Patent Application
20190242801
The Invention relates to a device for mounting a tablet testing device with a calibration unit, which unit serves to calibrate and adjust the breaking force of a breaking jaw of a tablet testing device for measuring the breaking force of tablets. By means of said device, the velocity of a breaking jaw and the set hardness of breaking may be calibrated in regular intervals, such as that modern quality control standard for pharmaceutical measuring devices are matched.
The device is used to temporarily fit a tablet testing device for calibration, wherein said device is connected to the tablet testing device for the purpose of calibration. During normal use, the bulky and huge device is separated and stored away from the tablet testing device.
Tablets need to be tested for breaking strength before put into commerce. Typically high-through put tablet testing device are used for that purpose. Such devices comprise a testing chamber, an opposing jaw and a movable breaking jaw which breaking jaw jams the tablet in between the opposing jaw and the breaking jaw. Further said tablet testing devices comprise an actuator unit for actuating the breaking jaw and a measuring device for measuring the velocity of the breaking jaw and the set breaking force. Frequently, said tablet testing devices are used for measuring the dimension of tablets, wherein the breaking jaw of the tablet testing device is not moved onto the tablet up to the point of break but is stopped at a preset maximum force and the distance of movement is determined and used for calculating lenght, width and diameter of a tablet.
Examples of such tablet testing devices are known from the state of the art. Document DE102015114600 B3 describes a device and a method for testing tablets wherein the device comprises a testing chamber, a breaking jaw, an opposing jaw and an abutment that is preferably arranged orthogonally to the opposing jaw, further wherein the device comprises a movable strip of tin fitted for positioning and aligning a tablet for testing, and wherein the longitudinal axis of said tin strip corresponds to its direction of movement and is oriented in an angle less than 90° relative to the longitudinal axis of movement of the breaking jaw, and wherein the tablet is positionable along the abutment by the movement of the tin strip into one direction and along the opposing jaw by movement of the tin strip into the opposite direction.
The testing chamber of tablet testing devices often contains a longitudinal positioning surface into which tablets are given after a thinning step, for individual measurement. To this end, said tablets are thinned out by a thinning device first and are then positioned one-by-one on a measuring surface confined the the breaking jaw and opposing jaw. Subsequently, the breaking jaw is moved onto the opposing jaw, wherein the individual tablet to be assessed is placed in between the breaking and the opposing jaw and is finally jammed in between these. The closing-in movement takes places at slow speed, in order to have the tablet affixed in the desired position. After jamming, the breaking forces is risen up to the point of breaking. Often the dimension of a tablet is determined along with the breaking strength by stopping the breaking jaw at a preset breaking force, prior to breaking the tablet.
The measurement of dimension and breaking strength of the tablet follows standardized and precisely prescribed methodological steps. Measurements are standardized and documented in the textbooks for the art. An example of such is the German ‘Deutsches Arzneibuch’. Another example which comprises descriptions of the dimensional and breaking strength measurement and testing for tablets, is the american ‘United States Pharmacopeial Convention’, edition USP 40 of Dec. 1, 2017, chap. 1217 ‘General Information’, pages 1750 to 1752, wordwide web:
http://app.uspnf.com/uspnf/pub/index?usp=40&nf=35&s=2&officialOn=December%201,%202017
In there, it is described that calibration of devices of measurement is imperative, otherwise measurements of tablets are not reproducible. The increase in breaking force has to take place at constant rate, as a sudden increase in compressing force will provoke random decomposition of the tablet and breaking by shearing forces instead. In particular the velocity of moving the breaking jaw onto the tablet and the breaking force necessitated for reproducible breaking of the tablet have to be calibrated.
Commercially available tablet testing devices that are in use at customer's facilities, hence need to calibrated in regular intervals for obtaining reliable results. Typical calibration intervals are annual periods, for instance.
Hitherto calibration is carried out according to the state of the art with tools that have always to be collected piecemeal once a new calibration run is scheduled. This is laborious and costly in time for preparation. Therefore it would be a big advantage to have a readily mounted device available in case of need, by means of which a tablet testing device can be made ready for calibration by simply mounting a or connecting to a calibration device. A permanent unit for making a tablet testing device fit for calibration is usually not desirable; this because commercial tablet testing devices of manageable size and can be easily transported. A permanent calibration unit built in to the tablet testing device would increase space consumption of existing tablet testing devices in quite an undesirable extend.
Accordingly there is the problem of making available a device which allows of equipping a tablet testing device in a simple way for a single calibration run within a given calibration interval. The present invention solves this problem by means of a calibration device which contains a measuring device, a computer unit, a communication interface to the tablet testing device, and means of connection between the measuring device, the computer unit and the communication interface.
By connecting said calibration device with the tablet testing device, the tablet testing devicemay be prepared quickly and easily for calibration. A tablet testing device may be equipped easily, and without loss of time, with a device for calibration, the latter which is only used during the calibration round within the scheduled calibration interval. During normal operation, the bulky and spacious calibration device is kept and stored separate from the tablet testing device. Further, additional sources of error are avoided due to the instant tablet testing device because calibration is carried out by means of the readily assembled calibration device.
