provided with a θ-axis swiveling mechanism 33 for causing the lens-processing tool 31 to swivel about a θ-axis 32 that extends horizontally in a forward-and-backward direction that is perpendicular to both the X-axis and the Z-axis; and a Y-axis movement mechanism 36 for causing the lens-processing tool 31 to move in a horizontal direction that is parallel to the θ-axis 32. The θ-axis swiveling mechanism 33 is provided with a θ-axis servo motor 34 that is provided with a rotating shaft 34a that rotates about the central axis line of the θ-axis 32; and an L-shaped θ-bracket 35 attached to a distal end of the rotating shaft 34a. The Y-axis movement mechanism 36 is provided with a spindle case 37 and a Y-axis microhead 38, which defines the position of the spindle case 37 in the Y-axis direction. The spindle case 37 is mounted on the θ-bracket 35 in a state that allows movement in the Y-axis direction.
A spindle 39 is rotatably supported in the spindle case 37. The spindle 39 is rotationally driven using a spindle-driving motor 40. The lens-processing tool 31 is coaxially attached in an upward orientation to the upper end of the spindle 39. A rotational mechanism 41 of the lens-processing tool 31 is configured from the spindle case 37, the spindle 39, and the spindle-driving motor 40.
The conveyor unit 50 is provided with a conveyor 52 for conveying lens cases 51, and a conveyor-driving motor 53 for rotationally driving the conveyor 52. A conveyor-advancing/retracting cylinder 54 allows the conveyor 52 and the conveyor-driving motor 53 to be moved between a position between the upper axial unit 10 and the lower axial unit 30, and a position withdrawn therefrom on the Y-axis.
An example of an operation for conveying lenses using the conveyor 52 will be described. At the withdrawn position, the conveyor 52 conveys the lens cases 51, replaces the lens case 51 containing a processed lens with the lens case 51 containing an unprocessed lens, transfers the lens case 51 that has reached the end of the conveyor 52 to a conveyor of the next stage, and receives the lens case 51 ejected by a conveyor of the previous stage.
The conveyor 52 then moves forward, causes the lens case 51 to be positioned below the upper axial unit 10, supplies the lens 11 to the lens holder 12 or receives the processed lens 11 from the lens holder 12, and moves to a rearward position.
The upper axial unit 10 positions the lens holder 12 directly above the lens case 51 that is loaded on the conveyor 52 that has moved forward, uses, e.g., a vacuum to suction the lens of the lens case 51 onto the lens holder 12, and temporarily withdraws. After the lens case 51 has moved to the rear along with the conveyor 52, the lens 11 that is held on the lens holder 12 is moved into position for processing by the plate-shaped or cup-shaped lens-processing tool 31.
After processing by the plate-shaped or cup-shaped lens-processing tool 31 has completed, the lens holder 12 causes the lens 11 to be moved back from the lens-processing tool 31. The lens holder 12 waits until the conveyor 52 moves forward and the lens case 51 is positioned below, then, e.g., removes the suction when directly above the lens case 51, and drops the lens 11 into the lens case 51, in which the lens is stored. The lens holder 12 is then withdrawn.
(Example of Operation)
An example of the operation of the lens-processing device 1 having this configuration will be described.
In the initial position shown by the broken line in
X=Xd (m)
θd=sin−1(Xd/r) (degrees)
Zd=r(1−cos θd) (m)
The feed amount Xd in the X-axis direction is gradually increased, and a movement is made from the initial position Xo to L (m). The feed amount Zd (m) and the swivel amount θd (degrees) are calculated according to the feed amount Xd, and the operations for propulsion in the Z-axis direction and swiveling about the θ-axis are performed to synchronize with the propulsion in the X-axis direction. After the feed amount Xd has reached L (m), the feed amount Xd is reversed and gradually reduced, and negative movement is made from the initial position Xo to R (m). The operations for feeding in the Z-axis direction and swiveling about the θ-axis are also performed in concert with propulsion in the X-axis direction at this point. The lens surface 11a can thereby be processed while the lens 11 is maintained in a horizontal state.
During the operation for processing the lens surface, the rotational mechanism 41 of the lens-processing tool causes the lens-processing tool 31 to rotate about the rotational center line 31c. The lens surface 11a of the lens 11 is pressed on the processing surface 31a of the lens-processing tool 31 from above, and therefore the lens 11 rotates following the rotation of the lens-processing tool 31. The processing operation is performed in a state in which the lens 11 is vacuum-suctioned on the lens-holding surface 12a of the lens holder 12 or in a state in which the vacuum suction has been removed.
When the movement stroke of the lens-holder shaft 13 in the Z-axis direction is greater than the maximum value of the feed amount in the Z-axis direction, the calculation of Zd and the drive control for the Z-axis movement mechanism can be omitted.
Providing a positive value to the processing radius r allows the lens surface 11a that has a convex surface to be processed, as shown in
If the processing radius r is taken to be infinite, only lateral movement (propulsion in the X-axis direction) is produced, and therefore an Oscar-type lens-processing mode can be implemented if the movement is made in conjunction with movement in the Y-axis direction. An inclined-axis-type lens-processing mode can be implemented if movement in the direction of the X-axis, Z-axis, and Y-axis is prevented; swiveling about the θ-axis is prevented; the lens 11 and the lens-processing tool 31 are immobilized at desired positions and angles; and processing is performed.
The lens surface 11a can also be processed as shown in
When a small number of work pieces (lenses) are present, the outside diameter is large, or in order to establish simple and inexpensive manufacturing means, a turntable that is made to rotate by electrical power, air indexing, or other means may be put in place of the conveyor unit 50; and the work pieces provided and retrieved thereby. It shall also be apparent that the work pieces may be attached and detached by manual labor without using a device for replacing the work pieces.
The Y-axis microhead 38 of the lower axial unit 30 can also be replaced by a Y-axis movement mechanism composed of a feed screw and a servo motor. Simultaneously driving the Y-axis movement mechanism and the X-axis movement mechanism in such instances allows planetary-format lens processing to be implemented.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/002654 | 6/11/2009 | WO | 00 | 10/31/2011 |
