UNIQUE HIGH SPEED TABLET DRILLING LASER SYSTEM

Abstract

An apparatus for high speed laser drilling of tablets, particularly controlled-release tablets is disclosed. The apparatus comprises of a rotary disk (118) with radial slots (401) to hold the tablets in position with help of centrifugal force. The apparatus further comprises a laser system (120) configured to fire a laser beam in order to draw a line of required length on tablets to drill a precise hole at high speed. The laser system (120) is enabled to draw a line on tablet at a speed equal to that of rotational speed of tablets on the rotary disk (118).

Claims

1. An apparatus for drilling holes into a plurality of tablets, wherein the apparatus comprises: a laser system (120) configured to fire a laser beam pulse, via movable mirrors, in order to generate a projected line, wherein the projected line enables in drilling a hole on desired side of a tablet based upon matching of the speed of the movable mirrors with the speed of a rotating disk (118) holding the tablet, and wherein the deflection of the laser beam pulse is preset.

2. The apparatus of claim 1, wherein each laser system (120) generates the projected line of thickness set based on focus spot size by setting focal distance setting.

3. The apparatus of claim 1, wherein the length of the projected line is set to match the diameter of the hole and control the circularity of the hole.

4. The apparatus of claim 1, wherein the laser system (120) is deployed either at the top of the rotary disk (118) or bottom of the rotary disk (118) or on both sides.

5. The apparatus of claim 1, wherein the laser system (120) is further configured to drill multiple holes by generating broken projected lines in a single rotation, wherein the multiple holes are drilled by blanking the laser beam.

6. The apparatus of claim 1, wherein the design and assembly contour of the radial slots of the rotary disk (118) enables accurate holding of one or more tablets.

7. The apparatus of claim 1, wherein the rotary disk (118) is replaced with a substitute rotary disk within a time period of 5 seconds in order to drill the tablets of varied sizes.

8. The apparatus of claim 1, wherein the length of the projected line is proportional to the width of the laser beam pulse.

9. The apparatus of claim 1, wherein the depth of the hole is proportional to the length of the laser pulse width.

10. A method for drilling holes into controlled release tablet at high speed using a laser system apparatus, the method comprising: firing a laser beam pulse by the laser system (120), via movable mirrors, in order to generate a projected line, wherein the projected line enables in drilling a hole on desired side of a tablet based upon matching of the speed of the movable mirrors with the speed of a rotating disk (118) holding the tablet, and wherein the deflection of the laser beam is preset.

11. The method of claim 10, wherein the multiple holes are drilled by generating broken projected lines in a single rotation, wherein the multiple holes are drilled by blanking the laser beam.

12. The method of claim 10, wherein the laser system (120) is fired after locating the desired side of tablet surface to be drilled.

13. The method of claim 10, wherein the length of the projected line is proportional to the width of the laser beam pulse.

14. The method of claim 10, wherein the depth of the hole is proportional to the length of the laser pulse width.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0012] The foregoing summary, as well as the following detailed description of preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings example constructions of the invention; however, the invention is not limited to the specific systems disclosed in the drawings:

[0013] FIG. 1 shows isometric view of the high-speed laser drilling apparatus according to one exemplary embodiment of the invention.

[0014] FIG. 2 shows front view of the high-speed laser drilling apparatus according to one exemplary embodiment of the invention.

[0015] FIG. 3 shows exploded view of the rotary disk according to one exemplary embodiment of the invention.

[0016] FIG. 4 shows assembled view of the rotary disk according to one exemplary embodiment of the invention.

DETAILED DESCRIPTION

[0017] Some embodiments of this invention, illustrating all its features, will now be discussed in detail.

[0018] The words “comprising,” “having,” “containing,” and “including,” and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items.

[0019] It must also be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, the preferred, systems and methods are now described.

[0020] The disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms.

[0021] The present invention relates to a laser drilling apparatus to precisely drill a hole in osmotic tablets with increased efficiency.

[0022] FIG. 1 shows an isometric view of the apparatus according to one exemplary embodiment of the invention. FIG. 2 illustrates the front view of the apparatus according to one exemplary embodiment of the invention. As illustrated in FIG. 1, the apparatus comprises a drilling section 117 which comprises of hopper and a rotary disk 118 comprising multiple radial slots. The tablets from hopper are sorted out on the rotary disk 118. Each radial slot holds one or more tablets. As the disk rotates at high speed, the rotary disk passes through colour sensors 104 and 105, and then through top galvo 103 and bottom galvo 106. Depending on the reading of the colour sensors 104 and 105, a top laser 116 or a bottom laser 114 is fired. The firing of the laser beam drills holes in the tablets contained in the radial slot. When the laser drilling is completed, it is ejected immediately by an air blow from bottom of the rotary disk and a chute on to another similar rotary disk 119 of the camera inspection section 107 as shown in FIG. 1. The camera inspection section 107 comprises a colour sensor 108 that identifies the surface of the tablet on which hole is made. Next, the cameras (109, 110) checks the quality of holes by comparing the circularity and diameter of the holes with the predefined reference values of the circularity and the diameter. Further, the cameras (109, 110) also checks location of the hole with respect to the geometrical centre of the tablet. Depending on the quality of holes produced, or presence of absence, of the hole the tablet enters the production chute 111 or the rejection chute 112. In case of bi layer tablets the colour sensor of this rotary disk in the inspection section diverts the tablet to recycle chute 113 and is collected in separate bin. HMI 101 and operation panel 102 are provided on the front side of the apparatus to control the apparatus. The HMI 101 is used for control data entry and to display errors, alarms and warnings to the user. The operation panel 102 (or HMI 102) displays the set up and camera set up for inspection parameters and on line images of running tablets with go no go messages in real time.