The computer unit contains a computer comprising the data necessary for calibration, based on which calibration is carried out. Said data were fed into the computer by programming, for instance. Operational control of the measuring device and the computer unit, during a calibration run, is via the display unit and the data entering unit of the tablet testing device. By means of the device of the instant invention, modern quality control standards for pharmaceutical measuring devices can be easily obeyed to.
Typically, the calibration device is used to calibrate the velocity by which the breaking jaw is moved onto the tablet, or the breaking force required for breaking a tablet. According to the present invention, is equally possible to calibrate only the velocity of the breaking jaw or the breaking force required for breaking a tablet.
In particular a device is provided for calibrating a tablet testing device, which calibration device is a measuring system for velocity or breaking force of a breaking jaw, comprising
at least one measuring device for measuring velocity or breaking force of a breaking jaw of a tablet testing device,
a computer unit for reading and evaluating data obtained during measurement, and characterized in that
the calibration device comprises a communication interface to a tablet testing device, the testing device comprising a display unit and a data entering unit, and
connection means between the one or several measuring devices, the computer unit and the communication interface, such as that
the calibration unit may be connected to the tablet testing device via the communication interface, whereby the data obtained by the measuring device can be transmitted via by communication interface to the tablet testing device, thus making said data visible on said display unit and processable by said data entering unit, and
wherein the computer unit may be used for evaluating the data obtained by measuring velocity and breaking force, whereby the actuator of the breaking jaw of the tablet testing device may be controlled and calibrated.
In one embodiment of the invention, the measuring device is a distance measurement unit, or a load cell or both. The distance measurement unit can be an optical measuring unit, for instance. An optical measuring unit can be a laser-guided measuring device in return. Further optical measuring units and load cells for determining the force applied at breaking hardness are exemplarily described in patent application WO 201103581 A1. A distance measurement unit, in a simple embodiment, can be a series of electric contacts which serve to measure the distance of travel of an object moving along. The electric contacts are arranged in a staggered manner and their number corresponds to the distance units traveled. For measuring the distance of travel, the contacts are triggered subsequently by the breaking jaw whilst travelling a distance by a counter contact, which allows of measuring the distance of travel.
In another embodiment of the invention, the communication interface to a tablet testing device is a USB plug-in connection. Thereby the device is connected to the tablet testing device. By means of a USB plug-in part, as is routine and is commonly used in computer hardware, a fast and standardized communication line between the device and the tablet testing device is feasible. Other means of communication such as wireless data communication devices may be used as well.
The receiving port for the USB plug-in connection may be placed at the tablet testing device at any site, preferably is connected to the display unit of the tablet testing device. It goes without saying that the computer unit of the calibration device of the present invention is compatible with the computer of the tablet testing device.
In another embodiment of the present invention the connection means between the one or several measuring devices, the computer unit and the communication interface are electric wires.
The computer unit preferably is a computer unit which autonomously evaluates data on velocity and breaking force obtained by measurement and is transmitting them to the display unit and the data entering unit of the tablet testing device. Computer units for calibration of tablet testing devices are known from the state of the art, likewise computer software for operating such computer units.
In case the device according to the present invention comprises several measuring devices and the tablet testing device comprises already calculation software for calibration, then in a simple embodiment the computer unit may be a junction box which forwards the data obtained by measurement of velocity or breaking force to the computer of the tablet testing device.
In an embodiment of the invention, calibration of velocity or breaking force of a breaking jaw of the tablet testing device is feasible. In the former case, the devices contains a distance measuring unit and in the latter case a load cell. In a preferred embodiment of the invention the device of the present invention allows of calibrating velocity and breaking force. Accordingly the device comprises a distance measurement unit and a load cell. Therein the computer unit is fitted as to calibrate either the breaking force or both the velocity and the breaking force. Correspondingly the computer unit then comprises suitable software.
With the device according to the present invention, it is feasible to store or record data obtained for velocity or breaking force or both, additionally or alternatively to performing calibration. In that case the computer unit comprises software for storage or recordation.
In an embodiment of the invention the device for calibration is mountable or screwable. This way it may be installed onto the tablet testing device easily and with little delay. In particular the measuring device for velocity and breaking force may be installed with ease. The joining by screwing of said measuring devices onto the tablet testing device can be done by screws, for instance. The mounting of said measuring devices onto the tablet testing device can be done by pin connectors, for instance.
It is further an aspect of the invention to provide a method for calibrating a tablet testing device by means of which a tablet testing device is calibrated with the presently described device. By means of the instant method the device described above for calibrating is connected with a tablet testing device, the velocity and breaking force of a breaking jaw is calibrated, and the device for calibrating is removed again.
In particular a method is provided for calibrating the velocity and breaking force of a breaking jaw of a tablet testing device, wherein
in a tablet testing device, a tablet intended to be measured is inserted into a testing chamber, between a breaking jaw and an opposing jaw of the tablet testing device,
the breaking jaw is moved towards the opposing jaw of the tablet testing device at a given velocity, and wherein the method is characterized in that
the tablet testing device is connected to a device for calibration as is described above, which testing device comprises at least one measuring device for measuring the velocity or breaking force of a breaking jaw, a computer unit, a communication interface, and means of connection between the one or several measuring devices, the computer unit and the communication interface,
wherein during measurement, the distance of travel per time unit or the breaking force is measured, thereby measuring the velocity or breaking force of the breaking jaw and calibrating it versus the values stored, and
wherein the tablet testing device is disconnected from the calibration device after the calibration run again.
Breaking force in the present context means the force required to bread a tablet. In a preferred embodiment of the method of the invention, both the breaking force as well as the velocity of the breaking jaw is measured and calibrated versus the values stored.
In a further embodiment of the present invention the calibration is conducted versus benchmarked calibration values pre-stored in the computer unit. To this end the computer unit was programmed with suitable reference values for calibration. In the context of the present invention to perform the calibration based on data which are comprised in the computer unit of the tablet testing device. In that case, the above described device serves to mount but the measuring devices onto the tablet testing device which measuring devices are then connected via the junction box and the connection means further via the communication interface to the tablet testing device. Further it is possible in the context of the present invention that the benchmarked calibration values, versus which calibration is conducted, are stored on an external computer. Said external computer may be a pc, for instance. Accordingly the device of the instant invention may be connected to the PC and the tablet testing device in any possible way, for conducting calibration. For example, the device for calibration may be connected via USB plug-in parts as communication interfaces with a PC which has stored the benchmarked calibration values, and with the computer of a tablet testing device that is usually used for conducting measurements, for the purpose of calibration whilst the measuring devices of the calibration device are mounted on the tablet testing device.
In one embodiment of the method the velocity of the breaking jaw is adjusted at a value of from 0.1 mm/second to 3.0 mm/second by calibrating. This value has proven very beneficial when measuring tablets.
When calibrating the tablet testing device of the tablet testing device of the instant invention, in an embodiment of the method a measurement for linearity deviation is conducted during the calibration run. Such measurement is often conducted during calibration of a tablet testing device and exemplarily described in the document ‘The United States Pharmacopeial Convention’, edition USP 40 of Dec. 1, 2017, Chap. 1217 ‘General Information’, pages 1750 to 1752, worldwide web:
http://app.uspnf.com/uspnf/pub/index?usp=40&nf=35&s=2&officialOn=December%201,%202017
The measurement for linearity deviation is carried out in that along the distance of travel of the breaking jaw a measurement of up to three spots in a line is made.
The device for calibrating tablet testing devices is mounted or screwed on the tablet testing device during calibration. To this end, the device for calibrating tablet testing devices comprises screw or pin connections.
Further in typical and preferred embodiment, a calibration of the tablet testing device is done by means the device described above. Alternatively, it is still feasible within the context of the present invention, to have stored or recorded only the data thus obtained. Said data may be evaluated and presented graphically later, e.g. on a monitor.
It is further claimed a method for measuring tablets, which makes use of one of the above described devices. It is claimed in particular a method for measuring tablets which is characterized in that one of the above described devices is employed. By means of a tablet testing devices thus calibrated, the breaking hardness of tablets is determined in particular.
Within the context of the method of the present invention and as a further advantage, it is possible to determine the dimensions of the tablet after calibration of the velocity and breaking force of the breaking jaw. This because for determining for determining the dimensions of the tablet, the breaking jaw must be moved at a pre-set speed and with a pre-set breaking force onto the tablet. As regards the dimensions of a tablet, that may be e.g. length, width or the radius of a tablet.
For determining the dimensions, the breaking jaw is moved onto the tablet at a pre-set and precisely calibrated velocity. Shortly before making contact with the tablet, the speed of movement of the breaking jaw is reduced. The breaking jaw is moved at a lowered speed onto the tablet until reaching a predetermined and calibrated breaking force and jamming the tablet without breaking it. Thereby the dimensions of the tablet are determined. After determining the dimensions of the tablet, the breaking force is subsequently carefully increased, until the tablet is breaking. Concomitantly, the breaking force is measured. For such measurement, regular and precise calibration of the velocity and breaking forces of a breaking jaw of a tablet testing device is essential. The calibration of velocity and breaking force of a tablet testing device are well manageable by the method of the instant invention.
The invention has the advantage of devising a simple and reliable device that can be transported and by means of which a calibration of the velocity or breaking force of the breaking jaw in a tablet testing device is possible in no time. This way a calibration can be conducted in a time saving and simple manner, avoiding sources of error.
The invention is illustrated by four drawings wherein it is understood that the drawings are representing embodiments but are not limiting to the invention.
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For calibration a device (1) is mounted in direction of the arrow onto the tablet testing device. The device (1) is then connected via a communication interface (7), an USB plug-in part for instance, with the computer (15) of the tablet testing device (8) and the PC of the external computer (16). By means of that, calibration versus the stored benchmarked calibration values may be performed. After calibration, the device (1) for calibration is disconnected again from the tablet testing device (8), the computer of the tablet testing device (15) and the PC as an external computer (16).
| Number | Date | Country | Kind |
|---|---|---|---|
| 18155871 | Feb 2018 | EP | regional |