[0023] The tablets to be drilled are introduced into the hopper which is situated above the rotary disk. The controlled-release tablets are mostly manufactured with two different colours on two surfaces. The hole is drilled on one of the two surfaces. The drug is delivered by osmotic push technology. The layer below the drilled drug layer swells up when the tablet is introduced in liquid environment, it pushes the drug out from the drilled hole. The surface of tablets is coated with non-soluble bio-compatible coating and so drug is delivered only through the outlet that is provided by the drilled hole.

[0024] The tablets from hopper are transferred onto the rotary disk which has radial slots of required width. The width of these slots may be varied according to the size of the tablet. The rotary disks (118,119) can be easily replaced for different sized tablets. In accordance with an embodiment of the present invention, the time required for replacing the rotary disks is less than 5 minutes as compared to several hours taken by the conventional apparatuses available in the art. The tablets are lined up along the contour of the radial slots. The tablet on the circumference of the disk is the target tablet that must be laser drilled. The contour of the radial slots provides proper stability required to hold the tablet in place when it is being fired by the laser. The radial rotating disks (118,119) rotates at high speed and the resulting centrifugal force keeps the tablets flowing into the radial slots and holding them at their place. Such kind of design eliminates the need of any active or passive clamping required to hold the tablets.

[0025] Each of the rotary disks (118,119) is an assembly of three plates 301, 302 and 303 as shown in FIG. 3. The plate 303 has semi-circular notches 402 (as shown in FIG. 4) on the circumference. When the target tablet reaches the circumference of the rotary disk 118, the notches enables the target tablet to be viewed from below the rotary disk 118 as well. Further, as shown in FIG. 4, each rotary disk has radial slots (401) to hold the tablets.

[0026] Now, again referring to FIG. 1, the rotary disk 118 is rotated at high speed and before passing through the laser system, the rotary disk 118 is passed through the colour sensors (104, 105). The colour sensor 104 is situated above the disk to determine the colour of the top surface of the tablet. The colour sensor 105 is situated beneath the rotary disk to sense the colour of the bottom surface of the tablet. Based on the colour sensed by either of the colour sensors (104, 105), it is decided whether the top laser 116 or the bottom laser 114 is to be fired. Further, as shown in FIG. 1, a galvo scanner 103 and a galvo scanner 106, placed at the top and the bottom of the rotary disk 118 respectively, is configured to assist the laser drilling operation. More particularly, the galvo scanner 103 and a galvo scanner 106 is configured to deflect the laser beam at a predefined trajectory of a line generated by software programming and synchronize the speed of the laser beam with the circumferential speed of the disk and hence the speed of the tablet.

[0027] According to embodiments of the present invention, the high-speed laser firing system fires the laser via the galvo mirrors (also referred as galvo scanners) in order to draw a line of length as per the pre-calibrated depth to length look up table. The drawing of line by the laser system has same speed as that of rotation of tablets on the disk. The diameter of the hole is decided by one time setting of the focus spot size by adjusting focal distance setting. This method ensures that the resulting hole maintains desired diameter. The circularity can be adjusted by adjusting the length of line and beam movement speed tuning, and laser on/off delay timings. In an embodiment, the diameter of the hole is within a range of 0.5 mm to 1 mm. For drilling such small holes, accurate circularity is difficult to maintain at high speed. Therefore, drilling by drawing the line proves to be efficient for making such holes as compared to drawing a circle profile on the tablet.

[0028] In accordance with embodiments of the present invention, the apparatus shown in FIG. 1 is further configured to drill multiple holes required to control time of the drug release by drawing spaced broken line. The apparatus enables drawing the of such broken lines just by laser beam blanking and accordingly drill multiple holes in a single rotation. When the laser is drawing a line, if there should be more than one holes, the laser is blanked, and thus two different holes at different places on the same tablet surface are formed.

[0029] Once all the above processes are completed in the drilling section, the tablets are passed on to the adjacent inspection section 107 where they are inspected individually by the cameras (109, 110). The inspection section comprises of identical rotary disk 119 as that of the drilling section. The camera 109 and the camera 110 may be positioned at the top and bottom of the identical rotary disk 119. Just before the tablets are passed through the cameras (109,110), the tablets are passed through a colour sensor 108. The colour sensor 108 is configured to sense the colour of the top surface of the tablets. Based on the colour sensed, one of the cameras (109,110) captures the snapshot of the tablet. The snap is analyzed and the placement of hole, the diameter, circularity and depth is checked. If the tablet passes the test, the tablet is taken up by the production chute 111. The tablets which are not perfectly drilled are either rejected or recycled through rejection chute 112 and recycle chute 113 respectively.

[0030] Thus, the apparatus of present invention works without any special complex arrangement to hold the tablets for drilling. Further, the apparatus facilitates in quick changing of rotary disk as per the requirements of the tablets to be drilled of varied sizes. Time required for changing the rotary disk is less than 5 minutes. The overall change part manufacturing cost of the apparatus disclosed therefore is minimal.

[0031] The preceding description has been presented with reference to various embodiments of the invention. However, Persons skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described apparatus and methods of operation can be practiced without meaningfully departing from the principle, spirit and scope of this invention.